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Aim: The aim was to validate the Systolic Time Intervals (STI) measured by Ballistocardiography (BCG) with STI derived from simultaneously performed Transthoracic Echocardiogram (TTE) and attempt to create an AI algorithm that automatically calculates Tei Index from BCG tracings. Study design: Cross-sectional study. Place and Duration of Study: Department of Cardiology and Department of Electrophysiology of Sri Jayadeva Institute of Cardiovascular Sciences & Research, Bangalore, India, between January 2020 and January 2021. Methodology: Two hundred seventy-four patients with clinically indicated TTE were enrolled in the study, average age was 52. Simultaneous recordings on BCG and TTE were done. 150 patients had clinically usable TTE images for accurate calculations. STI was calculated independently by operators experienced in TTE and BCG. Results were compared using Pearson’s R. A proprietary AI algorithm for automatically calculating the MPI, was trained over a subset of patients. Its accuracy in detecting STI was compared to that of TTE and manually calculated STI from BCG. Results: There was a strong positive correlation (r=0.766, P=50). The AI algorithm had correlation of 0.54(p

Research on effort and motivation commonly assesses how the sympathetic branch of the autonomic nervous system affects the cardiovascular system. The cardiac pre-ejection period (PEP), assessed via impedance cardiography, is a common outcome, but assessing PEP requires identifying subtle points on cardiac waveforms. The present research examined the psychometric value of the RZ interval (RZ), which has recently been proposed as an indicator of sympathetic activity, for effort research. Also known as the initial systolic time interval (ISTI), RZ is the time (in ms) between the ECG R peak and the dZ/dt Z peak. Unlike PEP, RZ involves salient waveform points that are easily and reliably identified. Data from two experiments evaluated the suitability of RZ for effort paradigms and compared it to a popular automated PEP method. In Studies 1 (n = 89) and 2 (n = 71), participants completed a standard appetitive task in which each correct response earned a small amount of cash. As expected, incentives significantly affected PEP and RZ in both experiments. PEP and RZ were highly correlated (all rs ≥ 0.89), and RZ consistently yielded a larger effect size than PEP. In Study 3, a quantitative synthesis of the experiments indicated that the effect size of RZ's response to incentives (Hedges's g = 0.432 [0.310, 0.554]) was roughly 15% larger than PEP's effect size (g = 0.376 [0.256, 0.496]). RZ thus appears promising for future research on sympathetic aspects of effort-related cardiac activity.

Introduction: Several handheld thumb ECG devices for on-demand recording of heart rhythm have become available lately. These can be used both by health-care providers and purchased by laypersons for private use.Area covered: This profile describes the Coala Heart Monitor. This device differs from other handheld ECG monitors in three aspects: 1) it records both thumb and chest ECGs, 2) it uses both RR-dispersion and P-wave morphology for detecting atrial fibrillation, and 3) in synchronization with the chest ECG, it also records heart sounds presented as a phonocardiogram making measurement of systolic time intervals possible. The sensitivity and specificity for detecting atrial fibrillation are high. The use of systolic time interval in patients with heart failure has so far not been evaluated.Expert opinion: The increasing use of long-term prescribed and privately owned handheld ECG devices for on-demand recording of heart rhythm will most probably cause a paradigm shift in arrhythmia diagnostics. Coala Heart Monitor´s use of both chest and thumb recordings as well as analyzing both RR-dispersion and P-wave morphology may offer an advantage in diagnosing atrial fibrillation.

PURPOSE: To assess right ventricular systolic time intervals, specifically, time to peak velocity (TPV) in the pulmonary artery as a marker of persistent pulmonary hypertension of the newborn (PPHTN). METHODS: This was a retrospective case–control study of 30 infants with pulmonary hypertension requiring intensive care management. Cardiac ultrasounds were re‐analysed, comparing TPV measurements to a group of 31 controls who had cardiac ultrasounds performed for incidental murmurs with structurally normal hearts. RESULTS: Time to peak velocity was significantly shorter in the PPHTN group compared to controls, 47 vs. 95 ms, respectively. This was statistically significant with a P‐value of

Worsening heart failure (HF) is associated with shorter left ventricular systolic ejection time (SET), but there are limited data describing the relationship between SET and clinical outcomes. Thus, the objective was to describe the association between SET and clinical outcomes in an ambulatory HF population irrespective of ejection fraction (EF).We identified ambulatory patients with HF with reduced EF (HFrEF) and HF with preserved EF (HFpEF) who had an outpatient transthoracic echocardiogram performed between August 2008 and July 2010 at a tertiary referral centre. Multivariable logistic regression was used to evaluate the association between SET and 1-year outcomes. A total of 545 HF patients (171 HFrEF, 374 HFpEF) met eligibility criteria. Compared with HFpEF, HFrEF patients were younger [median age 60 years (25th-75th percentiles 50-69) vs. 64 years (25th-75th percentiles 53-74], with fewer females (30% vs. 56%) and a similar percentage of African Americans (36% vs. 35%). Median (25th-75th percentiles) EF with HFrEF was 30% (25-35%) and with HFpEF was 54% (48-58%). Median SET was shorter (280 ms vs. 315 ms, P 0.001), median pre-ejection period was longer (114 ms vs. 89 ms, P 0.001), and median relaxation time was shorter (78.7 ms vs. 93.3 ms, P 0.001) among patients with HFrEF vs. HFpEF. Death or HF hospitalization occurred in 26.9% (n = 46) HFrEF and 11.8% (n = 44) HFpEF patients. After adjustment, longer SET was associated with lower odds of the composite of death or HF hospitalization at 1 year among HFrEF but not HFpEF patients.Longer SET is independently associated with improved outcomes among HFrEF patients but not HFpEF patients, supporting a potential role for normalizing SET as a therapeutic strategy with systolic dysfunction.

