The Impact of Antitachycardia Pacing with Defibrillation

Chronic recurrent ventricular tachycardia (VT) can be reproducibly terminated by programmed endocardiaJ right ventricular stimulation. However, antitachycardia pacing can be associated with possible acceleration of VT, while frequent episodes of VT and patient discomfort can limit treatment by an implantable cardioverter defibrillator (ICD). The combined use of antitachycardia pacing and the AICD (automatic implantable cardioverier defibrillator) was evaluated in 6 out of 51 patients (age 57 ± 11 years) in whom the AICD had been implanted because of recurrent VT. In each instance VT could be terminated by temporary overdrive pacing. The interactive mode of VT termination by a pacemaker (Tachylog) as well as by the AICD was assessed after implantation. In the automatic mode, the Tachylog functioned as a bipolar, ventricular inhibited (VVI) device with antitachycardia burst stimulation capability, allowing two to five stimuli at intervals of 260–300 ms and one or two interventions. During follow-up of 47 ± 24 months, the Tachylog terminated VT reliably 50–505 times per patient. When burst stimulation accelerated VT, termination was achieved by AICD discharge. Thus, drug resistant VT can be terminated by antitachycardia pacing to avoid patient discomfort. In the event of tachycardia acceleration, VT was terminated by the AICD. A universal pacemaker-defibrillafor should combine antibradycardia and antitachycardia pacing with back-up cardioversion defibrillation.     

Combination of Antitachycardia Pacemaker and Automatic Implantable Cardioverter/Defibrillator for Ventricular Tachycardia

Antitachycardia pacing for ventricular tachycardia (VT) is associated with the possibility of fibrillating the heart; on the other hand, the frequency of VT and patient discomfort can limit treatment with the automatic implantable cardioverter/defibrillator (AICD). To contribute to the further development of a universal pacemaker, we evaluated the combined use of the antitachycardia pacemaker ("tachylog") and the AICD in five patients with recurrent VT. In the automatic mode, the "tachylog" worked as a bipolar VVI pacemaker. For antitachycardia pacing, a burst of rapid ventricular pacing was delivered at about 80% of the cycle length. During a follow-up period of 5 +/- 2 months (range, 3 to 8) two to 291 successful interventions of antitachycardia pacing were counted from diagnostic data which had been collected by the pulse generator during the course of treatment. When the antitachycardia pacemaker failed to terminate VT, the AICD was activated. In the individual case, between 0 and 41 discharges of the AICD were delivered. The high pulse energy of the AICD did not damage the antitachycardia pacemaker; no interference of the two devices was observed. Future antitachycardia systems should be more flexible with regard to detection and termination modes, combining antitachycardia pacing with back-up defibrillation.     

Long-Term Efficacy of an Antitachycardia Pacemaker and Implantable Defibrillator Combination

Antitachycardia pacemakers and implantable cardioverter defibrillators (ICD) were implanted in 14 patients to control recurrent hemodynamically stable ventricular tachycardia (VT), All patients underwent extensive preimplant testing in the elecrrophysiology laboratory documenting that in each patient at least 50 episodes of VT could be reliably terminated by an external model of the antitachycardia pacemaker. The burst scanning mode of anfitachycardia pacing was used in all patients. ICDs were implanted solely as a back up should acceleration of VT occur, and all had high nonprogrammable rate cutoffs (mean 191 ± 12 beats/min). During a mean follow-up of 25 ± 6 months, 6,029 episodes of VT were treated in the 14 patients. Only 103 ICD discharges were required (approximately one discharge per 60 episodes of VT). Ten of the 14 patients received discharges from their ICDs. No deaths have occurred. All devices remain active and in the automatic mode. Thus, an antitachycardia pacemaker and ICD combination can safely and effectively terminate VT in highly selected patients who are subjected to extensive preimplant testing. In such patients, the vast majority of episodes of VT can be terminated with antitachycardia pacing, and only rarely is a discharge required from the ICD.     

