Pacing for Carotid Sinus Syndrome and Sick Sinus Syndrome

BRIGNOLE, M., ET AL: Pacing for Carotid Sinus Syndrome and Sick Sinus Syndrome. The real incidence of pacemaker implants for carotid sinus syndrome (CSS) and the relation between CSS and sick sinus syndrome (SSS) is not precisely known. Patients who needed pacing therapy because of atrial bradyarrhythmias were investigated by means of carotid sinus massage, dynamic ECG, and invasive electrophysiological sinus node evaluation. Of 298 consecutive patients receiving a pacemaker implant, 36 (12%) had a severe cardioinhibitory carotid sinus reflex with reproducible spontaneous symptoms (CSS), 33 (11%) had sinus bradycardia < 50 beat/min or an abnormal electrophysiological evaluation (SSS) and 24 (8%) had both (CSS + SSS). The annual incidence was 40, 37, and 26, respectively, implants per year/million of inhabitants (total incidence 325). Patients affected by CSS, if compared with those affected by SSS, showed: a higher prevalence of syncope (97% vs 42%); more syncopal, episodes per patient (2.9 ± 2 vs 1.8 ± 0.9); a lower prevalence of associated cardiac diseases (53% vs 100%); cardiac enlargement (36% vs 88%); heart failure (6% vs 36%) and paroxysmal atrial fibrillation (0% vs 42%); and a more frequent indication for VVI pacing (75% vs 3%). In patients with CSS + SSS, intermediate characteristics were present. In conclusion, CSS is as frequent an indication to cardiac pacing as SSS; clinical differences justify a distinction between them, even if they are associated in 26% of cases.     

Incidence and Predictors of Loss of Pacing in the Atrium in Patients with Sick Sinus Syndrome

Atrial and dual-chamber pacemakers may be associated with reduced morbidity in patients with the sick sinus syndrome (SSS). In some patients, however, subsequent development of chronic atrial fibrillation or atrial lead failure make long-term pacing in the atrium not feasible. We analyzed the incidence and predictors of loss of atrial pacing in 395 consecutive patients with SSS (376 with dual-chamber pacemakers and 19 with single-chamber atrial pacemakers). None of them was in established atrial fibrillation at time of implant. Patients were followed-up for 55 ± 35 months. Actuarial survival of effective atrial pacing was 92.5% at 1 year, 85% at 5 years, and 76.5% at 10 years. Overall, 60 patients lost atrial pacing. The most frequent cause was the development of chronic atrial fibrillation (53 patients). By multivariate analysis (Cox proportional-hazards model), independent predictors of Joss of pacing in the atrium were preimplant episodes of paroxysmal atrial fibrillation (PAF) lasting more than 1 hour (P < 0.001; hazard ratio (HR) = 4.3); prior history of PAF for more than 5 years (P < 0.001; HR = 2.67; and endocardial P wave < 2 mV (P = 0.014; HR = 1.96). In a subgroup of patients (n = 187) who had echocardiograms, a left atrium > 50 mm was also an independent predictor of loss of atrial pacing (P = 0.028; HR = 2.28). Conclusions: 1) most patients with SSS can maintain long-term atrial pacing; 2) loss of pacing in the atrium is related to the previous history of PAF, left atrial enlargement, and low amplitude of the endocardial P wave at implant; and 3) patients with these risks variables are less than ideal candidates for atrial pacing modes. In them, the implant of DDDR units might be indicated, to provide wide flexibility in case reprogramming to a ventricular pacing mode is required.     