Traditionally, impedance derived measures of cardiac autonomic balance (CAB) and regulation (CAR) are calculated using indices of heart rate variability (HRV) that primarily reflect parasympathetic nervous system activity (e.g., high-frequency HRV | HF-HRV) and pre-ejection period (PEP; a systolic time interval and measure of sympathetic activity). However, HF-HRV and PEP are considered measures of chronotropic and inotropic cardiac influence, respectively. Left ventricular ejection time (LVET) is a systolic time interval that reflects sympathetic chronotropic influence, and therefore may be a more appropriate measure for calculating CAB and CAR compared to PEP. Thus, the current study evaluates both PEP and LVET in the calculation of CAB and CAR. Data from 158 healthy participants (mean age = 19.09 years old, SD = 1.84 years) were available for analyses. CAB and CAR values were calculated using both HF-HRV and the root mean square of successive differences, in addition to both PEP and LVET, in accordance with previously established guidelines. Analyses showed that correlations were significantly weaker between CAB and CAR calculated using LVET for both HF (z = 5.12, p < 0.001) and RMSSD (z = 5.26, p < 0.001) than with PEP. These data suggest that LVET, compared to PEP, provides better “autonomic space” as evidenced by a lack of correlation between CAB and CAR computed using LVET. We stress that future research consider calculating CAB and CAR using chronotropic measures for both parasympathetic and sympathetic activity, as doing so may yield more accurate and independent measures of cardiac autonomic activity compared to a mixture of inotropic (i.e., PEP) and chronotropic (i.e., HF-HRV) measures.

This chapter contains the description of the foundations of the impedance cardiography (ICG) as a noninvasive method for continuous determination of stroke volume (SV), cardiac output, and systolic time intervals (preejection period and left ventricular ejection time). The origin of the signal, the used arithmetic formulas for SV evaluation, and limitations of the method were presented. It also presented the present and the possible future research and clinical applications of the ICG.

Background: Bioprosthesis (BP) used for aortic valve replacement (AVR) in aortic valve disease are subject to structural valve deterioration (SVD) after 20 years or less which leads to reintervention. The diagnostic of SVD can be challenging in the presence of patient-prosthesis mismatch (PPM) which occurs when the effective orifice area (EOA) of the BP is too small for the metabolic needs of a patient. Both SVD and PPM are mainly diagnosed with echocardiography and are characterized by high transprosthetic mean and peak pressure gradients (MG and PG) and maximal velocity (Vmax) as well as reduced EOA. Easily accessible parameters are needed to distinguish SVD from PPM. Acceleration time (AT), ejection time (ET) and AT/ET have been proposed as accurate to identify SVD in presence of PPM. However, these parameters need to be validated. Objectives: The main goal of the present study is to determine the accuracy of AT and AT/ET and to validate new echocardiographic parameters that can distinguish SVD from PPM. New parameters proposed for this study are MG/EOA and PG over mean flow rate (PG/MFR). Methods: In a retrospective study, we analyzed echocardiographic data of 653 patients who underwent AVR. PPM was defined as a projected EOA to body surface area inferior to 0.85 cm 2 /m 2 . SVD was defined using a multiparametric integrative approach including morphological (fibrocalcific remodeling, thickening and stiffening of valve leaflets) criteria and hemodynamic changes according to American Society of Echocardiography/European Association for Cardiovascular Imaging recommendations. Results: EOA was lower and MG higher for patients with SVD compared to those with pure PPM. PG/Q and MG/EOA were significantly higher in patients with SVD compared to patients presenting pure PPM (PG/MFR: 0.22 mm Hg/ml/s ± 0.01 vs 0.15 mm Hg/ml/s ± 0.01; MG/EOA: 31 mm Hg/cm 2 ±2 vs 16 mm Hg/cm 2 ±2, p Conclusion: AT and AT/ET are not accurate parameters to identify SVD in presence of PPM. MG/EOA and PG/MFR represent interesting alternatives to conventional parameters.

Introduction: Systolic Time Interval (STI) is a simple,noninvasive and precise technique to assess left ventricular (LV) function. It measures aortic Pre-Ejection Period (PEP) over Left Ventricular Ejection Time (LVET) from echocardiogram. Thyrotoxicosis will enhance LV function and cause reduction of STI. This study was perform to measure the changes of STI after administration of high dose L-thyroxine and to determine the correlation between high dose L-thyroxine administration and STI. Materials and Method: A Total of 22 patients were screened. Those with cardiac diseases and high Framingham risk score were excluded. Nine patients were started on high dose L-thyroxine (7x their usual dose) once a week during the month of Ramadan.Thyroid hormones ( T3,T4,TSH)Â and STI (PEP/LVET) were measured at baseline and within 24 hrs after high dose L-thyroxine ingestion. Results: All patients have normal thyroid hormones level and normal cardiac function at baseline. The median dose (mcg) of L-thyroxine was 600 (437.5,700) while the median level of fT4 (pmol/L) was 17.43(12.38,20.8). Despite the significant increment of fT4 after Lthyroxine ingestion [baseline 13.21(8.19,14.63) vs high dose 17.43(12.38,22.55) p; 0.011] there was no significant change in STI [baseline 0.3(0.2,0.4) vs high dose 0.28(0.26,0.45) p; 0.513]. There was no correlation found between the dose of Lthyroxine and STI (r=0.244 , p;0.526). Conclusion: Administration of high dose Lthyroxine did not significantly alter STI despite significant increment of fT4 level unlike the naturally occurring thyrotoxicosis.Therefore ‘exogenous’ administration of high dose L-thyroxine is cardiac safe.

