The Annals of Thoracic Surgery, Vol 31, 3-20, Copyright © 1981 by The Society of Thoracic Surgeons
Myocardial preservation with nifedipine: a comparative study at normothermia
RE Clark, IY Christlieb, JA Spratt, PD Henry, AE Fischer, JR Williamson and BE Sobel
Sixty-four dogs were placed on normothermic total cardiopulmonary bypass,
and global ischemia was induced for 1 hour during which continuous
infusions (240 ml per hour) (N = 39) or bolus injections (150 to 200 ml
every 30 minutes) (N = 23) into the proximal aortic root were performed.
The control groups (N = 26) had infusion or injection of normal saline
solution, normal saline solution + 25 mEq/L of potassium chloride, or
Normosol-R pH 7.4. The cardioplegic solution (N = 15) contained 25 mEq/L of
potassium chloride in Normosol-R pH 7.4, 0.25 mg/ml of lidocaine, 500 mg/dl
of glucose, and 1.8 microU/ml of insulin. The nifedipine group (N = 23) had
infusion or injection of 0.167 to 0.2 microgram/ml of nifedipine in saline
solution, Normosol-R pH 7.4, or the cardioplegic solution. Left ventricular
performance was assessed by phasic and mean measurements of left
ventricular peak and end-diastolic pressures and its first derivative, left
and right atrial pressures, and ascending aortic blood flow. Calculations
of stroke work index and total peripheral resistance were performed.
Morphological examinations, and light and electron microscopic examinations
of heart slices were done. The results demonstrated a consistent
superiority of the nifedipine group in terms of performance after bypass
compared with the cardioplegic or control group. Normal preischemic stroke
work indices and Sarnoff curves were present 2 hours after bypass for the
nifedipine-treated groups. The cardioplegic solution was ineffective when
given continuously but gave modest protection when given as a bolus
injection. It is concluded that the concept of the efficacy of calcium
blockade during ischemia and the initial reperfusion period for enhanced
myocardial protection is valid.
