Long-Term Antitachycardia Pacing Experience for Supraventricular Tachycardia

A pacemaker was used to control drug-resistant reentrant supraventricular tachycardia (SVT) in 40 patients. An antitachycardia pacemaker was implanted in 37 for SVT; in one for ventricular tachycardia that could also be used to terminate SVT; in one SVT could be terminated with an activity rate variable pacemaker; and in one a DDD pacemaker was used for prevention and termination of SVT. Twenty patients had AV nodal reentrant tachycardias, eight had tachycardias due to a concealed accessory pathway, eight had a Wolff-Parkinson-White syndrome, three had reentrant atrial tachycardias, and one had atrial flutter. Twenty-two patients were paced from the right atrium, five from the coronary sinus, ten from the right ventricle, and three had a DDD pacemaker. During a total follow-up period of 1,503 (mean 38) months an estimated 16,240 episodes of tachycardia were terminated promptly at home, 58 required several attempts, 57 episodes lasted longer than 30 minutes but did not require medical attention, and 11 required hospital admission. Hospital admission for SVT decreased from one per patient-month (in the 3 months before implantation) to 1 per 137 patient-months after implantation. Additional reentrant tachycardias occurred in 13 patients. Antiarrhythmic drug therapy in combination with a conservative antitachycardia pacing mode was required in four patients paced from the atrium to avoid pacing induced atrial fibrillation. Antiarrhythmic drug therapy was used in 42% of patients to help control SVT. Conclusions: (1) Drug-resistant SVTs can be safely and effectively managed on the long-term with antitachycardia pacemakers. (2) Rapid termination of SVT improved the quality-of-life significantly by avoiding prolonged episodes of tachycardia and repetitive hospital admissions.     

A Case Report Demonstrating Spontaneous Change in Tachycardia Terminating Window

A patient who received a patient-activated pacemaker system for termination of paroxysmal, drug-resistant, ventricular tachycardia is described. During the pre-implant invasive electrophysiological (EP) study and the three post-implant non-invasive EP studies, tachycardias were easily and reproducibly terminated by two stimuli using the interval scanning mode. On the fourth day post-implant, this pacing mode no longer terminated tachycardia at rest. A new pacing mode using more stimuli was then found to terminate the tachycardia reproducibly under various physiological conditions. This case report demonstrated a spontaneous change in the tachycardia terminating window and the usefulness of versatility in antitachycardia pacemaker systems.     

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

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 forseveral 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. 133 ±24 (p<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 toprove useful in the long-term treatment of many patients with recurrent ventricular tachycardia.     

Clinical Experience with a New Software-Based Antitachycardia Pacemaker for Recurrent Supraventricular and Ventricular Tachycardias

The Intermedics Intertach 262-12 tachycardia reversion pulse generator was implanted in 14 patients (six male, eight female, mean age at implantation 45 +/- 16 years) with recurrent symptomatic tachycardias. Six patients had atrioventricular (AV) nodal reentrant tachycardia, three patients had orthodromic tachycardia with Wolff-Parkinson-White syndrome, two had circus movement tachycardia via a concealed bypass tract, two had ventricular tachycardia, one patient had atrial flutter. Mean duration of symptoms before implantation was 8 +/- 4 years and mean number of antiarrhythmic drug trials was 3.5 +/- 1. The primary tachycardia response made consisted of autodecremental pacing in one patient, burst pacing in two patients, and adaptive scanning of the initial delay or burst cycle length in eleven patients. The secondary tachycardia response mode consisted of autodecremental pacing in four patients, burst pacing in three patients and burst scanning in four patients. Tachycardia response was automatic in all but one patient with ventricular tachycardia. During a follow-up period of 30.5 +/- 10.6 months, one patient with ventricular tachycardia died from a nonarrhythmic cause. Reinterventions were necessary due to electrode fracture in one patient and due to pacemaker software defect in another one. Two patients underwent surgical cure of their arrhythmia: one patient with atrial flutter and one patient with AV nodal reentry tachycardia, 24 months and 11 months postpacemaker implantation, respectively. Four patients required digitalis to prevent pacing induced atrial fibrillation. Other proarrhythmic effects were not encountered. The pacemaker proved to be a versatile system with reliable tachycardia detection and termination functions. It provided a valuable adjunctive therapy in these selected patients.     

