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HINTRINGER, F., et al.: Comparison of the Specificity of Implantable Dual Chamber Defibrillator Detection Algorithms. The aim of the study was to compare the specificity of dual chamber ICDs detection algorithms for correct classification of supraventricular tachyarrhythmias derived from clinical studies according to their size to detect an impact of sample size on the specificity. Furthermore, the study sought to compare the specificities of detection algorithms calculated from clinical data with the specificity calculated from simulations of tachyarrhythmias. A survey was conducted of all available sources providing data regarding the specificity of five dual chamber ICDs. The specificity was correlated with the number of patients included, number of episodes, and number of supraventricular tachyarrhythmias recorded. The simulation was performed using tachyarrhythmias recorded in the electrophysiology laboratory. The range of the number of patients included into the studies was 78–1,029, the range of the total number of episodes recorded was 362–5,788, and the range of the number of supraventricular tachyarrhythmias used for calculation of the specificity for correct detection of these arrhythmias was 100 (Biotronik) to 1662 (Medtronic). The specificity for correct detection of supraventricular tachyarrhythmias was 90% (Biotronik), 89% (ELA Medical), 89% (Guidant), 68% (Medtronic), and 76% (St. Jude Medical). There was an inverse correlation (r =−0.9, P = 0.037) between the specificity for correct classification of supraventricular tachyarrhythmias and the number of patients. The specificity for correct detection of supraventricular tachyarrhythmias calculated from the simulation after correction for the clinical prevalence of the simulated tachyarrhythmias was 95% (Biotronik), 99% (ELA Medical), 94% (Guidant), 93% (Medtronic), and 92% (St. Jude Medical). In conclusion, the specificity of ICD detection algorithms calculated from clinical studies or registries may depend on the number of patients studied. Therefore, a direct comparison between different detection algorithms based on clinical data is difficult. In contrast, simulation of supraventricular tachyarrhythmias using a uniform database may be a better tool for direct comparison of the specificity of ICD detection algorithms. (PACE 2004; 27:976–982) [ABSTRACT FROM AUTHOR]

Presents a letter to the editor in response to an article by Firat Duru on ventricular tachyarrhythmias.

The article presents a case study of a 45-year-old man with fever and neurological disorder symptoms who was taken to the emergency room because weakness and sensory loss of the right limb. He survived without severe neurological deficits. He had also undergone drug-refractory atrial fibrillation before admittance. The article discusses the atrioesophageal fistula as life-threatening complication with mortality rate of 80 percent.

Background: As a preventive procedure, minimizing periprocedural risk is crucially important during left atrial appendage closure (LAAC). Methods: We included consecutive patients receiving LAAC at nine centres and assessed the relationship between baseline characteristics and the acute procedural outcome. Major procedural complications were defined as all complications requiring immediate invasive intervention or causing irreversible damage. Logistic regression was performed and included age and left-ventricular function. Furthermore, the association between acute complications and long-term outcomes was evaluated. Results: A total of 405 consecutive patients with a median age of 75 years (37% female) were included. 47% had a history of stroke. Median CHA2DS2-VASc score was 4 (interquartile range, 3–5) and the median HAS-BLED score was 3 (2–4). Major procedural complications occurred in 7% of cases. Low haemoglobin (OR 0.8, 95% CI 0.65–0.99 per g/dL, p = 0.040) and end-stage kidney disease (OR 13.0, CI 2.5–68.5, p = 0.002) remained significant in multivariate analysis. Anaemia (haemoglobin < 12 and < 13 g/dL in female and male patients) increased the risk of complications 2.2-fold. Conclusions: The major complication rate was low in this high-risk patient population undergoing LAAC. End-stage kidney disease and low baseline haemoglobin were independently associated with a higher major complication rate. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Supraventricular Tachycardia," by Ganz and Friedman in the January 19, 1995 issue.

