Mechanism and prediction of sudden cardiac death in arrhythmia patients using electrophysiological studies

Thirty nine cases, in which sudden cardiac death (SCD) was suspected, were studied to evaluate the mechanism and the prediction of SCD in arrhythmia-patients using electrophysiological studies (EPS). The 39 cases (28 male and 11 female) were located by surveying 2098 patients who underwent EPS for the evaluation of arrhythmias. Age at time of EPS ranged from 4 to 86 years, average 50.5 years. Time from EPS to death was 2 to 163 months, average 27.9 months. Underlying heart disease was: dilated cardiomyopathy in 11, old myocardial infarction in 5, ischemic heart disease in 5, hypertensive heart disease in 5, valvular heart disease in 3, hypertrophic cardiomyopathy in 2, arrhythmogenic right ventricular dysplasia in 1, myocarditis in 1, sarcoidosis in 1, cor pulmonale in 1, and no obvious heart disease in 4. Fifteen had a permanent pacemaker implanted. SCD in cases without a permanent pacemaker (24 cases): 2 had chronic complete A-V block (one BH block, one HV block), 1 had advanced A-V block (HV block), 3 had bundle branch block with first degree HV block, 9 had ventricular tachycardia (VT), 3 had sick sinus syndrome (SSS), 3 had paroxysmal atrial flutter, 1 had WPW syndrome and paroxysmal atrial fibrillation, 1 had paroxysmal atrial tachycardia, and 3 had premature ventricular beats and first degree HV block. SCD in cases with permanent pacemaker (15 cases): 5 had SSS, and 10 had A-V block. In 3 of the 5 with SSS and 7 of the 10 with A-V block, VT was found before pacemaker implantation. In our study, brady and tachyarrhythmias coexisted in 25 cases (64%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Bradyarrhythmias: clinical significance and management

Clinicians have long recognized the potentially serious manifestations of extreme bradycardia. However, even marked bradycardia can often be physiologic, and in the presence of impaired ventricular function may offer important compensatory hemodynamic effects. Disorders of the sinoatrial node producing bradycardia include failure of impulse formation, sinoatrial conduction block, concealed sinus-perinodal reentry, carotid sinus hypersensitivity and the constellation of brady- and tachyarrhythmias that compose the "sick sinus syndrome." Bradycardia can also result from intraatrial block, atrioventricular nodal block or infranodal block. In addition, paroxysmal supraventricular tachyarrhythmias may produce concealment into the atrioventricular junction and simultaneous suppression of sinus node rhythmicity, resulting in long pauses. Pseudobradycardias manifesting as slow peripheral pulse rates can result from frequent, nonconducted early atrial premature beats, from ventricular bigeminy or runs of ventricular extrasystoles or from mechanical alternans. Cardiac pacemakers play an important role in the management of patients with severe symptoms attributable to bradyarrhythmias. However, excessive use of pacemakers and the inappropriate selection of physiologically unfavorable pacemaker systems should be avoided. Frequently, patients who are only mildly symptomatic with bradycardia should not receive a cardiac pacemaker because the prognosis is favorable. Patients with the tachy-bradycardia syndrome often require both pharmacologic and pacemaker therapy. In selected patients electrophysiologic testing may be helpful, but the majority of patients are best managed by careful attention to the history, electrocardiogram and ambulatory electrocardiographic recordings.     

Clinical characteristics of patients with dilated cardiomyopathy and bradyarrhythmias.

The clinical characteristics of patients with dilated cardiomyopathy and bradyarrhythmias were studied. Among 50 patients with dilated cardiomyopathy, 6 had bradyarrhythmias. Among these patients were one with sinus bradycardia, one with atrial fibrillation and slow ventricular responses and sick sinus syndrome (SSS), one with SSS with advanced AV block, and 3 with advanced AV block. The average age at the onset of their cardiac symptoms (60.3 +/- 12.1 years (mean +/- SD)) was significantly (p less than 0.01) higher than that of 43 patients without bradyarrhythmias (40.0 +/- 17.6). The left ventricular diastolic dimension and ejection fraction were similar among patients with and without bradyarrhythmias. In 31 follow-up patients without bradyarrhythmias, 8 (25.8%) died of cardiac causes; whereas, in 5 patients with bradyarrhythmias, 4 had been implanted with pacemakers and 3 (60.0%) died of cardiac causes. Furthermore, the age at the onset of cardiac symptoms in patients with any kind of conduction disturbance, except tachyarrhythmia, was 50.4 +/- 16.5 years (n = 25), which was significantly higher (p less than 0.02) than that of patients without conduction disturbances (37.7 +/- 19.3 years, n = 23). We concluded that bradyarrhythmias are not rare complications in patients with dilated cardiomyopathy, and the mortality rate tends to be higher in patients with bradyarrhythmias than in those without them. Furthermore, the risks of conduction disturbances and bradyarrhythmias were higher in the elderly patients.     

