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This study investigated the sensitivity and specificity of identifying heart failure with reduced ejection fraction (HFrEF) from measurements of the intensity and timing of arterial pulse waves. Previously validated methods combining ultrafast B-mode ultrasound, plane-wave transmission, singular value decomposition (SVD), and speckle tracking were used to characterize the compression and decompression ("S" and "D") waves occurring in early and late systole, respectively, in the carotid arteries of outpatients with left ventricular ejection fraction (LVEF) < 40%, determined by echocardiography, and signs and symptoms of heart failure, or with LVEF ≥ 50% and no signs or symptoms of heart failure. On average, the HFrEF group had significantly reduced S-wave intensity and energy, a greater interval between the R wave of the ECG and the S wave, a reduced interval between the S and D waves, and an increase in the S-wave shift (SWS), a novel metric that characterizes the shift in timing of the S wave away from the R wave of the ECG and toward the D wave (all P < 0.01). Receiver operating characteristics (ROCs) were used to quantify for the first time how well wave metrics classified individual participants. S-wave intensity and energy gave areas under the ROC of 0.76–0.83, the ECG-S-wave interval gave 0.85–0.88, and the S-wave shift gave 0.88–0.92. Hence the methods, which are simple to use and do not require complex interpretation, provide sensitive and specific identification of HFrEF. If similar results were obtained in primary care, they could form the basis of techniques for heart failure screening. NEW & NOTEWORTHY: We show that heart failure with reduced ejection fraction can be detected with excellent sensitivity and specificity in individual patients by using B-mode ultrasound to detect altered pulse wave intensity and timing in the carotid artery. [ABSTRACT FROM AUTHOR]

Systolic time interval (STI) estimation is an established noninvasive method for the quantifiable assessment of left ventricular (LV) performance in well-being and disease states; it stays valuable for clinical application and forms no burden to the subjects. This manuscript reviews the potential clinical applications and prognostic value of STI for the assessment of LV systolic function in cardiovascular disease (CVD). STIs could be obtained by several noninvasive imaging modalities such as transthoracic echocardiography, tissue Doppler imaging M-mode echocardiography, conventional echocardiography, and so on. In view of that, a literature review for studies reporting the clinical applications of STI in assessing LV systolic function among CVD patients was carried out using PubMed search. Accordingly, the current review describes how STI can be measured; reliability of cardiac time interval measurement in patients with CVD and its role in a clinical setting. With the advent of modern techniques, STI could be easily measured in a clinical setting. Likewise, STI parameter, particularly preejection period and LV ejection time ratio (PEP/LVET), has got the highest degree of correlation with LV ejection fraction (LVEF) in assessing LV performance. Furthermore, reproducibility of systolic ejection time (SET) achieved by the TDI M-mode method is outstanding and better when compared with the reproducibility of SET obtained by the conventional pulsed Doppler method. Furthermore, prolonged SET is independently related with enhanced outcomes among heart failure with reduced EF (HFrEF, i.e., EF ≤40%) but not HF with preserved EF (HFpEF, i.e., EF >40%) patients, indicating that stabilizing SET would be helpful in the case of systolic dysfunction. Clinically, tissue Doppler-derived time intervals could be beneficial to analyze abnormal cases in comparison with other invasive and noninvasive methods of ventricular function examination. Furthermore, phonoelectrocardiography-derived STI parameters, particularly electromechanical activation time-to-LVET ratio, may have a significant role in the diagnostic approach of heart failure (HF) in patients with undifferentiated dyspnea. In addition, in HF patients, PEP/LVET of >0.43 helps to detect LVEF

Introduction: Left ventricular (LV) systolic function evaluation is based on ejection fraction assessment. Due to the great sensitivity of the examination and the ease of measurement, systolic time intervals (STIs) are ideally appropriate for studying the effects of pharmacologic agents upon the heart. In this context, the present study aimed to estimate and compare STI in patients with ischemic heart disease (IHD) with clinical heart failure and among control subjects without clinically established LV dysfunction based on their LV ejection fraction (LVEF). Materials and Methods: This case–control study included 33 IHD patients as cases and 32 healthy subjects as controls. All subjects underwent pulsed-Doppler echocardiogram to estimate STIs: total electromechanical systole (QS2), preejection period (PEP), and LV ejection time (LVET). Results: A significant difference between PEP (145.23 ± 23.20 vs. 82.99 ± 8.63, P < 0.00001), LVET (231.34 ± 40.89 vs. 265.39 ± 31.98, P = 0.000947), and PEP/LVET ratio (0.63 ± 0.15 vs. 0.31 ± 0.08, P < 0.00001) between cases and controls was found. On subgroup analysis, a weak correlation was found in patients with LVEF ≤40% and PEP/LVET (r = −0.3677, P = 0.1958). In addition, a relatively strong correlation between LVET and heart rate (r = −0.432, P = 0.012) was found among the cases. Conclusion: The current study results showed that the differences in the values of STI among cases than in controls could be an indicator of LV systolic dysfunction. In addition, this method may have impending applications in the management of IHD.

The cardiac function is influenced by respiration. In particular, various parameters such as cardiac time intervals and the stroke volume are modulated by respiratory activity. It has long been recognized that cardio-respiratory interactions modify the morphology of cardio-mechanical signals, e.g., phonocardiogram, seismocardiogram (SCG), and ballistocardiogram. Forcecardiography (FCG) records the weak forces induced on the chest wall by the mechanical activity of the heart and lungs and relies on specific force sensors that are capable of monitoring respiration, infrasonic cardiac vibrations, and heart sounds, all simultaneously from a single site on the chest. This study addressed the changes in FCG heartbeat morphology caused by respiration. Two respiratory-modulated parameters were considered, namely the left ventricular ejection time (LVET) and a morphological similarity index (MSi) between heartbeats. The time trends of these parameters were extracted from FCG signals and further analyzed to evaluate their consistency within the respiratory cycle in order to assess their relationship with the breathing activity. The respiratory acts were localized in the time trends of the LVET and MSi and compared with a reference respiratory signal by computing the sensitivity and positive predictive value (PPV). In addition, the agreement between the inter-breath intervals estimated from the LVET and MSi and those estimated from the reference respiratory signal was assessed via linear regression and Bland–Altman analyses. The results of this study clearly showed a tight relationship between the respiratory activity and the considered respiratory-modulated parameters. Both the LVET and MSi exhibited cyclic time trends that remarkably matched the reference respiratory signal. In addition, they achieved a very high sensitivity and PPV (LVET: 94.7% and 95.7%, respectively; MSi: 99.3% and 95.3%, respectively). The linear regression analysis reported almost unit slopes for both the LVET (R2 = 0.86) and MSi (R2 = 0.97); the Bland–Altman analysis reported a non-significant bias for both the LVET and MSi as well as limits of agreement of ±1.68 s and ±0.771 s, respectively. In summary, the results obtained were substantially in line with previous findings on SCG signals, adding to the evidence that FCG and SCG signals share a similar information content. [ABSTRACT FROM AUTHOR]

Objectives: Hyperthyroidism is a common endocrinopathy affecting middle-aged to elderly cats, with multisystemic repercussions. Hyperthyroid humans show decreased lung compliance and increased cardiac output with subsequent left heart failure leading to pulmonary capillary congestion. Prognosis worsens with the development of increased pulmonary vascular pressures (ie, pulmonary hypertension [PH]) in hyperthyroid humans. The effect of excess thyroid hormone concentration on pulmonary arterial hemodynamics is unknown in cats. Assessing pulmonary vascular pressures in veterinary medicine relies heavily on echocardiographic measurements performed at the level of the heart and pulmonary trunk. This study investigated right-sided cardiac and pulmonary arterial hemodynamics in hyperthyroid cats using echocardiography. Methods: Echocardiographic examinations of hyperthyroid cats identified through a bi-institutional database search were reviewed for the determination of systolic pulmonary arterial pressure (PAP) and 20 other metrics. Values were compared with those of a healthy cat group using non-parametric statistical analyses. Results: Systolic PAP could not be determined in 23/26 hyperthyroid and 13/14 healthy cats owing to unmeasurable tricuspid regurgitation flow velocity. Hyperthyroid cats were roughly twice as old (P <0.001) and had 2–4-fold higher respiratory rates (P <0.001) than healthy cats. Hyperthyroid cats showed an increase in acceleration time-to-ejection time ratio of pulmonary flow (1.4-fold, P = 0.001), pulmonary artery velocity time integral (1.2–1.6-fold, P = 0.001), maximal pulmonary velocity (1.3–1.7-fold, P = 0.002), stroke volume (1.5-fold, P = 0.001) and cardiac output (1.6-fold, P <0.001) vs healthy cats. None of the other echocardiographic metrics reached statistical significance. Conclusions and relevance: Systolic PAP estimation proved unsuitable as a sole measurement for the assessment of PH in hyperthyroid cats owing to the frequent inability to interrogate tricuspid regurgitant flow velocity. Hyperthyroid cats have altered echocardiographic measures of pulmonary hemodynamics dissimilar to those reported in hyperthyroid humans. Differential effects of thyrotoxic cardiomyopathy on ventricular systolic function may underlie species differences. [ABSTRACT FROM AUTHOR]