Biventricular Pacing and Ventricular Repolarization. Introduction:Biventricular pacing has been shown to improve the clinical status of patients with congestive heart failure, but little is known about its influence on ventricular repolarization. The aim of our study was to evaluate the effect of biventricular pacing on ECG markers of ventricular repolarization in patients with congestive heart failure.Methods and Results:Twenty-five patients with congestive heart failure, sinus rhythm (SR), and complete LBBB (6 females; age 61± 8 years; NYHA class II–III; echocardiographic ejection fraction 21± 5%; QRS≥ 130 ms) underwent permanent biventricular DDDR pacemaker implantation. A high-resolution 65-lead body-surface ECG recording was performed at baseline and during right-, left-, and biventricular pacing, and the total 65-lead root mean square curve of the QRST complex and the interlead QT dispersion were assessed. The QRS duration was increased during right (RV)- and left ventricular (LV) pacing (127± 26% and 117± 40%; P<0.05), as compared to SR (100%) and biventricular pacing (93± 16%; ns). The QTc interval was increased during RV and LV pacing (112± 12% and 114± 14%; P<0.05) as compared to SR (100%) or biventricular pacing (99± 12%). There was no effect on JT interval during all pacing modes. The T peak-end interval was increased during right (120± 34%; P<0.01) and LV pacing (113± 29%; P<0.05) but decreased during biventricular pacing (81± 19%; P<0.01). A similar effect was found for the T peak-end integral and the T peak amplitude. QT dispersion was increased during right ventricular (129± 16 ms; P<0.05) and decreased during biventricular pacing (90± 12 ms; P<0.01), as compared to SR (114± 22 ms).Conclusions:Using a high-resolution surface ECG, biventricular pacing resulted in a significant reduction of ECG markers of ventricular dispersion of repolarization.(J Cardiovasc Electrophysiol, Vol. 16, pp. 1-7, May 2005) [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the long-term performance of the SonRtip atrial lead. Background: To optimize atrioventricular and interventricular timing and thereby potentially improving cardiac resynchronization therapy (CRT) responder rates, a lead integrated technology and a cardioverter/defibrillator-based algorithm measuring peak endocardial acceleration have been introduced. Long-term performance of the atrial lead (SonRtip PS55D, Sorin/MicroPort CRM, Italy) embedded with such a sensor has not been reported so far. Methods: Between 2012 and 2018, 143 patients underwent implantation of the SonRtip atrial lead in four Austrian medical centers. Conventional bipolar atrial leads implanted during the same period in 526 patients receiving CRT were used as control cohort. Results: Among 669 patients included in the study, 10 (1.5%) showed increased atrial pacing thresholds and/or decreased atrial sensing amplitudes and/or sudden increase in atrial lead impedance (above 3000 Ω) after an uneventful early postoperative period. Seven (70%) of the malfunctioning leads were SonRtip leads (p <0.001). Lead replacement was needed in 4.2% of SonRtip leads (six out of 143) and in 0.38% of all other conventional atrial leads (two out of 526) (p <0.001). Because of unaltered atrial sensing properties, a wait and see strategy was chosen in two patients–one of them with a SonRtip lead. The implanted atrial lead in the latter person experienced a sudden increase in pacing threshold (4V/0.35ms). Conclusions: While short-term safety and stable technical performance of the SonRtip atrial lead could be confirmed, our study found an unexpectedly high malfunction rate over a longer follow-up period. [ABSTRACT FROM AUTHOR]

Objective Vitamin K antagonists (VKA) are associated with increased vascular calcification which may lead to an elevated cardiovascular risk. If the direct anticoagulants (DOACs) have similar negative vascular effects is unknown. We evaluated the influence of different anticoagulation strategies on coronary artery disease (CAD) using coronary computed tomography angiography (CTA). Methods Overall 702 consecutive patients with non-valvular atrial fibrillation (AF) who underwent CTA for AF ablation planning were enrolled and stratified according to their anticoagulation into VKA, DOAC (all agents) and a control group without oral anticoagulation. Patients were propensity score matched 1:1:1, significant structural heart disease and comorbidities were excluded. CT images were evaluated for plaque burden (calcium score, segment involvement score (SIS) and non-calcified SIS, stenosis grading) and plaque morphology (high risk plaque features: low attenuation, positive remodeling, napkin-ring sign, spotty calcification). Results Final analysis included 303 patients (101 patients each group) and showed increased overall plaque burden in patients using VKA compared to DOAC users and the control group (mean affected segments 2.58 vs 1.58 vs 2.100, p = 0.008), and a higher prevalence of high-risk plaque (HRP) features (42.6% vs 13.9% vs 26.7%, p < 0.0001). Patients treated with DOACs did not differ in conventional CT findings from the control group and showed an even lower prevalence of selected HRP features compared to the control group: low-attenuation plaques (4.0% vs. 14.4%, p = 0.014) and napkin-ring sign (0 vs. 5.0%, p = 0.029). Conclusion Vitamin K antagonists are associated with a higher plaque burden and increased high-risk plaque features, whereas DOACs may yield a benefit in cardiovascular atherosclerosis. [ABSTRACT FROM AUTHOR]

Background: Sleep disordered breathing is a common but often undiagnosed comorbidity in heart failure patients. Cardiac implantable electronic devices used for cardiac resynchronization therapy (CRT) may detect sleep apnea by use of a transthoracic impedance sensor. Validation of the AP scan® algorithm (Boston Scientific®) was performed by using the diagnostic gold standard polysomnography (PSG). Methods: Forty-one patients with impaired left ventricular ejection fraction, frequent right ventricular pacing due to atrioventricular block and heart failure symptoms despite optimal medical therapy underwent upgrading to biventricular pacing. Within one month after left ventricular lead implantation, sleep apnea was assessed by single-night PSG and AP scan® measurements. Results: AP scan® measurements were valid in only 21 of 41 (51.2%) patients in the index night of the PSG. The PSG determined apnea-hypopnea index did not correlate statistically significant with the AP scan® measurements (r = 0.41, 95% confidence interval -0.05–0.72, p = 0.07). The degree of overestimation is displayed by using the Bland-Altman method: mean difference -12.4, standard deviation ± 15.8, 95% confidence interval -43.3–18.6. Conclusions: In heart failure patients receiving CRT upgrading, the AP scan® algorithm may need further improvement before it can be recommended for sleep apnea detection. [ABSTRACT FROM AUTHOR]

