Improvement of electrical synchrony in cardiac resynchronization therapy using dynamic atrioventricular delay programming and multipoint pacing.

BACKGROUND: Optimization of cardiac resynchronization therapy (CRT) is often time-consuming and therefore underused in a clinical setting. Novel device-based algorithms aiming to simplify optimization include a dynamic atrioventricular delay (AVD) algorithm (SyncAV, Abbott) and multipoint pacing (MPP, Abbott). This study examines the acute effect of SyncAV and MPP on electrical synchrony in patients with newly and chronically implanted CRT devices. METHODS: Patients with SyncAV and MPP enabled devices were prospectively enrolled during implant or scheduled follow-up. Blinded 12-lead electrocardiographic acute measurements of QRS duration (QRSd) were performed for intrinsic QRSd (Intrinsic), bi-ventricular pacing (BiV), MPP, BiV with SyncAV at default offset 50 ms (BiVSyncAVdef ), BiV with SyncAV at patient-specific optimised offset (BiVSyncAVopt ), MPP with SyncAV at default offset 50 ms (MPPSyncAVdef ), and MPP with SyncAV at patient-specific optimised offset (MPPSyncAVopt ). RESULTS: Thirty-three patients were enrolled. QRSd for Intrinsic, BiV, MPP, BiVSyncAVdef , BiVSyncAVopt , MPPSyncAVdef , MPPSyncAVopt were 160.4 ± 20.6 ms, 141.0 ± 20.5 ms, 130.2 ± 17.2 ms, 121.7 ± 20.9 ms, 117.0 ± 19.0 ms, 121.2 ± 17.1 ms, 108.7 ± 16.5 ms respectively. MPPSyncAVopt led to greatest reduction of QRSd relative to Intrinsic (-31.6 ± 11.1%; p < .001), showed significantly shorter QRSd compared to all other pacing configurations (p < .001) and shortest QRSd in every patient. Shortening of QRSd was not significantly different between newly and chronically implanted devices (-51.6 ± 14.7 ms vs. -52.7 ± 21.9 ms; p = .99). CONCLUSION: SyncAV and MPP improved acute electrical synchrony in CRT. Combining both technologies with patient-specific optimization resulted in greatest improvement, regardless of time since implantation. Whats new Novel device-based algorithms like a dynamic AVD algorithm (SyncAV, Abbott) and multipoint pacing (MPP, Abbott) aim to simplify CRT optimization. Our data show that a combination of patient tailored SyncAV optimization and MPP results in greatest improvement of electrical synchrony in CRT measured by QRS duration, regardless if programmed in newly or chronically implanted devices. This is the first study to our knowledge to examine a combination of these device-based algorithms. The results help understanding the ideal ventricular excitation in heart failure.

A new experimentally validated formula to calculate the QT interval in the presence of left bundle branch block holds true in the clinical setting.

BACKGROUND: The evaluation of the QT interval in the presence of left bundle branch block (LBBB) is associated with the challenge to discriminate native QT interval from the prolongation due to the increase in QRS duration. The newest formula to evaluate QT interval in the presence of LBBB suggests: modified QT during LBBB = measured QT interval minus 50% of LBBB duration. The purpose of this study is therefore to validate the abovementioned formula in the clinical setting. METHODS: Validation in two separate groups of patients: Patients who alternated between narrow QRS and intermittent LBBB and patients with narrow QRS who developed LBBB after transcatheter aortic valve implantation (TAVI). RESULTS: The acquired mean native QTc intervals and those calculated by the presented formula displayed no significant differences (p > .99 and p > .75). CONCLUSIONS: In this study we proved for the first time the validity and applicability of the experimentally acquired formula for the evaluation of the QT interval in the presence of LBBB in a clinical setting.

Insulation failure and externalized conductor of a single-coil Kentrox lead: an ongoing story?

Conductor externalization is a frequent complication with the St. Jude Medical Riata lead. Single case reports also reported externalization of conductors for dual-coil Biotronik leads. Up to now, conductor externalization has not yet been reported for any single coil leads. We report for the first time an externalization of conductors in a Biotronik Kentrox single-coil implantable cardioverter defibrillator (ICD) lead.

Q Wave in the Inferior Leads: There Is More Than Scar.

Q waves can regularly be observed in the 12-lead electrocardiogram either due to heart axis underlying pathology such as subacute myocardial infarction, myocardial scar, or accessory pathways. Rarely, other entities such as circumscribed hypertrophy can induce significant Q wave and represent an important differential diagnosis especially in younger patients. In the setting of atypical chest pain determination of the correct diagnosis can be challenging. Therefore, circumscribed hypertrophy should be taken into account to avoid unnecessary invasive procedures.