心室起搏管理对病态窦房结综合征患者心功能的影响

目的：观察心室起搏管理（managed ventricular pacing,MVP）对病态窦房结综合征（sick sinus syndrome,SSS）患者心功能的影响.方法：42例植入具有MVP功能的双腔起搏器（Medtronic Adapta ADD01/ADDR01/ADDRL1）的SSS患者,先以双腔起搏（DDD/R）模式工作6个月,再程控为MVP模式工作6个月,统计两种模式下右心室起搏比例,并比较两种模式下患者心功能的变化.结果：在DDD/R模式下,平均右心室心尖部起搏比例达43.6％,左心室射血分数（left ventricular ejection fraction,LVEF）从（56.5±2.6）％下降至（54.1±3.0）％（P=0.001）,左心室舒张末期直径（left ventricular end-diastolic diameter,LVEDD）从（49.6±2.6）mm升高至（51.4±2.4）mm（P=0.002）,B型利钠肽（B-type natriuretic peptide,BNP）从（77.0±16.2） pg/mL升高至（87.2±16.4） pg/mL（P=0.032）.在MVP模式下,平均右心室心尖部起搏比例仅为1.8％,LVEF从（54.1±3.0）％上升至（55.4±1.4）％（P=0.042）,LVEDD从（51.4±2.4）mm下降至（50.2±2.0）mm（P=0.016）,BNP从（87.2±16.4） pg/mL下降至（86.5±14.9） pg/mL（P=0.852）.另外,DDD/R模式下有4例患者发生阵发性心房颤动,而MVP模式下仅1例发生阵发性心房颤动,但差异无统计学意义（P=0.180）.结论：与DDD/R模式比较,MVP模式能显著减少右心室起搏比例,且对心功能有较好的保护作用.     

Transesophageal Programmed Atrial Pacing as a Method of Selecting Patients with Sick Sinus Syndrome for Permanent Atrial Pacing

Many recent studies have shown transesophageal programmed atrial pacing (TP) as a very practical, safe and convenient way for assessment of sinus node function and AV conduction. On the other hand, permanent atrial pacing is known to be superior to ventricular pacing due to arrhythmogenic and hemodynamic reasons. This is the reason why we decided to use TP as a method of choosing patients with sick sinus syndrome (SSS) for permanent atrial pacing. Sixty-three patients with symptomatic (58) and asymptomatic (5) SSS in a variety of clinical situations were examined in this way. The following electrophysiological features were examined: sinus cycle length, sinus node recovery time as well as corrected time, secondary pause after overdrive stimulation, sinoatrial conduction time, Wenckebach point, induction of supraventricular arrhythmias by S1, S2, S3 programmed stimulation and burst pacing. Patients with abnormal parameters were examined once more after intravenous atropine 0.2 mg/kg to evaluate parasympathetic component. Standard 12-lead ECG was performed in ail, and Holter monitoring in most of patients.
Twenty-six patients were candidates for permanent AAI pacing. Failures occurred in eight patients usually due to low P wave amplitude and electrode instability. Eighteen patients received AAI pacing systems: eight with brady-tachycardia syndrome, nine with brady-arrhythmia and one with sinoatrial block. In the follow-up of 5–28 months in one patient occurred high degree AV block (11°) during digitalis therapy. Reduction of doses made this block disappear. Examination of Wenckebach point and possibility of inducation of supraventricular lachyarrhythmias in cases of atrial overexcitability are particularly useful in selecting patients for AAI pacing. (PACE, Vol 11 November Part II 1988)     

Antibodies to Human Sinus Node in Sick Sinus Syndrome

The incidence of autoantibodies against human conducting tissue was studied in 45 pacemaker patients with sick sinus syndrome (SSS), in 17 patients with bradyarrhythmia, and jive patients with hypertensitive carotid sinus syndrome. Antibodies against the human sinus node were demonstrated in 29% of patients with SSS and in 24% of patients with bradyarrhythmia; a tenfold risk of SSS could be calculated in patients with this antibody as compared to age-matched controls. At least two subtypes of anti-sinus node antibodies were demonstrated: an antibody absorbable and another one not absorbable with ventricular myocardium. Patients with SSS and prior myocarditis of rheumatic fever have a threefold incidence of that antibody, demonstrating that anti-conducting tissue antibodies are etiologic indicators for former inflammatory heart disease. These antibodies may play a role in the secondary immunopathogenesis of sick sinus syndrome. This hypothesis emerges as an interesting new pathogenetic concept.     

