The Treatment of Ventricular Tachycardia Using an Automatic Tachycardia Terminating Pacemaker

Implanted cardiac pacemakers may be used in the management of selected patients with ventricular tachycardia unresponsive to other forms of medical and surgicaJ therapy. We would like to report the successful treatment of such a patient utilizing a new multiprogrammable automatically activating ventricular burst pacemaker. Thorough electrophysiologic study preceded implantation, and was instrumental in choosing an effective terminating technique, in identifying the need for adjunctive drug therapy, and in testing the safety and efficacy of the implanted system. (PACE, Vol. 4, September-October, 1981)     

Noninvasive Assessment of Ventriculo-Atrial Conduction and Early Experience with the Tachycardia Termination Algorithm in Pacemaker-Mediated Tachycardia

Since the advent of physiologic dual chamber pacing systems, pacemaker-mediated tachycardia (PMT) has occurred and the need for invasive measurement of ventriculo-atrial conduction (VAC) has arisen. The variability in VAC and the potential for PMT often make it necessary to assess for the presence or absence of VAC at different points in time. We noninvasively evaluated 20 pacemaker patients for the presence or absence of VAC. We compared ventriculo-atrial conduction time (VACT) obtained with the atrial sense event maker with that obtained from Holter monitoring and invasive methods. The incidence of spontaneous (S) and induced (I) PMT and the efficacy of the tachycardia termination algorithm (TTA) was assessed. Fourteen of 20 had VAC with invasive or noninvasive methods. Twelve of 19 had PMT (63%); three were sustained (greater than 15 beats). We conclude that VACT assessed with the atrial sense event marker (ASEM) yielded a high correlation when compared to the Holter monitor data obtained utilizing our methodology. PMT is commonly a nonsustained (less than 15 beats) event, and the TTA is effective in sustained PMT. Myopotential sensing, atrial premature contractions and loss of atrial capture are common mechanisms in the initiation of PMT.     

External Monitoring-Induced Pacemaker-Driven Tachycardia: A Case Report

A 55-year-old African-American woman with a history of end-stage renal disease secondary to systemic lupus erythematosus, dual-chamber pacemaker placement secondary to sick sinus syndrome, and a previous subarachnoid hemorrhage presented via ambulance to our Emergency Department (ED) from an outside hospital with the report of altered mental status, hyperkalemia, and hypoglycemia. In the ED, the patient's initial physical examination revealed a stable, normal heart rate. Reassessment after placement of external monitoring devices found the patient to be tachycardic at approximately 132–135 beats/min, with minimal variation in rate. The patient was also tachypneic during this episode, up to a respiratory rate of 38 breaths/min. When misplaced external monitoring device leads were removed during pacemaker interrogation, the patient's heart rate dropped to the 70s. Reapplication of the external monitoring leads replicated the tachycardia. With permanent repositioning of the leads in the ED, the tachycardia did not return. The placement of the leads was determined to have caused a plethysmography-induced pacemaker-driven tachycardia.     

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.     

Irregular Pacemaker Tachycardia in a Patient with WPW Syndrome and an A-V Universal Pacemaker

We describe a case of an irregular pacemaker circus movement tachycardia in a patient with the Wolff-Parkinson-White syndrome and a normally functioning A-V universal (DDD) pacemaker (Cordis Sequicor 233 D). The mechanism of the artificial circus movement tachycardia, which uses the pacemaker as the anterograde limb and a septally located accessory atrioventricular pathway as the retrograde limb, is discussed.     