Cephalic Vein Cutdown Is Superior to Subclavian Puncture as Venous Access for Patients with Cardiac Implantable Devices after Long-Term Follow-Up.

BACKGROUND: Cephalic vein cutdown (CVC) and subclavian vein puncture (SVP) are the most commonly used access sites for transvenous lead placement of cardiac implantable electronic devices (CIEDs). Limited knowledge exists about the long-term patency of the vascular lumen housing the leads. METHODS: Among the 2703 patients who underwent CIED procedures between 2005 and 2013, we evaluated the phlebographies of 162 patients scheduled for an elective CIED replacement (median of 6.4 years after the first operation). The phlebographies were divided into four stenosis types: Type I = 0%, Type II = 1-69%, Type III = 70-99%, and Type IV = occlusion. Due to the fact that no standardized stenosis categorization exists, experienced physicians in consensus with the involved team made the applied distribution. The primary endpoint was the occurrence of stenosis Type III or IV in the CVC group and in the SVP group. RESULTS: In total, 162 patients with venography were enrolled in this study. The prevalence of high-degree stenosis was significantly lower in the CVC group (7/89, 7.8%) than in the SVP group (15/73, 20.5%, p = 0.023). In the CVC group, venographies showed a lower median stenosis (33%) than in the SVP group (median 42%). CONCLUSIONS: The present study showed that the long-term patency of the subclavian vein is higher after CVC than after SVP for venous access in patients with CIED.

[Stress testing: a relevant examination in rhythmology]. / Die Ergometrie: eine relevante Untersuchungsmethode in der Rhythmologie.

In recent years, imaging techniques have improved enormously. This leads to a decrease in stress testing indication for diagnosis and management of coronary artery diseases. However, stress testing remains an indispensable diagnostic tool for assessing patients' physical activity and their circulatory behavior during exercise. Using stress testing helps to assess patients' heart rate behavior or even to detect or trigger cardiac arrhythmias, for example, assessment of chronotropic competency, tachycardia-triggering or detection of a sudden heart rate drop with relevant bradycardia. The present review focuses on the assessment of stress testing in rhythmology. Since abnormal findings, which may indicate the presence of coronary heart disease, may occur during exercise testing, relevant ischemic criteria are also briefly addressed.

[Appropriate procedure for pacemaker and ICD malfunction]. / Sachgerechtes Vorgehen bei Herzschrittmacher- und ICD­Fehlfunktion.

Malfunctions in implanted pacemaker and defibrillator systems can affect all components of the device (battery, capacitor, central processing unit (CPU), connector, soldering points, electrodes). The resulting problems can manifest themselves as inadequate therapy, a lack of therapy despite the need for stimulation or shock release in case of ventricular tachyarrhythmia, or as an ineffective delivery of therapy. The high number of implanted pacemaker and defibrillator systems, the increased life expectancy and the technical progress of cardiac "device" therapy mean that the treating physician is confronted with increasingly complex problems in the follow-up. In addition to the knowledge of the basic function of these devices, a structured procedure to detect and treat malfunctions in a timely manner is required. In this review, frequent malfunctions of pacemaker and defibrillators are presented, individual problems are pointed out, and solutions and treatment options are shown.

[Fitness to drive in patients with cardiovascular implantable electronic devices]. / Fahreignung bei implantierten kardiovaskulären elektrischen Geräten.

The term CIED (cardiovascular implantable electronic devices) merges two groups of devices: pacemakers (PM) and defibrillators (ICD). PMs improve the symptoms of patients with bradycardic disorders, while ICDs reduce mortality in patients with increased risk for sudden cardiac death. However, these patients are still at risk of suffering malignant arrhythmias. Even after implantation of a pacemaker, syncope may occur. If these arrhythmias arise while driving, other individuals could be endangered. Therefore, it is important and obligatory for the treating physician to clarify this issue regarding driving restrictions to all patients, who present an indication for device treatment. The present publication focuses on the principal points of present guidelines and recommendations regarding fitness to drive in patients with cardiac disorders (especially with CIED).

Is there a prognostic relevance of electrophysiological studies in bundle branch block patients?