Introduction: Left ventricular (LV) systolic function evaluation is based on ejection fraction assessment. Due to the great sensitivity of the examination and the ease of measurement, systolic time intervals (STIs) are ideally appropriate for studying the effects of pharmacologic agents upon the heart. In this context, the present study aimed to estimate and compare STI in patients with ischemic heart disease (IHD) with clinical heart failure and among control subjects without clinically established LV dysfunction based on their LV ejection fraction (LVEF). Materials and Methods: This case-control study included 33 IHD patients as cases and 32 healthy subjects as controls. All subjects underwent pulsed-Doppler echocardiogram to estimate STIs: total electromechanical systole (QS2), preejection period (PEP), and LV ejection time (LVET). Results: A significant difference between PEP (145.23 ± 23.20 vs. 82.99 ± 8.63, P < 0.00001), LVET (231.34 ± 40.89 vs. 265.39 ± 31.98, P = 0.000947), and PEP/LVET ratio (0.63 ± 0.15 vs. 0.31 ± 0.08, P < 0.00001) between cases and controls was found. On subgroup analysis, a weak correlation was found in patients with LVEF =40% and PEP/LVET (r = -0.3677, P = 0.1958). In addition, a relatively strong correlation between LVET and heart rate (r = -0.432, P = 0.012) was found among the cases. Conclusion: The current study results showed that the differences in the values of STI among cases than in controls could be an indicator of LV systolic dysfunction. In addition, this method may have impending applications in the management of IHD. [ABSTRACT FROM AUTHOR]

This study determined the beverage hydration index (BHI) and postprandial cardiac autonomic activity after consuming an isotonic beverage (IB) compared to distilled water (DW). Twenty-two participants (50% female; mean ± SD; age, 27 ± 3 year; height, 169.1 ± 12.6 cm; weight, 73.3 ± 13.8 kg; BF%, 23 ± 10%) completed two experimental trials where they consumed 1 L DW or an IB; after which urine volume and cardiac autonomic activity was measured through 240 min. Cardiac autonomic activity was quantified using heart rate (HR), log transformed heart rate variability measures (root mean square of successive R–R intervals; RMSSD; low frequency, LF; and high frequency, HF) and systolic time intervals (pre-ejection period, PEP). BHI was significantly greater after IB consumption at min 0 (MD [95% CI]; 1.31 [0.35, 2.27]), 180 min (0.09 [0.022, 0.16]), and 240 min (0.1 [0.03, 0.17]) compared to DW (p = 0.031). Net fluid balance was significantly greater in IB than DW at 180 min (90 [−16.80, 196.81]) and 240 min (106 [−13.88, 225.88]) (p = 0.037). HR decreased over time in both beverage trials but was higher following IB ingestion at 0 min (3.9 [−2.42, 10.22]), 30 min (5.3 [−0.94, 11.54]), and 60 min (2.7 [−3.42, 8.82]) (p = 0.0002). lnHF was greater 30 min post DW ingestion compared to IB (0.45 [−0.23, 1.13]) (p = 0.039). IB promotes greater fluid retention capacity compared to DW within 4 hours of consumption. The variations in cardiac autonomic measures may warrant further investigation in clinical populations (i.e., patients with autonomic failure). [ABSTRACT FROM AUTHOR]

Forcecardiography (FCG) is a novel technique that measures the local forces induced on the chest wall by the mechanical activity of the heart. Specific piezoresistive or piezoelectric force sensors are placed on subjects' thorax to measure these very small forces. The FCG signal can be divided into three components: low-frequency FCG, high-frequency FCG (HF-FCG) and heart sound FCG. HF-FCG has been shown to share a high similarity with the Seismocardiogram (SCG), which is commonly acquired via small accelerometers and is mainly used to locate specific fiducial markers corresponding to essential events of the cardiac cycle (e.g., heart valves opening and closure, peaks of blood flow). However, HF-FCG has not yet been demonstrated to provide the timings of these markers with reasonable accuracy. This study addresses the detection of the aortic valve opening (AO) marker in FCG signals. To this aim, simultaneous recordings from FCG and SCG sensors were acquired, together with Electrocardiogram (ECG) recordings, from a few healthy subjects at rest, both during quiet breathing and apnea. The AO markers were located in both SCG and FCG signals to obtain pre-ejection periods (PEP) estimates, which were compared via statistical analyses. The PEPs estimated from FCG and SCG showed a strong linear relationship (r > 0.95) with a practically unit slope, and 95% of their differences were found to be distributed within ± 4.6 ms around small biases of approximately 1 ms, corresponding to percentage differences lower than 5% of the mean measured PEP. These preliminary results suggest that FCG can provide accurate AO timings and PEP estimates. [ABSTRACT FROM AUTHOR]

New Findings: What is the central question of this study?First, we validated easy‐to‐use oscillometric left ventricular ejection time (LVET) against echocardiographic LVET. Second, we investigated progression of left ventricular ejection time index (LVETI), pre‐ejection period index (PEPI), total electromechanical systole index (QS2I) and PEP/LVET ratio during 60 days of head‐down tilt (HDT).What is the main finding and its importance?The LVETosci and LVETecho showed good agreement in effect direction. Hence, LVETosci might be useful to evaluate cardiovascular responses during space flight. Moreover, the approach might be useful for individual follow‐up of patients with altered ejection times. Furthermore, significant effects of 60 days of HDT were captured by measurements of LVETI, PEPI, QS2I and PEP/LVET ratio. Systolic time intervals that are easy to detect might be used as parameters reflecting cardiovascular deconditioning. We compared left ventricular ejection time (LVET) measured via ultrasound Doppler on the left ventricular outflow tract with oscillometrically measured LVET, measured at the brachialis. Furthermore, we assessed the progression of the left ventricular ejection time index (LVETI), the pre‐ejection period index (PEPI), the Weissler index (PEP/LVET) and the total electromechanical systole index (QS2I) during prolonged strict head‐down tilt (HDT) bed rest, including 16 male and eight female subjects. Simultaneous oscillometric and echocardiographic LVET measurements showed significant correlation (r = 0.53 with P = 0.0084 before bed rest and r = 0.73 with P < 0.05 on the last day of bed rest). The shortening of LVET during HDT bed rest measured with both approaches was highly concordant in their effect direction, with a concordance rate of 0.96. Our results also demonstrated a significant decrease of LVETI (P < 0.0001) and QS2I (P = 0.0992) and a prolongation of PEPI (P = 0.0049) and PEP/LVET (P = 0.0003) during HDT bed rest over 60 days. Four days after bed rest, LVETI recovered completely to its baseline value. Owing to the relationship between shortening of LVETI and heart failure progression, the easy‐to‐use oscillometric method might not only be a useful way to evaluate the cardiovascular system during space flights, but could also be of high value in a clinical setting. [ABSTRACT FROM AUTHOR]