Termination Of Sustained Tachycardia By External Noninvasive Pacing

Invasive cardiac pacing has proved useful in the induction and termination of reentrant sustained tachycardias. In one of our two cases, programmed ventricular extra-stimulation was used to induce sustained ventricular tachycardia from the endocardial surface of the right ventricle. Induced ventricular tachycardia was terminated by burst ventricular pacing with an external cardiac pacemaker. In our second patient, external pacing was effective at inducing and terminating sustained supraventricular tachycardia. These patients illustrate that the principles of terminating sustained reentrant tachycardia with invasive pacing may also apply to noninvasive external pacing. The usefulness of this approach in treating reentrant tachycardias needs further evaluation.     

Preliminary Studies with an Implantable Multimodal A-V Pacemaker for Reciprocating Atrioventricular Tachycardias

The efficacy of a recently developed programmable implantable pacemaker which can be used in the management of supraventricular tachycardias (with, or without, associated bradyarrhythmias) was evaluated in the cardiovascular laboratory and at the bedside in the coronary care unit. Although this pacemaker functions primarily in a DVI-DVO mode, it was also made (iatrogenically) to operate in a DOO mode. The study was performed in six patients with reciprocating atrioventricular tachycardias (four of the long P-R--short R-P type and two of the short P-R--long R-P type). Both DVI-DVO and DOO pacing abolished all episodes of tachycardia in five of the patients. However, DOO pacing was also capable of initiating episodes of tachycardia in two of the six patients. The events observed in two of the patients raise the possibility that (reversed) ventriculoatrial sequential pacing may be required in some tachycardias of the short P-R--long R-P type. This preliminary study suggests that programmability of pacing modes, rates, and intervals is a desirable feature that pacemakers used to manage drug-resistant tachycardias should have.     

Termination of Ventricular Tachycardia by an Implantable Atrial Pacemaker and External Pacemaker Activator

An atrial pacemaker was implanted in a patient who had dilated cardiomyopathy, sinus node dysfunction, and drug-resistant ventricular tachycardia (VT). VT episodes were terminated by atrial overdrive pacing using an implanted pacemaker and a newly developed hand-held external programmer/transmitter. Although successful cases of termination of intractable VT by ventricular pacing have recently been reported, the ventricular method might increase the risk of accelerating VT. Atrial overdrive pacing is a safer method since it minimizes the possibility of tachycardia acceleration and, combined with antiarrhythmic drugs, it appeared to be a unique and useful approach for the treatment of drug-resistant VT.     

The Importance of Antitachycardia Pacing for Patients Presenting with Ventricular Tachycardia

The initial experience from electrophysiological studies showed that pacing induced termination of ventricular tachycardias is usually possible but requires a critical pacing sequence. Studies on the resetting phenomenon showed, in most instances of failure of termination, that the "limiting factor" to produce ventricular tachycardia termination is usually failure to produce block within the circuit rather than failure to access or interact with the ventricular tachycardia origin. The resetting response is related to tachycardia termination in a number of ways. Of note is that a steeply increasing resetting pattern usually predicts tachycardia termination. Between 50% and 90% of induced ventricular tachycardias will be terminated by trains of rapid ventricular pacing. The analysis of the pacing rate necessary for termination shows that it varies widely. Paced cycle lengths of < 80% of tachycardia cycle length are necessary in at least 20% of tachycardias. In contrast, the incidence of acceleration is closely related to the paced cycle length: it is negligible with paced cycle lengths over 80% of tachycardia cycle length and increases to 36% with paced cycle lengths below 76% of tachycardia cycle length. Present information about efficacy of antitachycardia pacing in spontaneous tachycardias suggests that it is extremely effective, with over 90% success. However, it is likely that these data correspond to a selected group of tachycardias.     