Clinical Use of Permanent Pacemaker for Conversion of Intraatrial Reentry Tachycardia in Children

The use of the implanted atrial-based pacemaker to overdrive postsurgical intraatrial reentry tachycardia (IART) was evaluated in a large group of pediatric patients over a 14-year study period. The authors sought to determine the feasibility of this noninvasive technique in the management of this specialized population and to determine factors associated with successful conversion. They examined 128 manual overdrive attempts performed on 22 consecutive patients. There were 10 patients with post-Fontan repair, 7 with post-Mustard/Senning procedure, and 5 with miscellaneous lesion types. The number of IART episodes for overdrive pacing per patient ranged from 1 to 15. The first overdrive pacing attempt was successful in 63% (14/22) of the patients. The mean IART cycle length was 278 +/- 59 ms. The mean pacing rate for effective conversion of IART was 66 +/- 10% faster than the IART rate. By controlling for repeated measures for individual patients, three factors were found to be independently associated with a successful outcome: (1) lesion type other than Fontan surgery (P = 0.007), (2) lack of acceleration of IART with the overdrive attempt (P < 0.001), and (3) patient use of amiodarone with attempt (P = 0.005). There were three procedural complications: two inadvertent overdrive pacing episodes, and one episode of acceleration of IART cycle length and conduction resulting in need for cardioversion. Manual pacemaker overdrive conversion of IART is a useful adjunct in the management of postsurgical IART in the pediatric population and should be considered as an initial treatment option.     

Ninety-Six Episodes of Spontaneous Ventricular Tachycardia in 1 Week: Success of Ramp Pacing by a Pacer-Cardioverter-Defibrillator

This case report describes the flexibility and usefulness of a pacer-cardioverter-defibrillator for the management of a 63-year-old patient with malignant ventricular tachyarrhythmias. Ninety of 96 episodes of ventricular tachycardia were terminated successfully with ramp pacing in a 1-week period. In those patients who have frequent episodes of ventricular tachycardia that respond to antitachycardia pacing, the multifunction device can add to the patient's comfort and increase acceptance of this type of device.     

Ventricular Tachycardia and the Cystic Heart: A Case Report

BackgroundHydatid cysts are caused by Echinococcus granulosus infection, and hydatidosis is recognized as a re-emerging zoonotic disease globally. While the liver is the most commonly affected organ, other organs can also be affected, including the heart. Because of the low sensitivity and specificity of serologic diagnostic tests, ultrasound and echocardiography are increasingly used to make the diagnosis of cardiac hydatid cyst.Case reportWe report the case of a cardiac hydatid cyst, detected by point-of-care ultrasound (POCUS), in a 79-year-old woman who presented with shortness of breath and was in ventricular tachycardia. The diagnosis was further confirmed with a computed tomography scan. Although cases of alveolar and liver hydatid cysts are seen, this is the first case of a cardiac hydatid cyst in Bhutan.Why Should an Emergency Physician Be Aware of This?This case illustrates the importance of POCUS in reaching a diagnosis, particularly in resource-poor areas where other sophisticated diagnostic tools are not easily available. A cardiac hydatid cyst must be in the differential for structural causes of dysrhythmias. This is especially so because treatment of unstable dysrhythmias in the acute setting of an emergency department has to be modified from the usual algorithm in the presence of a cardiac hydatid cyst, due to the potentially fatal risk of cyst rupture and anaphylaxis.     

Catecholamine Induced Double Tachycardia: Case Report in a Child

A six-year-old girl with syncope in association with atrial flutter-fibrillation and ventricular tachycardia produced by exercise or emotion is presented. The tachycardias could be reproduced by low-dose isoproterenol infusion and were blocked by high dose propranolol therapy. Catecholamine-induced tachyarrhythmias should be suspected in children with unexplained syncope in association with exercise or emotion.     

Mechanisms of Spontaneous Tachycardia Termination in a Patient with the Wolff-Parkinson-White Syndrome and Dual Atrioventricular Nodal Pathways

A patient with the Wolff-Parkinson-White syndrome and recurrent bouts of paroxysmal supraventricular tachycardia underwent electrophysiologic studies. These studies revealed evidence of dual atrioventricular nodal pathways and a septal accessory pathway. The tachycardia circuit involved anterograde conduction over a slow atrioventricular nodal pathway and retrograde conduction over the accessory pathway. Spontaneous tachycardia termination was frequently observed, was almost always abrupt, and was associated with a beat-to-beat decrease in the A-H interval, In this patient, the mechanism for spontaneous tachycardia termination appeared to be an abrupt shift in anterograde conduction from the slow to the fast pathway, advancing the tachycardia so that the block occurred in the accessory pathway (or atrium). To our knowledge, this mechanism of spontaneous tachycardia termination has not been described previously. Use of agents to facilitate fast atrioventricular nodal conduction (i.e., atro-pine) may be effective in tachycardia termination for these patients.     