Systolic time interval (STI) estimation is an established noninvasive method for the quantifiable assessment of left ventricular (LV) performance in well-being and disease states; it stays valuable for clinical application and forms no burden to the subjects. This manuscript reviews the potential clinical applications and prognostic value of STI for the assessment of LV systolic function in cardiovascular disease (CVD). STIs could be obtained by several noninvasive imaging modalities such as transthoracic echocardiography, tissue Doppler imaging M-mode echocardiography, conventional echocardiography, and so on. In view of that, a literature review for studies reporting the clinical applications of STI in assessing LV systolic function among CVD patients was carried out using PubMed search. Accordingly, the current review describes how STI can be measured; reliability of cardiac time interval measurement in patients with CVD and its role in a clinical setting. With the advent of modern techniques, STI could be easily measured in a clinical setting. Likewise, STI parameter, particularly preejection period and LV ejection time ratio (PEP/LVET), has got the highest degree of correlation with LV ejection fraction (LVEF) in assessing LV performance. Furthermore, reproducibility of systolic ejection time (SET) achieved by the TDI M-mode method is outstanding and better when compared with the reproducibility of SET obtained by the conventional pulsed Doppler method. Furthermore, prolonged SET is independently related with enhanced outcomes among heart failure with reduced EF (HFrEF, i.e., EF =40%) but not HF with preserved EF (HFpEF, i.e., EF >40%) patients, indicating that stabilizing SET would be helpful in the case of systolic dysfunction. Clinically, tissue Doppler-derived time intervals could be beneficial to analyze abnormal cases in comparison with other invasive and noninvasive methods of ventricular function examination. Furthermore, phonoelectrocardiography-derived STI parameters, particularly electromechanical activation time-to-LVET ratio, may have a significant role in the diagnostic approach of heart failure (HF) in patients with undifferentiated dyspnea. In addition, in HF patients, PEP/LVET of >0.43 helps to detect LVEF <35% by pulsed Doppler echocardiography. Moreover, LVET continues to be an independent predictor of incident HF and provides incremental prognostic value on the future HF risk and death but not myocardial infarction. In conclusion, STI measurement could be useful, particularly in identifying LVEF <35% in the case of refractory HF patients. This could be beneficial in the selection of patients requiring cardiac resynchronization, specifically when accurate LVEF evaluation by echocardiography proves challenging in atrial fibrillation or if the evaluation is done by a trainee echocardiographer. Furthermore, the cardiac time intervals including SET can be acquired irrespective of rhythm. Good image quality is required for the assessment of LVEF. In contrast, evaluation of SET could be useful in the case of echocardiograms with poor quality images. As a final point, the present review suggests using an echocardiographic parameter like STIs to procure additional information regarding the risk of mortality in patients with HFrEF along with LVEF measurement. [ABSTRACT FROM AUTHOR]

The cardiac function is influenced by respiration. In particular, various parameters such as cardiac time intervals and the stroke volume are modulated by respiratory activity. It has long been recognized that cardio-respiratory interactions modify the morphology of cardio-mechanical signals, e.g., phonocardiogram, seismocardiogram (SCG), and ballistocardiogram. Forcecardiography (FCG) records the weak forces induced on the chest wall by the mechanical activity of the heart and lungs and relies on specific force sensors that are capable of monitoring respiration, infrasonic cardiac vibrations, and heart sounds, all simultaneously from a single site on the chest. This study addressed the changes in FCG heartbeat morphology caused by respiration. Two respiratory-modulated parameters were considered, namely the left ventricular ejection time (LVET) and a morphological similarity index (MSi) between heartbeats. The time trends of these parameters were extracted from FCG signals and further analyzed to evaluate their consistency within the respiratory cycle in order to assess their relationship with the breathing activity. The respiratory acts were localized in the time trends of the LVET and MSi and compared with a reference respiratory signal by computing the sensitivity and positive predictive value (PPV). In addition, the agreement between the inter-breath intervals estimated from the LVET and MSi and those estimated from the reference respiratory signal was assessed via linear regression and Bland–Altman analyses. The results of this study clearly showed a tight relationship between the respiratory activity and the considered respiratory-modulated parameters. Both the LVET and MSi exhibited cyclic time trends that remarkably matched the reference respiratory signal. In addition, they achieved a very high sensitivity and PPV (LVET: 94.7% and 95.7%, respectively; MSi: 99.3% and 95.3%, respectively). The linear regression analysis reported almost unit slopes for both the LVET (R2 = 0.86) and MSi (R2 = 0.97); the Bland–Altman analysis reported a non-significant bias for both the LVET and MSi as well as limits of agreement of ±1.68 s and ±0.771 s, respectively. In summary, the results obtained were substantially in line with previous findings on SCG signals, adding to the evidence that FCG and SCG signals share a similar information content.

Aim To assess the value of systolic time intervals [as simple echocardiographic parameters of left ventricle (LV) systolic performance] and its relation to intraventricular dyssynchrony (by speckle tracking) of the LV in patients with dilated cardiomyopathy. Patients and methods All the studied individuals were subjected to ECG and transthoracic echocardiography to measure LV dimensions and systolic function by conventional and speckle-tracking echo. Left ventricular pre-ejection time (LVPET), left ventricular ejection time (LVET), and the ratio of LVPET to LVET were also measured (LVPET/LVET). Twodimensional strain to measure time to peak negative strain value of the LV segments was averaged to calculate TPS-SD. Results The enrolled population were 153 cases, divided into 123 patients and 30 normal individuals. There was a significant lower LV global longitudinal strain % in the patient group. Moreover, insignificant shorter LVET was seen in the patients. LVET had an inversely significant correlation with QRS duration and dyssynchrony index. The LVPET and PET/ LVET ratio had a significant linear correlation with QRS duration and dyssynchrony index measured by twodimensional strain (r=0.4, P<0.01). Conclusion Systolic time interval can be easily and accurately measured in patients with DCM and may be considered as an indicator for presence of LV intraventricular dyssynchrony. [ABSTRACT FROM AUTHOR]

Forcecardiography (FCG) is a novel technique that measures the local forces induced on the chest wall by the mechanical activity of the heart. Specific piezoresistive or piezoelectric force sensors are placed on subjects’ thorax to measure these very small forces. The FCG signal can be divided into three components: low-frequency FCG, high-frequency FCG (HF-FCG) and heart sound FCG. HF-FCG has been shown to share a high similarity with the Seismocardiogram (SCG), which is commonly acquired via small accelerometers and is mainly used to locate specific fiducial markers corresponding to essential events of the cardiac cycle (e.g., heart valves opening and closure, peaks of blood flow). However, HF-FCG has not yet been demonstrated to provide the timings of these markers with reasonable accuracy. This study addresses the detection of the aortic valve opening (AO) marker in FCG signals. To this aim, simultaneous recordings from FCG and SCG sensors were acquired, together with Electrocardiogram (ECG) recordings, from a few healthy subjects at rest, both during quiet breathing and apnea. The AO markers were located in both SCG and FCG signals to obtain pre-ejection periods (PEP) estimates, which were compared via statistical analyses. The PEPs estimated from FCG and SCG showed a strong linear relationship (r > 0.95) with a practically unit slope, and 95% of their differences were found to be distributed within ± 4.6 ms around small biases of approximately 1 ms, corresponding to percentage differences lower than 5% of the mean measured PEP. These preliminary results suggest that FCG can provide accurate AO timings and PEP estimates.

Background: Impedance cardiography (ICG) is a noninvasive hemodynamic monitoring tool which can define hypertensive patients’ hemodynamic profiles and help to tailor antihypertensive therapy. This study assesses the concordance between ICG-derived indexes used to evaluate left ventricular performance and transthoracic echocardiography (TTE) in hypertensive patients. Methods: In this IMPEDDANS post-hoc analysis, the ICG-derived indexes are compared with TTE by Bland–Altman method. Statistical significance of the relationship between the values obtained was assessed by generalized linear mixed-effects models. Results: In supine position, Bland–Altman analysis showed good concordance for cardiac output (CO) (mean difference of 0.006 mL/min [−0.120; 0.133]), cardiac index (CI) (mean difference of 0.016 mL/min/m2 [−0.471; 0.504]), pre-ejection period (PEP) (mean difference of −0.216 ms [−4.510; 4.077]), left ventricular ejection time (LVET) (mean difference of −0.140 ms [−6.573; 6.293]), and systolic time ratio (STR) (mean difference of −0.00004 [−0.008; 0.008]). In orthostatic position, good concordance was found for CO (mean difference 0.028 mL/min [−2.036; 1.980]), CI (mean difference −0.012 mL/min/m2 [−1.063; 1.039]), and STR (mean difference −0.101 [0.296; 0.094]). No significant difference between methods was identified by the linear mixed-effects models. Conclusion: The ICG-derived indexes CO, CI, PEP, LVET, and STR in supine position have good agreement with TTE. Therefore, ICG can be used to accurately evaluate left ventricular performance.