The Initial Systolic Time Interval (ISTI), obtained from the electrocardiogram (ECG) and impedance cardiogram (ICG), is considered to be a measure for the time delay between the electrical and mechanical activity of the heart and reflects an early active period of the cardiac cycle. The clinical relevance of this time interval is subject of study. This paper introduces a method using ISTI to evaluate and predict the circulatory response to fluid administration in patients after coronary artery bypass graft surgery and presents preliminary results of a pilot study by comparing ISTI with cardiac output (CO) responsiveness. Also the use of the pulse transit time (PTT), earlier recommended for this purpose, was investigated. The results showed an inverse relationship between ISTI and CO at all moments of fluid administration and also an inverse relationship between the changes ΔISTI and ΔCO before and after full fluid administration. No relationships between PTT and CO or ΔPTT and ΔCO were found. It is concluded that ISTI is dependent upon preload, and that ISTI has the potential to be used as a clinical parameter assessing preload.

Aim The aim of this study was to evaluate the haemodynamic correlates of heart sound (HS) parameters such as third HS (S3), first HS (S1), and HS-based systolic time intervals (HSTIs) from an implantable cardiac device. Methods and results Two unique animal models (10 swine with myocardial ischaemia and 11 canines with pulmonary oedema) were used to evaluate haemodynamic correlates of S1, S3, and HSTIs, namely, HS-based pre-ejection period (HSPEP), HS-based ejection time (HSET), and the ratio HSPEP/HSET during acute haemodynamic perturbations. The HS was measured using implanted cardiac resynchronization therapy defibrillator devices simultaneously with haemodynamic references such as left atrial (LA) pressure and left ventricular (LV) pressure. In the ischaemia model, S1 amplitude (r = 0.76 ± 0.038; P = 0.002), HSPEP (r = −0.56 ± 0.07; P = 0.002), and HSPEP/HSET (r = −0.42 ± 0.1; P = 0.002) were significantly correlated with LV dP/dtmax. In contrast, HSET was poorly correlated with LV dP/dtmax (r = 0.14 ± 0.14; P = 0.23). In the oedema model, a physiological delayed response was observed in S3 amplitude after acute haemodynamic perturbations. After adjusting for the delay, S3 amplitude significantly correlated with LA pressure in individual animals (r = 0.71 ± 0.07; max: 0.92; min: 0.17) as well as in aggregate (r = 0.62; P 25 mmHg, with a sensitivity = 58% and specificity = 90%. Conclusions The HS parameters such as S1, S3, and HSTIs measured using implantable devices significantly correlated with haemodynamic changes in acute animal models, suggesting potential utility for remote heart failure patient monitoring.

To investigate the effects of acute aerobic and resistance exercise on the arterial stiffness and the left ventricular systolic time interval(STI), high school students(16.4±.8 yrs, n=15) were tested at resting state, immediately after exercise, recovery 1hr, and 2hr. Experiments were performed in 3 conditions; control without any handling, aerobic exercise with track running at 80% HRR, and resistance exercise with maximal repetitions at 60% RM on bench press, arm curl, leg press and leg curl. Data were analyzed by repeated two-way ANOVA on time and exercise type. As results, ABPI, baPWV and AIx, that were arterial stiffness variables, were tend to decrease at immediately after aerobic and resistance exercise, but these variables were recovered and increased than the resting values during recovery 1hr and 2hr. The patterns of STI, LVET and PEP/LVET, that were left cardiac contractility variables, were similar with those of arterial stiffness variables during recovery periods after aerobic and resistance exercise. In conclusion, the arterial stiffness was decreased at immediately after aerobic and resistance exercise, but they were increased during recovery. These changes of arterial stiffness variables seemed to be independent with left cardiac contractility variables.