Incidence and Predictors of Syncope in Paced Patients with Sick Sinus Syndrome

In spite of a normal pacemaker/unction, syncope still occurs in some patients with sick sinus syndrome (SSSJ. Causes often remain unknown. To identify predictors and etiologies of this bothersome symptom, we studied 507 patients who received atrial, ventricular, and dual-chamber pacemakers for SSS. During a mean follow-up of 62 ± 38 months, actuarial incidence of syncope was 3% at 1 year, 8% at 5 years, and 13% at 10 years. Causes were vasovagal (18%), orthostatic hypotension (25.5%), rapid atrial tachyarrhythmias (11.5%), ventricular tachycardia (5%), acute myocardial ischemia (2.5%), and pacemaker/lead malfunction (6.5%), In 13 patients (29.5%), syncope remained unexplained. The only preimplant predictor for syncope was syncope as primary indication for pacemaker implant. Electrocardiographic correlation with bradycardia was not a predictor of relief of syncope during the follow-up. In conclusion: (1) syncope in paced patients with SSS has multiple etiologies and may be multifactorial; (2) the only predictor of syncope after pacemaker implant is the occurrence of preimplant syncope as the main indication for pacing; (3) extensive Holier monitoring is not useful to document bradycardic origin of syncope nor to predict its recurrence; (4) SSS probably overlaps with other entities such as autonomic dysfunction, vasovagal syncope, carotid sinus hypersensitivity, and venous pooling, which would provide an explanation for recurrent syncope in patients with normal pacemaker function.     

Atrial Inhibited Pacing in the Sick Sinus Node Syndrome: Clinical Value and the Demand for Rate Responsiveness

A consecutive series of 66 patients (males = 32; mean age +/- SD = 71 +/- 9 years) given atrial inhibited pacemakers for sick sinus nodes were followed to study the incidence of lead failures, chronic atrial tachyarrhythmias, and atrioventricular conduction disturbances. The need for rate responsive pacing was also assessed. Pre and postoperative investigation could include carotid sinus massage, Holter monitoring, exercise testing, and invasive electrophysiology. The mean follow-up time +/- SD was 32 +/- 29 months (median = 26 months). Three patients (5%) had their pacemakers replaced due to lead failures (loss of sensing = 2; exit block = 1). Two pacemakers (3%) were replaced after 5 and 22 months due to atrial fibrillation. Four patients (6%) received new pacemakers because of development of second-degree or complete atrioventricular block after 1, 6, 12, and 31 months, respectively. During exercise, most patients (76%) responded with an increase in sinus rate at least as marked as that achievable with the currently available rate responsive pacemakers. Assuming careful patient selection, atrial inhibited pacing is well suited for many patients with sinus node dysfunction and preserved atrioventricular conduction. There is a limited need for rate responsive pacemakers in these patients.     

The Natural History of Sick Sinus Syndrome

A literature review has addressed the two major factors in disease progression in sick sinus syndrome: atrioventricular block and atrial fibrillation. An incidence of atrioventricular block of 8.4 percent in a follow-up period of 34.2 months is considered clinically significant and sufficient to justify use of a ventricular lead in pacemaker management. Atrial fibrillation occurs much more commonly [22.3%] in ventricular pacing than with atrial demand pacing (3.9%) in a 21/2 year observation period. Coincident with the reduction in arrhythmia achieved by atrial demand pacing is a significant reduction in systemic embolism (1.6% vs. 13%]. This is considered largely to be due to the improved rhythm control with AAI pacing but also possibly to the avoidance of retrograde atrioventricular conduction. The benefits of AAI pacing in terms of mortality in sick sinus syndrome have not yet been fully assessed. In the future, DDI pacing is recommended with, in some patients, the addition of another sensor to provide rate responsiveness on exercise.     

Pacing of the Atria in Sick Sinus Syndrome Trial: Preventive Strategies for Atrial Fibrillation

SPITZER, S.G., et al .: Pacing of the Atria in Sick Sinus Syndrome Trial: Preventive Strategies for Atrial Fibrillation. This study examines the effects of various atrial lead positions in physiological pacing on the incidence of AF in patients with sick sinus syndrome. The lead is implanted in the RA free wall, in the RA appendage, near the coronary sinus ostium (CSO) or, in dual site RA pacing, in the appendage and the CSO. Since CSO and dual site right atrial pacing aim at modifying the pathological substrate, pacing of two-thirds of all cardiac cycles is attempted by adapting the basic rate and the rate response option. The results of this study are expected to assist in the development of guidelines for the placement of atrial pacing leads in sick sinus syndrome. (PACE 2003; 26[Pt. II]:268–271)     

Is Chronic Atrial Stimulation a Reliable Method for Single Chamber Pacing in Sick Sinus Syndrome?

