射频消融和DDD起搏器治疗典型心房扑动伴缓慢心室率五例

目的探讨典型心房扑动(简称房扑)伴缓慢心室率的介入治疗。方法5例房扑伴缓慢心室率患者,房扑频率240～260次/分,房室传导比例5:1～6:1。1例患者已置入VVI起搏器,但仍有症状。对房扑采用解剖学影像定位法消融下腔静脉与三尖瓣环的峡部。对缓慢心室率采取DDD起搏器治疗(1例VVI改换DDD)。结果消融中房扑终止,峡部达双相阻滞,房扑终止后1例为Ⅱ度Ⅱ型房室传导阻滞,4例为Ⅲ度房室传导阻滞。均成功置入DDD起搏器。随访7～37个月,房扑未见复发,起搏器工作良好,患者症状消失。结论射频消融和DDD起搏器联合治疗典型房扑伴缓慢心室率患者有效而且安全。     

Possible acute and chronic synergistic effect of dual chamber pacing and disopyramide in obstructive hypertrophic cardiomyopathy: a case report

It remains unclear whether the combination of dual‐chamber (DDD) pacing and disopyramide can achieve prolonged left ventricular outflow tract (LVOT) gradient reduction and symptom relief in patients with obstructive hypertrophic cardiomyopathy (HCM). In an HCM patient with a severe LVOT gradient, the combination of DDD pacing and disopyramide achieved marked improvement of gradient in the catheter laboratory and also after medium‐term follow‐up. The patient's severe dyspnoea was alleviated during the follow‐up period. This combination might enable physicians to treat and manage elderly symptomatic obstructive HCM patients with a severe LVOT gradient more effectively and less invasively.     

Effect of biventricular pacing on left ventricular outflow tract pressure gradient in a patient with hypertrophic cardiomyopathy and normal interventricular conduction

We report a case of hypertrophic obstructive cardiomyopathy (HOCM) that was markedly improved by biventricular pacing. A 55-year-old woman with HOCM presented with palpitation and presyncope. Electrophysiologic study revealed an atrioventricular nodal reentrant tachycardia. After radiofrequency catheter ablation, a Mobitz type II atrioventricular block developed and a permanent pacemaker implantation was decided. Cardiac catheterization showed a left ventricular outflow tract (LVOT) gradient of 130 mmHg. Right dual-chamber and atrial-synchronous left ventricular epicardial pacing failed to reduce the gradient. After biventricular pacing, LVOT gradient decreased to 20 mmHg. Biventricular pacing may be an alternative therapy for patients with HOCM.     

Similar pattern of diastolic function adaptation of both ventricles to programmed atrioventricular interval modification in patients with DDD pacing.

OBJECTIVE: To evaluate both left ventricular (LV) and right ventricular (RV) diastolic performance adaptation to variable atrioventricular interval (AVI), in patients with DDD pacing for complete heart block and to investigate a possible interaction between LV and RV in this specific cohort of patients. METHODS: We studied 22 consecutive patients (mean age 65.2 +/- 14.3 years) who underwent DDD pacemaker implantation following admission for complete heart block. One day following implantation, patients were paced at 3 different pacing modes, under the same programmed heart rate and a different AVI (100, 150 and 200 ms respectively). Standard Doppler echocardiography of mitral and tricuspid valve inflow was performed to evaluate LV and RV diastolic function, during each pacing mode. RESULTS: Left ventricular and RV diastolic performance adaptation to variable AVI modifications was similar, showing a progressive increase of late diastolic filling velocities and a subsequent decrease of E/A wave ratios following AVI prolongation. A short AVI of 100 or 150 ms was associated with improved LV and RV diastolic filling dynamics. CONCLUSIONS: In elderly patients with complete heart block and unimpaired systolic function undergoing DDD pacemaker implantation, both ventricles share a similar pattern of diastolic function adaptation to AVI modifications and that might be the reflection of ventricular interaction under this specific pacing mode.     

