Deleterious effects of long-term single-chamber ventricular pacing in patients with sick sinus syndrome: the hidden benefits of dual-chamber pacing.

Nine hundred fifty patients who received three modes of primary pacemaker systems (581 dual-chamber universal [DDD], 84 atrioventricular-sequential ventricular-inhibited [DVI] and 285 ventricular-inhibited [VVI]) over 12 years were studied retrospectively to determine the effect of pacing mode on patient longevity and the subsequent development of chronic atrial fibrillation or flutter. All patients were followed up continuously for 7 to 8 years. Patients were classified according to indication for permanent pacing (sick sinus syndrome or other indication), age at pacemaker implantation (less than or equal to 70 or greater than 70 years) and history of atrial tachyarrhythmia. Fourteen percent of patients developed atrial fibrillation at some time during the study period. Of those, 4% had a DDD pacemaker, 8% had a DVI pacemaker and 19% had a VVI pacemaker. At 7 years, atrial fibrillation was significantly more frequent in the VVI group than in the DDD and DVI groups. In patients with sick sinus syndrome, the incidence rate was even higher in the VVI group but approximately the same in the DDD and DVI groups. Patients in the VVI and DVI groups who had had previous atrial tachyarrhythmia had a significantly higher incidence of atrial fibrillation at 7 years than did those in the DDD group. During the entire period there were 130 deaths in the study group, including 22% of patients with a DDD pacemaker, 38% of those with a DVI pacemaker and 50% of those with a VVI pacemaker. Patient survival at 7 years was lower in the VVI group than in the DDD or DVI groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical efficacy of permanent cardiac pacing in patients with bradysystolic forms of disturbances of cardiac rhythm and conduction

From 1996 to 2002 primary implantations of pacing systems because of bradysystolic disturbances of cardiac rhythm and conduction had been carried out in 311 patients. Indications were disturbances of atrioventricular conduction in 168 and sick sinus syndrome in 143 patients. According to type of permanent pacing patients were divided into 3 groups: with single-chamber ventricular on demand pacing (VVI, n=215), with single-chamber atrial pacing (AAI, n=39), and with dual-chamber pacing (DDD, n=57). As characteristics illustrating long term clinical results of permanent pacing we used development of the pacemaker syndrome; development of permanent atrial fibrillation; risk of thromboembolic complications and strokes; progression of heart failure; total, cardiovascular mortality and their structure; 7 year survival.     

VVI与DDD起搏对病窦综合征患者远期疗效的比较

比较VVI与DDD起搏方式对病窦综合征患者的临床疗效。研究病窦综合征患者212例,按不同起搏方式分为两组:VVI组105例、DDD组107例。研究终点:①在每次预定的随访中,以标准12导联ECG、Holter及心电监护诊断心房颤动(简称房颤);②卒中:当患者有大于24h脑缺血事件而产生神经系统症状或24h内死于脑血管事件,可确诊为卒中;③死亡:心血管事件死亡。患者出院后1,3,6个月定期随访,以后每隔半年随访一次。随访时,记录标准12导联ECG存档。每例患者至少有一份ECG,部分患者做Holter,了解有无阵发性房颤及术后发生持续性房颤的时间,患者的症状及体征。结果:①与VVI组比较,DDD组房颤发生率明显降低(10.3%vs24.8%,P<0.05);②VVI组患者6例出现脑卒中(5.7%),而DDD组无1人发生脑卒中,两组差异有显著性(P<0.05);③VVI组共有3例在术后3,4年发生慢性充血性心力衰竭,最后死于恶性心律失常,而DDD组患者均无因心力衰竭住院,随访至今无死亡。DDD组11例房颤均在2年内发生,其中第1年7例,而VVI组有26例房颤发生的时间较为弥散,2年内发生8例(30.8%),其余在3~8年内陆续发生。结论:病窦综合征患者安装双腔起搏器治疗发生房颤和脑卒中的机率明显减少。     