BACKGROUND: The present European guidelines suggest a diagnostic electrophysiological (EP) study to determine indication for cardiac pacing in patients with bundle branch block and unexplained syncope. We evaluated the prognostic relevance of an EP study for mortality and the development of permanent complete atrioventricular (AV) block in patients with symptomatic bifascicular block and first-degree AV block. HYPOTHESIS: The HV interval is a poor prognostic marker to predict the development of permanent AV block in patients with symptomatic bifascicular block (BFB) and AV block I°. METHODS: Thirty consecutive patients (mean age, 74.8 ± 8.6 years; 25 males) with symptomatic BFB and first-degree AV block underwent an EP study before device implantation, according to current guidelines. For 53 ± 31 months, patients underwent yearly follow-up screening for syncope or higher-degree AV block. RESULTS: Thirty patients presented with prolonged HV interval during the EP study (mean, 82.2 ± 20.1 ms; range, 57-142 ms), classified into 3 groups: group 1, <70 ms (mean, 62 ± 4 ms; range, 57-67 ms; n = 7), group 2, >70 to ≤100 ms (mean, 80 ± 8 ms; range, 70-97 ms; n = 18), and group 3, >100 ms (mean, 119 ± 14 ms; range, 107-142 ms; n = 5). According to the guidelines, patients in groups 2 and 3 received a pacemaker. The length of the HV interval was not associated with the later development of third-degree AV block or with increased mortality. CONCLUSIONS: Our present study suggests that an indication for pacemaker implantation based solely on a diagnostic EP study with prolongation of the HV interval is not justified.

Long-term survival with Cardiac Contractility Modulation in patients with NYHA II or III symptoms and normal QRS duration.

AIMS: Cardiac Contractility Modulation (CCM) is a treatment for heart failure based on electrical signals applied during the absolute refractory period. CCM improves myocardial molecular and biochemical characteristics of heart failure and improves exercise tolerance and quality of life. However, the long term impact on survival has not been described. METHODS AND RESULTS: Survival was determined retrospectively from a cohort of 68 consecutive heart failure cases with NYHA II or III symptoms and QRS duration ≤130ms, implanted with a CCM device between May 2002 and July 2013 in either Bochum or Ludenscheid, Germany. Results were compared with predicted survival (Seattle Heart Failure Model; SHFM) pre-implant for each patient. Mean follow-up was 4.5years (range 0.25-10.3years). Baseline characteristics were as follows: mean age 61years, 88% male, 68% with ischemic heart disease, 78% with an ICD, mean NYHA class 2.9±0.3, LVEF 26%±6% (range 15-40%) and mean QRS duration 106±11ms. Mortality rates (Kaplan-Meier analysis) at 1-, 2- and 5-years were lower with CCM than predicted by SHFM for the cohort (0% with CCM vs. 6.1% per SHFM, 3.5% vs. 11.8%, and 14.2% vs. 27.7%, respectively, p=0.007). CONCLUSIONS: Long-term mortality rates in heart failure patients with NYHA (II-III) and QRS≤130ms are lower when treated by CCM than predicted for the cohort. These findings warrant substantiation in a prospective study.

A randomized comparison of 5 versus 12 hours per day of cardiac contractility modulation treatment for heart failure patients: A preliminary report.

BACKGROUND: Cardiac contractility modulation (CCM) signals are non-excitatory electrical signals delivered during the absolute refractory period intended to improve contraction and cardiac function. Clinical trials have shown that CCM treatment significantly improves exercise tolerance and quality of life in symptomatic heart failure patients. Studies with CCM therapy typically include CCM delivery for 3, 5 or 7 h per day, although other configurations are also commonly used. Each has been associated with improved outcomes in heart failure, but it is not clear whether different application durations are associated with the various degrees of benefit. The purpose of the current pilot evaluation study was to evaluate the quality of life, exercise tolerance, and cardiac function, over a 6-month period when CCM was delivered for 5 h/day vs. 12 h/day. Increasing the daily CCM therapy duration is safe and as good as the standard CCM periods of application per day. METHODS: This single center pilot evaluation study involved 19 medically refractory symptomatic patients with heart failure and reduced left ventricular function who underwent implantation of an Optimizer™ system (Impulse Dynamics, Orangeburg, NY, USA). Patients were randomized into one of two treatment groups; 5 h/day CCM treatment or 12 h/day CCM treatment. Subjects and evaluating physicians were blinded to the study group. Subjects returned to the hospital after 12 and 24 weeks. Efficacy evaluations included changes from baseline to 24 weeks in Minnesota Living With Heart Failure Questionnaire score (MLWHFQ), maximal oxygen consumption in the cardio-pulmonary stress test (peak VO2), New York Heart Association classification (NYHA), 6-min walk distance (6MWD), and ejection fraction (EF). RESULTS: At the end of 24 weeks, clinical improvement was observed in the entire cohort in all efficacy measures (mean change from baseline of -17.1 in MLWHFQ, -0.86 in NYHA, and improvement trend of 1.48 mL O2/kg/min in peak VO2, 31.3 m in 6MWD, and 2.25% in EF). There were no significant differences, either clinically or statistically, between the groups receiving CCM for 5 h/day vs. 12 h/day. Three subjects were voluntarily withdrawn before completing the study. One subject died from pneumonia after 125 days, and 6 serious adverse events were reported, none of which was classified as related to either the device or the procedure. CONCLUSIONS: Together with previously reported experience with CCM, delivery of CCM therapy is equally safe and appears similarly effective over the range of shorter (5 h) to longer (12 h) daily periods of application. Given the small sample size, further studies are warranted.