Background: The electromechanical activation time (EMAT) normalized by cardiac cycle length (%EMAT) and the third heart sound (S3) strength, as measured by automated acoustic cardiography, are predictive of postdischarge adverse events in patients with acute heart failure (AHF). The aim of this study was to evaluate whether the acoustic cardiography-guided management improves outcomes in patients with AHF when it is compared with the conventional therapy.Methods and Results: This prospective single-blind study randomized 225 patients with AHF (74.1 ± 14.5 years of age, 26.2% women, and left ventricular ejection fraction 38.4 ± 14.4%) before discharge to the EMAT-guided group (n = 114) with the postdischarge treatment goals to reduce %EMAT to < 15% and S3 < 5, and the symptom-guided group (n = 111) to adjust medications without knowledge of the results of acoustic cardiography. The primary endpoints were rehospitalization for heart failure and total mortality during 1-year follow-up. The 2 groups were well matched in age and predischarge %EMAT and S3 strength. After a mean follow-up period of 238.1 ± 140.8 days, a significant reduction in the primary endpoints was seen in the EMAT-guided group compared with the symptom-guided group (43 events vs 61 events, P = 0.0095). Kaplan-Meier curves demonstrated significant differences in the time to first event, favoring the EMAT-guided group in the total study population (n = 225, hazard ratio and 95% confidence interval: 0.61, 0.42-0.91, log-rank P = 0.0129), as well as in the prespecified subgroup of patients with predischarge %EMAT > 15% (n = 85; 0.32, 0.16-0.65, P = 0.0008).Conclusions: In patients hospitalized due to AHF, EMAT-guided postdischarge management was superior to the conventional symptoms-driven therapy in terms of 1-year outcomes (ClinicalTrials.gov number NCT01298232). [ABSTRACT FROM AUTHOR]

Hamdi Boubaker,1,2 Mohamed Habib Grissa,1,2 Kaouther Beltaief,1,2 Zohra Dridi,3 Mohamed Fadhel Najjar,4 Wahid Bouida,1,2 Riadh Boukef,5 Soudani Marghli,6 Semir Nouira1,2 1Department of Emergency, Fattouma Bourguiba University Hospital, 2Research Laboratory (LR12SP18), University of Monastir, 3Department of Cardiology, 4Department of Biochemistry, Fattouma Bourguiba University Hospital, Monastir, 5Department of Emergency, Sahloul University Hospital, Sousse, 6Department of Emergency, Tahar Sfar University Hospital, Mahdia, Tunisia Background: The goal of this study was to determine the value of systolic time intervals and their change during Valsalva maneuver (VM) in the diagnosis of left ventricular dysfunction (LVD) in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD).Methods: We included 166 patients admitted to the emergency department for AECOPD. Measurement of systolic time intervals included electromechanical activation time (EMAT), left ventricular ejection time (LVET), and EMAT/LVET ratio. These were performed at baseline and during the first strain phase of the VM using a computerized phonoelectrocardiographic method. The diagnosis of LVD was determined on the basis of clinical examination, echocardiography, and brain natriuretic peptide. The values of systolic time intervals were compared between patients with and without LVD; their diagnostic performance was assessed using the area under receiver operating characteristic (ROC) curve.Results: Patients with LVD (n=95) had a significantly higher EMAT and lower LVET and EMAT/LVET ratio compared to patients without LVD (n=71); the area under ROC curve was 0.79, 0.88, and 0.90, respectively, for EMAT, LVET, and EMAT/LVET ratio. All baseline systolic time intervals changed significantly during VM in patients without LVD but they did not change in patients with LVD. The area under ROC curve increased to 0.84 and 0.93, ­respectively, for EMAT and EMAT/LVET ratio but did not change for LVET.Conclusion: Simple and noninvasive measurements of systolic time intervals combined with VM could be helpful to detect or rule out LVD in patients admitted to the emergency room for COPD excacerbation. The EMAT/LVET ratio seems to have the best diagnostic value. Keywords: chronic obstructive pulmonary disease, exacerbation, systolic time intervals, Valsalva maneuver

Objectives: This study investigated indirect measures of post-exercise parasympathetic reactivation (using heart-rate-variability, HRV) and sympathetic withdrawal (using systolic-time-intervals, STI) following upper- and lower-body exercise.Design: Randomized, counter-balanced, crossover.Methods: 13 males (age 26.4±4.7years) performed maximal arm-cranking (MAX-ARM) and leg-cycling (MAX-LEG). Subsequently, participants undertook separate 8-min bouts of submaximal HR-matched exercise of each mode (ARM and LEG). HRV (including natural-logarithm of root-mean-square-of-successive-differences, Ln-RMSSD) and STI (including pre-ejection-period, PEP) were assessed throughout 10-min seated recovery.Results: Peak-HR was higher (p=0.001) during MAX-LEG (182±7beatsmin-1) compared with MAX-ARM (171±12beatsmin-1), while HR (p<0.001) and Ln-RMSSD (p=0.010) recovered more rapidly following MAX-ARM. PEP recovery was similar between maximal bouts (p=0.106). HR during submaximal exercise was 146±7 (LEG) and 144±8beatsmin-1 (LEG) (p=0.139). Recovery of HR and Ln-RMSSD was also similar between submaximal modalities, remaining below baseline throughout recovery (p<0.001). PEP was similar during submaximal exercise (LEG 70±6ms; ARM 72±9ms; p=0.471) although recovery was slower following ARM (p=0.021), with differences apparent from 1- to 10-min recovery (p≤0.036). By 10-min post-exercise, PEP recovered to baseline (132±21ms) following LEG (130±21ms; p=0.143), but not ARM (121±17ms; p=0.001).Conclusions: Compared with submaximal lower-body exercise, HR-matched upper-body exercise elicited a similar recovery of HR and HRV indices of parasympathetic reactivation, but delayed recovery of PEP (reflecting sympathetic withdrawal). Exercise modality appears to influence post-exercise parasympathetic reactivation and sympathetic withdrawal in an intensity-dependent manner. These results highlight the need for test standardization and may be relevant to multi-discipline athletes and in clinical applications with varying modes of exercise testing. [ABSTRACT FROM AUTHOR]

Background: Impedance cardiography (ICG) is a noninvasive hemodynamic monitoring tool which can define hypertensive patients’ hemodynamic profiles and help to tailor antihypertensive therapy. This study assesses the concordance between ICG-derived indexes used to evaluate left ventricular performance and transthoracic echocardiography (TTE) in hypertensive patients. Methods: In this IMPEDDANS post-hoc analysis, the ICG-derived indexes are compared with TTE by Bland-Altman method. Statistical significance of the relationship between the values obtained was assessed by generalized linear mixed-effects models. Results: In supine position, Bland-Altman analysis showed good concordance for cardiac output (CO) (mean difference of 0.006 mL/min [−0.120; 0.133]), cardiac index (CI) (mean difference of 0.016 mL/min/m2 [−0.471; 0.504]), pre-ejection period (PEP) (mean difference of −0.216 ms [−4.510; 4.077]), left ventricular ejection time (LVET) (mean difference of −0.140 ms [−6.573; 6.293]), and systolic time ratio (STR) (mean difference of −0.00004 [−0.008; 0.008]). In orthostatic position, good concordance was found for CO (mean difference 0.028 mL/min [−2.036; 1.980]), CI (mean difference −0.012 mL/min/m2 [−1.063; 1.039]), and STR (mean difference −0.101 [0.296; 0.094]). No significant difference between methods was identified by the linear mixed-effects models. Conclusion: The ICG-derived indexes CO, CI, PEP, LVET, and STR in supine position have good agreement with TTE. Therefore, ICG can be used to accurately evaluate left ventricular performance. [ABSTRACT FROM AUTHOR]

The estimation of systolic time intervals (STIs) is done using continuous wave (CW) radar at 2.45 GHz with an on-body antenna. Motivation: In the state of the art, typically bioimpedance, heart sounds and/or ultrasound are used to measure STIs. All three methods suffer from insufficient accuracy of STI estimation due to various reasons. CW radar is investigated for its ability to overcome the deficiencies in the state of the art. Methods: Ten healthy male subjects aged 25–45 were asked to lie down at a 30 ^\circ incline. Recordings of 60 s were taken without breathing and with paced breathing. Heart sounds, electrocardiogram, respiration, and impedance cardiogram were measured simultaneously as reference. The radar antennas were placed at two positions on the chest. The antennas were placed directly on the body as well as with cotton textile in between. The beat to beat STIs have been determined from the reference signals as well as CW radar signals. Results: The results indicate that CW radar can be used to estimate STIs in ambulatory monitoring. Significance: The results pave way to a potentially more compact method of estimating STIs, which can be integrated into a wearable device. [ABSTRACT FROM PUBLISHER]

