Benefits of dual chamber pacing in sick sinus syndrome

The relevance of health related quality of life in paced patients

With the tremendous advances in cardiac pacing during the past four decades, cardiac pacemaker implantation is now a common clinical procedure. In recent years, the indications for permanent pacemakers have expanded. This increase in reasons for pacing and shift in mode of pacing have been caused by the evolution of pacemaker therapy from a life-saving measure (mortality), to one aimed at improving health-related quality of life (HRQoL). Until now the efficacy of pacing therapy has predominantly been measured using "objective" criteria. However, in recent years the importance of HRQoL as an outcome measure has increasingly been recognized as patients prefer quality over quantity of life. In this review we describe the development and testing of Aquarel, a new developed HRQoL questionnaire for pacemaker patients, composed of a generic core module with disease specific add-ons. Current and future research to improve the Aquarel questionnaire is also described.

Dual chamber versus single chamber ventricular pacemakers for sick sinus syndrome and atrioventricular block

BACKGROUND

Dual chamber pacing or single chamber atrial pacing ('physiologic' pacing) is believed to have an advantage over single chamber ventricular pacing in that it resembles cardiac physiology more closely by maintaining atrioventricular (AV) synchrony and dominance of the sinus node, which in turn may reduce cardiovascular morbidity and mortality thus contributing to patient survival and quality of life. However, a significant proportion of pacemakers currently implanted are single chamber ventricular pacemakers.

OBJECTIVES

The objective of this review was to assess the short- and long-term clinical effectiveness of dual chamber pacemakers compared to single chamber ventricular pacemakers in adults with AV block, sick sinus syndrome or both. An additional objective was to assess separately any potential differences in effectiveness between dual chamber pacing and single chamber atrial pacing. The clinical effectiveness of single chamber atrial pacing versus single chamber ventricular pacing was not examined.

SEARCH STRATEGY

The Cochrane Controlled Trials Register (The Cochrane Library Issue 3, 2002), MEDLINE (1966 to 2002), EMBASE (1980 to 2002) and the Science Citation Index (1980 to 2002) were searched on 19th August 2002. Citation lists and web sites were checked and researchers in the field contacted.

SELECTION CRITERIA

Parallel group or crossover randomised controlled trials of at least 48 hours duration comparing dual chamber pacing and single chamber ventricular pacing, and investigating cardiovascular morbidity, mortality, patient related quality of life, exercise capacity and complication rates.

DATA COLLECTION AND ANALYSIS

Data was extracted onto pre-piloted data extraction forms. Quality assessment was undertaken using a checklist, with a sub-sample of quality data independently extracted by a second reviewer. Where appropriate data was available, meta-analysis was performed. Where meta-analysis was not possible, the number of studies showing a positive, neutral or negative direction of effect and statistical significance were simply counted.

MAIN RESULTS

Five parallel and 26 crossover randomised controlled trials were identified. The quality of reporting was found to be poor. Pooled data from parallel studies shows a statistically non-significant preference for physiologic pacing (primarily dual chamber pacing) for the prevention of stroke, heart failure and mortality, and a statistically significant beneficial effect regarding the prevention of atrial fibrillation (odds ratio (OR) 0.79, 95% CI 0.68 to 0.93). Both parallel and crossover studies favour dual chamber pacing with regard to pacemaker syndrome (parallel: Peto OR 0.11, 95% CI 0.08 to 0.14; crossover: standardised mean difference (SMD) -0.74, 95% CI - 0.95 to -0.52). Pooled data from crossover studies shows a statistically significant trend towards dual chamber pacing being more favourable in terms of exercise capacity (SMD -0.24, 95% CI -0.03 to -0.45). No individual studies reported a significantly more favourable outcome with single chamber ventricular pacing.

REVIEWERS' CONCLUSIONS

This review shows a trend towards greater effectiveness with dual chamber pacing compared to single chamber ventricular pacing, which supports the current British Pacing and Electrophysiology Group's Guidelines regarding atrioventricular block. Additional randomised controlled trial evidence from ongoing trials in this area will further inform the debate.

