Sound Caused by Diaphragmatic Contraction Resulting from Transvenous Cardiac Pacemaker

¹ Director, Cardiac Catheterization Laboratory; Attending Physician, The Long Island College Hospital; Clinical Associate Professor of Medicine, State University of New York, Downstate Medical Center, Brooklyn
² Associate Attending Physician, The Long Island College Hospital; Clinical Instructor of Medicine, State University of New York, Downstate Medical Center, Brooklyn

A presystolic "click" 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.