Electrical Termination of Tachyarrhythmias by Discrete Pulses

Reentrant tachycardias can often be terminated by discrete pacing stimuli that penetrate the reentrant circuit. The ability of discrete stimuli to terminate an arrhythmia depends on the timing of the stimulus, the distance from the site of reentry where the stimulus is applied, the electrophysiologic properties of the myocardium between the site of stimulation and the site of reentry, and the size of the reentrant circuit.
Modes of pacing used to terminate tachycardia have included single or multiple timed extrastimuli, overdrive pacing, burst pacing and competitive asynchronous (underdrive) pacing. Patient-triggered devices that deliver asynchronous pacing stimuli are routinely available. Newer devices have been developed that automatically sense the onset of tachycardia and respond with pacing stimuli. These devices have been highly effective in selected patients with supraventricular tachycardia. The seriousness of occasional pacing-induced acceleration of ventricular tachycardia or conversion to ventricular fibrillation has limited the application of these devices in patients with ventricular arrhythmias. Pre-implantations electrophysiologic studies are necessary to document arrhythmia mechanisms and to determine the feasibility of various pacing modalities in treating the tachycardia. The potential for complicating arrhythmias (atrial fibrillation/flutter or ventricular fibrillation) must also be tested.
Future devices designed for terminating tachycardias with discrete pulses should be capable of being programmed to respond with one or more of the various modalities available. These devices should automatically and reliably sense both tachycardia onset and termination, and should adjust their responses appropriately if initial stimulation sequences fail to terminate the arrhythmia.     

Externally Activated Antitachycardia Pacemaker With Noninvasive Electrophysiologic Re-testing Capability

An Omni Orthocor 234A special device pacemaker was implanted in nine patients for treatment of drug-resistant supraventricular tachycardia (three patients) or ventricular tachycardia (six patients). This device is activated using a special external unit, which delivers from six to 15 stimuli at preselected coupling intervals ranging from 195 to 500 ms. Serial noninvasive electrophysiology studies were performed either in the hospital or on an outpatient basis using the triggered mode, which can respond to programmed chest wall stimulation. Three patients with reciprocating supraventricular tachycardia were treated effectively by this device during an average follow-up of 2.2 years. Of the six patients with stable ventricular tachycardia amenable to pacemaker termination, only four remained successful during an average follow-up of 1.9 years. Such devices may find important use in serial noninvasive electrophysiologic testing during long-term clinical follow-up. The present form of this device is inadequate for widespread application, but may be useful for highly selected individuals.     

Tachycardias Initiated by Automatic Antitachycardia Pacemakers

Available automatic tachycardia-terminating pacemaker cannot distinguish between physiological and pathological tachycardia and, consequently, electrical stimulation during sinus tachycardia can occur. In order to evaluate whether this might be an arrhythmogenic problem or not the cardiac response in eight patients having paroxysmal supraventricular tachycardia treated with tachycardia-terminating pacemakers was studied during exercise. After tachycardia recognition, the implanted pulse generator automatically emits single or double critically timed premature stimuli for termination of the arrhythmia. Post-implantation examination revealed successful tachycardia termination by the pacemaker at rest, without the addition of any antiarrhythmic drugs, in all eight patients. During exercise tests, the sinus rate in seven patients exceeded the programmed tachycardia trigger rate resulting in triggered pacemaker stimulation. The native supraventricular tachycardia was initialed in four cases. In one of these patients, two short episodes of probable ventricular tachycardia were also recorded. This study demonstrates the clinical value of post-implantation assessments with exercise tests concerning the problem of pacemaker-initiated tachyarrhythmias. Tachycardia-terminating devices can induce tachycardias, and individual precautions must be taken in order to prevent or minimize the risk of pacemaker reversion of sinus rhythm to paroxysmal tachycardia or hazardous arrhythmias.     

