Significance of ventricular arrhythmias initiated by programmed ventricular stimulation: the importance of the type of ventricular arrhythmia induced and the number of premature stimuli required.

Abstract

An increasing number of premature ventricular stimuli are being used during programmed stimulation of the heart in the investigation of patients with documented or suspected ventricular arrhythmias. To analyze the significance of the different types of ventricular arrhythmias that are initiated, we evaluated in a prospective study the effect of from one to four ventricular premature stimuli in 52 patients without (non-VT group) and 50 patients with (prior-VT group) documented ventricular tachycardia or ventricular fibrillation. More than half of the patients in the prior-VT group had coronary heart disease. In the majority of patients of the non-VT group the heart was normal. In 44 of the 50 patients in the prior-VT group the clinically documented ventricular arrhythmia was initiated by programmed ventricular stimulation of the heart. In 88% of these 44 patients, one or two ventricular premature beats were required to initiate the clinical arrhythmia. A ventricular arrhythmia could be initiated in 31 of the 52 patients in the non-VT group. The ventricular arrhythmias included nonsustained monomorphic ventricular tachycardia (two patients), six to 25 complexes of sustained polymorphic ventricular tachycardia (24 patients), and ventricular fibrillation (five patients). In 70% of patients in the non-VT group three or four ventricular premature beats were required to initiate the ventricular arrhythmia. Our results indicate that not only the number of extrastimuli required to initiate ventricular arrhythmias but also the type of ventricular arrhythmia initiated differed between the two groups of patients. Nonsustained polymorphic ventricular tachycardia and ventricular fibrillation are nonspecific responses to aggressive stimulation protocols.Circulation 69, No. 1, 87-92, 1984. IN PATIENTS with ventricular tachycardia, programmed stimulation of the heart was initially introduced to study mechanisms of the arrhythmia. IA Subsequently it was realized that the method was of value to select the best mode of treatment -drugs, surgery, or pacemakers.5 13 Recently attention has been focused on the use of programmed electrical stimulation of the heart in patients resuscitated out of hospital'"'6 and those with unexplained syncope,'7 18 and for the identification of high-risk patients who have had myocardial infarction. [19][20] Over the past 10 years we have witnessed a gradual increase in the number of premature stimuli and stimu-

Proarrhythmic response to sodium channel blockade. Theoretical model and numerical experiments.

“…35 Multiple premature stimuli appear more effective than a single premature stimulus. 36 Our results suggest that the use of different drive and premature sites may be effective in initiating a reentrant rhythm. Recently, Frazier and coworkers37 showed that colliding wave fronts derived from perpendicular drive and premature stimulus sites could initiate a reentrant rhythm.…”

Modulated Dispersion Explains Changes in Arrhythmia Vulnerability During Premature Stimulation of the Heart

“…28 Moreover, during programmed stimulation, the likelihood of inducing reentry increased as the number of extrastimuli increased. 29,30 It is possible that a premature stimulus preconditioned the electrophysiological substrate and, accordingly, altered the likelihood of inducing reentry by a second (S 3 ) and possibly a third (S 4 ) premature stimulus. The results of the present study also suggested that in some circumstances, suitable conditions for reentry may not exist during baseline pacing but can form dynamically during premature stimulation of the heart.…”

Ventricular tachycardia in a young population without overt heart disease.

“…The use of a more rigorous and standarized stimulation protocol (double and triple extrastimulation) in all patients in the future would both increase the number of patients in whom ventricular tachycardia could be induced, and allow postulations regarding the mechanism. [55][56][57][58] Treatment. Once the decision to treat was made, a drug effective in preventing or controlling ventricular tachycardia could be identified in 14 of 17 patients (82%) with a combined approach of programmed stimulation, treadmill testing, and Holter monitoring.…”