Purpose: To determine the effects of sex and age on cardiovascular autonomic parameters in healthy adults as assessed by Finapres (finger arterial pressure) method and prolonged head-up tilt (HUT). Methods: We enrolled 81 healthy volunteers (41 females, 40 males, 18-74 years) for extensive cardiovascular autonomic function testing including blood pressure (BP) recordings, electrocardiography, and impedance cardiography at rest, under 60° HUT for 45 min, active standing for 5 min, Valsalva maneuver, and deep breathing (DB). Mean values and orthostatic changes, i.e., differences to baseline, of heart rate (HR), systolic and diastolic BP, stroke volume (SV), and total peripheral resistance (TPR), as well as DB ratio and Valsalva ratio were calculated. A generalized linear model (extended by generalized estimating equations) was used to assess sex- and age-related differences. Results: Mean HR at rest was higher in women than in men ( p = 0.035). In men, we observed significantly higher mean BP at rest ( p < 0.001 systolic and p = 0.004 diastolic) and during HUT ( p = 0.001 systolic and p < 0.001 diastolic), mean TPR at rest ( p = 0.034), and mean SV during HUT ( p < 0.001). We found no significant impact of sex on orthostatic changes of HR and BP. Mean TPR during HUT increased with age ( p = 0.001), particularly in older women. Orthostatic changes of HR and diastolic BP, DB ratio, and Valsalva ratio became attenuated with age ( p = 0.018, p = 0.006, p < 0.001, and p < 0.001, respectively). Conclusions: Our study suggests that aging rather than sex needs to be taken into account when interpreting HR and BP changes during prolonged HUT performance. [ABSTRACT FROM AUTHOR]

Abstract: Simulation of cardiac cryoablation by the finite element method can contribute to optimizing ablation results and understanding the effects of modifications prior to time-consuming and expensive experiments. In this work an intervention scenario using a 9Fr 8mm tip applicator applied to ventricular tissue was simulated using the effective heat capacity model based on Pennes’ bioheat equation. Using experimentally obtained refrigerant flow rates and temperature profiles recorded by a thermocouple located at the tip of the applicator the cooling performance of the refrigerant was estimated and integrated by time and temperature dependent boundary conditions based on distinct phases of a freeze–thaw cycle. Our simulations exhibited a mean difference of approximately 6°C at the applicator tip compared to temperature profiles obtained during in vivo experiments. The presented model is a useful tool for simulation and validation of new developments in clinical cardiac cryoablation. [Copyright &y& Elsevier]

Implantable cardioverter–defibrillator (ICD) therapy decreases arrhythmic and all-cause mortality in patients at high risk of sudden death. However, its clinical benefit in elderly patients is uncertain. The aim of this study was to assess the long-term efficacy of ICD treatment in elderly patients and to identify markers of successful ICD therapy and risk factors of mortality. We performed multivariate analysis of a prospective long-term database from 2 tertiary care centers including 936 consecutive patients with an ICD. Predictors of ICD therapy and risk factors for mortality were assessed in patients ≥75 years old at ICD implantation compared to younger patients. Mean follow-up time was 43 ±40 months. Rates of ICD therapy were similar in the 2 age groups. No significant predictors of ICD therapy could be identified in older patients. Median estimated survival was 132 months in patients <75 years and 81 months in those ≥75 years old (p = 0.006). Decreased ejection fraction (hazard ratio 1.62 per 10% decrease, p = 0.03) and impaired renal function (hazard ratio 1.57 per 10 ml/kg/m2 decrease in estimated glomerular filtration rate, p = 0.02) were independent risk factors of mortality in patients ≥75 years old. However, mortality of older patients was similar to that of the age-matched general population irrespective of delivery of ICD therapy. In conclusion, ICD therapy is effective for treatment of life-threatening arrhythmias in all age groups. However, prevention of sudden cardiac death may have limited impact on overall mortality in older patients. Despite a similar rate of appropriate ICD therapies, risk of death is increased 1.6-fold in ICD recipients ≥75 years old compared to younger patients. Patients with decreased ejection fraction and impaired renal function are at highest risk. [Copyright &y& Elsevier]