''Long-Term Results of Antitachycardia Pacing in Patients with Supraventricular Tachycardia

Between 1979 and 1984 the Cybertach-60, (Intermedics, Inc. Model 262-01), a programmable, automatic antitachycardia pacemaker was implanted in 11 patients who had drug-refractory supraventricular tachycardia (SVT). The patients have been followed for a total of 64-108 (mean 84 months). All patients were symptomatic and had failed two or more drugs and six patients had required prior DC cardioversion. The mechanism of supraventricular tachycardia was atrioventricular (AV) nodal reentry in six patients, AV reentry in four patients, and atrial tachycardia in one patient. Preoperatively all patients had reliable termination of the tachycardia without induction of atrial fibrillation by pacing methods available to Cybertach-60. Postimplant, Cybertach-60 reliably terminated all episodes of tachycardia without ancillary drug therapy. Nevertheless, at long-term follow-up antitachycardia pacing was effective and safe in the minority (36%), with only four patients out of eleven still using a pacemaker for supraventricular tachycardia. One of these four patients required additional drug therapy. In one of the patients, the Cybertach-60 was replaced after 78 months by a more advanced device, (Intertach, Intermedics, Inc.) because of a depleted Cybertach-60 battery. In seven patients who no longer use antitachycardia pacing for termination of tachycardia, one patient developed atrial fibrillation during tachycardia termination (at 58 months postimplant). Three patients experienced induction of tachycardia or atrial fibrillation by the pacemaker due to undersensing of sinus P waves (at 36, 48, and 51 months).(ABSTRACT TRUNCATED AT 250 WORDS)     

Atrial Antitachycardia Pacing in Patients with Supraventricular Tachycardia: Clinical Experience with the Intertach Pacemaker

MCCOMB, J.M., ET AL.: Atrial Antitachycardia Pacing in Patients with Supraventricular Tachycardia: Clinical Experience with the Intertach Pacemaker. During a 3-year period, 22 patients with recurrent supraventricular tachycardia have been treated with antitachycardia pacemakers [Intermedics Intertach, 262–12, n = 17, and Intertach II, 262–16, n = 5). Eighty-two percent were female, the mean age was 44 ± 14 years; 86% had atrioventricular node reentrant tachycardia. Symptoms had occurred over 11.8 ± 7.1 years, with 3.6 hospital admissions per patient, despite 4.7 ± 2.1 antiarrhythmic drugs. Following pacemaker implantation, during a follow-up of 14.8 ± 11.5 months, only two patients have been readmitted to a hospital because of supraventricular tachycardia (mean 0.1 per patient). One patient is taking an antiarrhythmic agent, and four are taking beta adrenergic blocking agents. Thus, 23% are taking cardioactive drugs (it was anticipated that two patients would continue on drugs after pacemaker implantation). There have been no serious complications. Atrial antitachycardia is thus an effective therapy in carefully selected patients with recurrent supraventricular tachycardia, reducing hospital admissions for supraventricular tachycardia and reducing the need for antiarrhythmic drugs.     

Transcutaneous Cardiac Pacing for Termination of Tachyarrhythmias

ALTAMURA, G., ET AL.: Transcutaneous Cardiac Pacing for Termination of Tachyarrhythmias. Transcutaneous cardiac pacing (TCP) was used for interruption of tachyarrhythmias in 31 patients: 20 with ventricular tachycardia (VT); eight with atrioventricular reentrant tachycardia (AVRT) and three had atrioventricular nodal tachycardia (AVNT). The stimulators used (Pace Aid 50/52) allow pacing at programmable rates (50–160 ppm) and output (10–200 mA at 20-msec pulse duration), when possible overdrive pacing was used. Short bursts of stimuli were delivered with increasing current intensity until interruption of the arrhythmia or to the maximum energy tolerated by the patient. VTs were interrupted in eight of the 20 patients: four of the six (67%) treated by overdrive pacing and four of the 14 (29%) were treated by underdrive pacing. Supraventricular tachycardias (SVT) were terminated in eight of the 11 patients: seven out of eight (88%) AVT, and one out of three AVNT (33%). We observed two cases of arrhythmia worsening: a VT acceleration and induction of ventricular fibrillation in a patient with AVNT. TCP was well tolerated by the majority of the patients. We conclude that TCP is an effective method for interruption of ventricular and supraventricular reentrant tachycardias, but the risk of arrhythmia worsening must be considered.     