To evaluate the feasibility of chronic atrial pacing (AAI) in sick sinus syndrome (SSS), 22 patients (pts) with bradytachycardia syndrome (BTS) and 17 patients with only bradyarrhythmias (BA) were studied on the incidence of supraventricular tachycardias (SVT) and occurring AV block. A scoring system based on symptoms of SVT was developed (grade 0–5). All patients had proven normal AV conduction before PM implantation. In the BTS-group, nine patients (41%) had symptomatic SVT at the end of follow-up (mean 53 months), despite drug therapy. These patients had a high SVT score on entry (mean 3.2). High degree AV block occurred in three patients. Although in the BA-group SVT arose in six patients (35%), there was only one symptomatic patient at the end of follow-up (mean 36 months). In this group, only one patient developed high degree AV block. Atrial stimulation should be considered as a reliable therapy in patients with SSS and low SVT score before PM implantation when normal AV conduction is present.     

Thyrotoxicosis Induced Sick Sinus Syndrome: Medical Therapy May Avoid Permanent Pacing

A 65-year-old white female developed sick sinus syndrome associated with thyrotoxicosis which resolved upon achieving a euthyroid state, thus obviating the need for permanent pacemaker implantation. TSH was less than 0.1 ng/dL, and 24-hour iodine uptake was 28%. After correction of the hyperthyroid state with propylthiouracil and potassium iodine, sinoatrial pauses up to 6 seconds resolved over 10 days. A subsequent sinus node recovery time was normal and no symptoms recurred over 22 months.     

Reproducibility of Transesophageal Pacing in Patients with Wolff-Parkinson-White Syndrome

The purpose of this study was to assess, in patients with ventricular preexcitation, the time dependent physiological variation of antegrade conduction properties in the AV node and in accessory pathways (Aps) as a function of autonomic tone variation induced by posture and physical effort, using noninvasive transesophageal atrial pacing. In 74 WPW patients (mean age 21.31 ± 9.46 yrs), AV node and Kent antegrade effective refractory periods (at pacing cycle lengths 600. 400, and 320 ms), Wenckebach point, shortest preexcited ER intervals during sustained atrial fibrillation (AF) or atrial pacing, as well as the inducibility of AV reentry tachycardia (A VRT) and AF/flutter (AFL) were assessed. AH measurements were carried out at rest, in supine and upright positions, and during effort. A second study was carried out approximately 3 months after the first study. The coefficients of variation (CVs) and reproducibility (CRs) were calculated. For each parameter, the differences between the mean of the two studies were not statistically significant. The CVs and CRs ranged between 0.4% and 4% and between 2 and 28 ms, respectively. AF was induced in 40 (54%) of 74 patients at the first study and in 30 (40.5%) of 74 patients at the second study. AVRT was induced in 33 (45%) of 74 patients at the first study and in 38 (51.3%) of 74 patients at the second study. The reproducibility was 45% for AF/AFL and 65% for reentry tachycardia. Transesophageal atrial pacing is a reliable method for noninvasive reproducible evaluation of ante- grade electroph ysiological properties of both the AV node and APs in WPW patients. However, the effect of autonomic balance variation has to be taken into account and precisely defined because it may significantly affect the inducibility of supraventricular arrhythmias and the estimation of the absolute values of the vulnerable parameters.     

Reappearance of Persistent Normal Sinus Rhythm in a Patient with the Sick Sinus Syndrome Following Cardiac Pacing for 10.5 Years

A patient with symptomatic sick sinus syndrome which manifested as a brady-tachy syndrome, was admitted to our institute in 1969. Following cardiac pacing for 10.5 years, the brady-tachy syndrome disappeared and normal sinus rhythm was restored. Her stable normal sinus rate has persisted up to the present, 2.5 years after termination of pacing.     