Background: Little is known about the effect of cardiac resynchronization therapy (CRT) on endo- and epicardial ventricular activation. Noninvasive imaging of cardiac electrophysiology (NICE) is a novel imaging tool for visualization of both epi- and endocardial ventricular electrical activation. Methodology/Principal Findings: NICE was performed in ten patients with congestive heart failure (CHF) undergoing CRT and in ten patients without structural heart disease (control group). NICE is a fusion of data from high-resolution ECG mapping with a model of the patient's individual cardiothoracic anatomy created from magnetic resonance imaging. Beatto- beat endocardial and epicardial ventricular activation sequences were computed during native rhythm as well as during ventricular pacing using a bidomain theory-based heart model to solve the related inverse problem. During right ventricular (RV) pacing control patients showed a deterioration of the ventricular activation sequence similar to the intrinsic activation pattern of CHF patients. Left ventricular propagation velocities were significantly decreased in CHF patients as compared to the control group (1.6±0.4 versus 2.1±0.5 m/sec; p<0.05). CHF patients showed right-to-left septal activation with the latest activation epicardially in the lateral wall of the left ventricle. Biventricular pacing resulted in a resynchronization of the ventricular activation sequence and in a marked decrease of total LV activation duration as compared to intrinsic conduction and RV pacing (129±16 versus 157±28 and 173±25 ms; both p<0.05). Conclusions/Significance: Endocardial and epicardial ventricular activation can be visualized noninvasively by NICE. Identification of individual ventricular activation properties may help identify responders to CRT and to further improve response to CRT by facilitating a patient-specific lead placement and device programming. [ABSTRACT FROM AUTHOR]

Abstract: Background: Brugada syndrome (BS) is associated with an increased risk of sudden cardiac death (SCD) caused by ventricular tachyarrhythmia. Thus, implantable cardioverter defibrillators (ICD) became the main therapeutic option in these patients. We aimed to investigate the prevalence of BS in the Eastern Alps as well as the benefit of ICD therapy in this collective. Methods: During physical examination before military service, 47,606 Austrian men were screened for Brugada ECG pattern. Furthermore, we followed 4491 patients with arrhythmia during the last two decades, of which 26 patients (20 male; age at diagnosis: 43.2±11.6 years) revealed BS. Diagnosis was based on characteristic ECG either at rest (11 patients) or after provocation with Ajmaline (15 patients). Results: The nationwide screening revealed one individual with Brugada ECG (prevalence of 2.10/100,000 inhabitants). Prior to diagnosis of BS, syncope and SCD survival were observed in 7 and 4 patients, respectively; the remaining 15 patients were asymptomatic. ICD were implanted in 17 patients (15 male). Three asymptomatic patients received no ICD because no tachyarrhythmia was inducible on programmed stimulation. Six asymptomatic patients without family history of sudden death refused further evaluation. Mean ICD follow-up period was 57.0±32.2 months. Two patients (11.7%) needed defibrillation therapy. Four patients (23.5%) received exclusively inappropriate shocks (three due to T-wave oversensing, one due to atrial fibrillation). Conclusions: Brugada syndrome has a low prevalence in the Eastern alpine region. Patients with BS benefit from ICD implantation, but less frequently than anticipated. The problem of inappropriate ICD discharges is still of major concern. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: To assess whether fusion of multislice computed tomography (CT) images with electroanatomical (EA)-mapping data using a new image integration module (CartoMerge™) is feasible and accurate to navigate ablation catheters in right and left atrial catheter ablation. Material and methods: Twenty-four patients were examined with ECG-gated cardiac multislice CT (64mm×0.6mm, 0.33s) 1 day before left atrial (LA) (15 patients) radiofrequency or right atrial cavotricuspid isthmus ablation (9 patients). CT data were fused with the non-fluoroscopic EA-mapping data by using dedicated software (CartoMerge™) and the value of CT was analysed. Results: In 23/24 (96%) patients, CT images could be fused with the EA-map. The alignment error was 2.16±0.35mm. In 15/15 (100%) patients, CT added relevant anatomical information regarding the course of the esophagus or the pulmonary veins before LA-ablation. CT added useful information in only 3/8 (37.5%) of patients undergoing right atrial cavotricuspid isthmus ablation. Conclusion: 3D-navigation of RF-ablation catheters in the atria assisted by image fusion of multislice CT with EA-mapping data is feasible and accurate. CT added relevant anatomical information about the left atrium and the pulmonary veins before LA-ablation, CT also provided information about the course of the esophagus which might help to avoid thermal injury. CT image fusion might be of minor value before right atrial cavotricuspid isthmus catheter ablation. [Copyright &y& Elsevier]