Is alcohol ablation of the septum associated with recurrent tachyarrhythmias?

QUESTIONS UNDER STUDY: Alcohol ablation (AA) of the septum has been introduced as new therapy in hypertrophic cardiomyopathy (HCM). It was feared that iatrogenic myocardial infarction due to AA may induce re-entry tachyarrhythmias and increase sudden cardiac death. METHODS AND RESULTS: Twenty-four patients (mean age 52 years) underwent successful AA. Clinical follow-up (FU) ranged from 0.3 to 0.7 years (mean 2.8). One patient died (suicide) 4 years after AA. Left ventricular (LV) outflow gradient (peak-to-peak) decreased (median) after AA from 43 (IQR 25 to 4) mmHg to 1 (IQR 0 to 12) mmHg (rest) (p <0.001) and from 130 (IQR 75 to 165) mmHg to 13 (IQR 0 to 31) mmHg (postextrasystolic) (p <0.001). Transient AV block occurred in 22% (5/24) necessitating temporary pacing. A permanent pacemaker was implanted in 4% (1/24). NYHA-class was 2.5 (IQR 2.0 to 3.0) before and 1.5 (IQR 1.3 to 2.0) (p <0.001) after AA. During FU, 2 pacemakers were implanted due to bradycardia (no AV block). A right bundle branch block was found in 13% (2/24) before and 46 % (11/24) after AA (p = 0.003). Non-sustained ventricular tachycardia (NSVT) was observed in 13% (2/16) before and 22% (5/23) (p = 0.46) after AA. Two patients required ICD implantation. CONCLUSIONS: Long-term FU is excellent in HCM after AA. The pressure gradient drops below 25 mm Hg in 95% (23/24) of all patients. Transient AV block occurs in 22% (5/24), but permanent pacemaker implantation is rarely needed (13%, 2/24). Severe NSVT occurs in 13% (2/16) before and 22% (5/23) after AA but ICD implantation is only occasionally required.     

Long-term effects of dual-chamber pacing with periodic echocardiographic evaluation of optimal atrioventricular delay in patients with hypertrophic cardiomyopathy >50 years of age

Various treatment modalities have been introduced to reduce the subaortic pressure gradient in patients with obstructive hypertrophic cardiomyopathy, including pacemaker insertion. Complete ventricular capture during pacing is essential and requires optimization of the atrioventricular interval (AVI). In this study, a protocol using echocardiographic examination assessing the changes in the left ventricular outflow tract (LVOT) gradient in different AVIs, pacing rates, and pacing modes was used for optimal pacemaker programming. Twenty-five patients with obstructive hypertrophic cardiomyopathy were implanted with DDD pacemakers and evaluated prospectively. The LVOT gradient was measured during periodic evaluations every 3 to 6 months. Gradient measurements were done with 5 different AVIs and 3 different rate combinations. After each evaluation, the optimal AVI, pacing rate, and mode were set on the basis of the minimal LVOT gradient not associated with systolic arterial cuff pressure reduction. Follow-up ranged from 18 to 126 months. Peak LVOT gradient immediately decreased in 92% of patients. During follow-up, the optimal AVI was prolonged in most patients. Sixty-four percent of patients showed a clear relation between pacemaker modifications and gradient reduction. In 75% of these patients, optimal gradient reduction required repeated AVI and pacing rate programming on the basis of echocardiographic evaluation. Symptoms decreased in 92% of patients, and New York Heart Association class improved significantly (3.1+/-0.7 vs 1.3+/-0.4, p<0.001) during follow-up. The symptomatic reduction was positively correlated with the LVOT gradient reduction. In conclusion, DDD pacing is effective in reducing the LVOT gradient and improving functional capacity in adult patients with hypertrophic cardiomyopathy. Pacemaker programming with the periodic echocardiographic evaluation of the optimal AVI, pacing rate, and mode is imperative for optimal results.     