Reproducibility of Electrophysiologic Parameters of Extrinsic Sinus Node Function in Patients with and without Sick Sinus Syndrome

In a group of 50 patients we investigated the daily reproducibility of the resting heart rate (RHR), the maximal corrected sinus node recovery time (CSNRTM), the pacing rate at which the CSNRTM occurred (OP), and the sinoatrial conduction time (SACT) during basal state. The study population was divided into two groups according to the presence or absence (as evidenced during the initial electrophysiologic study) of sinus node disease: group I included 35 patients with normal sinus node function, and group II included 15 patients with sick sinus syndrome. The electrophysiologic study was repeated approximately at the same hour and under similar conditions after an interval of at least two days (mean: 3.2 days for group I and 4.7 days for group II). The results showed good reproducibility with the exception of RHR in group I which slightly but significantly decreased in the second electrophysiologic study. The daily variations of the sinus node parameters appeared to be of similar levels in the two groups except for the CSNRTM; this parameter showed wide variations in single values in both groups, more marked in group II than in group I. Furthermore, if the CSNRTM and/or SACT were normal, it was likely that they would remain normal whatever the electrophysiologic status of the patient. Inversely, the change of status from abnormal to normal CSNRTM or SACT was not uncommon in patients with electrophysiologic signs of sinus node disease.     

Transesophageal Atrial Pacing Complications in Patients Suspected of Tachy-Brady Syndrome

RACZAK, G., ET AL.: Transesophageal Atrial Pacing Complications in Patients Suspected of Tachy-Brady Syndrome. The clinical effects of transesophageal atrial pacing (TAP) were assessed in 308 patients. Indications for TAP included evaluation for pacemaker implantation in patients suspected of sinus node dysfunction and determination of the suitable type of pacemaker. Most patients underwent program stimulation including rapid as well as burst stimulation. In one patient, following the study, cerebral arterial embolism occurred, most likely secondary to an induced arrhythmia. That was the only single case of permanent consequences following TAP. Additionally, one patient was accidentally stimulated in the ventricle using low voltage electric current that induced ventricular fibrillation. This was promptly reversed with defibrillation. Twenty-six patients in whom an arrhythmia was previously induced, required medical therapy, two of whom required cardioversion, and 24 required drug therapy, subsequent to clinical intolerance of the arrhythmia. No lethal complications occurred.     

Chronic Ventricular Pacing with Ventriculoatrial Conduction Versus Atrial Pacing in Three Patients with Symptomatic Sinus Bradycardia

Three patients with symptomatic sinus bradycardia due to sick sinus syndrome were treated with permanent ventricular pacing for periods rang-ing from 2.5 to 4 years. All three patients had ventriculo-atrial conduction on routine electrocardiography. Although ventricular pacing was effective, they complained of fatigue, lightheadedness, and near syncope. Hemodynamic studies revealed the presence of regular cannon waves in the right atrium as well as in the pulmonary artery wedge pressure curves. Temporary atrial pacing resulted in disappearance of the cannon waves and a significant rise in cardiac output (32–48%). After narmal atrio-ventricular conduction was confirmed by rapid atrial stimulation and His bun-dle electrocardiography, the pacing mode was changed to permanent atrial pacing on demand. The effort tolerance of the patients marked by improved, and the previ-ously mentioned symptoms disappeared. Control hemodynamic studies 9 to 12 months affer impiantation of the atrial demand pacemaker showed that the im-provement in cardiac performance was maintained.     

Atrioventricular Conduction in Sick Sinus Syndrome

With the increasing recognition of the pacemaker syndrome and with the availability of newer methods of pacing therapy, the status of the atrioventricular (AV) conduction in patients with Sick Sinus Sydrome (SSS) becomes crucial in the choice of mode of pacing. At the Philippine Heart Center, from April 1983 to November 1986, the sinus and AV node function studies of 46 patients who, by electrophysiological studies had sinus node dysfunction (SND)-SN recovery time (SNRT) >1400 msec, were reviewed. These were arbitrarily classified according to duration of SNRT into: Group A—borderline SND, SNRT from 1,401 to 1,499 msec (n = 4); Group B—mild SND, SNRT from 1,500 to 2,499 msec fn = 25); Group G—moderate SND, SNRT from 2,500 to 3499 msec fn = 6); Group D— severe SND, SNRT of 3,500 m and above (n = 11). Out of the 46, 14 (30%) had concomittant AVN dysfunction (AVND)—antegrade block rate < 130 beats per minute (BPM). The percentage occurrence of AVND was noted as follows: Group A—25% (1/4); Group B—28% (7/25); Group G—50% (3/6); Group D—27% (3/11). Out of the 14 patients with concomittant AVND, 5(35%) had antegrade block rate < 100 BPM, 3 in Group R and 2 in Group D. The study shows that AVND occurs in only 30% of SSS patients. Its occurrence and severity has no bearing on the degree of SND. In these, antegrade block was at a rate higher than 100 BPM in the majority of patients. The data suggest that most of SSS patients may benefit from atrial demand pacemaker which therapeutically is of more advantage over the ventricular demand type inasmuch as AV synchrony is retained, thus pacemaker syndrome is prevented.     

