ICD implantation with and without combined myocardial revascularisation--incidence of ICD therapy and late survival.

BACKGROUND: Our aim was to evaluate the occurrence of implanted cardioverter-defibrillator (ICD) shock and antitachycardia pacing (ATP), the effect of ICD therapies on mortality and the impact of revascularisation strategies on arrhythmic events. PATIENTS AND METHODS: We investigated 130 CAD patients undergoing ICD implantation between 1984 and 1999. RESULTS: Freedom of shock was 66 +/- 7 %, 48 +/- 9 % and 48 +/- 9 % after 1, 3 and 5 years in patients with revascularisation and 62 +/- 8 %, 43 +/- 8 % and 23 +/- 11 % in patients without revascularisation, respectively; p = n. s. Freedom from ATP was similar in both groups - in patients with revascularisation, 64 +/- 6 %, 58 +/- 7 % and 58 +/- 7 % and without revascularisation 56 +/- 8 %, 51 +/- 9 % and 38 +/- 10 %, respectively; p = n. s. There were no significant differences in cumulative survival between patients with and without revascularisation; p = n. s. CONCLUSIONS: CAD patients with VT/VF and with implanted ICD have, despite successful revascularisation, the same rate of device therapy and mortality as patients without an indication of revascularisation. This implies that patients with chronic ischemic heart disease and ventricular tachyarrhythmias continue to be at risk of sudden death after CABG/PTCA; evaluation for ICD implantation is warranted.

Alternative to the transvenous approach in pediatric pacing - long-term experiences with bipolar epicardial pacing leads.

BACKGROUND: Cardiovascular anatomy and limited venous access may preclude the implantation of endocardial pacing systems in children as well as adults with congenital heart disease. Thus, the implantation of myo/epicardial pacing leads is required in these patients. The less favorable long-term results experienced in the past with myocardial screw-in leads are often used to justify the transvenous approach whenever possible, even in infants. However, encouraging preliminary results were reported from modern bipolar steroid eluting epicardial pacing leads. Further follow-up data are now warranted to obtain arguments for the dispute regarding the preferable or optimal pacing approach in infants and small children. Methods From January 1994 to November 2000 a total of 64 bipolar steroid-eluting epicardial pacing leads (Medtronic CapSure Epi 10366 and 4968, Medtronic, Inc, Minneapolis, MN, USA) were implanted in 52 children at our institutions (52 electrodes in ventricular and 12 in atrial position). The median age of the children was 25.5 months (range 0.03 to 193 months). As part of a prospective multicenter study these leads were continuously followed in combination with AutoCapture devices since December 1996. Results Telemetry data demonstrated at discharge low pacing thresholds both for the ventricular (0.8±0.37Volt @ 0.5ms) and the atrial leads (0.8±0.4Volt @ 0.5ms) as well as excellent sensing signals (P wave 2.9±1.4mV and R wave 10.6±5.5mV) without significant changes during follow-up up to 24 months. AutoCapture controlled pacing could be applied in 46/52 (88%) children rendering a calculated battery service life of 14.8±2.9 years with a VVIR device (Regency SR 5130, St. Jude Medical, Sylmar, CA, USA) and 10.8±1.1 years with a dual chamber device (Affinity DR 5330, St. Jude Medical, Sylmar, CA, USA). Apart from the necessity to reposition three leads in the immediate postoperative period no late lead related complications have been experienced during follow-up. Conclusions The new steroid-eluting bipolar epicardial pacing lead demonstrates a high reliability and consistent extraordinary pacing as well as sensing thresholds. AutoCapture controlled pacing is feasible in most patients and may result in marked battery service life extension. Hence epicardial pacing can now be highly recommended as the first choice for permanent pacing in infants and children.

Morphology discriminator feature for enhanced ventricular tachycardia discrimination in implantable cardioverter defibrillators.

The morphology discriminator (MD) feature is an electrogram template matching algorithm that intends to improve tachycardia discrimination in implantable cardioverter defibrillators (ICDs). The aim of this study was to evaluate the performance of this feature during spontaneously occurring ventricular and supraventricular tachyarrhythmias and exercise induced sinus tachycardia. Twenty-three patients (20 men, 3 women; mean age 54.3 +/- 13.8 years) with pectorally implanted Ventritex Contour MD, Angstrom MD, and Profile MD ICDs were studied. The stability of the acquired morphology template and performance of the algorithm during spontaneous tachyarrhythmias were evaluated at follow-up. A treadmill exercise test was performed in 16 patients along with continuous telemetric monitoring of matching scores. A satisfactory template could be acquired at baseline in 22 (96%) patients. Variations in electrogram morphology necessitated new template acquisition in seven (30%) patients at first follow-up (6-8 weeks postimplant). During a mean follow-up of 9.1 +/- 3.7 months, 56 ventricular tachycardia (VT) and 15 supraventricular tachycardia episodes (sinus tachycardia in two-thirds) in 11 patients were all appropriately discriminated by the MD feature. Exercise testing showed appropriate discrimination of sinus tachycardia in 15 (94%) of 16 patients. A common observation was postshock changes in electrogram morphology that resulted in transient mismatch with the template. In conclusion, the recently introduced MD feature in ICDs has a high sensitivity for detection of VT and high specificity for rejection of sinus tachycardia. Postshock changes in electrogram morphology have been observed that may cause inappropriate redetection. Marked variations of electrogram morphology over time may be a concern in some patients, especially during lead maturation.

DDD pacing mode survival in children with a dual-chamber pacemaker.

BACKGROUND: The persistence of DDD pacing is well documented in adults, however, in children survival of the DDD pacing mode is less clear. METHODS: We studied the survival of dual-chamber (DDD) pacing in 36 children aged 1 week to 16 years who underwent implantation of a dual-chamber pacing system between January 1986 and October 1998. The children were divided in the following two groups: 26 had epicardial pacing systems and 10 had endocardial pacing systems. RESULTS: During long-term follow-up 11 patients lost the DDD pacing mode. The DDD pacing survival rate at 3 months and 1, 2, and 5 years was 80%, 77%, 73%, and 69%, respectively. Age, weight, congenital heart disease, and epicardial pacing leads were not found to be risk factors for loss of DDD pacing mode. However, P-wave values of less than 2.5 mV at implantation of epicardial leads were associated with loss of the DDD pacing mode. CONCLUSIONS: The majority of children remain in the DDD pacing mode during long-term follow-up. A P-wave value of less than 2.5 mV at implantation of epicardial leads is a risk factor for loss of the DDD pacing mode.