Dejan Danilovic

Automatic home monitoring of implantable cardioverter defibrillators

AIMS With the expanding indications for implantable cardioverter defibrillator (ICD) and reports of unexpected ICD failures, home monitoring (HM) was proposed to decrease follow-up workload and increase patient safety. Home monitoring implantable cardioverter defibrillators offer wireless, everyday transfer of ICD status and therapy data to a central HM Service Center, which notifies the attending physician of relevant HM events. We evaluated functionality and safety of HM ICDs. METHODS AND RESULTS A total of 260 patients with HM ICDs were monitored for a mean of 10 +/- 5 months. Time to HM events [medical (ventricular tachycardia/ventricular fibrillation) and technical (ICD system integrity)] since ICD implantation and since the latest in-clinic follow-up was analysed. Mean number of HM events per 100 patients per day was calculated, without and with a 2-day blanking period for re-notifying the same type of event. About 41.2% of the patients had HM events (38.1% medical, 0.8% technical, and 2.3% both types). Probability of any HM event after 1.5 years was 0.50 (95% confidence interval: 0.42-0.58). More than 60% of new HM event types occurred within the first month after follow-up. A mean of 0.86 event notifications was received per 100 patients per day or 0.45 with the 2-day blanking period. CONCLUSION Home monitoring is feasible and associated with an early detection of medical and technical events.

Invasive optimization of cardiac resynchronization therapy: role of sequential biventricular and left ventricular pacing.

Background: Aim of this invasive study was to characterize and quantify changes in left ventricular (LV) systolic function due to sequential biventricular pacing (BV) as compared to right atrial triggered simultaneous BV (BV0), LV, and right ventricular (RV) pacing in patients with congestive heart failure (CHF).

Clinical Performance of Automatic Closed‐Loop Stimulation Systems

Inos pacemakers use contraction dynamics to regulate the pacing rate according to the Closed‐Loop Stimulation (CLS) principle. The physician can program only the lower and upper rate limits, while the internal rate responsive parameters are continually adjusted to changing patient conditions. Seventy‐two patients with sinus node disease were enrolled in the multicenter Rate Behavior of the Pacing System Inos2 CLS during Daily Life (RAPID) study to evaluate the appropriateness of CLS rates during daily activities and the long‐term stability of the system. The pacemakers clearly differentiated between climbing stairs, descending stairs, and slow walking, with the corresponding peak rates of 104 ± 18, 95 ± 15 , and 88 ± 11  beats/min , respectively ( P < 0.001 for any pair of activities). The peak CLS rate during the color‐word test was significantly higher than that at rest ( 80 ± 8 vs 67 ± 7  beats/min, P = 0.002 ). The 24‐hour heart rate trends retrieved from the pacemaker memory at 3, 6, and 12 months after implantation appeared appropriate in all patients except for two whose pacing rates were occasionally too fast during the night. Mean diurnal and nocturnal rates determined at 3‐month, 6‐month, and 12‐month examinations fluctuated only slightly, from 74.6–75.3 beats/min (diurnal, P = NS ) and from 67.0–68.1 beats/min (nocturnal, P = NS ), indicating a satisfactory long‐term stability of the system. The incidence of atrial pacing events during the entire follow‐up was 82 ± 18% . A 6.5–8.3 beats/min difference, on average, between day and night (P < 0.001) and distinction between different daily activities seem to evidence sensitivity of the automatic CLS‐driven pacemakers to physiological demands despite minimum programming requirements. (PACE 2003; 26[Pt. I]:1432–1437)

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 550 Ω. 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.

Long-term symptom improvement and patient satisfaction following catheter ablation of supraventricular tachycardia: insights from the German ablation registry