Background Systolic time intervals (STI) measured using Transthoracic Echo (TTE) have been shown to be sensitive indicators of contractile performance, but TTE is limited to a hospital setting. Recent advances in technology have enabled the simultaneous measurement of Electrocardiograms (ECG) and Seismocardiograms (SCG) using wearable devices. However, the use SCG to measure STIs has not been validated in a mobile setting, or on pathological subjects. Purpose To test the validity of an automated algorithm for measuring STIs using a wearable device recording ECG and SCG, in subjects with varying degrees of left ventricular dysfunction. Methods 179 Patients with suspected left ventricular dysfunction were assessed using TTE performed by a Cardiologist. Patients were simultaneously fitted with a novel wearable device worn on a chest strap, recording SCG and single-lead ECG data, while the cardiologist measured the pre-ejection period (PEP) and left ventricular ejection time (LVET) with the patient in a supine position. Of these subjects 29 (16.2%) were diagnosed with Dilated cardiomyopathy (DCM), and 109 (60.8%) had Ischemic Heart disease. The SCG and ECG data recorded on the wearable device was then analysed using a peak-detection algorithm, which detected the Q,R,S points on the ECG, and then determined the 4 most prominent peaks in the SCG signal corresponding to each R-peak. Heart rate, patient's age, gender and SCG time intervals were then used in a DecisionTree algorithm to determine the values of PEP and LVET, which were were then compared against those determined by the cardiologist using TTE. Results The correlation coefficient (r2) between PEP calculated using TTE, and the values obtained from the algorithm analyzing SCG data was 0.92 while the mean error was 7.47%. The r2 between the LVET calculated using the TTE and the algorithm was 0.75, while the mean error was 8.53% (p-value Results All Subjects With IHD Without IHD With DCM Without DCM Number of Subjects 178 109 69 29 149 PEP (r2) 0.92 0.89 0.94 0.88 0.91 PEP (% age error) 7.47 7.50 7.42 6.99 7.56 LVET (r2) 0.75 0.81 0.66 0.55 0.83 LVET (% age error) 8.53 6.69 11.4 20.42 6.16 DCM, Dilate Cardiomyopathy; IHD, Ischemic Heart Disease. ECG + SCG signals for a DCM patient Conclusion The algorithm-derived STIs measured by SCG correlate well with those measured by TTE across most patient groups, including those with Dilated Cardiomyopathy and Ischemic Heart Disease, opening prospects for continuous remote monitoring of STIs in a mobile setting. Acknowledgement/Funding Fourth Frontier Technologies

There are a number of methods and diagnostic tools for assessing the health of the heart. The systolic time intervals (STI) have been clinically useful parameters representing cardiac cycle and measuring the ventricular performance. In this study, a continuous wavelet transform (CWT) based approach for quantifying the systolic time intervals, in particular, the pre-ejection period (PEP) and the left ventricular ejection time (LVET), using electrocardiogram (ECG) and phonocardiogram (PCG) signals are proposed. The proposed CWT-based STI quantification approach is composed of three main stages: ECG signal processing, PCG signal processing, and computation of the systolic time intervals. The proposed CWT-based STI quantification approach is validated using ECG and PCG data recorded from both healthy subjects and subjects suffering from various cardiovascular diseases. The computational results suggest that the proposed CWT-based STI quantification approach has a considerable capability for clinical applications. The means of average absolute errors on PEP and LVET quantifications are, respectively, 13.4251 ms and 27.1348 ms. The best total score achieved is 868.9192.

The systolic time intervals of hearts are related to health. People with myocardial dysfunction will have a longer pre-ejection period (PEP) and a shorter left ventricle ejection time (LVET) than healthy people. The purpose of this paper is intended to detect PEP and LVET accurately from electrocardiography (ECG) and phonocardiogram (PCG). Generally, there are several kinds of noises from environment or breathing in PCG. It is necessary but difficult to extract the best signals we want. Our approach is to use a simple DSP-based method in PCG to detect aortic valve opening (AVO) and aortic valve closure (AVC) times as well as R-peak time in ECG. Then, the PEP and LVET can be calculated. We evaluated PEP and LVET of 72 files from 46 people. To the annotated data, the PEP range is around 5 ms to 100 ms; the LVET range is around 170 ms to 380 ms. Our PEP results have 63.96% accuracy within 20 ms absolute error and 91.74% accuracy within 40 ms absolute error; LVET have 75.48% accuracy within 40 ms absolute error and 93.53% accuracy within 80 ms absolute error.

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&nbsp

Objective: We investigated the repeatability of systolic time intervals (STIs) in healthy subjects using a combination of seismocardiogram (SCG) and electrocardiogram (ECG). STIs have been extensively used in the past to quantify heart performance, particularly the left ventricle. In this study, STIs included pre-ejection period (PEP), left ventricular ejection time (LVET), and their ratio. Approach: We conducted the repeatability test of STI estimation through two experiments. The first involved three consecutive one-minute recordings separated by one-minute intervals, and the second involved two one-minute recordings separated by 24 hours. Twenty healthy subjects participated in our study. We considered the coefficient of variation (CV) to quantify the repeatability. As there was no agreed upon values for optimal CV values, we compared our results with an alternative method using a combination of impedance cardiography (ICG) and ECG. Similar to our method, the alternative method was noninvasive and could be employed for personal heart monitoring. We also studied the repeatability after STIs were corrected for heart rate using two approaches. The first approach used a multiplicative factor per subject based on the heart rates in each recordings of that subject. The second approach employed sex-specific regression models for all subjects (Weissler's equations). Main results: We found that the repeatability of our method (SCG and ECG) was in agreement with the alternative method (ICG and ECG) in both experiments. Moreover, the Weissler's equations approach for heart rate increased the repeatability. Significance: It can be concluded that estimation of PEP, LVET and their ratio through SCG and ECG signals was repeatable in healthy subjects.