Update on sick sinus syndrome, a cardiac disorder of aging

Sick sinus syndrome (SSS) is usually a disease of the elderly produced by idiopathic degeneration of the sinoatrial node. Its initial manifestations range from asymptomatic to nonspecific and include palpitations, fatigue, confusion, and even syncope and sudden death. Electrocardiographic evidence of SSS includes inappropriate sinus bradycardia, sinus pause or arrest, or sinus exit block. These bradyarrhythmias may alternate with tachyarrhythmias, especially atrial fibrillation, to create the tachycardia-bradycardia syndrome. The diagnosis of SSS may be established by electrocardiography or ambulatory monitoring in the majority of cases. Medications such as digoxin, beta-blockers, and calcium blockers may initiate or worsen the manifestations of SSS. Permanent pacing is indicated for symptomatic bradyarrhythmias. Progression of SSS is mostly dependent on the presence and severity of associated coronary or hypertensive heart disease.     

Sick sinus syndrome after surgery for congenital heart disease.

The course and prognosis of 16 infants and children with sick sinus syndrome associated with cardiac surgery is reviewed. The dysrhythmia was observed most ofter after extensive atrial reconstructive surgery in patients with transposition of the great arteries and with atrial septal defect. In 12 (75%) of the patients, sick sinus syndrome was detected in the immediate postoperative period. Tachyarrhythmias and bradyarrhythmias were presnet in 12 and isolated bradyarrhythmias in four. Temporary pacing was used in two and permanent pacing was required in five. Death in two non-paced patients was attributable to arrhythmias. Postmortem examination in one patient revealed a suture in the sinoatrial node. Careful attention to the anatomy of the sinoatrial node, its artery and the internodal tracts during surgery may prevent the development of sick sinus syndrome. In patients with dysrhythmia, a careful search should be undertaken to document the abnormal rhythm with the use of Holter monitoring. The insertion of a pacemaker is indicated in patients with tachyarrhythmias requiring cardioversion or antiarrhythmic drug therapy and those without adequate lower escape mechanisms.     

Long-term follow-up after cardiac pacing in bradyarrhythmias

Fifty-nine patients aged 39-80 years underwent implantation of a cardiac pacemaker and were followed for up to 9 years (average duration of pacing 39 months). Atrioventricular conduction disturbances (complete atrioventricular block, 2 : 1 atrioventricular block, bifascicular block, and atrial fibrillation with slow ventricular rate) were present in 49 patients and sick sinus syndrome (sinus arrest or sino-atrial block, and bradycardia-tachycardia syndrome) in 10. Pacing was required because of Adams-Stokes attacks in 41 patients, 2 of whom also had congestive heart failure. It was required in 6 because of frequent dizziness, in 10 because of congestive heart failure, and in 2 because of low cardiac output. The symptomatic improvement after cardiac pacing was well recognized in most of our patients, and 32 (54 percent) of the 59 patients pursued normal physical and daily activity. Although the efficacy of pacemaker therapy was of limited value in some patients with congestive heart failure or underlying or coexisting diseases, the beneficial effects following pacemaker implantation were: (1) abolishment of transient neurologic symptoms such as Adams-Stokes attack, (2) relief from a constant fear of a recurrence of an Adams-Stokes attack or sudden cardiac death, and (3) improvement in restricted physical activity due to low cardiac output. Thus, we conclude that pacemaker implantation in most patients with bradyarrhythmias is beneficial not only for the treatment of the acute problem but also because it prolongs life and greatly enhances its quality. However, in spite of the beneficial effects after pacemaker implantation, we still observe a number of complications connected with the use of a permanent pacemaker. Therefore, our policy is to implant a permanent pacemaker following the execution of sufficient studies of the bradyarrhythmia and the etiology of symptoms, and then under taking long-term follow-up of the patients.     