Comparative survival following permanent ventricular and dual-chamber pacing for patients with chronic symptomatic sinus node dysfunction with and without congestive heart failure

To determine whether survival following permanent ventricular demand pacing differs from survival following permanent dual-chamber pacing in patients with symptomatic sinus node dysfunction (unexplained sinus bradycardia, subsidiary rhythms, sinus arrest, sinoatrial block, or the bradycardia/tachycardia syndrome), we followed 79 patients who received a VVI pacemaker (group 1) and 49 patients who received a DVI or DDD pacemaker (group 2) for 1 to 5 years. There was no significant difference in sex distribution, mean age, or the incidence of coronary heart disease, hypertension, valvular heart disease, diabetes mellitus, stroke, or renal failure between groups 1 and 2. Overall, the predicted cumulative survival rates at 1, 3, and 5 years were 89%, 82%, and 74%, respectively, for group 1 and 94%, 86%, and 78%, respectively, for group 2. In patients with preexistent congestive heart failure (CHF), predicted cumulative survival rates at 1, 3, and 5 years were 78%, 69%, and 57%, respectively, for group 1 (n = 23) and 90%, 83%, and 75%, respectively, for group 2 (n = 16). Five-year predicted cumulative survival was significantly lower in group 1 patients with CHF than in group 2 patients with CHF (p less than 0.03). There was no significant difference in 5-year cumulative survival rates between groups 1 and 2 in patients without CHF. The results suggest that permanent dual-chamber pacing enhances survival to a greater extent than permanent ventricular demand pacing in patients with chronic symptomatic sinus node dysfunction and CHF.     

Pacing for sinus node disease: A therapeutic rationale

Symptomatic sinus node disease is a common indication for permanent pacemaker implantation. Single-chamber ventricular (VVI) pacing, single-chamber atrial (AAI) stimulation, and dual-chamber (DDD or DDI) systems are used to a varying extent at different implanting centers. Hemodynamic and clinical studies relevant to the choice of pacing mode in these patients are reviewed. The data currently available strongly support the use of pacing systems providing atrial stimulation. The choice between single-chamber atrial or dual-chamber pacing can be based on the relative importance assigned to a number of factors: Hemodynamic aspects, the risk of ventricular lead problems, cost, and complexity aspects favor AAI pacing, whereas patients with a substantial risk of developing atrioventricular block should receive a DDD or DDI unit.     

Congestive heart failure treated by the upgrade from VVI to DDD pacing

The case is presented of an elderly woman with normal left ventricular (LV) systolic function and VVI pacing complicated by severe congestive heart failure. The symptoms and findings of congestive heart failure became refractory to medical treatment and resolved with the upgrade of the VVI to a DDD system. Right heart catheterization during VVI pacing showed increased mean pulmonary capillary wedge and right atrial pressures both being normalized under DDD pacing. This case report illustrates the need to consider permanent physiological pacing in elderly patients, even in presence of normal LV systolic function, to ensure AV synchrony when the atrium can be paced, since diastolic LV dysfunction is quite common in these subjects.     

Influence of Cardiac Pacing Mode on Left Atrial Appendage Flow Velocity: Implication to Systemic Embolism During VVI Pacing

