Phrenic Nerve Stimulation as a Complication of the Implantable Cardiac Pacemaker

Abstract

A Chardack cardiac pacemaker was implanted in a 36-year-old white male with Adams-Stokes disease. Immediately postoperatively the left hemidiaphragm contracted synchronously with the pacemaker. Re-exploration allowed transplantation of the electrode leads away from the area of the phrenic nerve, and a distal phreniclasia was performed. No further phrenic stimulation occurred until 9 months, at which time a cervical phreniclasia was required. Four and one-half months later the left hemidiaphragm is not being stimulated. Experimental observations on dogs suggest that the stimulus for diaphragmatic contraction is transmitted to the phrenic nerve independent of the pericardial nervous connections, and that diaphragmatic response can be mediated only through efferent impulse in the phrenic nerve mechanism. Inquiries to other investigators revealed 7 other instances of diaphragmatic stimulation associated with implantation of cardiac pacemakers of various designs. It is suggested that myocardial electrodes be placed accurately into the myocardium wall anterior on the left ventricle as far away as possible from the phrenic nerve to prevent this troublesome complication. Should it occur and persist, cervical phreniclasia has been effective in 2 cases.