A case of Pickwickian syndrome treated by implantation of a cardiac permanent pacemaker

A 41-year-old male was admitted to our hospital with congestive heart failure and bronchopneumonia. During hospitalization extreme sinus bradycardia, sinus arrest up to 6.2 seconds and high grade AV block were observed to occur simultaneously with apneic episodes of ECG monitoring. After that, a diagnosis of Pickwickian syndrome was made in this obese patient. In spite of weight reduction, change of sleep position and acetazolamide administration, obstructive sleep apnea and severe bradyarrhythmias were not improve. These severe bradyarrhythmias and ventricular tachyarrhythmias may be one cause of the not infrequent sudden deaths in patients with this Pickwickian syndrome. In addition to the tracheostomy, we propose that implantation of a cardiac permanent pacemaker should be selected for the bradyarrhythmias in association with the Pickwickian syndrome.     

Arrhythmias documented by 24 hour continuous electrocardiographic monitoring in 50 male medical students without apparent heart disease.

Results are reported of portable 24 hour dynamic electrocardiographic monitoring in 50 male medical students without cardiovascular disease, as defined by normal clinical and noninvasive cardiovascular examination. During waking periods, maximal sinus rates ranged from 107 to 180 beats/min (mean +/- 5). Twenty-five subjects (50 percent) had episodes of marked sinus arrhythmia as defined by spontaneous changes in adjacent cycle lengths of 100 percent or more. Fourteen subjects (28 percent) had sinus pauses of more than 1.75 seconds, usually during sinus arrhythmia. Transient nocturnal type I second degree atrioventricular (A-V) block was noted in three subjects (6 percent). Of 28 patients (56 percent) having atrial premature beats, only 1 (2 percent) had more than 100 such beats (141) in 24 hours. Of 25 patients (50 percent) having premature ventricular contractions, only 1 (2 percent) had more than 50 such contractions (86) in 24 hours. In conclusion, frequent atrial and ventricular premature beats are unusual in a young adult male population. In contrast, bradyarrhythmias (including marked sinus arrhythmia with sinus pauses, sinus bradycardia and nocturnal A-V block) are common. These findings are useful in evaluating the clinical significance of arrhythmias detected with portable monitoring.     

Hemodynamic benefits of atrioventricular sequential pacing after cardiac surgery

The hemodynamic effects of atrioventricular (A-V) sequential pacing were assessed and compared with those of ventricular and of atrial pacing in 10 patients with and without heart block after cardiac surgery. Ventricular pacing alone was either hemodynamically detrimental or of no benefit in six of the eight patients who initially had sinus or accelerated junctional rhythms. Atrial pacing alone produced significant improvement in cardiac output in all patients who were not pacemaker-dependent. However, five of the eight patients with intact A-V conduction had further increases in cardiac output through A-V sequential pacing at shorter than intrinsic A-V intervals. Optimal A-V intervals for maximal cardiac output could be identified in all patients and varied widely. Significant changes in cardiac output occurred with relatively small deviations in the A-V interval. In selected patients after cardiac surgery, temporary A-V sequential pacing is a workable and valuable adjunctive form of hemodynamic support and is preferable to ventricular or atrial pacing.     

Familial complete atrioventricular block of adult onset

A family of complete atrioventricular block (FCAVB) of adult onset was reported. A 36-year-old-female had 1 degree AH block, atrial and ventricular premature beats and mild sinus node dysfunction. Her father had complete AV block and died of it. A 57-year-old uncle and a 52 years-old uncle had bradycardia from 44, 5 years of age and 51 years of age, respectively, and their ECG showed complete AV block with narrow QRS waves. They were implanted with permanent pacemakers. Her grandmother died a sudden death of Adams-Stokes attack. Acquired heart diseases were not seen in any of the family Thus, this family was thought a FCAVB of adult onset.     