Purpose: This study investigated non-invasive indices of post-exercise parasympathetic reactivation (using heart rate variability, HRV) and sympathetic withdrawal (using systolic time intervals, STI) following different exercise durations.Methods: 13 healthy males (age 26.4 ± 4.7 years) cycled at 70% heart rate (HR) reserve for two durations-8 min (SHORT) and 32 min (LONG)-on separate occasions: HRV (including natural logarithm of root mean square of successive differences, Ln-RMSSD) and STI (including pre-ejection period, PEP) were assessed throughout 10 min seated recovery.Results: Exercise HR was similar between SHORT and LONG (146 ± 7 and 147 ± 6 b min-1, respectively; p = 0.173), as was HR deceleration during 10 min recovery (p = 0.199). HR remained elevated above baseline (p < 0.001) throughout recovery for both trials (SHORT 82 ± 13 b min-1; LONG 86 ± 10 b min-1, at 10 min post-exercise). Ln-RMSSD was similar at end-exercise between trials (SHORT 1.10 ± 0.30 ms; LONG 1.05 ± 0.73 ms; p = 0.656), though it recovered more rapidly following SHORT (p = 0.010), with differences apparent from 1 min (SHORT 2.29 ± 1.08 ms; LONG 1.85 ± 0.82 ms; p = 0.005) to 10 min post-exercise (SHORT 2.89 ± 0.80 ms; LONG 2.46 ± 0.70 ms; p = 0.007). Ln-RMSSD remained suppressed below baseline throughout recovery following both trials (p < 0.001). PEP was the same at end exercise for both trials (70 ± 6 ms), with exercise duration having no effect on recovery (p = 0.659). By 10 min post-exercise, PEP increased to 130 ± 21 ms (SHORT) and 131 ± 20 ms (LONG), which was similar to baseline (p ≥ 0.143).Conclusions: Prolonged exercise duration attenuated the recovery of HRV indices of parasympathetic reactivation, but did not influence STI indices of sympathetic withdrawal. Therefore, duration must be considered when investigating post-exercise HRV. Monitoring these measures simultaneously can provide insights not revealed by underlying HR or either measure alone. [ABSTRACT FROM AUTHOR]

Systolic time intervals (STIs) provide noninvasive insights into cardiac sympathetic neural activity (cSNA). As the effect of exercise intensity on postexercise STI recovery is unclear, this study investigated the STI recovery profile after different exercise intensities. Eleven healthy males cycled for 8 min at 3 separate intensities: LOW (40%-45%), MOD (75%-80%), and HIGH (90%-95%) of heart-rate (HR) reserve. Bio-impedance cardiography was used to assess STIs - primarily pre-ejection period (PEP; inversely correlated with cSNA), as well as left ventricular ejection time (LVET) and PEP:LVET - during 10 min seated recovery immediately postexercise. Heart-rate variability (HRV), i.e., natural-logarithm of root mean square of successive differences (Ln-RMSSD), was calculated as an index of cardiac parasympathetic neural activity (cPNA). Higher preceding exercise intensity elicited a slower recovery of HR and Ln-RMSSD ( p < 0.001), and these measures did not return to baseline by 10 min following any intensity ( p ≤ 0.009). Recovery of STIs was also slower following higher intensity exercise ( p ≤ 0.002). By 30 s postexercise, higher preceding intensity resulted in a lower PEP (98 ± 14 ms, 75 ± 6 ms, 66 ± 5 ms for LOW, MOD, and HIGH, respectively, p < 0.001). PEP recovered to baseline (143 ± 11 ms) by 5 min following LOW (139 ± 13 ms, p = 0.590) and by 10 min following MOD (145 ± 17 ms, p = 0.602), but was still suppressed at 10 min following HIGH (123 ± 21 ms, p = 0.012). Higher preceding exercise intensity attenuated the recovery of indices for cSNA (from STIs) and cPNA (from HRV) in a graded dose-response fashion. While exercise intensity must be considered, acute recovery may be a valuable period during which to concurrently monitor these noninvasive indices, to identify potentially abnormal cardiac autonomic responses. [ABSTRACT FROM AUTHOR]

Objective- To determine the range of systolic times intervals using Pulsed-wave Doppler and m-mode echocardiography in normal, healthy Great Dane dogs. Design- Descriptive study. Animals- Thirty healthy Great Dane dogs. Procedures- This study examined 30 clinically healthy Great Dane dogs by the two-dimensional, M-mode and Pulsed-wave Doppler echocardiography. The dogs were awake and unsedated. The following parameters were measured on the both Pulsed-wave Doppler and M-mode echocardiographic images: pre-ejection period (PEP), left ventricular ejection time (LVET), ratio of PEP to LVET (PEP/LVET) and the total electrical-mechanical systole (QAVC). Acceleration time of aortic flow (AT) was also measured by Doppler mode. Results- The following values have been acquired: PEP = 0.067 ± 0.010 s; LVET = 0.188 ± 0.011 s; QAVC = 0.254 ± 0.016 s and PEP/LVET = 0.354 ± 0.054 measured by Mmode echocardiography and PEP = 0.062 ± 0.009 s; LVET = 0.193 ± 0.007 s; QAVC = 0.256 ± 0.011s; PEP/LVET = 0.323 ± 0.051 and AT = 0.080 ± 0.107 s measured by Doppler echocardiography. Conclusion and Clinical Relevance- On Doppler mode, there was a significant correlation between the body weight and PEP and PEP/LVET. M-mode echocardiography showed significant correlation between the body weight and body surface area and QAVC. Results of this study revealed the importance of determination of breed-specific echocardiographic parameters and indices, and evaluating of measured values with range using same method for accurate diagnosis.

We speculated that stroke volume would be higher and heart rate would be lower when the head and upper trunk were mainly upright in the Fowler's position. We therefore analyzed the effects of three trunk postures in Fowler's position on heart rate, blood pressure and circulatory volume. Heart rate (HR), blood pressure (BP), stroke volume (SV), cardiac output (Q), systemic vascular resistance (SVR), ejection time (ET) and pre-ejection period (PEP) were measured in 10 healthy male volunteers (mean age ± SEM, 20.7 ± 0.5 y; range, 19–23 y) while in three trunk postures in Fowler's position. Stroke volume and Q were measured using impedance cardiography. The three trunk postures were 30° of lower and upper trunk inclination (WT30°), 30° and 60° of lower and upper trunk inclination (UT 60°), respectively and 60° of upper and lower trunk inclination (WT60°). Both SV and ET were significantly higher and HR and PEP were lower at UT60° than at WT60° (p < 0.01) whereas these values did not significantly differ between WT30° and UT60° (p > 0.05). None of Q, SVR and BP significantly differed among the three conditions (p > 0.05). These findings suggested that SV and preload are higher when the upper trunk is upright (UT60°) than when the entire trunk is upright (WT60°) while in Fowler's position. In addition, Q might be maintained without increasing HR through vagal withdrawal when only the upper trunk is upright in healthy young males in Fowler's position. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effect of age on cardiovascular changes and plasma concentrations of adrenomedullin (ADM), catecholamines, endothelin-1 (ET-1) and plasma renin activity (PRA) in healthy men. A total of 15 young (21 ± 0.3 years) and 15 older (64 ± 0.7 years) healthy men performed two 3-min bouts of static handgrip at 30% of maximal voluntary contraction, alternately with each hand without any break between the bouts. During exercise heart rate (HR), blood pressure (BP), stroke volume (SV) and pre-ejection period (PEP) and left ventricle ejection time (LVET) were measured. Blood samples were taken before exercise, at the end of both exercise bouts and in the fifth minute of the recovery period. The handgrip-induced increases in HR and cardiac output were significantly smaller in older than in young men ( p < 0.01). SV decreased only in older men ( p < 0.001). There were no differences between groups in BP increases. The baseline plasma ADM and catecholamines were higher in older man compared to young subjects. Handgrip caused increases in plasma ADM, ET-1 and PRA only in older men ( p < 0.05). The increases in plasma ADM correlated positively with those of noradrenaline (NA), PRA, ET-1 and LVET and negatively with changes in total peripheral resistance (TPR), SV, PEP and PEP/LVET ratio. The increases in plasma ET-1 correlated positively with those of NA, PRA, TPR, mean BP and SV. These results revealed that ADM, ET-1 and angiotensin II can contribute to maintain vascular tone during static exercise in older but not in younger men. [ABSTRACT FROM AUTHOR]

The article describes the development of the Blue Box hand-held device for collecting and wirelessly transmitting cardiac parameters derived from integrated biosensors. Topics covered include the key physiologic parameters of heart failure decompensation, the potential of remote patient monitoring in reducing the burden of congestive heart failure (CHF) and the assessment of the value of parameters measured by Blue Box in correlating with cardiac output measured with Echo-Doppler.