Aims: The renal systolic time intervals (STIs), including renal pre-ejection period (PEP), renal ejection time (ET), and renal PEP/renal ET measured by renal Doppler ultrasound, were associated with poor cardiac function and adverse cardiac outcomes. However, the relationship between renal hemodynamic parameters and arterial stiffness in terms of brachial-ankle pulse wave velocity (baPWV) has never been evaluated. The aim of this study was to assess the relationship between renal STIs and baPWV. Methods: This cross-sectional study enrolled 230 patients. The renal hemodynamics was measured from Doppler ultrasonography and baPWV was measured from ABI-form device by an oscillometric method. Results: Patients with baPWV ≧ 1672 cm/s had a higher value of renal resistive index (RI) and lower values of renal PEP and renal PEP/ET (all P< 0.001). In univariable analysis, baPWV was significantly associated with renal RI, renal PEP, and renal PEP/renal ET (all P< 0.001). In multivariable analysis, renal PEP (unstandardized coefficient β = -3.185; 95% confidence interval = -5.169 to -1.201; P = 0.002) and renal PEP/renal ET (unstandardized coefficient β = -5.605; 95% CI = -10.217 to -0.992; P = 0.018), but not renal RI, were still the independent determinants of baPWV. Conclusion: Our results found that renal PEP and renal PEP/renal ET were independently associated with baPWV. Hence, renal STIs measured from renal echo may have a significant correlation with arterial stiffness.

Left ventricular ejection time (LVET) is an important component of systolic time intervals. It has been used as a surrogate for left ventricular contractility and stroke volume. We developed a method for the assessment of LVET from wrist cuff pulse waveforms. The waveforms are obtained from a partially inflated cuff held at the level of the heart. Each test involved acquisition of 10 second sample of waveform data. The data were processed after each test by specially developed software algorithm. Thirty tests were evaluated and compared with predicted values. The results showed the mean value of computed LVET equal to 309 ms and mean value of predicted LVET equal to 304 ms. We concluded that our method has the potential for use as a stand-alone method for evaluation of left ventricular contractility and for the determination of stroke volume.

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.

Cardiac parasympathetic activity may be non-invasively investigated using heart rate variability (HRV), although HRV is not widely accepted to reflect sympathetic activity. Instead, cardiac sympathetic activity may be investigated using systolic time intervals (STI), such as the pre-ejection period. Although these autonomic indices are typically measured during rest, the “reactivity hypothesis” suggests that investigating responses to a stressor (e.g., exercise) may be a valuable monitoring approach in clinical and high-performance settings. However, when interpreting these indices it is important to consider how the exercise dose itself (i.e., intensity, duration, and modality) may influence the response. Therefore, the purpose of this investigation was to review the literature regarding how the exercise dosage influences these autonomic indices during exercise and acute post-exercise recovery. There are substantial methodological variations throughout the literature regarding HRV responses to exercise, in terms of exercise protocols and HRV analysis techniques. Exercise intensity is the primary factor influencing HRV, with a greater intensity eliciting a lower HRV during exercise up to moderate-high intensity, with minimal change observed as intensity is increased further. Post-exercise, a greater preceding intensity is associated with a slower HRV recovery, although the dose-response remains unclear. A longer exercise duration has been reported to elicit a lower HRV only during low-moderate intensity and when accompanied by cardiovascular drift, while a small number of studies have reported conflicting results regarding whether a longer duration delays HRV recovery. “Modality” has been defined multiple ways, with limited evidence suggesting exercise of a greater muscle mass and/or energy expenditure may delay HRV recovery. STI responses during exercise and recovery have seldom been reported, although limited data suggests that intensity is a key determining factor. Concurrent monitoring of HRV and STI may be a valuable non-invasive approach to investigate autonomic stress reactivity; however, this integrative approach has not yet been applied with regards to exercise stressors.

The aim of this study was to evaluate the use of renal systolic time intervals measured by electrocardiographic gated Doppler ultrasonography for predicting adverse cardiac events. This longitudinal observation study enrolled 205 patients. Renal systolic time intervals, including pre-ejection period (PEP) and ejection time (ET), and ratio of renal PEP to ET, were measured by electrocardiographic gated Doppler ultrasound. The 14 adverse cardiac events identified in this population included 9 cardiac deaths and 5 hospitalizations for heart failure during an average follow up of 30.9 months (25th–75th percentile: 30–33 months). Renal PEP (hazard ratio = 1.023, P = 0.001), renal ET (hazard ratio = 0.975, P = 0.001) and renal PEP/ET (per 0.01 unit increase, hazard ratio = 1.060, P

During the cardiac cycle, both electrical and mechanical events are present. In fact, the electrocardiogram (ECG) allows the exploration of the electrical activity of the heart, while the phonocardiogram (PCG) constitutes a complementary tool to record the mechanical activity of the heart. The aim of our work is to develop a new approach for heart sounds segmentation based on the correlation between ECG and PCG signals for measurement of systolic time interval. Two different groups of simultaneous recordings of ECG and PCG signals were tested in this study. The performance of automatic heart sounds localisation process is compared with that of manual measurements made by two experts. The results obtained are interesting especially for pathological cases heart sound.

In this study, we develop an interface (human-machine) for monitoring the cardiovascular-respiratory system, through the evaluation of analogous indices obtained from a finger photoplethysmography pulse oximetry waveform. This interface consists of sensors, electronics associated with these sensors, acquisition card to make the communication with a local computer post and a graphical interface developed in visual basic environment for signals tracing and data archiving. In this work, we achieved the evaluation of representative indexes for the response to vascular filling, using systolic time intervals (STIs) namely, pre ejection period (PEP), respiratory change in pre ejection period (ΔPEP), left ventricular ejection time (LVET) and systolic time ratio (STR). Given that STIs, are highly correlated to the fundamental cardiac functions. In order to achieve this goal, a data collection study was conducted using synchronised acquisitions of electrocardiogram (ECG), photoplethysmogram (PPG) and pneumotachogram (PTG) signals.