生理性心脏起搏的选择及应用限制的探讨

１２１例安置生理性心脏起搏器的患者，完全性及高度房室传导阻滞４２例；病窦综合征７９例，其中窦性心动过缓、窦性停搏６０例、慢─快综合征１９例。安置ＤＤＤ起搏器４０例，２８例为心房变时性反应正常的完全性房室传导阻滞。安置ＡＡＩ、ＡＡＩＲ（变时性反应不良者选用）起搏器４９例。发生并发症１４例，均为采用心房电极起搏方式者。其中电极脱位３例、低感知４例、膈刺激现象及输出阻滞各２例、起搏器介导性心动过速３例，根据笔者的经验，对不同心律失常类型提出了选择生理性起搏方式的原则，并就其应用限制进行了讨论，强调全面评估病情是作出最佳选择的前提。     

Atrial pacing during selective aortocoronary saphenous vein bypass angiography

Selective aortocoronary bypass graft angiography was performed in 30 postoperative subjects. Thirty-one of 39 patent graft injections resulted in cardiac arrhythmias including sinus bradycardia, premature ventricular depolarizations, sinoatrial arrest and atrioventricular (A-V) block. In contrast, only 2 of 39 graft angiograms performed during right atrial pacing produced arrhythmias. We conclude the following: (1) Routine prophylactic right atrial pacing is a valuable method for preventing certain cardiac arrhythmias during aortocoronary graft opacification; and (2) the potential for rapid institution of right ventricular pacing provides safety in the event that angiographically induced A-V block occurs.     

回顾性调查线粒体疾病患者的心脏病变

目的 分析线粒体疾病心脏受累的表现,提高对该病的认识.方法 回顾北京协和医院20年来诊断的90例线粒体疾病患者临床与病理资料,包括心电图、动态心电图和心脏超声检查.结果 90例线粒体疾病患者中合并心脏病变29例.其中合并心肌病变5例(5.6%),为左心室肥厚2例、心脏扩大伴心力衰竭3例;合并先天性结构性心脏病4例(4.4%),包括三尖瓣或(和)二尖瓣脱垂各1例,房间隔或室间隔缺损各1例;各种不同程度心律失常20例(22.2%),包括安装永久起搏器者4例(3例在安装起搏器后1～3年才诊断为线粒体疾病),多种心律失常包括室性心动过速1例,阵发性房性心动过速1例,无症状的心律失常14例(分别是右束支传导阻滞4例,右束支合并左前分支传导阻滞1例,短PR间期综合征5例,B型预激综合征2例,室内传导阻滞2例).心脏传导阻滞在Kearns-Sayre综合征(9例)中发生率高达66.7%.8例患者检出线粒体基因A3243G突变.结论 线粒体疾病可以心肌病、心力衰竭、恶性心律失常为首发表现,对青壮年心肌病、伴发严重的心脏传导阻滞应尽可能寻找病因包括进行相关基因检查.此外,对所有诊断为线粒体疾病患者需定期进行心电图和超声心动图等检查以便尽早发现异常及早处理以改善预后.     

Familial occurrence of sinus bradycardia, short PR interval, intraventricular conduction defects, recurrent supraventricular tachycardia, and cardiomegaly.

Four members of a family presenting with sinus bradycardia, a short P-R interval, intraventricular conduction defects, recurrent supraventricular tachycardia (SVT), syncope, and cardiomegaly had His bundle studies and were found to have markedly shortened A-H intervals (30 to 55 msec.) with normal H-V times (35 to 50 msec.). Right atrial pacing at rates as high as 170 to 215 per minute failed to increase the A-H or H-V intervals significantly. The data are compatible with the presence of an A-V nodal bypass tract (James bundle) or even complete absence of an A-V node. Ventricular pacing and spontaneous ventricular premature beats resulted in a short ventriculoatrial conduction time (110 msec.) suggesting that if A-V nodal bypass tracts exist, they are utilized in an antegrade and retrograde fashion. None of the features of WPW syndrome was present. The mechanism of syncope in the mother and daughter was intermittent third-degree heart block. Both went on to develop permanent complete heart block despite electrophysiologic studies demonstrating 1:1 A-V conduction at extremely rapid atrial pacing rates and both required implantation of permanent pacemakers. The mechanism of syncope in the two brothers was possibly marked sinus bradycardia, but transient complete heart block has not been ruled out. Permanent pacemaker therapy was recommended for both. The nature of the cardiomegaly, which was mild in three patients, is not known. Although not well documented, several maternal relatives have had enlarged hearts, SVT, complete heart block, and syncope.     