Systolic time intervals are highly correlated to fundamental cardiac functions. Several studies have shown that thesemeasurements have significant diagnostic and prognostic value in heart failure condition and are adequate for longterm patient follow-up and disease management. In this paper, we investigate the feasibility of using heart sound (HS) to accurately measure the opening and closing moments of the aortic heart valve. These moments are crucial to define the main systolic timings of the heart cycle, i.e. pre-ejection period (PEP) and left ventricular ejection time (LVET). We introduce an algorithm for automatic extraction of PEP and LVET using HS and electrocardiogram. PEP is estimated with a Bayesian approach using the signal's instantaneous amplitude and patient-specific time intervals between atrio-ventricular valve closure and aortic valve opening. As for LVET, since the aortic valve closure corresponds to the start of the S2 HS component, we base LVET estimation on the detection of the S2 onset. A comparative assessment of the main systolic time intervals is performed using synchronous signal acquisitions of the current gold standard in cardiac time-interval measurement, i.e. echocardiography, and HS. The algorithms were evaluated on a healthy population, as well as on a group of subjects with different cardiovascular diseases (CVD). In the healthy group, from a set of 942 heartbeats, the proposed algorithm achieved 7.66 ± 5.92 ms absolute PEP estimation error. For LVET, the absolute estimation error was 11.39 ± 8.98 ms. For the CVD population, 404 beats were used, leading to 11.86 ± 8.30 and 17.51 ± 17.21 ms absolute PEP and LVET errors, respectively. The results achieved in this study suggest that HS can be used to accurately estimate LVET and PEP. [ABSTRACT FROM AUTHOR]

Abstract: The role of ventricular–arterial hemodynamic interaction in the occurrence of arterial dissection and rupture in vascular Ehlers–Danlos syndrome (vEDS) is unknown. We recently introduced an ultrasound-based method to extract, from common carotid artery (CCA) diameter waveforms, central arterial properties and left ventricular (LV) systolic time intervals. We obtained CCA diameters, compliance and distensibility coefficients, and LV isovolumic contraction and ejection periods (ICP and EP) of 19 vEDS patients (aged 27–65 yrs) and 19 age-matched healthy controls. CCA distension and compliance tended to be lower in vEDS subjects (p = 0.062 and p = 0.073), especially in younger patients. ICP (−12 ms) and EP (−24 ms) were shorter (p < 0.001), while heart rate was increased (+10 bpm; p < 0.001) in vEDS. The ICP/EP ratio and estimated isovolumic dP LV/dt indicated increased LV contractility in vEDS. In conclusion, vascular EDS patients tend to have a lower CCA compliance but a normal pulse pressure, most likely reflecting reduced physical fitness. [Copyright &y& Elsevier]

Aims Conventionally, the evaluation of left ventricular (LV) systolic function is based on ejection fraction assessment, which may be supplemented by other echocardiographic techniques, such as tissue Doppler imaging, 3D evaluation, and speckle tracking strains. However, these imaging modalities have a high technicity and are time-consuming, while being associated with reproducibility limitations. In this context, the usefulness of simpler measurements such as systolic time intervals (STI) by pulsed Doppler echocardiography must be emphasized. Methods and results In this multicentre study, left ventricular ejection fraction (LVEF), dP/dtmax, LV stroke volume, myocardial longitudinal deformation, aortic pre-ejectional period (PEP, ms), and left ventricular ejection time (LVET, ms) were prospectively investigated and compared in 134 consecutive heart failure (HF) patients and 43 control subjects. Feasibility of STI measurements was 100%. Intra-observer reproducibility was 98% for PEP, 96% for LVET, 87% for LVEF, and 93% for global longitudinal strain (GLS). By subgroup analyses, with increasingly altered LVEF or GLS, PEP significantly increased, whereas significantly LVET decreased, resulting in a significantly increased PEP/LVET ratio (P < 0.001). In the HF patients group, a correlation between LVEF and PEP/LVET was found, with r = 0.55 (y = −0.0083x + 0.75, P < 0.001). Based on receiver operating curve analyses, the area under the curve was 0.91 for PEP/LVET > 0.43, which allowed us to detect LVEF < 35% with a sensitivity of 87%, and a specificity of 84%. Conclusion STI can be easily and accurately measured in clinical practice, and may be used for detecting alterations in LV systolic function. Moreover, this method is likely to have potential applications in the management of HF patients. [ABSTRACT FROM AUTHOR]

Introduction: Fetal magnetocardiography (fMCG) is a promising new technique for assessing fetal rhythm; however, no prior studies have utilized fMCG to evaluate human fetal electromechanical physiology. Pre-ejection period (PEP) is an important measure of the electromechanical activation of the heart, and is altered by disease states and arrhythmias. Materials and Methods: A novel technique was used to assess fetal PEP and its relationship to other fetal systolic time intervals, RR interval, and gestational age (GA). 25 normal human fetuses between 19 and 38 weeks' gestation were studied using simultaneous pulsed Doppler ultrasound and fMCG. Correlations among PEP, ejection time, QRS width and RR interval were assessed using linear regression. Results: Across all subjects, PEP was found to correlate with GA (R = 0.57, p < 0.0001), QRS width (R = 0.35, p = 0.026), and RR interval (R = 0.37, p = 0.018). In individual sessions, PEP negatively correlated beat-to-beat with the preceding RR interval. Conclusion: PEP exhibits developmental trends that provide a better understanding of the normal development of the human fetal heart. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abstract: Objective: To study the applicability of anatomical M-mode (AMM) for assessment of left ventricular (LV) size and function in horses, evaluate agreement with conventional M-mode (CMM), determine reliability, and establish reference intervals for AMM measurements. Animals: 98 horses; 13.1 ± 5.6 years; 538 ± 78 kg. Methods: Two-dimensional and M-mode recordings were analyzed retrospectively. Standard LV dimensions and indices of LV function, including time intervals, were measured in CMM and compared with AMM studies in long-axis (lx) and short-axis (sx) views. Results: The percentages of measureable cycles were 99%, 97%, and 90% for routine LV studies in CMMsx, AMMsx, and AMMlx mode. For time intervals, ≥ 93% of cycles could be measured using AMM compared to a maximum of 77% using CMM. AMMsx measurements agreed well with CMMsx measurements for LV studies; the agreement of AMMlx with CMMsx was markedly lower. The LV ejection time and the duration of electromechanical systole, but not the LV pre-ejection period and the index of myocardial performance, showed fair agreement between methods. Intraobserver and interobserver measurement variabilities were low for most variables. Conclusions: AMM can replace CMM for assessment of LV dimensions in horses, but is not recommended for measurement of time intervals. [ABSTRACT FROM AUTHOR]

Objectives: Early identification of haemorrhage is difficult when a bleeding site is not apparent. This study explored the potential use of the finger photoplethysmographic (PPG) waveform derived left ventricular ejection time (LVETp) and pulse transit time (PTT) for detecting blood loss, by using blood donation as a model of controlled mild to moderate haemorrhage. Methods: This was a prospective, observational study carried out in a convenience sample of blood donors. LVETp, PTT and R-R interval (RRi) were computed from simultaneous measurement of the electrocardiogram (ECG) and the finger infrared photoplethysmogram obtained from 43 healthy volunteers during blood donation. The blood donation process was divided into four stages: (i) Pre-donation (PRE), (ii) first half of donation (FIRST), (iii) second half of donation (SECOND), (iv) post-donation (POST). Results and conclusions: Shortening of LVETp from 303+/−2 to 293+/−3 ms (mean+/−SEM; P<0·01) and prolongation of PTT from 177+/−3 to 186+/−4 ms ( P<0·01) were observed in 81% and 91% of subjects respectively when comparing PRE and POST. During blood donation, progressive blood loss produced falling trends in LVETp ( P<0·01) and rising trends in PTT ( P<0·01) in FIRST and SECOND, but a falling trend in RRi ( P<0·01) was only observed in SECOND. Monitoring trends in timing variables derived from non-invasive ECG and finger PPG signals may facilitate detection of blood loss in the early phase. [ABSTRACT FROM AUTHOR]