Aims To analyse outcomes of supraventricular tachycardia (SVT) ablations performed within a prospective German Ablation Quality Registry. Methods and results Data from 12 566 patients who underwent catheter ablation of SVT between January 2007 and January 2010 to treat atrial fibrillation (AFIB, 37.2% of procedures), atrial flutter (AFL, 29.9%), atrioventricular nodal re-entrant tachycardia (AVNRT, 23.2%), atrioventricular re-entrant tachycardia (6.3%), and focal atrial tachycardia (AT, 3.4%) were prospectively collected. Patients were followed for at least 1 year. The periprocedural success rate was 96.3%, ranging from 84.3% (focal AT) to 98.9% (AVNRT). Kaplan–Meier mortality estimate at 1 year was 1.4% overall, and as high as 2.6% in the AFL group and 2.8% in the focal AT group. Recurrence of ablated or another symptomatic SVT was observed in 3783 (32.6%) of patients, ranging from 17.2% (AVNRT) to 45.6% (AFIB). Repeat ablation was performed in 12.0% of patients. After 1 year, 74.1% of survivors perceived ablation therapy as successful, 15.7% as partly successful, and 9.6% as unsuccessful. Even in those patients with arrhythmia recurrence, 76.0% perceived ablation as successful or partly successful and 89.6% would still undergo repeat ablation in the same institution. Conclusion Ablation therapy for SVT is a safe procedure bringing symptomatic improvement and satisfaction to three quarters of patients after 1 year. Even in patients with arrhythmia recurrence, a high satisfaction level and adherence to the ablating institution could be documented. Strikingly high mortality and stroke rates in follow-up were observed in AFL patients, who apparently need consistent long-term anticoagulation and more medical attention.

Ventricular evoked response as clinical marker for hemodynamic changes in dilative cardiomyopathy.

The potential value of ventricular evoked response (VER) evaluation by implantable pacemakers as clinical marker for disease induced hemodynamic changes in the heart, has so far not been explicitly evaluated. We conducted a study to evaluate the reproducibility of the R spike and T wave measurements (R(VER) and T(VER)) under controlled clinical conditions and examine the correlation between VER parameters and standard echocardiographic measurements in the left ventricle. Additionally, the utility of the VER as a marker for NYHA classification and the presence of cardiomyopathy was investigated. The Physios CTM 01 pacemaker capable of recording authentic VER signal morphology, was used with low polarization fractal coated pacing leads to obtain high‐fidelity VER recordings in 26 patients with conventional pacing indications (mean age: 69.1 ± 11.8 years; 20 men). Three patients suffered from dilative cardiomyopathy (DCM), 14 from hyperthropic nonobstructive cardiomyopathy (HNCM), and nine had no myopathy but suffered from coronary artery disease (CAD). Five patients were in NYHA Class IV, 19 in Class III, and two in Class II. Mean R(VER) and T(VER) amplitudes were calculated from one‐minute VER recordings. Standard echocardiography parameters were determined during this recording. Two follow‐ups at a mean distance of 11.3 ± 5.7 month were performed. The reproducibility of R(VER) or T(VER) (correlation factors: 0.992 and 0.981, respectively) was superior to the reproducibility of any echocardiographic parameter (correlation factors 0.404–0.943). There was no strong correlation between VER and any echo parameter. Both R(VER) and T(VER) were significantly reduced in NYHA Class IV patients (P < 0.05), and nearly significantly reduced in DCM versus other patients (P = 0.05–0.09). HNCM made no difference to CAD. The investigation shows that analysis of VER parameters bears a promising potential for dynamic monitoring of diseases affecting the hemodynamics, and of therapeutic effects, by means of regular, nonburdening pacemaker follow‐up examinations. (PACE 2004; 27:166–174)

A Comparison of Chronaxies for Ventricular Fibrillation Induction, Defibrillation, and Cardiac Stimulation: Unexpected Findings and Their Implications

Fibrillation Induction Chronaxie and Its Implications. Introduction: A low‐energy (≤ 4 J) cardioversion shock (LEC) either terminates reentrant ventricular tachycardia (VT) or accelerates it to ventricular fibrillation (VF). Optimization of the duration and amplitude of LEC shocks could improve the success rate of VT termination without VF induction.

Patient-tailored implantable cardioverter defibrillator testing using the upper limit of vulnerability: the TULIP protocol

AIMS We evaluated the feasibility of the TULIP (Threshold test using Upper Limit during ImPlantation) protocol, which was designed to provide a confirmed, low defibrillation energy value during implantable cardioverter defibrillator (ICD) implantation with only two induced ventricular fibrillation (VF) episodes. METHODS AND RESULTS Ninety-eight patients (62 +/- 12 years, 86 male) from 13 clinical centres underwent an active can ICD implantation. A single coupling interval derived from electrocardiogram lead II during ventricular pacing was used for VF induction shocks at 13, 11, 9, and 6 J in a step-down manner until the upper limit of VF induction (ULVI) was determined. If ULVI >or=9 J, a defibrillation energy of ULVI + 4 J was tested. For ULVI <9 J, the defibrillation test energy was 9 J. In 79/98 patients (80.6%), two induced VF episodes were sufficient to obtain confirmed defibrillation energy of 11.1 +/- 3.3 J. The mean strength of the successful VF induction shock was 6.8 +/- 4.3 J, the coupling interval was 303 +/- 35 ms, and the number of delivered induction shocks until the first VF induction was 3.9 +/- 1.6. CONCLUSION TULIP is a safe and simple device testing procedure allowing the determination of confirmed, low defibrillation energy in most patients with two VF episodes induced at a single coupling interval.