(1) Background: The exact anatomic localization of the accessory pathway (AP) in patients with Wolff–Parkinson–White (WPW) syndrome still relies on an invasive electrophysiologic study, which has its own inherent risks. Determining the AP localization using a 12-lead ECG circumvents this risk but is of limited diagnostic accuracy. We developed and validated an artificial intelligence-based algorithm (location of accessory pathway artificial intelligence (locAP AI)) using a neural network to identify the AP location in WPW syndrome patients based on the delta-wave polarity in the 12-lead ECG. (2) Methods: The study included 357 consecutive WPW syndrome patients who underwent successful catheter ablation at our institution. Delta-wave polarity was assessed by four independent electrophysiologists, unaware of the site of successful catheter ablation. LocAP AI was trained and internally validated in 357 patients to identify the correct AP location among 14 possible locations. The AP location was also determined using three established tree-based, ECG-based algorithms (Arruda, Milstein, and Fitzpatrick), which provide limited resolutions of 10, 5, and 8 AP locations, respectively. (3) Results: LocAP AI identified the correct AP location with an accuracy of 85.7% (95% CI 79.6–90.5, p < 0.0001). The algorithms by Arruda, Milstein, and Fitzpatrick yielded a predictive accuracy of 53.2%, 65.6%, and 44.7%, respectively. At comparable resolutions, the locAP AI achieved a predictive accuracy of 95.0%, 94.9%, and 95.6%, respectively (p < 0.001 for differences). (4) Conclusions: Our AI-based algorithm provided excellent accuracy in predicting the correct AP location. Remarkably, this accuracy is achieved at an even higher resolution of possible anatomical locations compared to established tree-based algorithms. [ABSTRACT FROM AUTHOR]

The aim of the prospective, randomized, placebo-controlled Tyrolean Aortic Stenosis Study (TASS) was to characterize the natural history and risk factors and their possible modulation by new-onset atorvastatin treatment (20 mg/day vs placebo) in patients with asymptomatic calcified aortic stenosis. Forty-seven patients without previous lipid-lowering therapy or indications for it according to guidelines at study entry were randomized to atorvastatin treatment or placebo and prospectively followed for a mean study period of 2.3 ± 1.2 years. Patients'' prognoses were worse than expected, with 24 (51%) experiencing major adverse clinical events, in most cases the new onset of symptoms followed by aortic valve replacement. In multivariate regression analysis, independent risk factors for worse clinical outcomes were aortic valve calcification, as assessed by multidetector computed tomography, and plasma levels of C-reactive protein. In univariate analysis, mean systolic pressure gradient or an increased N-terminal–pro-B-type natriuretic peptide plasma level allowed the prediction of major adverse clinical events as well, whereas concomitant coronary calcification, age, and the initiation of atorvastatin treatment had no significant prognostic implication. As shown in a subgroup of 35 patients (19 randomly assigned to atorvastatin and 16 to placebo), annular progression in aortic valve calcification and hemodynamic deterioration were similar in both treatment groups. In conclusion, TASS could demonstrate a poor clinical outcome in patients with asymptomatic calcified aortic stenosis which can be predicted by new risk factors such as strong AVC or increased plasma levels of CRP or NT-proBNP. The study does not support the concept that treatment with a HMG-CoA reductase inhibitor (20 mg atorvastatin once daily) halts the progression of calcified aortic stenosis. [Copyright &y& Elsevier]

Objectives: There is still little information about the cardiorespiratory effects of cardiac resynchronization therapy (CRT) in patients undergoing all-day physical activity. This study aimed to assess the effects of CRT on ventilatory perfusion coupling during submaximal exercise. Methods: Metabolic and hemodynamic parameters were obtained during treadmill exercise testing as well as during rest for each single-right (RV), -left (LV) and biventricular (BiV) pacing mode as well as during intrinsic conduction (VVI 30) in 37 patients. Only responders to CRT (>10% increase in cardiac output (CO) during BiV pacing; n = 27) were included into the evaluation. Results: LV and BiV pacing increased systolic (144 ± 25 and 142 ± 28 vs. 118 ± 29 mm Hg, p < 0.05) and mean blood pressure (108 ± 19 and 109 ± 19 vs. 94 ± 25 mm Hg, p < 0.05) as well as CO (7.0 ± 0.6 and 7.2 ± 0.8 vs. 6.0 ± 0.6 l/min, p < 0.05 and p < 0.01) during exercise as compared to VVI 30. Simultaneously, LV and BiV pacing decreased dead space ventilation (18 ± 3 and 17 ± 3 vs. 20 ± 4, p < 0.01) and the ventilatory equivalent for oxygen (31 ± 4 and 31 ± 5 vs. 36 ± 6; p < 0.05) compared to intrinsic conduction. Conclusion: The improvement in ventilatory efficacy during CRT, which is demonstrated by the decrease in the ventilatory equivalent for oxygen, results from an increase in CO and thus from a reduction in the ventilatory perfusion mismatch. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Introduction: Radiofrequency (RF) catheter ablation targeting the slow pathway is currently the most effective treatment for patients with atrioventricular nodal reciprocating tachycardia (AVNRT). Gold exhibits a more than four times greater thermal conductivity than platinum, and the creation of deeper lesions was demonstrated in ex vivo animal experiments. The current clinical trial was initiated to compare gold catheters with standard platinum–iridium (Pt–Ir) material and to analyze differences in the increase of power or temperature as a function of time during RF ablation. Methods: A prospective, randomized multicenter study design was used to compare RF deliveries at the slow pathway with standard Pt–Ir tip catheters (128 patients), as well as gold alloy tip electrodes (124 patients) during AVNRT ablation. Results: Although there was a trend towards higher power delivery in the gold group (4.96 vs. 4.28 W/s), this trend was not statistically significant. Likewise, cumulative duration of all RF ablations, total procedure time, and power delivered at other time points were not significantly different between the groups. Also, the occurrence of AV-block and sensations of pain were similar in both treatment groups. However, charring on the catheter tip after the intervention was observed eightfold more frequently in the Pt–Ir group. Conclusion: In conclusion, power delivery cannot be significantly increased by RF ablation of AVNRT with gold electrodes. But the electrode material seems to be safe and well-tolerated and specifically did not increase the risk of AV-block. The significant reduction of coagulum formation on gold tips suggests a possible advantage of this material beyond its better conduction properties. [ABSTRACT FROM AUTHOR]