Background: Noninvasive assessment of left ventricular (LV) function is incompletely studied in horses. Objectives: The goals of this study were to investigate the feasibility, techniques, and reliability of tissue Doppler imaging (TDI) for characterization of LV radial wall motion in healthy horses. Animals: Three Standardbreds, 3 Thoroughbreds; age 8–14 years; body weight 517–606 kg. Methods: Repeated echocardiographic examinations were performed by 2 observers in unsedated horses using TDI. Test reliability was determined by estimating measurement variability, within-day interobserver variability, and between-day interobserver and intraobserver variability of all echocardiographic variables. Variability was expressed as coefficient of variation (CV) and the absolute value below which the difference between 2 measurements will lie with 95% probability. Results: Assessment of LV radial wall motion by TDI was feasible in all horses. Measurement variabilities were very low (CV < 5%) to low (CV 5–15%) for most variables. Within-day interobserver variability as well as between-day interobserver and intraobserver variabilities were low to moderate (CV 16–25%) for most variables. All pulsed-wave TDI variables of systolic LV function showed very low to low variability, whereas some of the variables of LV diastolic and LA function showed moderate to high (CV > 25%) variability. Pulsed-wave TDI variables appeared more reliable than color TDI variables. Conclusions and Clinical Importance: Measurement of TDI indices of LV function is feasible and reliable in adult Standardbred and Thoroughbred horses. The clinical relevance of LV function assessment by TDI remains to be determined. [ABSTRACT FROM AUTHOR]

Abstract: Background: The ratio of effective arterial elastance (Ea) to ventricular end-systolic elastance (Ees) indicates the status of ventriculo-arterial coupling. Aims: We investigated if systolic time intervals (pre-ejection period, PEP; ejection time, ET; and their ratio, PEP/ET) can be used to identify heart failure patients with abnormal ventriculo-arterial coupling. Methods: Age and sex-matched study subjects included 54 apparently healthy subjects with normal left ventricular (LV) function, and stable patients with LV diastolic (n =54) and systolic dysfunction (n =54). Ees and Ea were estimated non-invasively by echocardiography, and abnormal ventriculo-arterial coupling was defined as Ea/Ees>1.2. PEP, ET, and PEP/ET were measured automatically using electrocardiography, phonocardiography, and brachial pulse volume recording. Results: Ea/Ees>1.2 was present in 48.1% of subjects with systolic dysfunction. The PEP/ET was significantly associated with most parameters of LV structure and function, and Ea/Ees (r =0.67, p <0.001). Using PEP/ET≥0.423 as cut point, the sensitivity and specificity to identify patients with Ea/Ees>1.2 were 85.7% and 84.3%, respectively for the whole population, and 84.6% and 78.6%, for patients with systolic dysfunction. Conclusion: Abnormal ventriculo-arterial coupling was present in almost half of stable patients with systolic dysfunction. PEP/ET was useful in identifying such patients. [Copyright &y& Elsevier]

Abstract: Background: Electromechanical activation time (EMAT) is a systolic time interval defined as the time from Q-wave onset to the peak first heart sound. We assessed the correlation between systolic dysfunction and EMAT calculated using computerized acoustic cardiography. Methods: A total of 25 patients with heart failure contemporaneously underwent echocardiography, left-sided heart catheterization, and acoustic cardiography. Invasive pressure–volume hemodynamics included peak isovolumetric left ventricular (LV) pressure at the end-diastolic volume, end-diastolic pressure, dyssynchrony, and maximal +dP/dT. An EMAT/(R to R interval) (%EMAT) interval ≥ 0.15 was prospectively defined as abnormal. Results: An abnormal %EMAT correlated with a lower LV ejection fraction (50.9% ± 18.6% with normal EMAT vs 32.0% ± 10.9% with abnormal EMAT, P = .015), end-systolic elastance (3.07 ± 1.56 mm Hg/mL vs 1.43 ± 0.83 mm Hg/mL, P = .018), and peak isovolumetric LV pressure at the end-diastolic volume (317 ± 90 mm Hg vs 222 ± 67 mm Hg, P = .015). An abnormal %EMAT was associated with a higher end-systolic volume index (33.6 ± 29.3 mL/m2 vs 71.0 ± 35.8 mL/m2, P = .011), end-diastolic volume index (61.2 ± 29.8 mL/m2 vs 100.3 ± 40.8 mL/m2, P = .012), and dyssynchrony (26.1% ± 6.0% vs 31.5% ± 3.5%, P = .028). There was no difference in end-diastolic pressure (20.3 ± 7.9 mm Hg vs 21.4 ± 12.3 mm Hg, P = .78). Conclusions: An abnormal %EMAT was strongly associated with impaired LV contractility but had no association with LV filling pressures. This noninvasive, simple, point-of-care diagnostic test has potential applications when echocardiography cannot be obtained in a timely fashion to assess systolic function. [Copyright &y& Elsevier]

Introduction: Changes due to biventricular pacing have been documented by shortening of QRS duration and echocardiography. Compared to normal ventricular activation, the presence of left bundle branch block (LBBB) results in a significant change in cardiac cycle time intervals. Some of these have been used to quantify the underlying cardiac dyssynchrony, assess the effects of biventricular pacing, and guide programming of ventricular pacing devices. This study evaluates a simple noninvasive method using accelerometers attached to the skin to measure cardiac time intervals in biventricularly paced patients. Methods: Ten patients with biventricular pacemakers previously implanted for congestive heart failure were paced in the AAI mode, then in atrioventricular (AV) sequential mode from the right and left ventricles followed by biventricular pacing. Simultaneous recordings were obtained by 2D, Doppler echocardiography as well as by accelerometers. Similar recordings were obtained from 10 gender, aged matched, normal controls during sinus rhythm. Results: Compared to normals, heart failure patients paced in AAI mode had prolonged isovolumetric contraction time (IVCT), shorter ventricular ejection time (LVET), and prolonged isovolumetric relaxation (IVRT). With biventricular pacing the IVCT decreased, but the LVET and IVRT did not change significantly. There was excellent correlation between the echo and accelerometer-measured intervals. Conclusions: Shortening of the IVCT measured by an accelerometer is a consistent time interval change due to biventricular pacing that probably reflects more rapid acceleration of left ventricular ejection. The accelerometer may be useful to assess immediate efficacy of biventricular pacing during device implantation and optimize programmable time intervals such as AV and interventricular (VV) delays. [ABSTRACT FROM AUTHOR]

Central blood pressure waveforms contain specific features related to cardiac and arterial function. We investigated posture-related changes in ventriculoarterial hemodynamics by means of carotid artery (CA) pulse wave analysis. ECG, brachial cuff pressure, and common CA diameter waveforms (by M-mode ultrasound) were obtained in 21 healthy volunteers (19-30 yr of age, 10 men and 11 women) in supine and sitting positions. Pulse wave analysis was based on a timing extraction algorithm that automatically detects acceleration maxima in the second derivative of the CA pulse waveform. The algorithm enabled determination of isovolumic contraction period (ICP) and ejection period (EP): ICP = 43 ± 8 (SD) ms (4-ms precision), and EP = 302 ± 16 (SD) ms (5-ms precision). Compared with the supine position, in the sitting position diastolic blood pressure (DBP) increased by 7 ± 4 mmHg (P < 0.001) and R-R interval decreased by 49 ± 82 ms (P = 0.013), reflecting normal baroreflex response, whereas EP decreased to 267 ± 19 ms (P < 0.00 1). Shortening of EP was significantly correlated to earlier arrival of the lower body peripheral reflection wave (r² = 0.46, P < 0.001). ICP increased by 7 ± 7 ms (P < 0.001), the ICP-to-EP ratio increased from 14 ± 3% (supine) to 19 ± 3% (P < 0.001) and the DBP-to-ICP ratio decreased by 7% (P = 0.023). These results suggest that orthostasis decreases left ventricular output as a result of arterial wave reflections and, presumably, reduced cardiac preload. We conclude that CA ultra- sound and pulse wave analysis enable noninvasive quantification of ventriculoarterial responses to changes in posture. [ABSTRACT FROM AUTHOR]