Previous studies have shown that the incidence of thromboembolism is higher in patients with single-chamber ventricular demand (VVI) pacemakers than in patients with dual-chamber (DDD) pacemakers. However, data on left atrial appendage flow velocity in pacing patients are limited. To investigate the influence of the pacing mode on the left atrial appendage flow velocity, we studied 19 patients with permanent DDD pacemakers and measured the left atrial appendage flow velocity by transesophageal echocardiography at baseline (during DDD pacing) and after switching to VVI pacing. The indications for pacemaker implantation were second- and third-degree atrioventricular block (AVB group, n = 11) and sick sinus syndrome (SSS group, n = 8). Compared with the DDD pacing mode, there was a significant decrease in the left atrial appendage flow velocity during VVI pacing in both the SSS group (43 ± 14 vs 23 ± 7 cm / sec, P < 0.05) and the AVB group (59 ± 18 vs 41 ± 18 cm / sec, P < 0.05). In eight patients with persistent retrograde ventriculoatrial conduction during VVI pacing, the left atrial appendage flow velocity was markedly decreased (from 43 ± 16 to 25 ± 9 cm / sec, P < 0.05). In five (63%) of the eight patients, left atrial appendage flow velocity was less than 25 cm/sec. A reduction in left atrial appendage flow velocity when switching from DDD to VVI pacing may account for an increased risk of thrombus formation in the left atrial appendage (an increased thromboembolic risk in patients in sinus rhythm with VVI pacemakers).     

Incidence of arrhythmias after atrial or dual-chamber pacemaker implantation

The incidence of sustained atrial, pacemaker-mediated and ventricularrhythm disturbances was studied retrospectively in a consecutiveseries of112 patients without a history of preexisting atrialtachy arrhythmias, receiving an atrial or dual-chamber pacemaker. Early atrial fibrillation (during the first week) was recordedtwice. Late atrial fibrillation was seen in seven patients,flutter in one, yielding a total incidence of 8.9% for 22 months.There were no significant differences with respect to age, aetiology,electrocardiographic diagnosis, pacing history, or the measuredintracardiac P wave between the group with and the group withoutatrial fibrillation. Treatment with digoxin reverted three patientsto sinus rhythm, association of digoxin and amiodarone, sixpatients. One patient with congestive heart failure remainedin atrial fibrillation. Pacemaker-mediated tachycardia was not a major problem. Onepatient of a subgroup with known ventricular arrhythmia hada non-sustained ventricular tachycardia during programming atfollow-up; sustained ventricular tachycardia was not recorded.Reprogramming to VDD, DVI or VVI was done in 6/100patients. The incidence of atrial fibrillation or flutter in highly selectedpatients with dual-chamber or atrial pacing is moderately low.It is not possible to identify patients with a high risk fordevelopment of atrial fibrillation; when it occurs, it is easilycontrolled with drugs. DDD pacing seems to be safe in patients with a history of seriousventricular arrhythmias, treated with appropriate drugs.     

Comparison of dual chamber and ventricular rate responsive pacing in patients over 75 with complete heart block.

OBJECTIVE--To compare symptoms and exercise tolerance during dual chamber universal (DDD) and ventricular rate response (VVIR) pacing in elderly (> or = 75) patients. DESIGN--Randomised, double blind, crossover study. SETTING--Regional cardiac department. PATIENTS--Twenty elderly patients (mean age 80.5 (1) years) with high grade atrioventricular block and sinus rhythm. Patients with pre-existing risk factors for the pacemaker syndrome and chronotropic incompetence were excluded. INTERVENTION--After four weeks of VVI pacing following pacemaker implantation, patients underwent consecutive two week periods of VVIR and DDD pacing. MAIN OUTCOME MEASURES--Patient preference, symptom scores, "daily activity exercises," and perceived level of exercise (Borg score). RESULTS--Eleven patients preferred DDD mode to either VVI or VVIR mode. Mean (SE) total symptom scores during VVI, VVIR, and DDD pacing were 5.9 (1.1), 6.1 (1.0), and 3.5 (0.9) respectively (P < 0.01). The corresponding mean (SE) pacemaker syndrome symptom scores were 4.8 (0.7), 5.2 (0.8), and 2.9 (0.8) (P < 0.05). Symptom scores during VVI and VVIR pacing were not significantly different. Exercise performance and Borg scores were significantly worse during VVI pacing compared with VVIR or DDD pacing but did not significantly differ between VVIR and DDD modes. CONCLUSIONS--In active elderly patients with complete heart block both DDD and VVIR pacing are associated with improved exercise performance compared with fixed rate VVI pacing. The convenience and reduced cost of VVIR systems, however, may be offset by a higher incidence of the pacemaker syndrome. In elderly patients with complete heart block VVIR pacing results in suboptimal symptomatic benefit and should not be used instead of DDD pacing.     