Device Interaction—Antitachycardia Pacemakers and Defibrillators for Sustained Ventricular Tachycardia

We evaluated the combined use of permanent automatic antitachycardia pacemakers and implanted defibrillators in fen patients with recurrent monomorphic sustained ventricular tachycardia (VT). Pacemaker programming was VVI-T automatic burst in eight patients, VVI-T magnet mode in one patient, and VVI in one patient. Device interactions occurred in four patients, requiring changes in pacemaker programming. These included defibrillator multiple counting during pacing, in-appropriate pacemaker bursts initiating VT, inappropriate reset of the pacemaker antitachycardia mode by defibrillation, defibrillator discharge after pacemaker VT termination, and defibrillator VT reinitiation. Two patients required pacemaker programming out of the antitachycardia mode, and two required a change in antitachycardia pacing parameters. Seven patients remain in automatic VVI-T and three in VVI modes. Mean follow-up is 13 months and all patients are alive. Thus, although pacemaker/ defibrillafor combinations function well for patients with more than one VT rate, device interactions occur frequently and may require pacemaker reprogramming or elimination of the overdrive mode. Combined use of these devices should be cautiously considered when single device therapy is unsatisfactory. Devices that combine both pacing and defibrillation features may reduce adverse interaction.     

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.     

Safety and Efficacy of Pacing for Ventricular Tachycardia

This study was undertaken to determine the safety and efficacy of three different pacing modalities on the termination of ventricular tachyarrhythmias. Thirty-two patients were studied in the electrophysiology laboratory. Three randomized pacing modalities were selected for attempted conversion: auto increment, auto burst, and random burst. In all three groups, arrhythmias with cycle lengths shorter than 230 ms required DC shock, with one exception. Those longer than 230 ms were terminated by pacing in 85% of cases. There was a 15% rate of acceleration. Thus, antitachycardia pacing for ventricular tachyarrhythmias should be considered only with defibrillating back-up.     

Programmable External Automatic Antitachycardia Pacing as a Bridge to Definitive Therapy in Patients with Recurrent Sustained Ventricular Tachycardia

The efficacy and safety of external programmable automatic antitachycardia pacemakers (ATPs) used in the critical care setting for recurrent sustained monomorphic ventricular tachycardia (VT) was evaluated. Ten patients who had failed a mean of 4.0 +/- 1.4 antiarrhythmic medications (range 2-7) and who had previously required electrical cardioversion for VT were enrolled. Prior to ATP use, successful overdrive pacing termination of VT was demonstrated in all patients. Intertach (Intermedics, Inc.; n = 9) and Orthocor II (Cordis, Inc.; n = 1) ATPs were attached to temporary bipolar transvenous or epicardial pacing leads. Mean patient age was 66.4 +/- 11.5 years, and mean left ventricular ejection fraction was 22 +/- 7.5%. At the time of initial ATP use, mean VT cycle length was 347 +/- 88 msec (range 280-550 msec). A burst scanning antitachycardia pacing algorithm was used in each patient; one patient was also treated with a fixed rate burst adapted to VT cycle length. The duration of ATP use ranged from 2-25 days (median 5), successfully terminating greater than 3,369 VT episodes (median 3, range 0 to greater than 3,103 episodes per-patient). Two episodes of ATP induced rate acceleration occurred, each successfully terminated by the ATP. Only two patients required external cardioversion during ATP use, one for primary ventricular fibrillation and one for rapid polymorphic VT associated with antiarrhythmic drug withdrawal. ATPs also provided antibradycardia pacing and allowed for serial programmed ventricular stimulation. No complications were associated with transvenous catheter or ATP use.(ABSTRACT TRUNCATED AT 250 WORDS)     

Benefits and Potential Risks of Atrial Antitachycardia Pacing After Repair of Congenital Heart Disease