Abstract: Background: The third heart sound (S3) and systolic time intervals (STIs) are validated clinical indicators of left ventricular (LV) dysfunction. We investigated the test characteristics of a combined score summarizing S3 and STI results for predicting LV dysfunction. Methods and Results: A total of 81 adults underwent computerized phonelectrocardiography for S3 and STI (Audicor, Inovise Medical Inc), cardiac catheterization for LV end-diastolic pressure (LVEDP), echocardiography for LV ejection fraction (LVEF), and B-type natriuretic peptide (BNP) testing. LV dysfunction was defined as both an LVEDP >15 mm Hg and LVEF <50%. The STI measured was the electromechanical activation time (EMAT) divided by LV systolic time (LVST). Z-scores for the S3 confidence score and EMAT/LVST were summed to generate the LV dysfunction index. The LV dysfunction index had a correlation coefficient of 0.38 for LVEDP (P = .0003), −0.53 for LVEF (P < .0001), and 0.35 for BNP (P = .0008). This index had a receiver operative curve c-statistic of 0.89 for diagnosis of LV dysfunction; a cutoff >1.87 yielded 72% sensitivity, 92% specificity, 9.0 positive likelihood ratio, and 88% accuracy. Conclusions: In this preliminary study, the LV dysfunction index combined S3 and STI data from noninvasive electrophonocardiography, and yielded superior test characteristics compared to the individual tests for the diagnosis of LV dysfunction. [Copyright &y& Elsevier]

Abstract: New filtering algorithms; a modified scaled Fourier linear combiner (mSFLC) and a modified ensemble averaging (mEA) are proposed to remove the phase distortion of the impedance waveform caused by SFLC. Performance of the filters is assessed from the shape of the filtered waveform and the estimation of systolic time intervals. It was found that the mSFLC and mEA could compensate for drawbacks of the SFLC and precisely reproduce the impedance waveforms; however, misinterpretation and attenuation in the cardiac variables may be caused when abrupt changes or irregularities occur in the source waveform. [Copyright &y& Elsevier]

Abstract: The avian cardiovascular system is of special interest because avian hearts are relatively larger than mammalian hearts, and activation of ventricular myocardium in birds has a “flash” pattern. Systolic time intervals and indices of myocardial contractility were examined in anaesthetized open-chest chickens by polycardiography, including synchronous recordings of electrocardiogram, phonocardiogram, and apex cardiogram. The asynchronous contraction time, isometric contraction time, pre-ejection period and ejection time were 26±3 (Mean±SD), 21±9, 47±12, and 83±23 ms, respectively, for heart rates of 260±57 bpm. The myocardial tension index, isometric contraction index and the pre-ejection period/ejection time ratio were 0.39±0.11, 0.42±0.10, and 0.54±0.14, respectively. A “flash” pattern of ventricular myocardial depolarization causes more rapid excitation and as a consequence shorter asynchronous contraction time of relatively larger chicken hearts compared with rabbit hearts. Inverse relation (P <0.05) of the asynchronous contraction time to the heart rate in chickens is probably associated with the specific activation pattern of avian ventricles. Establishment of the values of systolic time intervals will facilitate a better understanding of cardiac function in birds. The obtained results are discussed in comparison with the rabbit. The indices calculated from the systolic time intervals show disadvantageous contractile function of chicken heart compared to rabbit heart. [Copyright &y& Elsevier]

The onset of ventricular depolarization defines the start of the preejection period (PEP), which is commonly used as an index of myocardial contractility and sympathetic control of the heart. Although the fiducial point for this onset has traditionally been the onset of the Q wave of the electrocardiogram, other measurement points have also been used in the literature, including the peak of the Q wave (i.e., the onset of the R wave). Conceptual, physiological, and empirical considerations addressing the reliability and validity of these alternative metrics support the application of the Q-wave peak/R-wave onset as the fiducial point for PEP measures. [ABSTRACT FROM AUTHOR]

In the present study, the ‘acoustic windows’ for the measurement of the left ventricular systolic time intervals is studied by means of 2-D echocardiography and cardiac Doppler ultrasonography, and the normal values in the horse ( n = 112) are determined. The left ventricular isovolumetric contraction time, the pre-ejection period (PEP), as well as the left ventricular ejection time (LVET) have been measured, and the values of the left ventricular total electromechanical systole (LVTES) and the PEP-to-LVET ratio have been calculated. It has been established that the most suitable window for the measurement of the aforementioned indices in 2-D echocardiography is the right parasternal window in a view in short axis at the level of the cardiac base to measure the aortogram. In Doppler ultrasonography, the preferred window is the left parasternal using the five chambers apical view. The following values have been acquired: PEP = 0.071 ± 0.01 s; LVET = 0.532 ± 0.097 s; LVTES = 0.6 ± 0.1 s and PEP-to-LVET = 0.138 ± 0.025 measured by 2-D echocardiography and PEP = 0.068 ± 0.009 s; LVET = 0.527 ± 0.076 s; LVTES = 0.598 ± 0.098 s and PEP-to-LVET = 0.131 ± 0.01 measured by Doppler ultrasonography. [ABSTRACT FROM AUTHOR]

SUMMARY: In this controlled study, systolic time intervals (STI) and diastolic functions were investigated in haemodialysis patients (HDp) with ejection fraction (EF) within normal limits. Echocardiographic findings in 86 HDp (M: F, 47:39, mean age 36 ± 13 years) and 51 healthy controls (M: F, 22:29, mean age 37 ± 10 years) were compared for STI parameters (prejection period (PEP), left ventricular ejection time (LVET) and STI index (PEP/LVET)) and diastolic dysfunction (isovolumetric relaxation time (IVRT) and E/A ratio and deceleration time). The pre-ejection period (114 ± 21 vs 94 ± 4 msec, P < 0.001) and STI index (0.41 ± 0.11 vs 0.34 ± 0.02, P < 0.001) were higher in the HDp compared with controls. Increased STI index and prolonged PEP in HDp were independent of left ventricular (LV) hypertrophy and hypertension. Diastolic dysfunction was present in 61% of the patients. The IVRT were also found to be longer in HDp compared with controls (97 ± 16 vs 75 ± 16 msec, P < 0.001), independent of the presence of LV hypertrophy or hypertension. Diastolic dysfunction indicated by IVRT > 100 msec and latent systolic dysfunction (STI index > 0.4) were randomly distributed, with nearly half (48%) of the patients with prolonged IVRT having an STI index within the normal limits and the other half of the patients with deteriorated STI index having a normal IVRT. The combined systolic and diastolic dysfunction was observed in 30% of the patients. It was concluded that STI indexes deteriorate before an overt systolic dysfunction (normal EF), and that systolic and/or diastolic dysfunction of the myocardium may appear singly or simultaneously because of a common pathogenetic mechanism of myocardial fibrosis. [ABSTRACT FROM AUTHOR]

Abstract Objectives The fetal cardiac isovolumetric contraction time is defined as the interval between mitral valve closure and aortic valve opening. The objective of this study was to develop a simple and reliable Doppler method for measuring fetal isovolumetric contraction time using a digital filtering and processing system. Methods Cardiac Doppler signals were recorded from 40 fetuses at 18–40 weeks’ gestation using a continuous-wave ultrasound transducer. The raw signal was digitized, filtered and divided into five different frequency ranges: 250–375, 375–500, 500–750, 750–1000 and 1000–1500 Hz. To determine the most suitable filter setting for detecting mitral valve closure and aortic valve opening signals, we examined whether they were detected clearly in each filter range. Results Both mitral valve closure and aortic valve opening signals were detected clearly in the 500–1000 Hz range. The atrioventricular flow and outflow noises in the 250–500 and 1000–1500 Hz ranges helped us to identify the signals. It was found that dividing the raw signals into three ranges of 250–500, 500–1000 and 1000–1500 Hz was the most suitable digital-filter setting for measuring isovolumetric contraction time. Conclusions We have developed a simple Doppler method for measuring fetal isovolumetric contraction time. The advent of digital processing has simplified the equipment and the simultaneous multidisplay of three different filtered signals enables easy and accurate measurement. [ABSTRACT FROM AUTHOR]

The operating principles and methods for the continuous determination of aortic blood flow (ABF) with the Dynemo 3000 system are described in detail. The system uses a novel transesophageal ultrasonic Echo-Doppler probe simultaneously to measure aortic diameter and blood flow velocity at the same anatomic level, in real-time. Non-invasive ABF measurement is combined with vital sign data from standard monitors to provide a composite hemodynamic profile including volume, afterload and contractility data used by the physician to optimize therapy. A review of the clinical validation and comparison to thermodilution measurements showing a significant positive correlation over a wide range of clinical flow situations is also briefly presented. [ABSTRACT FROM AUTHOR]