Subjective and Objective Response to Single- Versus Dual-Chamber Pacing

With two different questionnaires, we analyzed the feeling of well-being during dual chamber pacing mode and VVI mode in 25 randomly selected patients, mean age 66.7 years (range 22–84). All patients had high degree AV block and received either a DDD pacemaker (23 patients) or a VDD pacemaker. Under each pacing mode exercise tests were performed as well. Questionnaire 1 was answered during DDD or VDD mode. According to questionnaire 1, 76% of the patients remembered their symptoms before PM implantation. Eighty-two percent of the patients felt an improvement of their symptoms after the installation of the pacemaker. Questionnaire 2 was answered after a three-week period of VVI pacing. Fifty-six of the patients indicated a deterioration of their general conditions, 36% of the patients noted dizziness, 58% dyspnea, 40% reduced effort tolerance, and 22% a sleep disturbance. After a change to dual-chamber pacing, general well-being was better in 74% of the patients, dyspnea was noted in only 15%, effort tolerance was improved in 61%, and sleep was undisturbed in 97%. The physical work capacity (expressed as a product of Watts multiplied by minutes) tested on a bicycle ergometer was 400 ± 190 Wmin in VVI mode and 414 ± 272 Wmin in DDD/VDD mode (p = ns). The double products were 14,600 ± 4,934 and 22,066 ± 5,585 (p < 0.05), respectively. We conclude that dual-chamber pacing leads to a significant improvement in the quality of life for patients with symptomatic AV block.     

Pacemaker selection: time for a rethinking of complex pacing systems?

Evidence from randomized trials indicates that the clinical benefits of dual-chamber (DDD) pacing are modest: (i) no significant differences exist between physiological pacing and single-chamber pacing in mortality and stroke; (ii) ventricular desynchronization resulting from chronic right-ventricular pacing in DDD mode, induces a significantly increased incidence of atrial fibrillation (AF) and heart failure hospitalizations; (iii) AF pacing prevention and therapy algorithms have shown a modest to minimal or absent efficacy; (iv) the widespread use of physiological pacemakers is not an economically attractive strategy. Thus, these data provide a reliable body of evidence on which to make more rationale clinical decisions for individual patients and policy decisions for health costs saving. The cheaper single-chamber AAI(R) or VVI(R) has been shown to satisfy both conditions in most cases of sinus node disease and AV block.     

Pacemaker hemodynamics: Clinical implications

Our review of the current literature and experience in caring for pacemaker patients suggests that a consideration of hemodynamics is a logical way to approach pacemaker selection and programming. Multiple clinical factors enter into the selection of a pacemaker or pacemaker programming settings in each case. It appears that in patients with sinus node disease, atrial-inhibited or dual-chamber pacing provides the best chance for preventing the development of chronic atrial fibrillation with its attendant risks of embolism and stroke. It is clear that AV synchrony has beneficial hemodynamic effects at rest in most patients. The results of Labovitz would suggest that in patients with marked left atrial enlargement, this may be less so. The results of Stewart et al would further suggest that in patients with retrograde VA conduction, dual-chamber pacing is preferable. Retrograde VA conduction can be intermittent and this makes it difficult to use its absence on a single test to decide on the type of pacemaker to use. It appears that baseline left ventricular function does not determine the relative improvement in cardiac output observed with AV synchrony or rate-adaptive pacing. However, in patients with severe congestive heart failure even a small improvement in cardiac output may result in significant clinical improvement. Studies have shown that in any given patient, there may be an optimal AV interval at rest. In general, this ranges from 100 to 150 milliseconds. In normal individuals the optimal AV interval shortens with increased heart rate during exercise in a predictable and linear fashion. The hemodynamic benefits of a shortened AV interval with faster heart rates in pacemaker patients have not yet been shown. Intuitively, however, this would appear to be a desirable approach and will probably be added to the design of future generations of dual-chamber pacemakers. Studies of the effect of different pacing modes on secretion of atrial natriuretic factor are intriguing and may contribute more to our understanding of pacing hemodynamics in the future. During exercise, heart rate increase is more important than AV synchrony and this has been shown by several studies. Thus, in active patients with chronotropic incompetence due to sick sinus syndrome, the addition of rate-adaptive pacing is important. Because single-chamber rate-adaptive atrial pacing leaves the patient exposed to the risk of future development of AV block and DDD pacing does not provide chronotropic support, it is likely that the new rate-adaptive dual-chamber (DDDR) devices will be used in a significant number of these patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