STI (Systolic Time Interval) is one of the methods of non-invasive determination of cardiac function, which applies ECG, PCG and central artery putsation to synchronize photographic record and determine STI indicators. STI is both consistent both with cardiovascular angiography examination results, but also well related to directly measured hemodynamic parameters, which has laid a foundation of theory and practice for the wide application of STI. This thesis gives a regular summary and research analysis of the STI change characteristics of different groups.

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. 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. 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

The aims of this study were to investigate the correlation between renal and cardiac STIs, including pre-ejection period (PEP), ejection time (ET), and PEP/ET, and to assess the diagnostic values of renal STIs in predicting left ventricular ejection fraction (LVEF) 0.46 in prediction of LVEF

Siemocardiography is a non-invasive technique for cardiomechanical assessment by analyzing the local vibrations on chest surface which can be readily acquired from cost-effective accelerometers. The peaks in siesmocardiogram (SCG) signal correspond to underlying mechanical events in heart cycle and have numerious potential clinical and health-awareness applications. However, utilization of SCG signal requires annotation of these peaks that is challenging due to variations in inter-subject morphology and noise prone characteristics of SCG signal. In this paper, we propose an approach to automatically annotate the desired peaks in SCG signal that are required for systolic time intervals (STI). The approach is based on formulating sliding template for the oncoming beat which is less noisier and hence desired peak detection is easier. The information of peak detected in the sliding template is then used to narrow-down the search of desired peak in actual signal.

Systolic time intervals (STI) and echocardiography were recorded in 133 (70 men, 63 women) newly diagnosed non-insulin-dependent diabetics aged 45–64 years and in 144 (62 men, 82 women) non-diabetic control subjects of the same age. Both male and female diabetics had significantly increased pre-ejection period/left ventricular ejection time ratio (PEP/LVET) in STI as compared with the respective non-diabetic control subjects. Male diabetics showed a reduced ejection fraction (EF) in echocardiography, but no significant difference was found in this respect between female diabetics and controls. A significant negative correlation was found between 2-hour postglucose serum insulin level and EF in male and female diabetics. After adjusting for the effect of age, coronary heart disease, hypertension, obesity and haemoglobin concentration, male diabetics still had a higher PEP/LVET ratio and a lower EF than male controls. In women, no significant differences were found between diabetics and controls in the PEP/LVET ratio or EF adjusted for the above factors. The results of this study are compatible with the view that impaired left ventricular function may be an early phenomenon in the clinical course of non-insulin-dependent diabetes.

Systolic time intervals (STI) were recorded in 33 newly diagnosed non-insulin-dependent diabetics (19 men, 14 women, aged 44-64 years) before and after 3-8 months' dietary therapy. The mean (+/- SD) fasting blood glucose was 11.1 +/- 2.6 mmol/l before treatment and 7.8 +/- 1.8 at the second examination (p less than 0.001). Concomitantly with the decline in blood glucose concentration, the heart rate corrected pre-ejection period (PEP) decreased from 139 +/- 11.9 to 135 +/- 14.4 msec (mean +/- SD) (p less than 0.05), the heart rate corrected left ventricular ejection time (LVET) increased from 400 +/- 15.1 to 410 +/- 20.7 msec (p less than 0.0025) and the PEP/LVET ratio decreased from 0.39 +/- 0.06 to 0.36 +/- 0.06 (p less than 0.005). When the diabetics were divided into two groups according to the degree of the decline in blood glucose concentration, only those whose fasting blood glucose decreased by greater than or equal to 3 mmol/l showed significant changes in STI. No significant changes were observed in the mean heart rate or systolic blood pressure during the treatment. Cardiac dysfunction occurring in untreated non-insulin-dependent diabetics may be caused by metabolic factors and it may be reversed at least partially by correction of hyperglycemia.

Cardiac effects of ethanol ingestion (1.75 g/kg within 3 hours) were examined in 8 healthy males by echocardiography and systolic time intervals in a controlled study. Heart rate (HR) was increased by 15% (p less than 0.05) during intoxication when blood ethanol (mean +/- SD) was 33.7 +/- 4.1 mmol/l. Left ventricular (LV) end-diastolic dimension was simultaneously shortened by 4% (p less than 0.01) and LV end-systolic dimension by 3% (p less than 0.05). Stroke volume was reduced by 12% (p less than 0.05). Most subjects experienced hangover symptoms 12 hours after the beginning of ethanol intake; blood ethanol was 8.8 +/- 4.0 mmol/l. At this time, HR was raised by 17% (p less than 0.05), ejection fraction by 7% (p less than 0.05), and circumferential fiber shortening velocity by 19% (p less than 0.01); total peripheral resistance was decreased by 17% (p less than 0.001). The resultant increase in cardiac output amounted to 22% (p less than 0.01). In short, the main effect of ethanol at modest blood concentrations was to reduce LV preload without detectably impairing myocardial performance. Hangover was characterized by vasodilation as well as intensified LV myocardial and pump performances.