Relationship Between Selected Overdrive Parameters and the Therapeutic Outcome and Tolerance of Atrial Overdrive Pacing

ATTUEL, P., et al. : Relationship Between Selected Overdrive Parameters and the Therapeutic Outcome and Tolerance of Atrial Overdrive Pacing. There is a paucity of information on the influence of selected overdrive parameters on the clinical efficacy and tolerance of atrial overdrive algorithms to suppress atrial tachyarrhythmias. Data from a completed clinical trial investigating a new DDD+ overdrive algorithm implemented in a permanent pacemaker were analyzed. One‐hundred patients with standard pacing indications and atrial tachyarrhythmias were enrolled and followed for 6 months in DDD and 6 months in DDD+ mode in a randomized, crossover fashion. The overdrive step size was programmed at the discretion of the investigators between 4 and 12 beats/min, overdrive plateau length between 10 and 32 beats, and maximum overdrive rate between 100 and 160 beats/min. The effects of DDD+ versus DDD mode on burden and incidence of atrial tachyarrhythmias stored in the mode switch memory were examined as a function of the programmed overdrive parameters. An overdrive step size between 7 and 12 beats/min, and higher a maximum overdrive rate between 121 and 160 beats/min were slightly more effective than lower programmed values, though >500 randomized, crossover observations would have been necessary to verify statistical significance. Overdrive pacing related symptoms mandated early manual deactivation of overdrive pacing in 4.7% of 85 evaluated patients. Overdrive was disabled without testing tolerability of less aggressive overdrive values. There was no link between patient symptoms and programmed overdrive step size or overdrive plateau length values. (PACE 2003; 26[Pt. II]:257–263)

The influence of concomitant drug therapy on the efficacy of atrial Overdrive stimulation for prevention of atrial tachyarrhythmias

KONZ, K.‐H., et al .: The Influence of Concomitant Drug Therapy on the Efficacy of Atrial Overdrive Stimulation for Prevention of Atrial Tachyarrhythmias. Data from the completed “Suppression of Atrial Fibrillation by DDD+ Overdrive Pacing with Inos2 CLS (closed‐loop system) Pacemakers” multicenter trial were retrospectively evaluated to examine the influence of concomitant antiarrhythmic drugs on the clinical success of conventional single site right atrial overdrive pacing compared with DDD pacing. The DDD+ overdrive algorithm provided >90% atrial pacing at a rate slightly above the intrinsic atrial rate. Seventy‐five patients with conventional pacing indications and paroxysmal, recurrent atrial tachyarrhythmia have completed the study. They were randomized to 6 months of DDD or DDD+ pacing, followed by mode crossover and an additional 6‐month follow‐up in the alternate mode. The incidence of atrial tachyarrhythmia during each period was compared using data on sustained (>60 s) mode switch episodes stored in the pacemaker memory. A stable antiarrhythmic drug regimen was allowed during the study. β‐Adrenergic blockers and Class III antiarrhythmics, prescribed to 54.7% and 40.0% of patients respectively, were linked to minimal or no benefit of overdrive pacing compared with DDD pacing. In contrast, patients untreated with β‐adrenergic blockers or Class III drugs had a significant reduction in atrial tachyarrhythmia burden of >5 hours/patient per week (P < 0.05) during overdrive. Changes with Class I and Class IV antiarrhythmic drugs, prescribed to 18.7% and 13.3% of patients, respectively, were insignificant. Our data indicate that clinical trials that prohibit the use of β‐adrenergic blockers may record more favorable outcomes with dynamic atrial overdrive algorithms versus conventional DDDR pacing, than studies allowing concomitant β‐adrenergic blockade. (PACE 2003; 26[Pt. II]:272–277)