The Annals of Thoracic Surgery, Vol 34, 307-312, Copyright © 1982 by The Society of Thoracic Surgeons
Effect of sodium nitroprusside during the payback period of cardiopulmonary bypass on the incidence of postoperative arrhythmias
KV Arom, DM Angaran, WG Lindsay, WF Northrup and DM Nicoloff
This study was designed to determine whether a sodium nitropruside infusion
during the reperfusion (payback) period of cardiopulmonary bypass would
minimize arrhythmias during the early postoperative period of coronary
artery bypass surgery. A double-blind randomized study was carried out in
38 patients with no previous history of ventricular arrhythmias. Seventeen
received 5% dextrose in water (D5W) and 21 received sodium nitroprusside at
the rate of 2 microgram per kilogram per minute during the payback period.
The pump flow was kept constant at 2.2 liters per square meter per minute,
and mean pressure was maintained at greater than 50 mm Hg. There was a
statistically significant difference between the two groups in the number
of patients who developed ventricular arrhythmias (13 of 17, or 76%, in the
D5W group versus 6 of 21, or 29%, in the sodium nitroprusside group; p less
than 0.005). Twelve of the 13 patients in the D5W group experienced
arrhythmias (6 ventricular tachycardia and 6 ventricular premature
depolarization) within the first 24 hours, compared to 5 of 12 patients in
the nitroprusside group (3 ventricular tachycardia and 2 ventricular
premature depolarization). Only 1 patient in each group developed
ventricular arrhythmia after the first postoperative day. One patient in
each group experienced atrial arrhythmia during the first 24 hours. After
24 hours, atrial arrhythmias developed in 5 patients in the D5W group (35%)
and 3 patients in the sodium nitroprusside group (17%) (p greater than
0.05). The arterial pH ranged from 7.35 to 7.55, with a Po2 greater than 70
torr and a serum potassium of 3.7 +/- 0.36 mEq per liter in the D5W group
and 3.4 +/- 0.34 mEq per liter in the nitroprusside group during the period
of arrhythmias. Sodium nitroprusside given during the payback period of
cardiopulmonary bypass appears to minimize ventricular arrhythmias in the
early postoperative period of coronary artery bypass surgery.
