Electrocardiographic Patterns in Sick Sinus Syndrome
The first year’s experience of a new London pacemaker clinic shows a high incidence of sick sinus syndrome- 17 or 33% of 51 new patients. The diagnosis was made in 15 patients by documenting sinoatrial block with delayed escape mechanism either on routine electrocardiography or on 24 hour Holter monitoring ( 1 ). 2 patients showed persistent sinus bradycardia at less than 60 beats per minute and abnormal sinus node behaviour with intravenous atropine and isoprenaline (1) and after rapid atrial pacing (2). Clinically 14 of these patients presented with syncope as the primary symptom and 3 with dyspnoea. Of the important additional symptoms of sick sinus syndrome 5 had paroxysmal tachycardias and 3 had angina pectoris. Ventricular pacing is generally the chosen mode of therapy in patients with sick sinus syndrome. It is noteworthy that in only 12 of 14 syncopal patients were the attacks abolished by ventricular pacing. Both of the other patients were subsequently converted to atrial pacing with abolition of the attacks, the patients confirming dependance on atrial systole. Its persistent lack in ventricular pacing appeared to be due to retrograde atrial activation via the atrio-ventricular node. 2 of 3 dyspnoeic patients were given relief by ventricular pacing. The other patient required digitalis and diuretics. In contrast paroxysmal tachycardias were not well suppressed by pacing alone and 4 of 5 required drug therapy also. Angina pectoris required drug therapy in all patients.
KeywordsRosen Atropine Myopathy Mandel Isoprenaline
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