ABSTRACT
Ventricular tachycardia (VT) initiation and its relation to various clinical factors was studied by reviewing intracardiac electrograms from patients with implantable cardioverter-defibrillators. Events were divided into (1) sudden onset without preceding ventricular premature complexes (VPCs), (2) extrasystolic onset with VPCs, or (3) paced, depending on the type and morphology of the last 5 beats before initiation of VT. Prematurity index, sinus rate, cycle length, and presence of short-long-short sequence for each episode was noted. A total of 268 episodes of VT among 52 patients were analyzed. Extrasystolic initiation was the most frequent pattern (177; 66%) followed by sudden onset (75; 28%) and paced (16; 6%). Among extrasystolic onset, 99 episodes (56%) were due to multiple VPCs and 149 episodes (84%) had different VPC morphology than the subsequent VT. Among pacing-induced VT, 13 of 16 episodes were due to inappropriate pacing due to undersensing of prior R waves. Sudden-onset episodes were slower (mean cycle length 383+/-97 ms) than extrasystolic (mean cycle length 336+/-88 ms, p = 0.002) and paced (mean cycle length 313+/-85 ms, p = 0.01) onset. Patients in the sudden-onset group had better left ventricular ejection fraction (33+/-15%) than the extrasystolic (29+/-11%, p<0.001) and paced (28+/-14%, p<0.01) groups. Extrasystolic onset with multiple, late coupled VPCs was the most common pattern of VT initiation and was associated with lower ejection fraction. Sudden-onset initiation was more common with better preserved systolic function.
Subject(s)
Defibrillators, Implantable , Electrocardiography/methods , Tachycardia, Ventricular/physiopathology , Aged , Cardiac Complexes, Premature/complications , Cardiac Pacing, Artificial , Case-Control Studies , Female , Humans , Male , Tachycardia, Ventricular/diagnosis , Tachycardia, Ventricular/etiologyABSTRACT
Compared with adults patients (n = 309) receiving implantable cardioverter-defibrillators at the same institution, pediatric patients (n = 11) exhibited a trend toward lower defibrillation thresholds. At follow-up of 29 +/- 17 months, the incidence of recurrent arrhythmias was similar, but lead revisions and device infections were more common in the pediatric patients.
Subject(s)
Arrhythmias, Cardiac/therapy , Defibrillators, Implantable/adverse effects , Adolescent , Adult , Child , Electrocardiography , Equipment Failure , Female , Follow-Up Studies , Heart Diseases/therapy , Humans , Male , Postoperative Complications/epidemiology , RecurrenceABSTRACT
Multiple technologic advances in the implantable cardioverter defibrillator (ICD) have resulted in smaller size, easier implantation, and improved detection, therapy, and stored diagnostic information. Advanced dual-chamber ICDs are currently available that allow dual-chamber rate-responsive pacing with mode switching, enhanced detection algorithms, antitachycardia pacing, low-energy cardioversion, high-energy shocks, and extensive diagnostics. Based on improvements in lead systems and improved energy waveforms, almost all devices are being implanted with nonthoracotomy leads in the pectoralis area. The results of recent clinical trials have expanded indications for the ICD for primary and secondary prevention of sudden cardiac death. With advances in capacitor and battery technology coupled with improved lead systems and waveform resulting in lower defibrillation thresholds, it is likely that lower-output, smaller devices will be developed. In the future, ICDs may have expanded indications and may incorporate physiologic sensors to access hemodynamic significance of arrhythmias and algorithms for prediction and prevention of cardiac arrhythmias.
