Clinical Usefulness of Chest Wall Stimulation in Patients with Automatic Tachycardia Terminating Pacemakers

Chest wall stimulation may be used diagnostically and therapeutically in the follow-up of patients with automatic tachycardia-terminating pulse generators. In this report, we present our experience with chest wall stimulation in the follow-up of five patients with implanted Intermedics CyberTach 60 automatic tachycardia-terminating pacemakers (three for supraventricular tachycardia and two for ventricular tachycardia). Chest wall stimulation delivered at a rate faster than the rate detection criterion of the pulse generator often precipitates reentry tachycardia, making it possible to perform a noninvasive electrophysiologic study. In addition, chest wall stimulation may be invaluable in the termination of reentry tachycardia which is unsensed by an implanted pulse generator either because the rate is too slow, or below the rate detection criterion, or because the intracardiac signal does not attain the sensitivity of the pulse generator.     

Transtelephonic Monitoring of a Tachycardia-terminating Pacemaker

A 66-year-old female with recurrent supraventricular tachycardia which worsened progressively was treated with an implanted tachycardia-terminating pacemaker after treatment with antiarrhythmic drug therapy had failed. The pacemaker had the capacity to detect and respond to tachyarrhythmias. Reliable sensing and termination of the patients tachycardia was accomplished in over 100 inductions of the tachyarrhythmia. Use of this tachycardia-terminating pacer has given us several new insights that may be important in the care and follow-up of all pacemaker patients.     

Double Sensing by Atrial Automatic Tacbycardia-Terminating Pulse Generator

This report describes two cases of double sensing of the P and QRS signals by an implanted atrial bipolar automatic burst tachycardia-terminating puise generator (Inlermedics CyherTach 60) used for the treatment of supraventricular tachycardia. Double sensing occurred during normai sinus rhythm at a rate slower than the tachycardia detection criterion and caused inappropriate delivery of burst stimulation. These observations underscore the importance of the far-field QRS signal in the detection of supraventricular tachycardia by automatic puise generators sensing the atrial eiectrogram.     

''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)     

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.     

Limitations to Activation of the Antitachycardia Burst Pacing Function of the Symbios 7008 Pacemaker in the Universal (DDD) Mode

The Symbios 7008 antitachycardia pacemaker was implanted in five patients for control of supraventricular tachycardia. Shortly after implantation in the first two patients, it was noted that the burst pacing sequence was not automatically activated by tachycardia when the pacemaker was in the DDD mode. Data from these two and the subsequent three patients were evaluated to explain this observation. The problem was primarily related to the operation of the device during the postventricular atrial refractory period. In all patients, the atrial electrogram encroached upon the programmed postventricular atrial refractory period because VA conduction during SVT was less than the lowest programmable interval (155 ms). Atrial events occurring during this interval will not trigger the tachycardia termination sequence. In all five patients, the size of the atrial electrogram decreased substantially (48 +/- 10%; mean +/- SD) during supraventricular tachycardia compared to sinus rhythm. In at least two of the five patients, decreased atrial size during supraventricular tachycardia may also have resulted in intermittent failure of atrial sensing during tachycardia, even at the most sensitive setting (0.6 mV). The latter may remain a problem even if the technical fault in SVT detection in the DDD mode were corrected. Two related problems were noted in the DDD mode: ventricular events during rapid SVT do not reset the low rate interval, resulting in random low rate pacing; and, automatic prolongation of atrial refractory period by two successive ventricular events without an intervening atrial sensed event compounds problems of atrial sensing. All of these problems were easily circumvented in all patients by noninvasive reprogramming to the DVI mode in which supraventricular tachycardia detection is based on ventricular sensing. These findings have implications for the future design of such devices.     

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.     

Surgical Therapy for Sinoatrial Reentrant Tachycardia

Sinoatrial reentry is an uncommon cause of paroxysmal supraventricular tachycardia. This paper presents a case of supra ventricular tachycardia, refractory to medical therapy, in which the sinus node formed part or all of the reentrant circuit. The mechanism of the arrhythmia was confirmed by catheter mapping during electrophysiological study and by intraoperative epicardial mapping. Cryosurgical ablation of the right atrium in the region of the sinus node has led to cure of her arrhythmia and emergence of a stable ectopic atrial pacemaker rhythm.     