Percutaneous transluminal septal myocardial ablation in drug-resistant hypertrophic obstructive cardiomyopathy: 18-month follow-up results.

OBJECTIVE: Surgery has been the only therapeutic option in patients with hypertrophic obstructive cardiomyopathy (HOCM) who are resistant to standard treatment. Percutaneous transluminal septal myocardial ablation (PTSMA) by alcohol-induced occlusion of the septal artery for the reduction of left ventricular outflow tract (LVOT) gradient is a novel method. However, long-term clinical follow-up is insufficient. This study reports the acute and mid-term results after PTSMA in symptomatic patients with HOCM. METHODS: Six patients (4 men and 2 women) with symptomatic HOCM and inadequate response to pharmacologic therapy had their major septal branches ablated with alcohol. Mean duration of follow-up was 1.5 years. RESULTS: There was reduction in LVOT gradient in all patients (100%) with a mean reduction of 50 mmHg. Two patients developed complete heart block (CHB) and 3 patients developed bifascicular block. CHB persisted in 1 patient. Two patients died within 8 days of the procedure; one due to cerebrovascular accident and 1 due to asystole. The patient who died of asystole had CHB but refused permanent pacemaker implantation. CHB reverted in 1 patient and bifascicular blocks persisted in 3 patients. Clinical and echocardiographic follow-up was achieved in the 4 surviving patients after 1.5 years. All surviving patients had LVOT gradient reduction and clinical improvement. CONCLUSION: PTSMA for HOCM is a non-surgical technique for reducing LVOT gradient. Heart blocks are one potential complication, and may require pacemaker implantation. Long-term follow-up and a larger series of patients are required to determine conclusive therapeutic significance.     

Pacing Mode and Long-Term Survival in Elderly Patients with Congestive Heart Failure: 1980-1985

Dual-chamber pacing may improve short-term hemodynamics and functional class in some patients with congestive heart failure, even in the absence of conventional indications for pacemaker implantation. However, the impact of different pacing modes on survival of patients with congestive heart failure is controversial. In this retrospective study we analyzed survival data from 546 elderly patients, aged 70 years and older, who underwent implantation of a permanent dual-chamber (DDD, n = 62, DVI, n = 102) or single-chamber (VVI) pacemaker (n = 382) between 1980 and 1985. Survival was further analyzed according to the presence or absence of congestive heart failure, and pacemaker mode (DDD vs. DVI vs. VVI). Overall, dual-chamber pacing (DDD and DVI) was associated with a more favorable long-term outcome when compared with single-chamber ventricular pacing, although differences were only significant for DDD pacing (P = 0.002). When patients with and without preexisting congestive heart failure were analyzed separately, survival following dual-chamber pacing (DDD and DVI) was significantly better than survival following single-chamber pacing in patients without congestive heart failure (P = 0.03), but not in patients with preexisting heart failure (P = 0.139). When patients were analyzed according to the electrophysiological indication for pacemaker implantation, overall survival of patients with AV block (P = 0.0025) but not sinus node dysfunction (P = 0.346) was improved with dual-chamber pacing. This survival advantage in patients with AV block following dual-chamber pacing was lost in the presence of heart failure P = 0.11). These findings suggest that dual-chamber pacing, in particular DDD pacing, improves the survival in elderly patients without preexisting congestive heart failure. In contrast to the short-term hemodynamic improvement observed in selected patients with congestive heart failure, dual-chamber pacing in elderly patients with congestive heart failure, paced for conventional indications, is not associated with improved survival when compared with single-chamber ventricular pacing.     