Systolic time intervals, the pre-ejection period (PEP), left ventricular ejection time (LVET) and PEP/LVET ratio were studied in ten thyrotoxic and ten hypothyroid patients. LVET and PEP intervals were corrected for heart rate (LVETc and PEPc). The measurements were repeated after 1-28 months when the patients were euthyroid following appropriate therapy. Compared with the euthyroid values, the PEPc intervals and PEP/LVET ratios were significantly decreased (p less than 0.01) in the thyrotoxic and increased (p less than 0.001) in the hypothyroid patients. In both groups the LVETc intervals were significantly prolonged (p less than 0.001). In four of the hypothyroid patients the PEP/LVET ratios were markedly increased (above 0.60, mean 0.66), and above 0.41 in the euthyroid state (reference value 0.35 +/- 0.05). In the other hypothyroid patients and in thyrotoxic patients the euthyroid PEP/LVET ratios were within the reference values. The systolic time intervals were not influenced by propranolol therapy in the thyrotoxic patients. Our results suggest increased myocardial contractility unaffected by adrenergic blockade in thyrotoxicosis, and reduced contractility in hypothyroidism.

Left ventricular performance in 54 patients with acute myocardial infarction was studied by means of systolic time intervals (STI) and ejection fraction (EF) determined using radionuclide technique. The data were correlated to clinical parameters of left ventricular heart failure and size of infarction. Thirty-seven patients were studied in the convalescent period with repeated registrations at 6, 10 and 24 weeks. Patients with left ventricular heart failure had markedly depressed EF, significantly different from EF in the non-heart failure group. STI did not show any difference. A strong correlation between infarct size and EF could be demonstrated. STI discriminated significantly transmural from non-transmural infarctions, and presented significant differences between those with normal EF (greater than 50%) and patients with EF below 35%. No significant changes could be found in left ventricular performance during the convalescent period, except for an increase in corrected preejection period (PEPc) probably due to drugs. The correlation between EF and STI was poor, the highest correlation coefficient being 0.55 between EF and the ratio PEP/LVET.

Relationships Between Systolic Time Intervals and Heart Rate During Initial Response to Orthostatic Manoeuvre in Men of Different Age An analysis of transient changes in physiological parameters in response to the standardized tests could be used to evaluate the efficiency of the regulatory processes. Relationships between systolic time intervals and heart rate following the action of standing up from the supine position were investigated in 41 healthy men, aged 20 to 59 years, classified into three groups: (22 to 26 yrs, n=14), (33 to 49, yrs, n=13) and (51 to 59 yrs, n=14). The protocol consisted of the following sequence: laying down (20 minutes) - standing up (8 minutes). Ejection time, pre-ejection period, electromechanical systole, heart rate and the length of R-R intervals were continuously calculated using automatized impedance cardiography and electrocardiogram. The ratio of ejection time to pre-ejection period in young men was significantly higher in comparison with the other groups. The ratio of ejection time to the length of R-R interval increased with age in supine position and after standing up when R-R interval was maximal. It was suggested that changes of ejection time to pre-ejection period during the orthostatic manoeuvre are rather the result of balance between heart rate and hemodynamic factors, than solely related to heart rate.

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 (projection 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 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.

Assessment of systolic time interval represents an uncomplicated, sufficiently precise and cheap possibility in clinical practice of cardiac monitoring during treatment with doxorubicin (adriamycin) if the ratio between pre-ejection period interval (PEPI) and left ventricular ejection time interval (LVETI) ("Weissler index") for evaluation of left ventricular cardiac function is used. In an investigation of 352 female patients with metastatic carcinoma of the breast statistically ascertained dose-response relationships could be established as regards electrocardiographic disorders of repolarisation and the systolic time interval (P less than 0.001). Pre-irradiated patients showed more ECG changes (P less than 0.001) and higher PEPI : LVETI values (P less than 0.001) than patients without prior irradiation. There was no general influence of cytostatic treatment on systolic and diastolic blood pressure values. The upper limit of a therapeutic risk in evaluation of the systolic time interval for cardiac monitoring of doxorubicin treatment should be 0.45-0.50 for PEPI : LVETI. Above this borderline value precise cardiac evaluation including invasive methods should be attempted if continuation of treatment is indicated. This regime could help prevent the occurrence of life-threatening cardiac crises during treatment with doxorubicin.

Systolic time intervals have been used to detect and quantify the directional changes of left ventricular function. New methods of recording these cardiac timings, which are less cumbersome, have been recently developed and this has created a renewed interest and novel applications for these cardiac timings. This manuscript reviews these new methods and addresses the potential for the application of these cardiac timings for the diagnosis and prognosis of different cardiac diseases.

We present a Matlab framework for heart sound processing and analysis. This framework includes algorithms developed for segmentation of the main heart sound components capable of handling situations with high-grade murmur, and for measuring systolic time intervals (STI). Methods for cardiac function parameter extraction based on STI are also included. Currently, the proposed algorithms are being extended for multi-channel applications. The algorithms outlined in the paper have been extensively evaluated using data collected from patients with several types of cardiovascular diseases under real-life conditions.