Dominant frequency (DF) computed from action potentials is a key parameter for investigating atrial fibrillation in animal studies and computer models. A recent clinical trial reported consistent results computing DF from 30 Hz to 400 Hz bandpass filtered bipolar electrograms in humans. The DF (< 15 Hz and, thus, filtered out) was recovered by rectifying the signal, while the theoretical background of this approach was left uncommented. It is the focus of this paper to provide this background by a Fourier analysis. We demonstrate that it is mainly the timing of the narrow deflections (local activation at the catheter tip) which contribute to the DF peak in the frequency spectrum. Due to the typical signal morphology pronounced harmonic peaks occur in the spectrum. This is a disadvantage when computing the regularity index (RI) as a parameter for local organization and signal quality. It is demonstrated for synthetical and patient data that at low DF the RI is far below the optimal value one even for high underlying organization and good signal quality. The insight obtained promotes the development of better measures for organization. The finding that mainly timing of activation contributes to DF might promote the development of powerful realtime signal processing tools for computing DF. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to determine whether noninvasive imaging of cardiac electrophysiology (NICE) is feasible in patients with Wolff-Parkinson-White (WPW) syndrome in the clinical setting of a catheter laboratory and to test the accuracy of the noninvasively obtained ventricular activation sequences as compared with that of standard invasive electroanatomic mapping. Background: NICE of ventricular activation could serve as a useful tool in the treatment of cardiac arrhythmias and might help improve our understanding of arrhythmia mechanisms. Methods: NICE works by fusing the data from high-resolution electrocardiographic mapping and a model of the patient’s cardiac anatomy obtained by magnetic resonance imaging. The ventricular activation sequence was computed with a bidomain theory-based heart model to solve this inverse problem. Noninvasive imaging of cardiac electrophysiology was performed in 7 patients with WPW syndrome undergoing catheter ablation of the accessory pathway. The position error of NICE was defined as the distance between the site of earliest activation computed by NICE and the successful ablation site identified by electroanatomic mapping (CARTO; Biosense Webster, Diamond Bar, California) for normal atrioventricular (AV) conduction as well as for adenosine-induced AV block. Results: The error introduced by geometric coupling of the CARTO data and the NICE model was 5 ± 3 mm (model discretization 10 mm). All ventricular accessory pathway insertion sites were identified with an accuracy of 18.7 ± 5.8 mm (baseline) and 18.7 ± 6.4 mm (adenosine). Conclusions: The individual cardiac anatomy model obtained for each patient enables accurate noninvasive electrocardiographic imaging of ventricular pre-excitation in patients with WPW syndrome. Noninvasive imaging of cardiac electrophysiology might be used as a complementary noninvasive approach to localize the origin and help identify and understand the underlying mechanisms of cardiac arrhythmias. [Copyright &y& Elsevier]

Background: The aim of this study was to investigate whether transvenous lead removal is safe and effective in patients with lead vegetations greater than 1 cm in size. Methods: From 1991 to 2005, a total of 53 patients underwent pacemaker or ICD lead removal for vegetations. Transvenous lead removal using locking stylets and sheaths was performed in 30 patients (56.6%) and was found to be effective in 29 of those patients. In 1 patient, due to rupture of the lead, open heart removal of the ventricular lead remnant and tricuspid valve repair had to be performed due to persistent infection. In 23 of these patients, transesophageal echocardiography (TEE) verified vegetations greater than 1 cm in size. The remaining patients underwent primary lead removal using sternotomy and extracorporeal circulation (ECC). Pacemaker pocket infection was found in 16 patients (55.2%) of the transvenous study group and in 11 patients (45.8%) of the ECC group (P = 0.72). Results: Perioperative mortality was 5.7% (3 patients); all of them underwent primary ECC removal and had severe endocarditis of the tricuspid valve. None of the patients who underwent transvenous lead removal died and there were no further complications such as pericardial tamponade or major pulmonary embolism requiring further interventions, even in patients demonstrating large vegetations. Conclusions: This study demonstrates that transvenous lead removal is a safe and highly effective procedure for the removal of infected pacemaker and ICD leads, even in patients with large vegetations. Embolism to the lung proceeds mainly without further complications; however, patients with vegetations that might obstruct a main stem of the pulmonary artery should undergo ECC removal. [ABSTRACT FROM AUTHOR]