胺碘酮治疗阵发性室上性心动过速30例临床分析

目的：探讨胺碘酮治疗阵发性室上性心动过速的临床效果及安全性。方法：回顾性分析2011年1月至2012年12月收治的应用胺碘酮治疗阵发性室上性心动过速30例的临床资料。结果：本组30例中,3小时内恢复窦性心律25例（83．3％）,5小时内恢复窦性心律2例（6．7％）,8小时内恢复窦性心律2例（6．7％）,24小时内恢复窦性心律1例（3-3％）;治疗过程中未见严重副作用。结论：胺碘酮治疗快速性室上性心动过速安全有效。     

Long-Term Follow-Up of Patients Treated with Automatic Scanning Antitachycardia Pacemaker

The long-term efficacy of an automatic antitachycardia pacemaker was evaluated in 13 patients with supraventricular tachycardia and in two patients with ventricular tachycardia. Patients were followed for 4–53 months (median 16). The concertina scanning mode with 2–7 extrastimuli proved to be effective in all patients but one. During follow-up, two patients had to be reoperated due to sensing problems. Atrial flutter was induced during scanning in one patient, termination mode was triggered by sinus tachycardia in one patient despite beta blocker therapy, and in one patient after cessation of beta blocker treatment. The pacemaker did not induce any serious arrhythmias and no sudden deaths occurred. Seven patients were given beta blockers, one patient with ventricular tachycardia was additionally administered amiodarone. In conclusion, the PASAR 4171 (Telectronics, Englewood, CO, USA) automatic scanning pacemaker is an alternative or adjunctive means to chronic antiarrhythmic drug therapy in patients with supraventricular tachycardia, but further versatility with regard to sensitivity, refractory period, and tachycardia recognition is required to eliminate the shortcomings observed, including the need for additional beta blocker therapy.     

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.     

Long-Term Management of Ventricular Tachycardia by Implantable Automatic Burst Tachycardia-Terminating Pacemakers

This report describes the Jong-term follow-up of two patients who received implantable automatic burst tachycardia-terminating ventricular pacemakers for the treatment of drug-refractory sustained ventricular tachycardia. After implantation, both pulse generators continued to terminate ventricular tachycardia without any major complications. In one patient, after three years, many episodes of ventricular tachycardia were slower than the tachycardia-detection criterion rate of 137 per minute; ventricular tachycardia was then terminated by chest wall stimulation that activated the burst function of the pacemaker. In this particular patient, the pulse generator was removed after four and one-half years and replaced with a DDD system because of the pacemaker syndrome and attacks of ventricular tachycardia, often at a rate of about 100/minute. In the second patient, the pacemaker continued to terminate ventricular tachycardia for over five and one-half years as determined by the repeated activation of the flag (memory) function of the pacemaker indicating detection of tachycardia by the pulse generator and resultant delivery of burst pacing.     

Incessant Reciprocating Atrioventricular Tachycardia

The case of a patient suffering from incessant supraventricular tachycardia is presented. The electrophysiological study showed the presence of an accessory atrioventricular (A-V) bundle with nodal-like properties and long conduction times. This structure was used as the retrograde arm of the tachycardia circuit. Tachycardia was intermittent at rest, but had a sustained character during slight exercise. Administration of atropine and isoproterenol failed to sustain the arrhythmia and spontaneous initiation during sinus rhythm was no longer observed. During handgrip exercise a sustained tachycardia developed immediately. During ventricular stimulation a dual atrial response to a single paced ventricular premature beat was repeatedly observed, proving the availability of two separate A-V pathways for retrograde conduction. The case illustrates the labile nature of this type of accessory pathway, and suggests that autonomic changes can play an important role in the initiation, maintenance, termination, or even spontaneous cure of tachycardia in patients with this anomaly.     

Dual-demand pacing for refractory atrioventricular re-entry tachycardia.