Percutaneous Transluminal Septal Myocardial Ablation in Hypertrophic Obstructive Cardiomyopathy: Acute Results and 3-Month Follow-Up in 25 Patients

Objectives. We report the acute results and midterm clinical course after percutaneous transluminal septal myocardial ablation (PTSMA) in symptomatic patients with hypertrophic obstructive cardiomyopathy (HOCM).Background. In the treatment of HOCM, surgical myectomy and DDD pacemaker therapy are considered the standard procedural extensions to drug therapy with negatively inotropic drugs. As an alternative nonsurgical procedure for reducing the left ventricular outflow tract (LVOT) gradient, PTSMA by alcohol-induced septal branch occlusion was introduced. However, clinical follow-up has not been sufficiently described.Methods. In 25 patients (13 women, 12 men; mean [±SD] age 54.7 ± 15.0 years) who were symptomatic despite sufficient drug therapy, 1.4 ± 0.6 septal branches were occluded with an injection of 4.1 ± 2.6 ml of alcohol (96%) to ablate the hypertrophied interventricular septum. After 3-months, follow-up results of LVOT gradients and clinical course were determined.Results. The invasively determined LVOT gradients could be reduced in 22 patients (88%), with a mean reduction from 61.8 ± 29.8 mm Hg (range 4 to 152) to 19.4 ± 20.8 mm Hg (range 0 to 74) at rest (p < 0.0001) and from 141.4 ± 45.3 mm Hg (range 76 to 240) to 61.1 ± 40.1 mm Hg (range 0 to 135) after extrasystole. All patients had angina pectoris for 24 h. The maximal creatine kinase increase was 780 ± 436 U/liter (range 305 to 1,810) after 11.1 ± 6.0 h (range 4 to 24). Thirteen patients (52%) developed a trifascicular block for 5 min to 8 days requiring temporary (n = 8 [32%]) or permanent (DDD) pacemaker implantation (n = 5 [20%]). An 86-year old woman died 8 days after successful intervention of uncontrollable ventricular fibrillation in conjunction with beta-sympathomimetics in chronically obstructive pulmonary disease. The remaining patients were discharged after 11.3 ± 5.4 days (range 5 to 24), after an uncomplicated hospital course. Clinical and echocardiographic follow-up was achieved in all 24 surviving patients after 3 months. No cardiac complications occurred. Twenty-one patients (88%) showed clinical improvement, with a New York Heart Association functional class of 1.4 ± 1.1. A further reduction in LVOT gradient was shown in 14 patients (58%).Conclusions. PTSMA of HOCM is a promising nonsurgical technique for septal myocardial reduction, with a consecutive reduction in LVOT gradient. Possible complications are trifascicular blocks, requiring permanent pacemaker implantation, and tachycardiac rhythm disturbances. Clinical long-term observations of larger patient series and a comparison with conventional forms of therapy are necessary to determine the conclusive therapeutic significance.     

Relationship between clinical presentation of atrioventricular block and its localization defined by His bundle electrogram.

The frequency of clinical and electrocardiographic symptoms in dependence on the localization of the atrioventricular (AV) block, defined with the aid of His bundle electrogram, was investigated in 49 patients with 2nd-or 3rd-degree AV block. The Adams-Stokes syndrome, broad ventricular complex, and Mobitz II-type AV block were most frequently encountered in patients with infrahisian block, whereas Mobitz I type block was most frequently found in patients with suprahisian block. A chronic course of AV block was most frequent in patients with intrahisian block. The mean ventricular frequency of complete blockade was highest in suprahisian block, and lowest in infrahisian block. The localization of the block is a decisive factor for estimation of the prognosis and for indication of pacemaker implantation.     

Transcatheter aortic valve replacement without previous conduction disturbances: The importance of preventing iatrogenic pacemaker implantation

• Transcatheter aortic valve replacement (TAVR) patients given pacemakers operating in mandatory DDD mode had more ventricular pacing, heart failure hospitalization, and mortality compared with AAI‐DDD or VVI modes.
• AV conduction disturbances are often transient after TAVR. Minimizing ventricular pacing where possible avoids the risk of pacemaker‐induced cardiomyopathy.
• Pacemaker specialists should be consulted for any TAVR patient with mild rhythm abnormalities given the high incidence of AV block.
• Careful stratification of patients with conduction disturbances during TAVR may help identify the patients who will require an early permanent pacemaker implantation strategy.