Supraventricular Tachycardia Induced by Swallowing: A Case Report and Review of the Literature

A 64-year-old man who complained of palpitations brought on by swallowing was found to have short runs of paroxysmal supraventricular tachycardia (SVT) induced by swallowing. Electrophysiology studies suggested that the SVT was an automatic atrial tachycardia. An esophageal manometric study demonstrated that the tachycardia was coincident with relaxation of the upper esophageal spincter and preceded peristaltic activity in the esophageal body. Atropine and bethanechol did not affect the swallow-induced tachycardia. The patient's symptoms were controlled by verapamil and quinidine. After five months, these medications were discontinued, with no recurrence of symptoms. Based on analysis of ten prior cases and the present case, it appears that swallow-induced SVT generally occurs in men between the ages of 45–75 years who have no evidence of structural heart disease or an esophageal disorder. The SVT is usually either a nonsustained automatic atrial tachycardia or atrial fibrillation. The mechanism is conjectural, but the most likely possibility is a vagally-mediated neural reflex, probably involving a neu-rotransmitter other than acetylcholine.     

Accelerated Junctional Tachycardia at a Rate of 190 Beats/Minute Following Cryosurgery and Aneurysmectomy for Ventricular Tachycardia: A Case Report

In this case study we report a 59-year-old man who underwent combined aneurysectomy, endocardial resection, and cryosurgery for recurrent ventricular tachycardia. Following surgery he developed an accelerated junclional tachycardia with rates up to 190/min arising near the area of cryoablation which involved the junctional region. Using intracavitary recording and stimulation this tachycardia was shown to arise from ihe junctional area and had characteristics suggesting accelerated automaticity. During the electrophysiological study the focus of the tachycardia was temporarily obtunded by catheter trauma. After reappearance of the arrhythmia, successful suppression was achieved using diphenylhydantoin. (PACE, Vol. 5, May-June, 1982)     

A New Approach to the Prevention of Endless Loop Tachycardia in DDD and VVD Pacing

Endless loop tachycardia (ELT) is a possible complication in dual chamber pacing; it is usually prevented by programming the atrial refractory period (PVARP) longer than the retrograde ventriculoatrial (VA) conduction interval; this in some patients limits the upper rate. In 15 patients with a DDD (nine patients) or a single-pass lead VDD pacemaker (six patients) and retrograde atrial activation, telemetric recording documented a significant difference in amplitude of antegrade, and retrograde atrial potentials (VDD 1.21 ± 0.32 mV vs 0.56 ± 0.23 mV, P = 0.008; DDD 2.7 ± 1 vs 1.8 ± 1 mV, P - 0.038; Student's t-test for paired data). In 3/15 patients ELT stopped after programming of atrial sensitivity to a value. greater than the retrograde P wave amplitude; in 11/15 patients this occurred at a sensing value lower than or equal to retrograde P wave amplitude with a high pass band filter operating. One patient required PVARP lengthening. Holter monitoring showed no more ELTs. In most patients with a DDD or single-pass lead VDD pacemaker with widely programmable sensing amplitude and Hi/Low bandpass filters. individual programming of atrial channel sensitivity prevents ELT without affecting the PVARP and, consequently, upper rate limit.     