The study of left ventricular performance by means of systolic time intervals, especially represented by the PEP/LVET ratio and indices drawn from the first derivative of the apex cardiogram, makes possible a good approach to the functional anomalies of patients suffering from hypokinetic cardiomyopathies or hyperkinetic conditions of obstructive or unobstructive hypertrophic cardiomyopathies and of patients with hyperthyroid conditions. In hypokinetic states, the sensitivity and the specificity of the PEP/LVET ratio proved to be good, as was the case for indices taken from the first derivative of the apex cardiogram. However, the sensitivity and the specificity of the cardiogram were much better in the detection and evaluation of hyperkinetic conditions, hypertrophic cardiopathies or hyperthyroiditis. By providing the elements required for analysis of isometric contraction through indices drawn from the first derivative of the apex cardiogram and from the ejection phase, through the PEP/LVET ratio, and by adding exploitation of the diastolic phase, in particular through the A/H ratio exploring diastolic compliance, mechanocardiograms allow an all-round, quasi-physiopathological approach to disorders of left ventricular function during cardiomyopathies.

Systolic time intervals (STI) have significant diagnostic values for a clinical assessment of the left ventricle in adults. This study was conducted to explore the feasibility of using seismocardiography (SCG) to measure the systolic timings of the cardiac cycle accurately. An algorithm was developed for the automatic localization of the cardiac events (e.g. the opening and closing moments of the aortic and mitral valves). Synchronously acquired SCG and electrocardiography (ECG) enabled an accurate beat to beat estimation of the electromechanical systole (QS2), pre-ejection period (PEP) index and left ventricular ejection time (LVET) index. The performance of the algorithm was evaluated on a healthy test group with no evidence of cardiovascular disease (CVD). STI values were corrected based on Weissler’s regression method in order to assess the correlation between the heart rate and STIs. One can see from the results that STIs correlate poorly with the heart rate (HR) on this test group. An algorithm was developed to visualize the quiescent phases of the cardiac cycle. A color map displaying the magnitude of SCG accelerations for multiple heartbeats visualizes the average cardiac motions and thereby helps to identify quiescent phases. High correlation between the heart rate and the duration of the cardiac quiescent phases was observed.

Background: Pulmonary hypertension (PH) is commonly diagnosed by Doppler echocardiography (DE) of tricuspid regurgitation (TR). However, TR may be absent or difficult to measure. Hypothesis: Doppler-derived systolic time intervals of pulmonary artery (PA) flow may be used to predict PH in dogs. Animals: Seventy-three healthy dogs and 45 West Highland white terriers (WHWT) with interstitial pulmonary disease (IPD). Methods: Echocardiographic studies, including determination of right ventricular acceleration time (AT), ejection time (ET), and AT:ET ratio; right ventricular shortening fraction (RV-SF); and TR velocity, were performed. Pulmonary hypertension was defined by TR > 3.1 m/s. Results: In healthy WHWT, AT (median, range) was 73 ms (53 to 104) and AT:ET was 0.40 (0.28 to 0.55). AT:ET was minimally affected by age (R2= 0.04, 95% confidence interval [CI] 0.01–0.07, P < .001) but not by heart rate, body weight, or RV-SF. In all WHWT with TR, AT and AT: ET were inversely related to calculated systolic PA pressure (R2= 0.52, 95% CI 0.42–0.62, P < .001 and R2= 0.36, 95% CI 0.29–0.42, P = .001). Clinical cutoffs to predict systolic PH were defined for AT (58 ms; sensitivity [Se] 88% and specificity [Sp] 80%) and AT:ET (0.31; Se 73% and Sp 87%). Conclusion and Clinical Importance: PH is common in WHWT with IPD. Analysis of right ventricular AT and AT: ET may be predictive of PH and should be particularly useful if TR is absent.

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 (P0.05) 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.

The usefulness of automated measurements of the systolic time intervals in community screening deserves investigation. The systolic time intervals, including pre-ejection period (PEP), the left ventricular ejection time (LVET), and PEP/LVET were automatically and rapidly determined from signals of electrocardiography, phonocardiography, and pulse volume recording in 1087 residents agedor = 40 years in a community of homogeneous Chinese. Receiver operating characteristics analysis was performed to determine the cutoff values for PEP, ET, and PEP/LVET in predicting high N-terminal pro-brain natriuretic peptide (NT-proBNP). The prevalence of high NT-proBNP was 12.3% in men and 8.3% in women. NT-proBNP was linearly related to both PEP and PEP/LVET, while there was a U-shaped relationship between NT-proBNP and LVET. In men, the sensitivity and specificity in predicting high NT-proBNP levels were 60% and 60%, respectively, for PEPor = 89 ms; 60% and 62% for PEP/LVETor = 0.31; and 63% and 60% for LVET272 ms or LVETor = 310 ms. Various combinations of the criteria further improved either sensitivity or specificity. Women had slightly different cutoff values and performance for the various criteria of abnormal systolic time intervals and their combinations. Automated systolic time intervals appear to be useful in the screening of subjects with high NT-proBNP in a community.

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.

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±0.5y; range, 19–23y) 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° (p0.05). 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.

Blood pressure carries a great deal of information about people’s physical attributes. We analyzed the blood pressure signal in healthy subjects considering two positions, supine and sitting. 44 healthy subjects were studied. Parameters extracted from the blood pressure signal, related to time and frequency domain were used to compare the effect of postural position between supine and sitting. In time domain analysis, the time systolic interval and the time of blood pressure interval were higher in supine than in sitting position (p = 0.001 in both case). Parameters related to frequency peak, interquartile range, in frequency domain presented statistically significant difference (p < 0.0005 in both case). The blood pressure variability parameters presented smaller values in supine than in sitting position (p < 0.0005). In general, the position change of supine to sitting produces an increment in the pressure gradient inside heart, reflected in the blood pressure variability.