     

Impact of dual-chamber permanent pacing in patients with obstructive hypertrophic cardiomyopathy with symptoms refractory to verapamil and beta-adrenergic blocker therapy.

BACKGROUND. Patients with obstructive hypertrophic cardiomyopathy (HCM) with symptoms refractory to drugs (beta-blockers or verapamil) are candidates for cardiac surgery (left ventricular septal myectomy or mitral valve replacement). The present study examines prospectively the ability of dual-chamber (DDD) pacing to improve symptoms and relieve left ventricular outflow obstruction in such patients. METHODS AND RESULTS. Forty-four consecutive patients with obstructive HCM who had failed to benefit from pharmacotherapy underwent treadmill exercise tests, echocardiography, and cardiac catheterization before and 1.5-3 months after implantation of a DDD pacemaker. Symptoms (angina, dyspnea, palpitations, presyncope, and syncope), New York Heart Association functional class status (1.7 +/- 0.7 versus 3.4 +/- 0.5, p less than 0.00001), and exercise durations were improved at follow-up evaluation. This was associated with significant reduction in left ventricular outflow tract gradient (38 +/- 38 versus 87 +/- 43 mm Hg, p less than 0.0001) and significant increases in cardiac output and systemic arterial pressures. Notably, when pacing was discontinued and comparisons were made in sinus rhythm, treadmill exercise durations were greater and left ventricular outflow tract gradients were less at the follow-up evaluation compared with the baseline study. CONCLUSIONS. DDD pacing is an effective alternative to surgery in most patients with obstructive HCM with drug-refractory symptoms. The beneficial effects of pacing continue to be evident when pacing is acutely discontinued.     

Development of sinus node disease in patients with AV block: implications for single lead VDD pacing

OBJECTIVE: To investigate the incidence of sinus node disease after pacemaker implantation for exclusive atrioventricular (AV) block. DESIGN: 441 patients were followed after VDD (n = 219) or DDD pacemaker (n = 222) implantation for AV block over a mean period of 37 months. Sinus node disease and atrial arrhythmias had been excluded by Holter monitoring and treadmill exercise preoperatively in 286 patients (group A). In 155 patients with complete AV block, a sinus rate above 70 beats/min was required for inclusion in the study (group B). Holter monitoring and treadmill exercise were performed two weeks, three months, and every six months after implantation. Sinus bradycardia below 40 beats/min, sinoatrial block, sinus arrest, or subnormal increase of heart rate during treadmill exercise were defined as sinus node dysfunction. RESULTS: Cumulative incidence of sinus node disease was 0.65% per year without differences between groups. Clinical indicators of sinus node dysfunction were sinus bradycardia below 40 beats/min in six patients (1.4%), intermittent sinoatrial block in two (0.5%), and chronotropic incompetence in five patients (1.1%). Only one of these patients (0.2%) was symptomatic. Cumulative incidence of atrial fibrillation was 2.0% per year, independent of the method used for the assessment of sinus node function and of the implanted device. CONCLUSIONS: In patients undergoing pacemaker implantation for isolated AV block, sinus node syndrome rarely occurs during follow up. Thus single lead VDD pacing can safely be performed in these patients.     

History of Pacing in Hypertrophic Cardiomyopathy

The history of pacing in hypertrophic obstructive cardiomyopathy (HOCM) begins in 1964 and ends in the early 1990s when several well-documented articles confirmed that pacing the apex of the right ventricle could be considered as an effective primary therapy of severe, drug resistant HOCM. The first pacemaker implantation was reported in a patient with HOCM who developed a complete AV block. The efficacy of right ventricular (RV) pacing on the gradient was enhanced, but the concept of pacing in the absence of conduction abnormalities was not suggested. In 1967, Hassenstein was the first to demonstrate that right apex ventricular pacing in HOCM with intact AV conduction induced gradient reduction. He subsequently performed the first hemodynamic implantation several years later. The largest series confirming the undoubted efficacy of pacing in HOCM were reported by Jeanrenaud in Switzerland and Fananapazir in the USA in the early 1990s .     