Atrial reentry tachycardia is common after surgical repair of congenital heart disease. The arrhythmia is often difficult to treat and is occasionally life-threatening. This study reports experience with atrial antitachycardia (AAIT mode) pacing for the management of atrial reentry tachycardia, with emphasis on the risks and benefits of automatic pacing therapy. Eighteen patients (2–32 years of age) with a variety of congenital heart lesions underwent atrial antitachycardia pacemaker placement for recurrent atrial tachycardia that was amenable to pace termination prior to the implantation procedure. An appropriate antitachycardia program was determined by repeated induction and termination of atrial tachycardia using the noninvasive programmed stimulation mode of the pacemaker. Over 4–30 months of follow-up, 6 patients had 189 episodes of tachycardia successfully converted with AAI-T pacing, 4 patients had 8 episodes of tachycardia detected hut not successfully converted, and 8 patients had no episodes of tachycardia with antibradycardia pacing alone. The number of patients receiving pharmacological therapy other than digoxin or beta blockade fell from 12 to 6, Two subjects died suddenly, 1 while wearing a Holter monitor. In both, tachycardia was detected and pace cardioversion attempted. Conclusions: Atrial antitachyardia pacing is a useful tool in the management of patients with congenital heart disease and atrial arrhythmias; however, in selected cases, it may not prevent and may even exacerbate the lethal complications of the tachycardia. Antitachycardia function evaluation is recommended under varying levels of autonomic stress prior to institution of automatic therapy.     

Pacing for tachydysrhythmias

Advances in cardiac electrophysiology have clarified some of the mechanisms of tachydysrhythmias and have characterized tachycardias that are amenable to pace termination. Tachydysrhythmias most likely to be terminated by pacing techniques tend to be slow, re-entrant tachycardias. Although single extrastimulation can be effective, its yield is relatively low. Delivery of multiple extrastimuli or burst pacing are more effective than single extrastimulation at the expense of a higher risk of tachycardia acceleration or transformation of the rhythm to fibrillation. The use of pacing for the termination of tachydysrhythmias has primarily been limited to the acute care setting, although permanently implantable antitachycardia pacemakers are being used in increasing numbers. While these devices have been approved by the Food and Drug Administration (FDA) for the treatment of supraventricular tachydysrhythmias, their use to treat ventricular tachydysrhythmias has produced mixed results and remains investigational. In some cases of sustained ventricular tachycardia, automatic cardioverter/defibrillators have been implanted along with antitachycardia pacemakers to provide high-energy shock back-up in case of tachycardia acceleration by the pacemaker. Soon, devices will be available which will combine, in a single unit, antitachycardia pacing and high-energy cardioversion/defibrillation.     

A Comparison of Ventricular Arrhythmias Induced with Programmed Stimulation Versus Alternating Current

In patients undergoing implantation and testing of the implantable cardio-verter defibrillator (ICD), alternating current (AC) may be used to induce ventricular tachyarrhythmias in a prompt, safe, and efficient manner. These arrhythmias have been previously reported to be similar to those induced during programmed electrical stimulation (PES). We compared the ventricular tachyarrhythmias induced by both methods in 14 patients: 8 male, 6 female; mean age 61 years; coronary disease in 10, cardiomyopathy in 4; mean ejection fraction 31%. The presenting arrhythmia was nonsustained ventricuiar tachycardia (VT) in four, sustained monomorphic ventricular tachycardia (SMVT) in five, ventricular fibrillation (VF) in four, and unknown in one patient with syncope. PES (single, double, triple extrastimuli; burst pacing) and AC (1–2 sec application) stimulation via right ventricular endocardial electrode catheter was performed off antiarrhythmic drugs in the nonsedated state. PES induced SMVT in nine, polymorphic VT in two, and VF in three. AC induced VF in all patients. Although AC can reliably induce ventricular tachyarrhythmias during de/ibrillation threshold and ICD testing, there is poor correlation to PES induced tachyarrhythmias.     

Improvement of Quality of Life by Means of Antitachy Pacing: From PainFREE to the ADVANCE-D Trial

Background: Implantable cardioverter-defibrillators (ICD) can terminate ventricular tachyarrhythmias with shocks (painful) or antitachycardia pacing (painless). According to the results of the Pacing Fast VT Reduces Shock ThErapies Trials, antitachycardia pacing (ATP) can avoid painful shocks and also increase device longevity. The purpose of the ADVANCE-D (Atp DeliVery for PAiNless ICD ThErapy) study is to determine the most appropriate ventricular tachycardia (VT) therapy, so as to optimize painless therapy for life-threatening arrhythmias.
Methods and Results: The ADVANCE-D is a prospective, multicenter, parallel, two-arm randomized study designed to evaluate the efficacy of two different sequences of ATP therapies (burst 15 pulses, 88%, vs burst 8 pulses, 88%), during an episode of spontaneous arrhythmia classified as fast VT (FVT) in patients with a Class I or IIA indication for ICD implantation (single and dual chamber devices). The primary endpoint is to compare the efficacy of two ATP therapies for FVT episodes. The study will enroll a minimum of 900 patients within 2 years, followed-up for 12 months. The investigation is expected to be completed in 2007.
Conclusions: The ADVANCE-D trial is the first large randomized clinical investigation aimed to evaluate optimal programming and efficacy of ATP.     