Spot diagnosis of inferior axis and concordant R-pattern predicts left ventricular inflow tract tachycardia: Ablation from the great cardiac vein of an underdiagnosed entity.

BACKGROUND: The present literature holds an enormous variation concerning origin and ablation site of idiopathic ventricular arrhythmias (VA), ranging from 2.5 to 15% for the origin within the coronary venous system (CVS). The aim of the study was to detect positive predictive ECG morphology patterns to discriminate VA stemming from the CVS. METHODS: 110 consecutive patients (P) with 111 premature ventricular capture beat (PVC) morphologies undergoing successful ablation for VA were retrospectively analyzed concerning their ECG patterns. RESULTS: 20/110 P (18%) displayed their VA origin in the CVS with anterior/anterolateral left ventricular inflow tract (LVIT) (epicardial/GCV) in 16 P (14%), anterior/anterolateral LVIT (endo- and epicardial/GCV) in 3 P (3%), and anterior interventricular vein (AIV) 1 P (<1%). ECG morphology of all GCV cases demonstrated an inferior axis and concordant R-pattern in all precordial leads resulting in 100% sensitivity. One VA demonstrating this pattern was ablated outside at the LVOT resulting in 95% specificity for origin in the anterior/anterolateral LVIT. 3/20 P that were ablated in the CVS required additional endocardial ablation from the anterior/anterolateral LVIT resulting in 80% specificity for sole successful ablation in the CVS. CONCLUSION: An inferior axis and concordant R-pattern in all precordial leads serve as diagnostic markers for an LVIT origin in the surface ECG and suggest a high primary ablation success via the GCV.

New formula for evaluation of the QT interval in patients with left bundle branch block.

BACKGROUND: Left bundle branch block (LBBB) and QT prolongation both are associated with a worse prognosis. LBBB lengthens the QT interval. To date it is not known whether QT prolongation during LBBB differs in repolarization from QT prolongation during narrow QRS. OBJECTIVE: The purpose of the present proof-of-concept-study was to develop a formula that allows comparison of the adjusted QT interval during LBBB with reference values and thereby allows interpretation of the QT interval irrespective of QRS widening. METHODS: Sixty consecutive patients with sinus rhythm (SR) and narrow QRS underwent electrophysiologic study for ablation. In all patients, the intrinsic QRS ,QT, and JT times were measured during SR, and ventricular pacing from both the right ventricular apex (RVA) and the right ventricular outflow tract (RVOT) caused LBBB. We determined prolongation of the QT during as compared to SR (ΔQT). ΔQT was then divided by the QRS length during pacing QRS (QRSb). This describes the percentage of the QRS duration at LBBB, which must be subtracted from the measured QT (QTb) to determine the modified QT interval (QTm). RESULTS: The ratio of ΔQT to paced QRS was calculated as 48.3% (RVA) and 48.8% (RVOT) (mean 48.5%). The ratio intrinsic of JTi to paced JT was 1.0055 (RVA) and 1.0087 (RVOT). There was no significant difference in intrinsic JT vs paced JT (P = .2). CONCLUSION: Right ventricular pacing causes prolongation of the QT due to a paced LBBB without prolongation of the JT time. In our study, we showed that QT prolongation caused by LBBB constitutes 48.5% of the QRS width. This is the value that must be subtracted from the measured QT in LBBB in order to estimate the modified QT. Thus, the resulting formula for "modified QT" estimation in LBBB is QTm = QTb - 48.5% * (QRSb).