Disturbances in atrial rhythm and conduction following the surgical creation of an atrial septal defect by the Blalock-Hanlon technique

Disturbances in atrial conduction or rhythm, or both, were found in 16 of 27 patients undergoing the surgical creation of an atrial septal defect by the Blalock-Hanlon technique. These included P-wave aberrations of intra-atrial block and ectopic atrial rhythm, A-V rhythm, A-V dissociation, sinus bradycardia, atrial flutter, escape-capture bigeminy, and atrial premature beats. Some of these were transient and occurred within 2 weeks after surgery. It seems likely that tissue trauma engendered by the clamp and resection of the atrial septum with possible injury to the internodal conducting pathways may be the genesis of these early postoperative disturbances. Of the eight cases with transient disturbances, six occurred in this period. Later changes, such as intra-atrial block, sinus bradycardia, and atrial flutter, may be attributed to changes in atrial size secondary to the postoperative pathophysiology. Digitalis intoxication and congestive heart failure cannot be excluded as contributory factors in either the early or the late disturbances. It was not possible to correlate the incidence and nature of these disturbances with morbidity and mortality. In such severely ill, cyanotic infants, irregularities, however slight, may have altered cardiac function significantly and contributed to their deaths.     

Severe bradyarrhythmia linked to left atrial dysfunction in Fabry disease—A cross‐sectional study

Background

Fabry disease (FD) is a lysosomal storage disorder caused by an enzymatic deficiency. Conduction abnormalities and bradyarrhythmias are common and can occur prior to the onset of left ventricular (LV) hypertrophy. We aimed to describe the clinical, electrocardiographic and echocardiographic, including left atrial (LA) function, determinants of bradyarrhythmic events in FD.

Hypothesis

Bradyarrhythmic events are frequent in patients with FD and are associated with LA dysfunction.

Methods

We designed a cross‐sectional study that includes 53 FD patients (mean age, 45 years; 42% male). Clinical characteristics and electrocardiographic and echocardiographic data were collected. LA function was measured using biplane volumes and 2D speckle‐tracking echocardiography. Bradyarrhythmic events were defined as pause of more than 2 seconds (sinus pause or atrioventricular block) recorded on Holter, severe bradycardia (≤ 40 bpm on ECG) or implantation of a permanent pacemaker.

Results

Six (11%) patients had installation of a pacemaker, 4 (8%) patients had cardiac pause and 2 (4%) patients had an episode of severe bradycardia. Patients with bradyarrhythmic events were older and had a lower resting heart rate. On echocardiography, a significantly higher LV mass, a lower LV ejection fraction, and a more affected LA reservoir function were found in those with bradyarrhythmic events. Patients also experienced tachyarrhythmias frequently. Atrial fibrillation occurred in 11 (21%) patients and ventricular tachycardia in 4 (8%) patients.

Conclusions

Bradyarrhythmia are common manifestations of cardiac involvement in FD. Age, LV mass, LV ejection fraction and LA reservoir dysfunction can be useful markers associated with bradyarrhythmia.     

Familial atrioventricular heart block; an autosomal dominant trait.

A family of 28 individuals spanning four generations was investigated because of a finding of complete heart block in five members and the existence of a low degree of atrioventricular (A-V) heart block in a sixth member. The disorder was characterized by 1) adult onset in all, 2) complete A-V heart block in five and first degree A-V heart block in one, 3) sinus bradycardia in three, 4) atrial fibrillation in five, 5) abnormal QRS complex in five, 6) ventricular tachycardia in three, 7) left ventricular enlargement in all, and 8) mitral insufficiency in five. Proximal location of the A-V heart block was suggested by the fact that atropine caused acceleration of the ventricular rate and by the presence of a His bundle potential preceding the QRS complexes. Involvement of the distal conducting system was indicated by the widened QRS complex and a prolonged H-V interval. Pathologic examination in one case showed extensive sinus node fibrosis and interruption of the A-V node-His bundle connection. This disorder is probably due to an autosomal dominant trait.     

