Sound caused by diaphragmatic contraction resulting from transvenous cardiac pacemaker.

A presystolic "clickn beginning 0.1 second before the first heart sound occurred in a patient with a permanent pervenous cardiac pacemaker. Simultaneous fluoroscopy, phonocardiography and electrocardiography demonstrated that the "click" was generated by contraction of the left hemidiaphragm which was stimulated by the electrical discharge from the tip of the electrode catheter located in a tributary of the coronary sinus. E xtraneous sounds and auscultatory "clicks" caused by electronic cardiac pacemakers have been recently reported.'-x These extra sounds have been attributed to contractions of intercostal muscles stimulated by electrical discharge of the pacemaker. .An instance is reported in which the extra sound was caused by contraction of the diaphragm stimulated by the electrical discharge of a transvenous cardiac pacemaker electrode catheter which was in an abnormal location, ie, a tributary of the coronary sinus. A 76-year-old white man was hospitalized on August 23. 1967 because of chest pain, dyspnea and dizziness. An electrocardiogram revealed atrial flutter and complete heart block with a ventricular rate of 36 per minute. During temporary transvenous cardiac pacing, the electmcardio-graphic pattern was that of a left bundle branch block. A Medtronic permanent bipolar transvenous catheter, model No. 5816, was inserted via the right external jugular vein and was positioned in what was thought to be the apex of the right ventricle. Because a stable pacing site with a low threshold could not be located, a Medtronic permanent pacemaker, model No. 5870<=, with a rate of 68 per minute and output of 11.2 ma was connected to the transvenous electrode even though the pacing threshold was 3 ma. The electrocardiogram indicated a right bundle branch block. The patient was readmitted to the hospital on June 1, 1988 because of bone pain due to metastatic carcinoma. He stated that for one to two hours a day since discharge, he had felt a "jumping or pulsation" in the anterolaterd aspect of the left chest. There was no relationship to activity, position, time of day or meals. Visible and palpable sequential pulsations of the lower intercostal spaces in the ankrolateral aspect of the left hemithorax were noted at the pacemaker rate. Over the left hemithorax, an audible "click" was heard closely preceding the first heart sound and loudest at the anterior d a r y line. During normal breathing, the "click" was loudest in expiration and disappeared during deep, held inspiration as did the pulsations of the chest wall. …