Current physiologic pacemakers: A serious problem with a new device

Twenty adults underwent implantation of an automatic (DDD) pacemaker (Medtronic model 7000, Versatrax I) for treatment of symptomatic bradyarrhythmias. Only 9 patients had optimal DDD mode pacing during 78 paced months. In 3 patients, the DDD mode was changed to atrioventricular (AV) sequential (DVI) early because of risk imposed by sustained tachycardia upon underlying myocardial ischemia. The remaining 8 had had tachycardia due to pacemaker reentry, and 7 had neurologic and cardiovascular symptoms. DDD pacing was abandoned in 5 when reentry could not be interrupted by digitalis administration or reprogramming. Three continue to be paced in DDD mode despite intermittent reentrant tachycardias, with digitalis diminishing episodes of reentry in only 1. Mean ventriculoatrial conduction time was 229 ± 34 ms. Reentrant pacemaker tachycardia developed in 7 of 12 with normal or nearly normal AV conduction, but in only 1 of 5 with complete heart block. Preimplantation electrophysiologic study did not reliably detect and initial postoperative Holter monitoring did not predict reentrant tachycardia. The risk of reentry caused by a short, fixed atrial refractory period combined with the high occurrence of slow retrograde AV conduction, particularly in patients with normal or nearly normal anterograde conduction, renders the Versatrax I and other similar pacemakers unsuitable for DDD mode pacing in many patients.     

Optimization of atrioventricular delay and follow-up in a patient with congestive heart failure with an implanted DDD pacemaker: case report

It has been reported that cardiac function can be improved by implanting a DDD pacemaker (PM) and setting a short atrioventricular (AV) delay in patients with impaired cardiac function. A previous report found that the critical AV delay that induces diastolic mitral regurgitation (MR) may represent the upper limit of the optimal AV delay. The optimal AV delay can be predicted by a simple method: slightly prolonged AV delay minus the interval between the end of the atrial kick and complete closure of the mitral valve (duration of diastolic MR) at the AV delay setting. The patient was a 84-year-old man with an old myocardial infarction. He had repeated admissions to hospital for congestive heart failure. ECG showed prolongation of the PQ interval (0.28 s) and complete left bundle branch block. Cardiac function was improved by AV sequential pacing when the AV delay was set at 120ms. After DDD-PM implantation, the cardiothoracic ratio decreased from 57 to 45% and cardiac function was improved from New York Heart Association class III to I. The AV delay was optimized during follow-up. Four years after PM implantation, the patient was in good condition without further hospital admission.     

Late complete atriovenous block after percutaneous closure of a perimembranous ventricular septal defect.

Percutaneous closure of a perimembranous ventricular septal defect (VSD) is an alternative to surgical closure. Complications include arrhythmias and in particular early postoperative complete atrioventricular (AV) block. We report the cases of two patients, aged 2.5 and 4 years, treated with an eccentric VSD occluder device whom developed complete AV block 4 and 12 months after the procedure. The first patient experienced syncope, while the second one was completely asymptomatic. Both subjects underwent endocardial ventricular pacemaker implantation.     