Automatic Implantable Scanning Burst Pacemakers for Recurrent Tachyarrhythmias

Ninety patients (13 patients with supraventricular tachycardia and 72 patients with ventricular tachycardia) underwent electrophysiological study. Six out of 18 patients with supraventricular tachycardia (33%) and one out of 72 patients with ventricular tachycardia (1.4%) were considered suitable candidates for the scanning pacemaker. However, only six of the seven patients underwent implantation. The seventh patient decided not to undergo implantation and continued to have recurrent episodes of supraventricular tachycardia. The scanning pacemaker delivers extrastimuli at preset initial and coupled delay after four cycles of tachycardia. If tachycardia is not terminated, another set of extrastimuli are delivered with a decrement in the coupling cycle. During the follow-up period of 7-25 months (mean, 14.3 months), tachycardia cycle lengths and termination windows changed in four patients. The pacemakers in these patients were reprogrammed multiple times (2 to 6 times with a mean of 3.5) as the previous number of extrastimuli and intervals were ineffective in the termination of tachycardias. The major limitations of the extrastimulus pacemaker were: 1) only a small percentage of patients were suitable candidates for its use; (2) the initially selected termination window in the majority of patients was ineffective during the follow-up period due mainly to the changes in tachycardia cycle length and subsequent termination windows; and (3) the majority (five out of six patients in this series) of patients needed additional pharmacologic therapy to modify their tachycardia rates. However, despite these limitations, the scanning pacemaker may be an additional tool in the management of recurrent tachyarrhythmias in selected patients.     

Permanent Antitachycardia Pacemaker Therapy for Ventricular Tachycardia

This article describes our experience with an antitachycardia pacemaker alone (N = 3) or in combination with an automatic implontoble cardioverter defibrillator (AICD, N = 8) in the treatment of ventricular tochycardia. EJeven patients (mean ejection fraction 31%, mean oge 67 years) received an antitachycardia pacemaker. Nine had their units programmed for automatic antitachycardia pacing, one unit was programmed to automatic antitachycardia pacing by magnet activation only, and one to tachycardia detection and bradycardia support. Of the nine patients with automatic antitachycardia pacing, seven received appropriate and successful pace termination of spontaneous ventricular tachycardia at up to 120 times per month. Eight of these nine have had AICD implantations as well. There were no operative complications. Over a mean (± SD) follow-up of 12.1 ± 9.3 months (range 3–29 months), there have been two deaths, both due to heart failure. There have been four AICD discharges in three patients. Two units discharged in a clinically appropriate setting. The other two units, both with rate cutoffs <200 beats/min, were inadvertently triggered by the antitachycardia pacemaker and/or the underlying rate. In addition to the careful selection of the defibrillator rate cutoff, adverse device-device interactions were avoided by careful intraoperative lead positioning, and the disabling of bradycardia pacing when not needed or contraindicated. Antitachycardia pacing, with the safety provided by the AICD, is an effective treatment for patients with medically refractory ventricular tachycardia.     