Sick sinus syndrome

Sinus-node dysfunction is common in the elderly and, in most cases, does not cause any symptoms. Despite the high number of laboratory investigations, most diagnoses of sinus-node dysfunction are made by 12-lead electrocardiography, which shows severe sinus bradycardia, sinus arrest, or sinoatrial block. Continuous electrocardiographic monitoring, exercise testing, and electrophysiologic investigations (including pharmacologic interventions to cause complete autonomic blockade) are sometimes useful in detecting transient or latent sinus-node abnormalities. The term sick sinus syndrome should be reserved for patients with symptomatic sinus-node dysfunction. Sick sinus syndrome has a protean presentation with variable degrees of clinical severity. Symptoms are often intermittent, changeable, and unpredictable. Because these symptoms can be observed in several other diseases, none are specific to sick sinus syndrome. Owing to the nonspecific nature of its symptoms, sick sinus syndrome can be diagnosed only when clear electrocardiographic signs corroborate symptoms. In the absence of a demonstrable link between signs and symptoms, a diagnosis can be presumed only when signs of severe sinus dysfunction are present and when every other possible cause of symptoms has been excluded carefully. Sinus-node dysfunction frequently is associated with diseases of the autonomic nervous system, and autonomic reflexes play a major role in the genesis of syncope. Survival does not seem to be affected by sick sinus syndrome. Atrioventricular block, chronic atrial fibrillation, and systemic embolism are major pathologic conditions that affect the outcome of the syndrome. Treatment should be aimed at controlling morbidity and relieving symptoms. Cardiac pacing is the most powerful therapy; physiologic pacing (atrial or dual-chamber) has been shown definitively to be superior to ventricular pacing.

Psychometric properties of Aquarel. a disease-specific quality of life questionnaire for pacemaker patients

In cardiac pacing current clinical practice permits the use of ventricular or atrioventricular-synchronous pacemakers. However, it is not known which type of pacemaker results in superior clinical and patient outcomes. To date, there is no feasible and validated disease-specific questionnaire for pacemaker patients to assess quality of life (QoL) available. The Aquarel questionnaire was developed as a disease-specific extension to the Short-Form-36 (SF-36). A cross-sectional study was carried out in 74 pacemaker patients to evaluate validity and reliability of this instrument. Items were selected and scales constructed based on factorial analysis. Internal consistency, content validity and test-retest reliability were moderate to excellent. Correlations with the SF-36 scales, pacing mode and functional tests were as hypothesized, demonstrating the individual value and distinctiveness of the Aquarel subscales. The results support the feasibility and usefulness of evaluating QoL in pacemaker patients when using Aquarel as an extension to the SF-36.

Quality-of-life of pacemaker patients: a reappraisal of current instruments

Current clinical practice permits the use of single chamber ventricular or dual chamber pacemakers. However, it is not known which type of pacemaker results in superior clinical and patient outcomes. This is of growing importance because of the higher costs and increased risk of technical failures of dual chamber pacemakers. Patient outcomes can be assessed with quality of life questionnaires, but it is unclear which questionnaires are valid for use in pacemaker patients. This article reappraises studies on quality of life instruments for pacemaker patients. We searched MEDLINE (1985-1998) for studies assessing quality-of-life in general and in pacemaker patients. The SF-36 appeared to be the best among generic questionnaires because of its psychometric characteristics and experience of use. Concerning disease specific instruments, the Karolinska quality of life questionnaire has desirable content validity but lacks more rigorous psychometric validation, which constitutes a serious limitation. Previous studies suggested that implantation of atrioventricular pacemakers improves quality-of-life compared to ventricular pacemakers, but since no well-designed and validated questionnaire exists, these results should be interpreted with caution. The best outcome measure to evaluate quality-of-life in pacemaker patients would be a combination of a generic health profile with established reliability and validity supplemented with a cardiovascular assessment adjusted to suit pacemaker patients. By doing so, individual scores can be compared within a disease cohort and to same-aged, nondiseased persons, as well as other diseased populations. The development and validation of such an instrument is currently needed.

Noninvasive beat-to-beat arterial blood pressure measurement during VVI and DDD pacing: relationship to symptomatic benefit from DDD pacing

To noninvasively assess the hemodynamic effects of VVI and DDD pacing modes we measured beat-to-beat arterial blood pressure during VVI and DDD pacing in 30 patients with complete heart block (CHB), using fingertip photoplethysmography. Of these patients, 15 undertook a double-blind cross-over comparison of the symptomatic effects of VVI versus DDD pacing to determine the relationship between blood pressure changes and the occurrence of symptoms suggestive of the pacemaker syndrome during ventricular pacing. Mean (SD) systolic blood pressure was 11.7 (15.4) mmHg lower during VVI pacing compared to DDD pacing (P < 0.0005). The mean (SD) beat-to-beat variability of systolic blood pressure was 5.20 (2.87%) in VVI mode versus 2.12 (1.07%) in DDD mode (P < 0.0000005). In comparison with DDD pacing, the excess of symptoms experienced by patients during VVI pacing did not correlate with the change in mean systolic blood pressure, but was significantly correlated with the increase in beat-to-beat systolic blood pressure variation during VVI pacing (r = 0.58, P = 0.024). We conclude that noninvasive measurement of fingertip arterial beat-to-beat blood pressure is a rapid and simple method of assessing the hemodynamic effect of VVI pacing. Beat-to-beat blood pressure variability was related to symptomatic intolerance of VVI pacing and may have potential utility as an aid to diagnosis or as a predictor of pacemaker syndrome.