AAI pacing mode: When is it indicated and how should it be achieved?

AAI pacing offers better hemodynamic characterstics than dual-chamber pacing and is the optimal mode for patents with sick sinus syndrome without AV conduction disorders. AAI pacing may be achieved by single-chamber atrial, by programming a dual-chamber pacemaker to the AAI mode, or by programming a dual-chamber pacemaker to DDD mode with a long AV delay. The annual incidence of AV block development in patients with sick sinus syndrome is low, probably 1-5%, but there is no method of detecting patients immune to future development of AV block. Chronotropic is often present in patients with sick sinus but the value of additional rate response is not yet established. Our recommendations for the choice of the method of pacing are discussed.     

Pacemaker syndromes

The pacemaker syndrome refers to symptoms and signs in pacemaker patients caused by inadequate timing of atrial and ventricular contractions. The lack of normal atrioventricular synchrony may result in decreased cardiac output and increased in atrial pressure which elicits a systemic hypotensive reflex response. These hemodynamic disturbances mostly occur in the presence of retrograde VA conduction is present. The incidence of pacemaker syndrome is uncertain, and varies from 7% to 20% of all ventricular paced patients. Neurologic symptoms or symptoms suggesting low cardiac output or congestive heart failure are indicative of the pacemaker syndrome. These symptoms may vary from mild to severe, they are nonspecific and very common among cardiac patients with or without pacemaker. In many patients they are not even noted until AV synchrony is restored. The pacemaker syndrome is not restricted to the VVI stimulation mode. It can be seen, though rarely, in atrial and even dual-chamber pacing (VDD, DDI, DDD). In these cases it is usually occasional and may be due to inappropriate programming or selection of the pacing mode.     

Survival in patients with permanent pacemakers.

Atrioventricular block I has a benign natural course, and permanent pacing is not warranted. Second-degree AV block, including both type I and type II, can have an ominous course, especially in older patients with underlying heart disease. One study claims that the prognosis in patients with second-degree AV block, irrespective of type, is improved by permanent pacing. In spite of lack of controlled studies it has been convincingly shown that VVI pacing prolongs life in patients with high-grade AV block. Two studies suggest that atrial synchronous pacing in patients with congestive heart failure and high-grade AV block might improve their survival. Studies comparing survival with different pacing modes in patients with sinus node disease support the hypothesis that physiologic pacing can improve survival. Prophylactic pacemaker implantation even in symptomatic patients with chronic bifascicular block does not seem to protect them from sudden death.     

Blood B-type natriuretic peptide changes in different periods and different cardiac pacing modes

