病态窦房结综合征

病态窦房结综合征(sicksinussyndrome,SSS)是心源性昏厥的原因之一,是心血管比较常见的严重疾病,主要是窦房结(SAN)的器质性病变或功能性障碍,造成起搏和传导功能失常,以致产生一系列的心律紊乱、血流动力学障碍和心功能受损,严重者可发生阿-斯综合征或猝死,临床上已引起普遍重视。一、窦房结的解剖生理特点1. 细胞组成。(1)起搏细胞(pacemakercell)又称P细胞,位于窦房结中央,因肌原纤维少,不具收缩功能,只发放冲动,维持心脏节律性活动。P细胞受损,窦房结自律性降低或冲动形成障碍。(2)过渡细胞(transitionalcell)又称T细胞、移行细胞,…     

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.     

Sick sinus syndrome in childhood.

The clinical and electrocardiographic findings in five children with the sick sinus syndrome and an otherwise normal heart are described. There were three boys and two girls. Their age at onset of either bradycardia or symptoms ranged from 1 day to 7 years. In one patient, the youngest ever reported with this syndrome, bradycardia was noted before birth. Four children presented with neurological symptoms--attacks of dizziness, fainting spells, or syncope. One boy, treated for epilepsy before the underlying arrhythmia ws diagnosed, died suddenly while playing. One child had near-fatal syncope caused by ventricular tachycardia. Continuous 24-hour electrocardiographic monitoring is the best method of assessing the severity of the condition. Sinus bradycardia, sinuatrial block, and periods of sinus arrest up to 4.8 seconds were recorded. Two patients had associated atrioventricular block and were therefore presumed to have binodal disease. Atrial fibrillation or flutter occurred in three patients. Isolated sick sinus syndrome may be a life-threatening condition in childhood for which, in selected cases, the insertion of a permanent pacemaker is indicated.     

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.     

Sick sinus syndrome: the role of hypervagotonia

A 58-year-old man with persistent symptomatic sinus bradycardia (52 beats/min) showed a markedly prolonged postpacing pause (3240 msec) after atrial pacing at a cycle of 840 msec. In addition, Wenckebach block occurred following atrial pacing at a cycle length of 700 msec. After atropine (2 mg) postpacing pauses returned to normal value and type 1 second-degree AV block completely reversed to 1:1 AV conduction until paced rates greater than 140/min. It may be that in some patients marked and persistent vagal overactivity may predispose to "intrinsic" sinus node dysfunction; in later stages, sinus node function may paradoxically result unaffected by changes in autonomic tone.     

Sick sinus syndrome due to cardiac amyloidosis

In a patient suffering from cardiac amyloidosis a case of sick sinus syndrome, manifested by markedly prolonged recovery time of the sinus node, was documented by an atrial pacing study. The first A-V junctional escape interval was markedly prolonged following the termination of the atrial pacing, pointing to a coexisting A-V nodal dysfunction. The patient required a permanent artificial pacemaker implantation.     

Sick sinus syndrome cured by ... vitamin D?

I have presented the case of a 77-year-old woman with SSS who was treated unsuccessfully with antiarrhythmic drugs for 5 years. During the fifth year, she developed chronic atrial fibrillation. Two years later she started to take vitamin D for unrelated reasons, and first regained regular sinus rhythm and later stopped having episodes of atrial fibrillation. The patient has been now asymptomatic for over 2 years.     

Sick sinus syndrome: comparative study of atrial and ventricular stimulation tests

Subjects with a ventriculo-atrial block and normal sinus function exhibit acceleration of the sinus rhythm during incremental right ventricular pacing; this acceleration is nor observed or is hardly visible in patients with sinus node dysfunction. Incremental right ventricular pacing up to 150/min was performed in 16 patients with ventriculo-atrial block (Group A) referred for investigation of sinus node dysfunction and the results compared with the classical tests of atrial pacing (Strauss'graph, atrio-sino-atrial conduction time, sinus node recovery time). The same tests were carried out in 19 patients without sinus node dysfunction (Group B). In the latter group, sinus rhythm exceeded 80/min during right ventricular pacing at 150/min and the rate increased with respect to the basal rhythm was always greater than 10/min. In Group A premature atrial pacing gave abnormal results in 4 cases, sinus node recovery times were abnormal in 15 cases, and rapid right ventricular pacing abnormal in all cases (sinus rhythm less than 80/min and/or rate increase of less than 10/min). There was no relation between the increased sinus node recovery time and the degree of rate increase during rapid ventricular pacing. Incremental right ventricular pacing, therefore, seems to be a new method of investigating sinus node function but complementary studies are required to determine its limitations, the exact mechanism and to try to widen its application to subjects without ventriculo-atrial block.     

"Sick sinus syndrome in dermatomyositis"--a case report

A forty-five-year-old woman with a history of dermatomyositis for the past fifteen years developed sick sinus syndrome during an exacerbation of her illness. This association has not been previously described in the literature, as far as the author can determine.     

Sick sinus syndrome in a patient with myeloma-associated amyloidosis]

A 62-year-old woman was admitted with general malaise and anorexia in September, 1988. Multiple myeloma (IgA-lambda, Stage IIIb) was diagnosed, and amyloidosis was also diagnosed by abdominal fat aspiration biopsy. A partial remission was achieved by MEVP combination chemotherapy, and she was discharged in December, 1988. She was readmitted because of dizziness and palpitation in April, 1989. A diagnosis of sick sinus syndrome was made, and a VVI permanent pacemaker (PPM) was implanted. She was able to walk to our outpatient clinic for 10 months after the PPM implantation. However, right hemiplegia and aphasia were recognized on April 19, 1990. CT scans revealed low density in the areas of the left anterior and middle cerebral artery. The symptoms of congestive heart failure worsened progressively, and the patient, who had been confined to bed, died on March 5, 1991. She was the fifth myeloma-associated amyloidosis patient who received a PPM implantation. Her survival time was one year and ten months, and was the longest among a small number of reported cases with PPM implantation.