Atrial fibrillation in patients with permanent VVI pacemakers: risk factors for atrial fibrillation

OBJECTIVES

Atrial fibrillation (AF) does not only deteriorate the cardiac function and increases the thromboembolic risk but also triggers rapid and irregular ventricular rhythm in patients with atrial synchronous pacing. However, the risk factors for the development of AF in patients with pacemakers are not clearly determined yet. The present study was designed to determine the risk factors for AF in patients with VVI pacemakers.

METHODS

This study included 80 patients (41 sick sinus syndrome, 39 AV block) who were followed for more than 6 months or developed AF regardless of the duration of follow-up after implantation of VVI pacemakers. Patients were divided into two groups according to whether or not AF developed during follow-up (mean: 25.7 +/- 2.5 months): group A developed AF and group B did not. The underlying arrhythmias, cardiovascular risk factors, left atrial size, characteristics of P wave were compared between the two groups.

RESULTS

The mean age of the patients was 58.9 +/- 11.4 years and 28 (35%) were male. AF developed in 13 (16.3%) of 80 patients with VVI pacemakers. Sick sinus syndrome (SSS) as an underlying arrhythmia was significantly more frequent in group A than group B (84.6% vs. 44.8%, p < 0.01). P wave width was greater in group A (127.6 +/- 24.8 ms) than in group B (110.7 +/- 17 ms) (p < 0.05). There was, however, no significant difference in cardiovascular risk factors, left atrial size, P wave axis and amplitude between the two groups.

CONCLUSION

These results suggest that sinus node dysfunction and intra-atrial conduction delay may be the risk factors for AF in patients with VVI pacemakers. Further studies are needed to determine how sick sinus syndrome and intra-atrial conduction delay increase the risk for AF in patients with VVI pacemakers.

A comparison of quality-of-life in patients with dual chamber pacemakers and individually programmed atrioventricular delays

Dual chamber pacemakers are increasingly implanted to achieve optimal hemodynamics by AV synchrony, but the effect of AV delay programming on the patient's quality-of-life has been less well studied. The influence of an individually programmed AV delay between 100 and 250 ms on quality-of-life was investigated in a randomized, double-blind crossover study of 13 patients (69 +/- 10 years of age) with dual chamber pacemakers implanted because of high degree AV block. During radionuclide ventriculography at rest, the "optimal AV delay" with the maximal left ventricular ejection fraction and the "most unfavorable AV delay" with the least ejection fraction were determined. The ejection fraction at rest with the "optimal AV delay" was 51% +/- 10%, and with the "most unfavorable AV delay," 44% +/- 11% (P < 0.0001). The optimal AV delay determined by radionuclide ventriculography correlated well with the optimal AV delay determined by Doppler echocardiography using flow velocity integrals (r = 0.78, P < 0.0016). Each patient was assigned in random order to either AV delay during a 2-week period and then the pacing mode was switched for another 2-week period. At the end of each period, patients were assessed by a functional status questionnaire to assess physical capability and two further questionnaires to quantify cardiovascular symptoms or self-perceived health. There were no differences in the two AV delays regarding the patient's perceived physical capability and specific symptoms. The patient's total judgment was identical to the optimal AV delay (score 36% +/- 19%) and the most unfavorable AV delay (33% +/- 21%). Thus, in patients with a dual chamber pacemaker, an individually programmed AV delay affects left ventricular function at rest, but has no influence on quality-of-life. The determination of the flow velocity integral by Doppler echocardiography is a simple and reliable method to optimize the AV delay if necessary.

