Clinical Chemistry, Vol 19, 1300-1301, Copyright © 1973 by the American Association for Clinical Chemistry

Increased Lactate Dehydrogenase Isoenzyme-5 (LD₅) Activity Evidently Caused by Persistent Diaphragmatic Pressure on a Congested Liver

¹ Department of Clinical Biochemistry and Department of Medicine, University Hospital (University of Western Ontario), 339 Windermere Rd., London, Ontario N6G 2K3, Canada.

A patient with congestive cardiac failure owing to severe bradycardia had a transvenous cardiac pacemaker inserted, resulting in complete alleviation of the cardiac failure. Later, however, the pacer became displaced high into the superior vena cava, where it ceased to pace the heart but instead stimulated the right phrenic nerve. Consequently the rapid movement of the right hemidiaphragm pressing on the dome of an increasingly congested liver, for about one week before hospital admission, was associated with an unusually elevated LD₅ (lactate dehydrogenase, EC 1.1.1.27) activity in the serum.