Comparative Effectiveness of Pacing Techniques for Termination of Well‐Tolerated Sustained Ventricular Tachycardia

Abstract

Ventricular tachycardias can be terminated by a variety of pacemaker techniques, including rapid and slow stimulation. Fast tachycardias are typically poorly tolerated, and require prompt intervention, usually with rapid pacing. Termination of ventricular tachycardia by slow or single capture pacemaker stimulation techniques is attractive, because of its presumed safety and the possibility of using simple implantable pacers. To identify factors favoring termination, single capture stimulation was used in 390 episodes of ventricular tachycardia in 21 patients, 16 with coronary artery disease, able to tolerate ventricular tachycardia for several minutes. Single capture stimulation terminated 223 episodes (57%) in 18 patients, and two were accelerated. Of 157 episodes exposed to 2-3 programmed extrastimuli or rapid pacing 149 (94%) were terminated and 7 were accelerated. Direct current cardioversion was needed in 12 episodes. Without medications, only two patients tolerated VT. Only one patient had reliable termination with single capture stimulation over several days. Systolic blood pressure was similar in episodes terminated and not terminated by single capture stimulation, but the ventricular rate was significantly lower in episodes terminated, 116 +/- 19 vs. 1.33 +/- 24 (p less than 0.001). Termination of ventricular tachycardia was not affected by QRS morphology. Single capture termination of ventricular tachycardia is largely unpredictable, with limited reproducibility over a period of time. Although comparatively safe, single capture techniques are not likely to prove useful in the long-term treatment of many patients with recurrent ventricular tachycardia.

Electrophysiology of Ventricular Tachycardia:

“…Although increasing the number of stimuli from a single extrastimulus to bursts of rapid ventricular pacing increased the ability to terminate tachycardias from approximately 25% to 75%, an increasing incidence of acceleration of the tachycardia to a faster VT or VF was noted (35%). [106][107][108][109] Even VTs with rates >200 beats/min could be terminated by pacing 50% of the time, but the remainder required cardioversion. Thus, although a number of ATP modalities were developed for implantable devices, standalone ATP devices were never developed because acceleration of VT and/or degeneration of VT to VF by ATP was too unsafe.…”

Initial Clinical Experience With Endocardial Defibrillation Using an Implantable Cardioverter/Defibrillator With a Triple-Electrode System

“…In 9 of 10 patients in this article, defibrillation threshold obtained with the cutaneous patch electrode accurately reflected thresholds obtained with the subcutaneous patch.22 With the advent of hybrid devices in¬ corporating pacing and low-energy shock modes for tachycardia termination, the efficacy of these programmable parame¬ ters can also be tested prior to the device implant.23 This approach has been previously used for antitachycardia pace¬ makers. 24,25 Thus, the implant procedure would be abbrevi¬ ated and optimal device programming achieved rapidly. The results of late electrophysiologic studies paralleled implant and predischarge studies.…”

Interactions of antiarrhythmic drugs with implantable defibrillator therapy for atrial and ventricular tachyarrhythmias

“…In contrast, use of class 1C agents was associated with substantial increase of pacing threshold during short-and long-term therapy [37]. Data from the electrophysiologic laboratory suggest that the efficacy of antitachycardia pacing and lower energy cardioversion depend mainly on rate of the VT episode [48,49]. Because modern ICDs have extensive capabilities to antitachycardia pacing, antiarrhythmic drugs are frequently used to decrease the VT rate and make it more amenable to antitachycardia pacing.…”