Acute changes in left atrial and left ventricular diameters after physiological pacing

The present study examined alterations in left atrial diameter (LAD) and diastolic left ventricular diameter (LVDd) in 37 patients (72.2 +/- 9.8 years old) who received physiological pacemakers; 22 with atrioventricular (AV) block and 15 with sick sinus syndrome (SSS). After pacemaker implantation, LAD and LVDd were serially measured using echocardiography, and their diameters were expressed per body surface area (LADI and LVDdI; mm/m2). Pulmonary capillary wedge pressure (PCWP) and cardiac output (CO) were measured in ten patients with SSS and ten with AV block during both right ventricular and AV sequential pacing. After AV sequential pacing, CO increased in 19 of 20 patients (3.2 +/- 0.9 L/min to 3.9 +/- 1.0 L/min; P < 0.001). LADI decreased from 24.9 +/- 4.2 mm/m2 to 21.8 +/- 4.4 mm/m2 (P < 0.001) in 22 patients with AV block and from 24.1 +/- 3.4 mm/m2 to 20.4 +/- 3.8 mm/m2 (P < 0.001) in 15 SSS patients. However, LVDdI did not change significantly in either group of patients. The changes in LAD after the implantation of a physiological pacemaker occurred rapidly, i.e., LAD began to decrease within 1 minute after the procedure, and then reached a plateau. This plateau phase continued for at least 7 days during physiological pacing. There was a positive correlation between the changes in LADI after pacemaker implantation and those in PCWP observed during the AV sequential pacing performed prior to the implantation (r = 0.86; P < 0.001). The reduction in LAD following pacemaker implantation was rapid and seemed to be accompanied by improvement of cardiac function. Thus, it is suggested that the serial measurement of LADI is useful to predict the efficacy of physiological pacemaker implantation.

Permanent cardiac pacemakers in the elderly

OBJECTIVE

To review (1) Changes in cardiac impulse generation, conduction, and ventricular filling in normal aging and disease; (2) Pacemaker technology and nomenclature; (3) Expert guidelines about pacemaker use; (4) Studies of pacemaker effectiveness and utilization.

DESIGN

Articles were identified through a Medline search, review of articles' bibliographies, and contact with pacemaker manufacturer representatives for information on device features and costs. These articles were reviewed, and the relevant data are presented.

RESULTS

Abnormalities in impulse generation and conduction are common in the elderly. Pacemaker use is higher in the elderly than in other population groups. Hemodynamic changes associated with aging include an increased contribution of atrial contraction to ventricular filling. Pacemakers, which maintain the synchrony between the atria and ventricles, may be particularly advantageous in the elderly for this reason. Rate-responsive ventricular pacemakers improve the quality of life compared with fixed rate devices in some patients over the age of 75. Dual-chamber, sequential pacemakers are more likely to reduce symptoms of pacemaker syndrome than ventricular pacemakers and probably also prolong survival and reduce risk of atrial fibrillation in certain groups of patients. However, dual chamber devices are more expensive and require more frequent follow-up. Pacemaker utilization can vary widely by region. Decisions about pacemakers require explicit tradeoffs between risk and quality of life on one hand and cost on the other. In many clinical situations, there is controversy as to whether pacemakers should be used.

CONCLUSIONS

Pacemakers provide definite benefits to some patients, whereas in others, the likelihood of benefit is uncertain. More sophisticated devices may provide some additional benefit, but they are more costly. Further data is still required to define precisely which groups of patients substantially benefit from complex and expensive pacing modalities compared with simpler ones.

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)

"Subclinical" pacemaker syndrome: a randomised study of symptom free patients with ventricular demand (VVI) pacemakers upgraded to dual chamber devices

OBJECTIVE

To determine whether symptom free patients with single chamber pacemakers benefit from dual chamber pacing.

DESIGN

A randomised double blind crossover comparison of ventricular demand (VVI), dual chamber demand (DDI), and dual chamber universal (DDD) modes after upgrading from a VVI device.

SETTING

Cardiology outpatient department.

PATIENTS

Sixteen patients aged 41-84 years who were symptom free during VVI mode pacing for three or more years.

INTERVENTION

Pacemaker upgrade during routine generator change.

MAIN OUTCOME MEASURES

Change in subjective (general health perception, symptoms) and objective (clinical assessment, treadmill exercise, and radiological and echocardiographic indices) results between pacing modes before and after upgrading.

RESULTS

75% preferred DDD, 68% found VVI least acceptable with 12% expressing no preference. Perceived general well-being and exercise capacity (p less than 0.01) and treadmill times (p less than 0.05) were improved in DDD mode but VVI and DDI modes were similar. Clinical, echocardiographic, radiological, and electrophysiological indices confirmed the absence of overt pacemaker syndrome, although mitral and tricuspid regurgitation was greatest in VVI mode (p less than 0.01).

CONCLUSIONS

Most patients who were satisfied with long term pacing in VVI mode benefited from upgrading to DDD mode pacing suggesting the existence of "subclinical" pacemaker syndrome in up to 75% of such patients. The DDI mode offered little subjective or objective benefit over VVI mode in this population and should be reserved for patients with paroxysmal atrial arrhythmias. VVI mode pacing should be used only for patients with very intermittent symptomatic bradycardia or atrial fibrillation with a good chronotropic response during exercise.