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.     

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 Relationship between Pacing Site and Induction or Termination of Sustained Monomorphic Ventricular Tachycardia by Antitachycardia Pacing

Background: With the development of left ventricular pacing for cardiac resynchronization, there is an interest in the possibility of improving ventricular antitachycardia pacing (ATP) efficacy by pacing from the LV electrode(s).
Objective: This study assessed the efficacy of pacing delivered from the left coronary vein (LCV) compared to that delivered from the right ventricular apex (RVA) upon ventricular tachycardia (VT) induction and termination.
Methods: Sixty patients undergoing provocative ventricular electrophysiology (EP) studies in three centers were enrolled. Multipolar EP catheters were placed in the atrium, the RVA, and LCV. VT induction was attempted from the RVA and LCV in random order. Upon detection of monomorphic VT, burst ATP for up to 10 pulses at 88% VT cycle length was delivered from the RVA or LCV, in a random order, and crossed over when possible. Identical VT morphologies were reinduced to allow paired comparison of RVA versus LCV ATP.
Results: Data from 55 patients were analyzed. Thirty-four morphologically distinct monomorphic VT types were induced in 22 patients. ATP succeeded in 18 (55%) and VTs in 13 patients. RVA ATP terminated 15 of 23 (65%) VTs, and LCV ATP terminated 10 of 23 (43%) VTs (P = 0.14). ATP delivered ipsilateral to the earliest activation site required 5.0 ± 2.6 pulses to terminate compared to 4.8 ± 1.7 pulses when delivered from the contralateral site (P = 0.90). Paired comparison was possible for 13 VT morphologies in 11 patients. Paired RVA and LCV ATP efficacy was identical (54 % vs 54%, P = 1.0).
Conclusion: ATP delivered from a LCV lead offers no efficacy advantage over pacing from the RVA. (PACE 2010; 27–32)     

Holter Documented Sudden Death in a Patient with an Implanted Defibrillator

A 68-year-old man with recurrent attacks of monomorphic ventricular tachycardia (VT) received a pacer cardioverter defibrillator featuring antitachycardia pacing and cardioversion/defibrillation. Over 300 episodes of VT were successfully terminated by antitachycardia pacing. During Holter monitoring the patient experienced supraventricular tachycardia with delivery of multiple antitachycardia pacing, cardioversion, and defibrillation therapies ending with the death of the patient. The following factors played a role in the unfortunate outcome of this patient: 1. triggering of VT therapy by an unexpected high sinus rate; 2. atrial fibrillation induced by cardioversion therapy; 3. a gradual and continuous increase in rate during atrial fibrillation possibly caused by repeated VT and ventricular fibrillation therapies and/or by a thrombus, found at autopsy, in a bypass graft; and 4. the limited ability of presently available defibrillators to distinguish between ventricular and supraventricular arrhythmias.     

Role of Antitachycardia Pacing in Patients with Third Generation Cardioverter Defibrillators