Cardiopulmonary exercise test in patients with DDD pacemaker: report of two cases with increased exercise capacity by decreased ventricular tracking limit rate setting]

We reported 2 patients with complete A-V block with a DDD pacemaker whose exercise capacity was increased by decreased ventricular tracking limit rate setting (VTL) of their pacemakers. Cardiopulmonary exercise test was used for estimating exercise capacity. Case 1: A 15-year-old girl complained of fainting. Her electrocardiogram (ECG) revealed complete A-V block (atrial rates 100/min, ventricular rates 39/min). After implantation of a DDD pacemaker and the VTL setting at 152/min, her bradycardia disappeared, however, she complained of dyspnea after a few minutes' walk. We performed symptom-limited cardiopulmonary exercise test with a motor-driven treadmill. When the pacing rate reached VTL (152/min), ECG suddenly changed to approximately 2:1 pacing (80/min) and the patient complained of dyspnea. Concomitant rapid increases in VE, VCO2 and RQ suggested that dyspnea was caused by the marked change in pacing rates on VTL. With the lowered VTL (110/min), there was no rapid increase in VE, VCO2 and RQ, and dyspnea subsided when the pacing rate reached VTL. At the same time, the peak VO2 and exercise time were increased by 15% and 8%, respectively. Case 2: A 47-year-old man complained of syncope. His ECG revealed complete A-V block (atrial rates 100/min, ventricular rates 33/min). After a DDD pacemaker implantation (VTL: 150/min), he experienced dyspnea while walking up the stairs in his office. Like in Case 1, when the VTL was lowered from 150/min to 110/min, both the peak VO2 and exercise time were increased by 11%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Unterstützung der spontanen atrioventrukulären Überleitung bei Patienten mit DDD(R)-Schrittmachern Effektivität und Sicherheit

AIM: In a prospective and randomized multicenter study using a cross-over protocol we compared the efficacy and the safety of the ELA medical mode-switch algorithm (DDD/AMC = DDD to AAI) to conventional DDD stimulation in patients with spontaneous AV conduction. PATIENTS AND METHOD: Forty-eight patients with a mean age of 67 +/- 13 years were included. Underlying heart disease was present in 54%. Pacemaker indications were paroxysmal AV block (21%), sick-sinus syndrome (46%), paroxysmal AV block + sick-sinus syndrome (31%) and tachycardia-bradycardia syndrome (8%). Patients were excluded from the study in case of a permanent 1st to 3rd degree AV block, a right bundle-branch block with QRS > 120 ms, severe coronary heart disease or idiopathic cardiomyopathy. The programming of the pacemaker was randomized to either DDD/AMC or DDD and was crossed over after 1 month. The AV interval (AVI) which was programmed in conventional DDD pacing was calculated as AVI = PR (or AR) + 30 ms at rest or as AVI = PR (or AR) - 50 ms during exercise. When the DDD/AMC mode was programmed, the AV interval was calculated automatically. We analyzed the AV interval, the frequency of ventricular pacing, the number of pacemaker-induced tachycardias, the number of atrial tachyarrhythmias, and the final programming which was left to the physician's choice. RESULTS: The AV interval after conventional DDD stimulation was 201 +/- 38 ms vs 195 +/- 28 ms with DDD/AMC (p = ns). Ventricular stimulation was significantly less often in the DDD/AMC mode than in the DDD mode (15 +/- 17% vs 48 +/- 37%, p < 0.001). Thereby the DDD/AMC algorithm led to a 69% reduction of ventricular pacing which means an approximately 5.5 months prolongation of the battery lifetime. There was no significant difference in the incidence of pacemaker-induced tachycardias. At the end of the study 77% of the physicians programmed the DDD/AMC mode. CONCLUSION: The analyzed DDD/AMC mode-switch algorithm leads to a significant reduction of ventricular pacing in patients with spontaneous AV conduction or with only paroxysmal AV block. Thereby the battery lifetime is prolonged and the incidence of complications due to ventricular pacing can be reduced.     

Bidirectional Ventricular Tachycardia?

A 65‐year‐old woman was admitted to the hospital because of a syncopal episode with documented transient complete atrioventricular block. A DDD pacemaker was implanted. Post implantation, the patient was diagnosed with bidirectional ventricular tachycardia. Analysis of the arrhythmia and differential diagnosis is performed.