To observe blood B-type natriuretic peptide (BNP) level changes and the clinical implications in different periods and different cardiac pacing modes, the BNP levels of 105 patients with permanent cardiac pacing were assayed before pacemaker implantation and 1 day, 1 week, 1 month, 3 months, 6 months, and 9 months postoperatively. BNP level changes were compared in different periods and during different pacing modes. DDD(R) pacing mode was performed in 32 patients for 9 months and then changed to AAI(R) and VVI(R) pacing modes for 2 months, respectively. BNP levels were assayed during three different pacing modes. BNP levels did not change at any time with any pacing mode in patients with New York Heart Association (NYHA) heart functional class I to II before pacemaker implantation, however, BNP levels did change significantly with physiologic pacing mode and nonphysiologic pacing mode in patients with NYHA heart functional class III to IV before pacemaker implantation. BNP levels during physiologic pacing mode decreased significantly while it increased during nonphysiologic pacing mode. BNP levels were the lowest in AAI(R) pacing and the highest in VVI(R) pacing among the three pacing modes. The BNP level in DDD(R) pacing was between that for AAI(R) pacing and VVI(R) pacing. The results indicate that physiologic pacing should first be chosen in patients with bradycardia and congestive heart failure (CHF), and that AAI(R) was the best pacing mode if atrioventricular conduction function was normal.     

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.

     

A new dual-chamber pacemaker with an automatic antitachycardia system in the treatment of the bradycardia-tachycardia syndrome

A new dual-chamber pacemaker with automatic tachycardia terminating system was used in three patients with bradycardia-tachycardia syndrome. This pacemaker (Medtronic Symbios 7008) is a multiprogrammable, bipolar device with bidirectional telemetry and six permanent pacing modes (DDD-DVI-VVI-DOO-VOO-AOO). The antitachycardia system can be programmed in two different modes: underdrive dual demand and overdrive atrial burts (1 to 16 stimuli with selectable coupling interval from 135 to 360 msec). The pacing modes are automatically activated when five consecutive R-R cycles shorter than the tachycardia detection interval are sensed. The pacemaker may sense the ventricle (when set on VVI or DVI mode) or sense both the atrium and the ventricle (in DDD mode). The pacemaker was programmed on DVI mode in all three patients, and the overdrive atrial burst program was used for tachycardia termination, with promptly and costantly effective results. The underdrive dual demand program was tested after the implantation, but it did not show constant results because inefficacy or late termination of tachycardias.     

生理性起搏对老年缓慢性心律失常伴心功能不全患者的作用

目的：探讨生理性及非生理性起搏对伴有心功能不全的老年缓慢型心律失常患的作用。方法：在常规强心药物治疗同时安置永久起搏器。非生理性起搏组54例,生理性起搏组36例（使用DDD起搏为12例）。于术术、术后1周及术后6个月时用超声多普勒分别测定心功能参数。结果：生理性起搏组术后1周时左室射血分数（LVEF）、每搏量（SV）及心排量（CO）均明显改善,血流加速时间（AT）缩短,主动脉峰值血流速度（PV）加快。6个月后上述参数进一步改善,左室舒张末期内径（LVd)亦显缩小,该组患术后1周及术后6个月心功能改善情况均明显优于非生理性起搏器。DDD起搏A－V间期为100ms时心功能参数最理想。结论采用物＋生理性水久起搏术治疗老年缓慢型心律失常的心功能不全,可取得满意的近期和远期效果。     

生理性起搏对老年缓慢型心律失常伴心功能不全患者的作用

目的　探讨生理性及非生理性起搏对伴有心功能不全的老年缓慢型心律失常患者的作用。方法　在常规强心药物治疗的同时安置永久起搏器。非生理性起搏组 5 4例 ,生理性起搏组 36例 (使用DDD起搏为 12例 )。于术前、术后 1周及术后 6个月时用超声多普勒分别测定心功能参数。结果　生理性起搏组术后 1周时左室射血分数(LVEF)、每搏量 (SV)及心排量 (CO)均明显改善 ,血流加速时间 (AT)缩短 ,主动脉峰值血流速度 (PV)加快。 6个月后上述参数进一步改善 ,左室舒张末期内径 (LVd)亦显著缩小。该组患者术后 1周及术后 6个月时心功能改善情况均明显优于非生理性起搏器。DDD起搏者A V间期为 10 0ms时心功能参数最理想。结论　采用药物 +生理性永久起搏术治疗老年缓慢型心律失常患者的心功能不全 ,可取得满意的近期和远期效果。