The most effective antitachycardia pacing (ATP) mode is still a matter of debate. Randomized prospective testing of 3 different ATP modes was performed in B5 patients (pts) prior to and after cardioverter Defibrillator implantation (Ventak PHx 36 pts, Cadence V 100 29 pts). All 3 ATP modes included 4 stimulation attempts with 4–7 adaptive scanning burst pulses. Adaptive burst coupling interval was 75% in mode A, 81% in mode B and 69% in mode C. Autodecremental scanning within bursts was 8 msec in all, decremenial scanning between bursts was 8 msec in modes B and C. Each ATP mode had to be tested 3 times; all 3 ATP modes were randomly applied to each pt. During preoperative testing 91 of 133 VT episodes (68%) could be terminated by ATP. Termination was achieved in 68% with mode A, 68% with mode B and 73% with mode C, During predischarge testing, 251 VTs were induced and ATP was successful in 147 VTs (59%). Termination rate was 56% with mode A, 68% with mode B and 50% with mode C. During the mean follow-up of 12 months, 2301 arrhythmia episodes (AE) occurred. ATP was performed in 2097 AE (91%) and successful in 1920 AE (92%). Acceleration of VT occurred in 65 AE (3%) and unsuccessful ATP was observed in 112 AE (5%). It is concluded that ATP in general is highly effective in pts with sustained VT. None of the tested ATP modes, however, proved to be superior to the other.     

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.     

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.     

Atrial Automatic Tachycardia-Reversion Pacemakers: Their Economic Viability and Impact on Quality-of-Life

Refractory supraventricular tachyarrhythmias may be both difficult and costly to control medically and can interfere with the patient's lifestyle. Newer treatment modalities are available for their management, and these require comprehensive assessment. We therefore compared costs and selective indices of patient benefit in a group of 17 patients in whom an atrial antitachycardia (Intermedics Intertach 262–12) pacemaker was placed for refractory supraventricular tachyarrhythmias. Prior medical therapy was compared to subsequent automatic antitachycardia pacemaker treatment. The total medical costs (admissions, emergency room visits, office visits, and medication costs) and the number of hospitalizations and medications were compared prior to implantation (F/U 69.3 ± 61 months) and after implantation (F/U 15.3 ± 7.8 months). A detailed quality-of-life questionnaire was also obtained 36.6 ± 11 months after implantation. Results: There were significant per patient differences in total cost before and after implantation: monthly costs were $505 ±$833 before pacemaker implantation and $105 ±$117 monthly afterward (P < 0.005). Pacemaker implantation hospitalization costs were $19,063 ±$8,362. Monthly medication costs averaged $46 before versus $15 after implantation (P < 0.01). The number of medication types also differed with an average 5.5 medication types per patient before versus 1.2 after implantation (P < 0.001). There were 8.6 yearly hospital admissions in the whole group before implantation, versus 4.7 admissions in the group per year thereafter. Patients demonstrated significant improvement in 80% of the quality-of-life parameters studied. Conclusion: Adjunctive atrial automatic tachycardia-reversion pacemaker therapy may be cost-competitive over time when compared to medical therapy alone in patients with refractory supraventricular tachyarrhythmias and appears to improve overall quality-of-life.     

Electrophysiology and Indications for Pacing in the ''8O''s*

Newer electrophysiological studies have improved our understanding of the pathogenesis of cardiac arrhythmias. Bradycardias originate either from a dysfunction of impulse formation in the sinoatrial node or from a disturbed conduction of the impulse. Different pathogenetic mechanisms are discussed as causes of tachyarrhythmias: circus movement (re-entry) is primarily due to pathological changes in conduction and refractoriness. Focal impulse formation results from local disturbances of depolarization and repolarization of the cell membrane: increased automaticity, abnormal automaticity, triggered activity. Symptomatic bradycardias still represent the standard indication for cardiac pacing particularly with implantable pacemakers. Based on clinical electrophysiology, various types of pacemakers are available at present: atrial triggered and atrial pacing pacemakers, AV-sequential pacemakers, ventricular demand-pacemakers, stand-by pacemakers, and fixed rate pacemakers. The multiprogrammability of newer pacemaker devices is a very useful tool in avoiding secondary interventions. For antitachycardia pacemaker therapy there are essentially three methods in use: 1. overdrive pacing to prevent re-entry phenomena and automaticity and also to suppress tachyarrhythmias based on increased or abnormal automaticity; 2. competitive stimulation for termination of tachycardias by means of single impulses; and 3. rapid atrial stimulation to convert atrial flutter into atrial fibrillation and consequently to normal sinus rhythm. In very rare cases rapid ventricular stimulation is mandatory. The positive results achieved with temporary stimulation methods have led to the development of permanent (implantable) antitachycardia pacemakers for long-term therapy, which have proven to be a low-risk alternative in drug-resistant tachyarrhythmias.