ELLERY, S.,et al.: A New Endocardial“Over-the-Wire” or Stylet-Driven Left Ventricular Lead: First Clinical Experience. Transvenous left ventricular (LV) leads are primarily inserted“over-the-wire” (OTW). However, a stylet-driven (SD) approach may be a helpful alternative. A new polyurethane-coated, unipolar LV lead can be placed either by a stylet or a guide wire, which can be inserted into the lead body from both ends. The multicenter OVID study evaluates the clinical performance of this new steroid- and nonsteroid eluting lead. The primary endpoint is the LV lead implant success rate after identification of the coronary sinus (CS). Secondary endpoints include complication rate, short- and long-term lead characteristics, overall procedure and LV lead placement duration, total fluoroscopy time, and lead handling characteristics ratings. To date, 96 patients with heart failure (68± 9 years old, 76% men) are enrolled. The CS was identified in 95 patients and, in 85 (88.5%), the LV lead was successfully implanted. The final lead positioning was lateral in 41%, posterolateral in 35%, anterolateral in 18%, and great cardiac vein in 6% of patients. In 70%, the 85 successful implantations, both stylet-driven and guide-wire techniques were used, a stylet only was used in 22%, and a guide wire only in 8%. Mean overall duration of 85 successful procedures was 112± 40 minutes, total fluoroscopy time 28± 15 minutes, and the duration of LV lead placement was 35± 29 minutes. During a 3-month follow-up, the loss of LV capture occurred in three and phrenic nerve stimulation in six patients. The mean long-term pacing threshold is 0.8 V/0.5 ms and pacing impedance is 550Ω. The OVID data suggest that these new leads are safe and effective. The choice of both OTW and SD techniques during lead implantation offers greater procedural flexibility.(PACE 2005; 28:S31–S35) [ABSTRACT FROM AUTHOR]

STROHMER, B., et al.: Evaluation of Atrial Conduction Time at Various Sites of Right Atrial Pacing and Influence on Atrioventricular Delay Optimization by Surface Electrocardiography. Cardiac function and electrical stability may be improved by programming of optimal AV delay in DDD pacing. This study tested the hypothesis if the global atrial conduction time at various pacing sites can be derived from the surface ECG to achieve an optimal electromechanical timing of the left heart. Data were obtained from 60 patients following dual chamber pacemaker implantation. Right atrial septal pacing was associated with significantly shorter atrial conduction time (P < 0.0005) and P wave duration (P < 0.005), compared to standard right atrial pacing sites at the right atrial appendage or at the right free wall. The last two pacing sites showed no significant difference. In a group of 31 patients with AV block, optimal AV delay was achieved by programming a delay of 100 ms from the end of the paced P wave to peak/nadir of the paced ventricular complex. Optimization of AV delay resulted in a relative increase of echocardiographic stroke volume (SV) (10.9 ± 13.7%; 95% CI: 5.9–15.9%) when compared to nominal AV delay (170 ms). Optimized AV delay was highly variable (range 130–250 ms; mean 180 ± 35 ms). The hemodynamic response was characterized by a weak significant relationship between SV increase and optimized AV delay (R2= 0.196, R = 0.443, P = 0.047). The study validated that septal pacing is advantageous for atrial synchronization compared to conventional right atrial pacing. Tailoring the AV delay with respect to the surface ECG improved systolic function significantly and was superior to nominal AV delay settings in the majority of patients. (PACE 2004; 27:468–474) [ABSTRACT FROM AUTHOR]

BERGER, T., et al.: The Influence of High Versus Normal Impedance Ventricular Leads on Pacemaker Generator Longevity. As pacemaker generator longevity is dependent on current consumption and resistance of the pacing lead, the use of a high impedance pacing lead theoretically results in an extension of battery longevity. Therefore, the effect of high versus standard impedance ventricular leads on generator longevity was studied. In 40 patients (21 women, age 73 ± 13 years) with a standard dual chamber pacemaker indication, a bipolar standard impedance ventricular lead was implanted in 20 patients, the remaining patients received a bipolar high impedance lead in a randomized fashion. All patients received identical pacemaker generators and atrial leads. The estimated longevity of the generator was calculated automatically by a programmed pacemaker algorithm. After a mean follow-up of 39 ± 4.8 months, no significant differences were observed with respect to mean pacing and sensing thresholds of the atrial and ventricular leads in both groups. However, the high impedance leads displayed a significantly higher impedance and a significantly lower current drain as compared to standard impedance leads (1,044 ± 139 vs 585 ± 90 Ω, and 2.2 ± 0.4 vs 4.3 ± 1.1 mA). The extrapolated generator longevity was significantly longer in the high impedance lead group, as compared to the standard impedance lead group (107.3 ± 8.5 vs 97.6 ± 9.0 months; P = 0.02). In conclusion, implantation of a high impedance lead for ventricular pacing results in a clinically relevant extension of generator longevity. (PACE 2003; 26:2116–2120) [ABSTRACT FROM AUTHOR]