Entrainment of Ventricular Tachycardia in Postoperative Tetralogy of Fallot

The mechanism of ventricular tachycardia (VT) in postoperative tetralogy of Fallot has been ascribed to both reentry and triggered automaticity. We performed electrophysiologic studies on a patient with this condition and induced sustained uniform ventricular tachycardia by programmed extrastimulation. Pacing during the tachycardia at multiple cycle lengths from the right ventricular apex (RVA) and outflow tract (RVOT) produced constant but progressive fusion between the paced and tachycardia QRS. With termination of pacing, the last captured complex was unfused but coupled at the paced cycle length and then the tachycardia resumed at its intrinsic rate. Therefore, the VT was entrained. In addition, an area of slow conduction between the RVOT and RVA was demonstrated. These findings support a reentrant mechanism of this arrhythmia.     

A New Algorithm to Solve Endless Loop Tachycardia in DDD Pacing: A Multi-Center Study of 91 Patients

ELTs (endless loop tachycardias) are a common occurrence associated with DDD pacing. In order to detect and treat ELTs, an innovative automatic pacemaker algorithm was devised and evaluated. The basic principle of the algorithm rests on the relative stability of the ventriculoatrial conduction time (VACT) during ELTs. ELTs are suspected when the VACT remains stable and adheres to certain programmable limits referred to as VACT stability (16 or 31 msec); it is confirmed when the VACT remains stable after a programmable shortening of the AV delay (AVD) value, referred to as AVD shortening (47 or 63 msec). Ninety-one patients, 54 males and 37 females, were implanted with such an algorithm-specific device between January 10 and September 9, 1989. The reasons for implantation were as follows: 55 patients were implanted for AV block, 31 for sinus node dysfunction, and 2 for carotid sinus syndrome. Pacing parameters were programmed to favor ELT initiation (long AVD, short postventricular atrial refractory period [PVARP] and high atrial sensitivity) followed by basic programming of the algorithm (VACT stability set at 16 msec and AVD shortening set at 47 msec. Once this was done, a 24-hour Holter recording was obtained. Eighty-eight patients were thus analyzed, three being excluded from the final report due to the poor quality of the Holter tracings. In 43.2% of the sampling (38 patients), multiple episodes of ELT were identified, exhibiting a mean rate of 120 beats/min. In 26 of 38 cases (68.4%), the rate of ELT was found to be slower than the upper rate limit (URL).(ABSTRACT TRUNCATED AT 250 WORDS)     

Recipient P Wave Synchronized Pacing of the Donor Atrium in a Heart-Transplanted Patient: A Case Study

We present the case of a 23-year-old patient who underwent orthotopic heart implantation and subsequent implantation of an atrial dual chamber pacemaker. The stimulation rate in the donor atrium is controlled by the recipient's sinus node activity, thereby maintaining AV synchrony and allowing appropriate rate increase during exercise.     

Voltage Dip in Pacemaker Battery Supply: A New Cause of Pacemaker Mediated Tachycardia

A new cause of pacemaker medialed tachycardia was observed in a patient equipped with a Vitatron® Quintech 931 DDD pacemaker. In this type of pacemaker the microprocessor is switched off during the atrial refractory period. Beyond the recommended replacemenl lime, the internal resistance of the battery may increase to such an extent that switching on and off the microprocessor may cause voltage dips. Those voltage dips are erroneously interpreted as P waves hy the atrial sensing amplifier, which may cause self-triggering of the pacemaker and initiate a pacemaker mediated tachycardia.     

Pseudo-fracture of Pacemaker Lead Due to Securing Suture: A Case Report

With improved pacemaker lead design and materials, complications caused by lead problems have decreased.^4,5 There have been isolated reports of leads severed by suture material but they have been rare. Presented is a case of suture-induced "pseudo-fracture" in a urethane-insulated ventricular lined endocardial lead (Medtronic Model #6971-58). No loss of capture or sensing function has been encountered eight months following initial implantation. It is felt that the softer, stronger urethane permitted compression and resulted in a radiographic suggestion of a fractured lead, but lead integrity does not seem to have compromised. Although (his may be an inconsequential radiographic finding, it could lead to an inappropriate lead removal unless it is properly interpreted. (PACE, Vol. 4, November-December, 1981)