Arrhythmias late after repair of tetralogy of fallot: a Japanese Multicenter Study.

BACKGROUND: Arrhythmia is a major late complication in adults with repaired tetralogy of Fallot, although a large-scale study has not been carried out in Japan. METHODS AND RESULTS: A nationwide multicenter study with 512 operative survivors was performed. Actuarial survival rate at 30 years (maximum follow-up) was 98.4%. Fifty-four patients (10.5%) had clinically important arrhythmias, including 23 patients with bradycardia caused by sick sinus syndrome or atrioventricular block (AVB). A patient with complete AVB (CAVB) without pacemaker implantation (PMI) died later. Two patients had sustained ventricular tachycardia (VT) and syncope was reported in 18 patients with ventricular arrhythmias (VA). Atrial tachyarrhythmias were observed in 13 patients. Older age at operation was a risk factor for atrial fibrillation/flutter, longer postoperative survival duration for VA, and QRS duration >120 ms for VT. Perimembranous ventricular septal defect was related to CAVB. Right ventricular outflow patch was not a risk factor. Importantly, 60% of the subjects had QRS duration <120 ms. CONCLUSION: The prevalence of serious arrhythmias is low in Japanese TOF patients as compared with the results from Western countries. CAVB without PMI and VT are the major risk factors for late morbidity and mortality. The excellent result could be related to the narrow QRS after surgery.     

Permanent rhythm and conduction disorders in patients surgically treated for atrial septal defect

Atrial septal defect (ASD) represents a congenital heart disease with good prognosis, however, atrial arrhythmias are well-documented complications. A retrospective study was performed to assess the prevalence, types and risk factors of arrhythmias in patients with ASD after surgical correction. 920 patients were analyzed retrospectively; cases with complex congenital heart disease or another systemic alteration conditioning atrial rhythm disturbances were excluded. 460 patients with ASD corrected by surgery were followed at least for six months after the procedure. 29.3% of patients were male and 70.7% female. Direct closure was performed in 63%, pericardial patch was installed in 27%. 29 patients (6.3%) had conduction and rhythm disturbances before surgery, the most common arrhythmias were atrial flutter (34.5%), first degree A-V block (31%) and low right atrial rhythm (27.6%). Six months after atrial defect closure, 65 patients (14.13%) had arrhythmias, 44.6% atrial flutter, 20% ectopic atrial rhythm, 10.8% sick sinus syndrome. The risk of atrial arrhythmias was related to age at surgical repair, pulmonary hypertension and atrial arrhythmias before surgery.     

Excellent survival and low incidence of arrhythmias, stroke and heart failure long-term after surgical ASD closure at young age. A prospective follow-up study of 21-33 years.

AIMS: Although studies have suggested good long-term results, arrhythmias, pulmonary hypertension and left ventricular dysfunction are mentioned as sequelae long-term after surgical atrial septal defect closure at young age. Most studies were performed only by questionnaire and in a retrospective manner. The long-term outcome is very important with regard to future employment and acceptance on insurance schemes. METHODS AND RESULTS: One hundred and thirty-five consecutive ASD-patients, operated on in childhood, were studied longitudinally with ECG, echocardiography, exercise testing and Holter-recording 15 (10-22) and 26 (21-33) years after surgery. During follow-up no cardiovascular mortality, stroke, heart failure and no pulmonary hypertension occurred. Symptomatic supraventricular tachyarrhythmias were present in 6% after 15 years, and an additional 2% occurred in the last decade; 5% needed pacemaker implantation. No relation was found between arrhythmias and type of ASD, baseline data, right ventricular dimensions, or age at operation. Left and right ventricular function and dimension remained unchanged. Slightly more patients had right atrial dilatation at last follow-up. Exercise capacity was comparable with the normal Dutch population. CONCLUSIONS: The long-term outcome after ASD closure at young age shows excellent survival and low morbidity. The incidence of supraventricular arrhythmias is lower than in natural history studies of ASD patients and also lower than after surgical correction at adult age.