Intravenous Adenosine: A Noninvasive Diagnostic Test for Sick Sinus Syndrome

Adenosine has a well established negative chronotropic effect on the smoatrial node. The most wideJy utilized test of sinus node/unction remains the sinus node recovery time (SNRT), which generally requires catheterization. We compared the effect of adenosine (150 meg/kg IV) on the lengthening of sinus cycle length (ADO:SCL) in 12 control patients (group I) and in 11 patients with clinical sick sinus syndrome (SSS) (group III, eight of whom had undergone prior permanent pacemaker implantation. Using 675 msec as an abnormal result indicating sinus node dysfunction (two standard deviations above the mean value established in controls), ADO:SCL had a sensitivity and specificity of 64% and 100%, which were equal to that observed for the corrected sinus node recovery time (CSNRT) (abnormal value 550 msec). There was a significant difference in the CSNRT between group I (304 ± 149 msec) and group II (1,199 ±936 msec, P = 0.003). There was no significant difference in ADO:SCL between groups I (256 ± 210 msec) and group II (1,213 ± 1,719 msec, P = 0.069); however, there was substantial overlap between patients exhibiting an abnormal ADO:SCL and CSNRT. As such, a significant difference in ADO.-SCL was evident between group II patients (1,784 ± 1,950 msec, n = 7) exhibiting an abnormal CSNRT and group I patients, P = 0.014. In conclusion, ADO:SCL has the same sensitivity and specificity for sinus node dysfunction as compared to the CSNRT. Intravenous adenosine may prove to be a useful noninvasive test to assess the need for permanent pacemaker implantation.     

Long-Term Follow-up after Pacemaker Implantation in Sick Sinus Syndrome

In 74 symptomatic patients suffering from sick sinus syndrome, sur-vival after pacemaker implantation and additional drug therapy was determined. The 5-year survival was poor (47.2%). Evidence of other cardiac disease (present in 44.6%) influenced the prognosis unfavorably, especially in combination with con-tinuing symptoms. As yet the phase of SSS in which chronic cardiac pacing is re-quired, should be considered as a critical stage.     

AAIR Versus DDDR Pacing in Patients with Impaired Sinus Node Chronotropy: An Echocardiographic and Cardiopulmonary Study

The aim of this study was to compare AAIR and DDDR pacing at rest and during exercise. We studied 15 patients (10 men, age 65 ± 6 years) who had been paced for at least 3 months with activity sensor rate modulated dual chamber pacemakers. All had sick sinus syndrome (SSS) with impaired sinus node chronotropy. The patients underwent a resting echocardiographic evaluation of systolic and diastolic LV function at 60 beats/min during AAIR and DDDR pacing with an AV delay, which ensured complete ventricular activation capture. Cardiac output (CO) was also measured during pacing at 100 beats/min in both pacing modes. Subsequently, the oxygen consumption (VO₂at) and VO₂at pulse at the anaerobic threshold were measured during exercise in AAIR mode and in DDDR mode with an AV delay of 120 ms. The indices of diastolic function showed no significant differences between the two pacing modes, except for patients with a stimulus-R interval > 220 ms, for whom the time velocity integral of LV filling and LV inflow time were significantly lower under AAI than under DDD pacing. At 60 beats/min, CO was higher under AAI than under DDD mode only when the stimulus-R interval was below 220 ms. For stimulus-R intervals longer than 220 ms, and also during pacing at 100 beats/min, the CO was higher in DDD mode. The stimulus-R interval decreased in all patients during exercise. The time to anaerobic threshold, VO₂at ond VO₂at pulse showed no significant differences between the two pacing modes. Our results indicate that, at rest, although AAIR pacing does not improve diastolic function in patients with SSS, it maintains a higher CO than does DDDR pacing in cases where the stimulus-R interval is not excessively prolonged. On exertion, the two pacing modes appear to be equally effective, at least in cases where the stimulus-R interval decreases in AAIR mode.