Practical aspects of rate adaptive atrial (AAI,R) pacing: clinical experiences in 44 patients

Forty-four patients with sinus node disease and chronotropic incompetence but no evidence of AV conduction disturbances were treated with rate adaptive atrial (AAI,R) pacemakers. Medtronic Activitrax and Siemens Sensolog activity sensing single chamber pulse generators were used. Twenty-four patients (55%) had the bradycardia-tachycardia syndrome. The mean follow-up time is 20 +/- 14 months (range 1-48, median 17 months). All patients remain alive. Two patients were reoperated upon for lead problems without change of pacing mode. One patient developed symptomatic second-degree Wenckebach block during follow-up, and received a DDD,R system. Although 22 of the patients were treated with antiarrhythmic drugs postoperatively, no further cases of significant AV conduction disturbances were seen. During rapid atrial pacing, exercise-induced enhancement of AV conduction was a consistent finding, although less pronounced in patients treated with beta-blocking drugs. One patient developed permanent atrial fibrillation with an adequate ventricular rate. By systematic reprogramming procedures, QRS complex sensing through the atrial electrode could be demonstrated in 25 patients (23/28 with unipolar and 2/16 with bipolar leads). It could be counteracted effectively by pulse generator program selection in all cases. Forty-two of 44 patients (95%) remain in AAI,R pacing with normal function. Rate adaptive atrial pacing can be successfully applied in this patient group.

The pacemaker syndrome: old and new causes

The pacemaker syndrome refers to symptoms and signs in the pacemaker patient caused by inadequate timing of atrial and ventricular contractions. The lack of normal atrioventricular synchrony may result in decreased cardiac output and venous "cannon A waves." A sudden increase in atrial pressure at the onset of asynchrony may elicit a systemic hypotensive reflex response. A wide range of symptoms can be observed. The pacemaker syndrome is encountered in a significant number of patients with ventricular (VVI) pacemakers, mostly when 1:1 retrograde ventriculoatrial conduction is present. The risk of occurrence of the pacemaker syndrome is minimized if pacemaker systems are used which restore or maintain the normal atrioventricular contraction sequence. Hence, in sinus node disease, atrial stimulation with or without ventricular stimulation should be employed, while in high-grade atrioventricular block dual-chamber pacing is recommended. The pacemaker syndrome is not restricted to the VVI stimulation mode. It can be seen, though rarely, in atrial and dual-chamber pacing, and an awareness of these new causes is necessary. An established pacemaker syndrome can often be counteracted by adjusting the pulse generator function.

Double blind crossover comparison of the effects of dual chamber pacing (DDD) and ventricular rate adaptive (VVIR) pacing on neuroendocrine variables, exercise performance, and symptoms in complete heart block

OBJECTIVE

To compare the effects of dual chamber pacing (DDD) and ventricular rate adaptive pacing (activity sensing) (VVIR) in patients with complete heart block.

DESIGN

Double blind crossover comparison with one month in each pacing mode.

PATIENTS

10 consecutive patients aged 23-74 presenting with complete anterograde atrioventricular block at rest and on exercise and with an intact atrial rate response received Synergyst I (Medtronic) pacemakers.

MAIN OUTCOME MEASURES

Symptom scores, maximal exercise performance on a treadmill, and the plasma concentrations of atrial natriuretic peptide, adrenaline, and noradrenaline.

RESULTS

No significant differences were identified between pacing modes in symptom scores for dyspnoea, fatigue, and mood disturbance; exercise time; and maximal oxygen consumption. One patient with intact ventriculoatrial conduction developed pacemaker syndrome during VVIR pacing. Resting plasma concentrations of atrial natriuretic peptide were raised in complete heart block and were restored to normal by DDD pacing but not by VVIR pacing. Resting plasma catecholamine concentrations were normal in complete heart block and in both pacing modes. During exercise the increase in the concentrations of all three hormones was similar in both pacing modes.

CONCLUSIONS

In patients with complete anterograde and retrograde atrioventricular block, symptoms and maximal exercise performance were no better during DDD than during VVIR pacing.

Pacing in atrial arrhythmias

The history of pacing to control the atrial arrhythmias of sinoatrial node disease (SND) is reviewed and is demonstrated to have become more physiological in recent years. The importance of atrial stimulation is emphasized especially in the context of the natural history of SND. The role of single and dual chamber rate responsive pacing for correction of chronotropic incompetence is outlined and guidelines are proposed for the management of the different types of SND presentation.