An automatic dual-demand pacemaker has been used in six patients to treat refractory attacks of paroxysmal re-entry atrioventricular tachycardia that occurred in the Wolff-Parkinson-White syndrome. The pacemaker was designed to pace at a fixed rate of 70 beats per minute when sensed heart rates were either below this rate or above 150 beats per minute; in the latter case, it would compete with the paroxysmal tachycardia and interrupt it after a short period of random scaning. The best location for the permanent pacing electrode and the feasibility of using the pacemaker were tested in each case during a detailed preliminary intracardiac electrophysiological study. The permanent pacing electrode was positioned in the coronary sinus in three patients and was attached to the epicardium of either the left or right ventricle in another three. All patients were given regular oral doses of verapamil or propranolol to enhance the effectiveness of the pacemaker system and, with the latter, to prevent pacemaker activation during sinus tachycardia. Over a follow-up period of between 11 and 47 months, the pacemaker system remained completely effective in three patients, but developed unreliable sensing in another two (one coronary sinus and one left ventricular lead). In the sixth patient the pacemaker was only effective when the rate of the tachycardia remained below 170 beats a minute, as when she was resting supine; when sitting or standing, however, her tachycardia rate considerably exceeded this value and the pacemaker was ineffective. Explantation of the pacemaker and either successful cryosurgical ablation of the accesory AV pathway or treatment with amiodarone was undertaken in the three patients in whom the pacemaker had failed.     

Surgical Treatment of Supraventricular Tachycardia: A Five-Year Experience

Two hundred and eight patients underwent operative therapy of supraventricular tachycardia between June 1984 and June 1986. There were 196 patients with Wolff-Parkinson-White syndrome, one with AV nodal reentry, two with atrial flutter, one with ectopic atrial tachycardia, three with paroxysmal sinus tachycardia, and five with atrial fibrillation. Map guided or direct surgery was performed in all patients except the three with atrial fibrillation. Direct surgery was generally successful with failures including one patient with Wolff-Parkinson-White syndrome, one with atrial flutter, and the three patients with paroxysmal sinus tachycardia. There was no mortality. Major complications were uncommon and included three resternotomies for bleeding, one chylopericardium. Six patients required reoperation.     

Clinical Interest of a Sensor Driven Algorithm Limiting Ventricular Pacing Rate During Supraventricular Tachycardia in Dual Chamber Pacing

A sensor driven algorithm limiting ventricular pacing rate during supraventricular tachycardia (SVT) is included in a dual chamber rate modulated pacemaker sensitive to acceleration forces (Relay, 294-03, Intermedics Inc.). According to the intensity of concomitant exercise, the ventricular pacing rate is limited either to the programmed maximum pacing rate (MPR) or to an interim lower limit, called "conditional ventricular tracking limit" (CVTL). The MPR prevails over the CVTL when the sensor calculated pacing rate exceeds the minimal rate by more than 20 beats/mm. The purpose of the study is to determine the clinical safety and efficacy of this algorithm in patients with intermittent SVT. Method: a Relay was implanted in four patients with a bradycardia/tachycardia syndrome and in four patients with complete atrioventricular block (CAVB). All had episodes of paroxysmal atrial tachycardia. The units were programmed in DDDR: rate responsive parameters were adjusted by simulating the rate response during three levels of exercise to let the MPR override the CVTL only during strenuous exercise. Holter monitors and exercise testings were performed at 3-month follow-up. Results: in seven patients, Holter recordings showed Supraventricular arrhythmias at rest with a ventricular pacing rate limited to the CVTL. Appropriate rate increases during exercise testings were also demonstrated. Three devices had to be reprogrammed in DDIR tone patient suffering from nearly permanent atrial flutter and two patients not tolerating the CVTL pacing rate at rest). Conclusion: the CVTL algorithm is effective in protecting against high ventricular pacing rates during Supraventricular arrhythmias. It allows the selection of the DDDR mode even with a high MPR in patients with intermittent SVT.     

长RP间期阵发性室上性心动过速的电生理鉴别方法

阵发性室上性心动过速包括房室结折返性心动过速、房室折返性心动过速及房性心动过速等多种类型。目前临床上常用的鉴别方法包括心动过速时应用心室起搏拖带、希氏束不应期/非不应期的心室期前刺激及心房不同部位起搏的方法,窦性心律下应用希氏束旁起搏、心室不同部位/频率刺激等方法。心室起搏拖带可观察多个指标,为临床最常用的鉴别方法之一...     

