The Journal of Thoracic and Cardiovascular Surgery, Vol 88, 57-66, Copyright © 1984 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Verapamil cardioplegia: improved myocardial preservation during global ischemia
SC Balderman, AK Chan and AA Gage
To determine whether the calcium antagonist verapamil can produce
satisfactory myocardial preservation during global ischemia, we studied
three groups of eight dogs. Serial left ventricular biopsy specimens were
taken for adenosine triphosphate and creatine phosphate content. Arterial
and coronary sinus blood samples were obtained for lactate and oxygen
content determination prior to ischemia, immediately after the ischemic
interval, and after a 30 minute reperfusion period. Starling and
isovolumetric ventricular function curves were determined prior to ischemic
arrest and after 45 minutes of reperfusion. All animals were systemically
cooled to 25 degrees C, and the aorta was clamped for 120 minutes. Group I
had a potassium cardioplegic solution (30 mEq/L) chilled to 4 degrees C and
injected into the aortic root. The initial dose was 200 ml and an
additional 100 ml was infused at 20 minute intervals. Group II had a
solution containing verapamil (0.15 mg/kg/L), diluted in Ringer's solution
(4 degrees C), injected into the aortic root. The initial and subsequent
doses were as in Group I. Group III received the same solution as Group II,
but at room temperature. Alterations in lactate metabolism were not
significantly different in any of the three treatment groups. A reduction
in oxygen consumption was seen in Group III, but was not found to be
statistically significant. However, the reduction in coronary flow at the
end of reperfusion was statistically significant in Group III (p less than
0.05). Verapamil given at room temperature resulted in poor preservation of
left ventricular function and high-energy stores. Verapamil combined with
extreme hypothermia (Group II) provided excellent preservation of left
ventricular compliance and contractility. Cold verapamil cardioplegia was
superior to potassium cardioplegia for the preservation of adenosine
triphosphate.