Introduction: Atrial arrhythmias have emerged as a topic of great interest for clinical electrophysiologists. Noninvasive imaging of electrical function in humans may be useful for computer-aided diagnosis and treatment of cardiac arrhythmias, which can be accomplished by the fusion of data from ECG mapping and magnetic resonance imaging (MRI). Methods and Results: In this study, a bidomain-theory–based surface heart model activation time (AT) imaging approach was applied to paced rhythm data from four patients. Pacing sites were the right superior pulmonary vein, left inferior pulmonary vein, left superior pulmonary vein, coronary sinus, posterior wall of right atrium, and high right atrium. For coronary sinus pacing, the AT pattern of the right atrium was compared with a CARTO map. The root mean square error between CARTO geometry (85 nodal points) and the surface model of the right atrium was 8.6 mm. The correlation coefficient of the noninvasively obtained AT map of the right atrium and the CARTO map was 0.76. All pulmonary vein pacing sites were identified. The reconstructed pacing site of right posterior atrial pacing correlates with the invasively determined pacing catheter position with a localization distance of 4 mm. Conclusion: The individual anatomic model of the atria of each patient enables accurate noninvasive AT imaging within the atria, resulting in a localization error for the pacing sites within 10 mm. Our findings may have implications for imaging of atrial activity in patients with focal arrhythmias or focal triggers. (J Cardiovasc Electrophysiol, Vol. 14, pp. 712-719, July 2003). [ABSTRACT FROM AUTHOR]

Activation time (AT) imaging from electrocardiographic (ECG) mapping data has been developing for several years. By coupling ECG mapping and three-dimensional (3-D) + time anatomical data, the electrical excitation sequence can be imaged completely noninvasively in the human heart. In this paper, a bidomain theory-based surface heart model AT imaging approach was applied to single-beat data of atrial and ventricular depolarization in two patients with structurally normal hearts. In both patients, the AT map was reconstructed from sinus and paced rhythm data. Pacing sites were the apex of the right ventricle and the coronary sinus (CS) ostium. For CS pacing, the reconstructed AT pattern on the endocardium of the right atrium was compared with the CARTO map in both patients. The localization errors of the origins of the initial endocardial breakthroughs were determined to be 6 and 12 mm. The sites of early activation and the areas with late activation were estimated with sufficient accuracy. The reconstructed sinus rhythm sequence was in good qualitative agreement with the pattern previously published for the isolated Langendorff-perfused human heart. [ABSTRACT FROM AUTHOR]

Background. New markers for stroke risk stratification in patients with atrial fibrillation (AF) are on demand. Hence, we aimed to investigate the association of left atrial appendage (LAA) and left atrium (LA) morphological parameters in patients with cardio-embolic (CE) stroke due to AF in comparison to controls without stroke. Methods: A retrospective analysis of cardiac computed tomography angiography (CTA) examinations performed between 2006 and 2017 for clinical indications in 158 patients (median age 65 (54–73) years, 48.7% females) was conducted: 56 patients with CE stroke were compared to 102 controls not differing in gender, body mass index (BMI) and CHA2DS2-VASc score. Results: On multivariable regression analysis adjusted for CHA2DS2-VASc score and LA diameter CE stroke was independently associated with the following parameters: windsock LAA type (OR 2.55; CI: 1.04–6.26, p = 0.041), a greater lobe number (OR 1.54; CI: 1.13–2.10, p = 0.006), a greater LAA ostium area (OR 1.88; CI: 1.38–2.55, p < 0.001) and a greater left atrium wall thickness (LAWT) in the middle and right part, measured along the anterior LA wall in the axial plane (respectively, OR 1.94; CI: 1.26–3.0, p = 0.003 and OR 1.57; CI: 1.07–2.31, p = 0.021). Conclusions: The windsock LAA type, a greater LAA lobe number, a larger LAA ostium and a greater LAWT are associated with CE stroke. These CTA parameters could improve risk stratification for thromboembolic stroke. [ABSTRACT FROM AUTHOR]

A correction to the article "Sex and Age Effects on Cardiovascular Autonomic Function in Healthy Adults," which appeared in a 2015 issue is presented.