Radiofrequency Catheter Ablation of Sinus Node Reentrant Tachycardia

Sinus node reentrant tachycardia is a relatively uncommon (5%-5%) form of recurrent paroxysmal supraventricular tachycardia (SVT). We describe a case of symptomatic sinus node reentrant tachycardia in a 67-year-old male with ischemic heart disease, congestive heart failure, and depressed ventricular function. Adenosine administered during an electrophysiology study caused prolongation of the tachycardia cycle length due to atrial cycle length prolongation (without atrio-His prolongation) prior to tachycardia termination. Right atrial mapping revealed the earliest site of atrial activation in the high lateral right atrium just below the superior vena cava. Low energy (10 and 20 W) radiofrequency lesions were applied ai this site with termination of the tachycardia within 3 seconds of radiofrequency energy delivery. Tachycardia could not be reinduced after delivery of the radiofrequency lesions. The sinus node function immediately and 6 weeks after radiofrequency catheter ablation remained normal and the patient was without clinical recurrence of SVT. Mapping of sinus node reentrant tachycardia and elimination of the reentrant circuit with radiofrequency catheter ablation is possible without causing sinus node dysfunction. Adenosine causes prolongation of the atrial cycle length followed by termination of sinus node reentrant tachycardia.     

Neurohumoral and Hemodynamic Mechanisms of Diuresis During Atrioventricular Nodal Reentrant Tachycardia

Thirty-two consecutive patients with paroxysmal supraventricular tachycardias, with previously defined mechanisms of the tachycardias, were interviewed by noninvestigators about whether they experienced symptoms of diuresis during or at the termination of the tachycardias, to test the hypothesis that patients with AV nodal reentrant tachycardia would have a feeling of diuresis, polyuria, or both during or at the termination of the tachycardia. Twelve of the 13 patients with AV nodal reentrant tachycardia (92%), two of the 15 patients with AV reentrant tachycardia (13%), and one of the 4 patients with atrial flutter associated with 2:1 AV conduction (25%) felt diuresis during or at the termination of the tachycardias (AV nodal reentrant tachycardia vs other forms of tachycardia; P < 0.001). In 14 of the 32 patients, the right atrial pressure and plasma atrial natriuretic peptide (ANP) concentration were measured during both the tachycardias and sinus rhythm. The mean right atrial pressure during AV nodal reentrant tachycardia was significantly elevated compared to that during other forms of tachycardia (P < 0.01). The plasma ANP concentration during AV nodal reentrant tachycardia was also elevated significantly compared to that during other forms of tachycardias (P < O.OO1). There were no significant differences in the cycle lengths of the tachycardias, age, left atrial dimensions, or the left ventricular ejection fraction between the AV nodal reentrant tachycardia and the other forms of tachycardia. We concluded that the feeling of diuresis during or at the termination of tachycardia was a more common symptom in patients with AV nodal reentrant tachycardia. The higher secretion of plasma ANP from the right atrium might be involved in the mechanism of this symptom.     

Frequent Attacks of Supraventricular Tachycardia in a Patient Treated with an Automatic Scanning Pacemaker (PASAR): Holter Documentation of 554 Episodes

A 68-year-old woman suffering from frequent attacks of supraventricular tachycardia received an implantable, automatic scanning pacemaker for tachycardia termination (PASAR). Electrophysiological study had shown the mechanism to be atrioventricular reentry with retrograde conduction through a concealed bypass tract. During 1 year of follow-up, a total of twenty-one 24-hour Holter recordings documented 554 episodes of tachycardia. In spite of marked fluctuation in tachycardia rate from 135 to 195 bpm and a considerable variation in diurnal pattern of onset of episodes, a clinical improvement resulted. Previous episodes of tachycardia had been isolated and of longer duration. Following implantation, an unexpected observation was made of numerous episodes of supraventricular tachycardia confined to periods lasting up to several hours. This pattern seemed to result from the efficacy of tachycardia termination combined with a continued presence of factors responsible for initiation of tachycardia.