Attempted Entrainment of Circus Movement Tachycardias by Ventricular Stimulation

. Entrainment was attempted while pacing the right ventricle in 12 patients with circus movement tachycardias. At the onset of stimulation eight patients had short episodes of intraventricular and atrioventricular dissociation during which the paced impulses activated the various ventricular recording sites (right and left), but did not reach the atria. The latter occurred because the ventricular olectrograms were recorded from parts of the ventricles which were not essential components of the reentry circuit. Relatively long (greater than 5 s) runs of entrainment were not possible in any case because of the relatively prompt termination of the tachycardias. Whereas in three patients this was due to the abrupt appearance of retrograde block in the accessory pathway, in nine patients it happened when the sequential, anterograde and retrograde, penetration of the AV node resulted in AV nodal block of the subsequent, reentering atrial impulse. The findings in this study showed that, with the methodology used, entrainment of circus movement tachycardias by ventricular stimulation had to be defined conceptually, by the fulfillment of requirements which did not include its occurrence for at least 5 seconds. Furthermore, the results also suggested that entrainment and tachycardia termination were best demonstrated by a technique which allowed the emission of the first stimulus in a constant (late) moment of the cycle, with deliverance of one additional stimulus at the same cycle length in successive pacing runs.     

Supraventricular Tachycardia Control with Tachylog II: Long-Term Follow-Up

SULKE, A.N., ET AL.: Supraventricular Tachycardia Control with Tachylog 11: Long-Term Follow-Up. Ten patients aged 16–63 years (mean 36.3) had the Siemens P56T "Tachylog II" pacemaker implanted for treatment of drug refractory supraventricular tachycardia. The pacemaker incorporates a noninvasive electrophysiological study (EPS) facility and a sophisticated Holter function combined with a unique "learning" self-search antitachycardia algorithm. The Holter reveals that new tachycardias arise that are not previously detected at conventional EPS. The number of stimuli in the initiation sequences during noninvasive EPS proved highly variable, however, termination sequences remained constant in the long term. There was variability of timing of stimuli in the long term that was significantly greater for "new" tachycardias than for "original" arrhythmias. Long-term follow-up [at 1 month, 6 months, and 1 year] have shown that 90% of patients have good tachycardia control without the need for drugs. All patients confirm the acceptability of this pacemaker for control of their arrhythmias in the long term.     

Intravenous Disopyramide Phosphate and Ventricular Overdrive Pacing in the Termination of Paroxysmal Ventricular Tachycardia

Both antiarrhythmic drugs and bursts of rapid ventricular pacing provide alternatives to DC cardioversion for the treatment of paroxysmal ventricular tachycardia. This report considers the individual and combined success of burst ventricular pacing and intravenous disopyramide phosphate in the tretment of 11 examples of paroxysmal ventricular tachycardia. Rapid ventricular pacing, at a rate of up to 50 beats/min faster than the tachycardia rate terminated 7 of the tachycardias. Intravenous disopyramide resulted in increased tachycardiac cycle length (342 +/- 34 ms-385 +/- 56 ms), increased QRS complex width (147 +/- 42 ms-180 +/- 41 ms) and termination of 8 the tachycardias. The remaining 3 tachycardias could be terminated by bursts of ventricular pacing following the infusion of disopyramide. Of these, 2 could not be terminated prior to disopyramide. The use of both techniques allowed the extinction of all 11 tachycardias and prevented the need to proceed to DC conversion.     

Clinical Experience with the Intertach 262-12 Pulse Generator in Patients with Recurrent Supraventricular and Ventricular Tachycardia

FROMER, M., ET AL.: Clinical Experience with the Intertach 262-12 Pulse Generator in Patients with Recurrent Supraventricular and Ventricular Tachycardia. An antitachycardia pulse generator, the Intermedics Intertach 262-12 was implanted in 16 patients (14 patients with supraventricular tachycardia of various origins and two patients with recurrent ventricular tachycardia), who were not responsive to various antiarrhythmic drug regimens. The follow-up was from 6–49 months (mean 30.9 ± 13.8). Five patients had a follow-up of over 3 years. The device was used in all patients. One patient with ventricular tachycardia died from a nonarrhythmic cause. Loss of responsiveness to burst pacing was observed in 1/14 patients with supraventricular tachycardia and nontolerance of antitachycardia pacing in one patient. Overall clinical success of pacing was observed in 13/16 patients = 81%. The pacemaker proved to be a versatile system with reliable tachycardia detection and termination functions.