Blood potassium cardioplegia administration. Comparison of myocardial protection offered by three techniques
F. P. Catinella, J. N. Cunningham Jr, R. K. Srungaram, I. M. Nathan, E. A. Knopp, G. Paone, F. G. Baumann, P. X. Adams and F. C. Spencer
To investigate the best method of administration of blood potassium
cardioplegia, 19 dogs were studied while undergoing 120 minutes each of
aortic crossclamping (myocardial temperature, less than 15 degrees C).
Group 1 (six dogs) underwent a single 120-minute period of aortic
crossclamping with the heart protected by multiple reinjections (1,000 mL
every 30 minutes) of blood potassium cardioplegia solution (potassium
chloride, 30 mEq/L; pH, 8; temperature, less than 15 degrees C). Group 2
(six dogs) underwent four separate 30-minute periods of aortic
crossclamping, but allowing hearts to beat in a nonworking state for 20
minutes at 35 degrees C between each arrest interval. Hearts in group 3
(seven dogs) were initially arrested as described above, following which a
continuous infusion (75 mL/min; KCl, 10 mEq/L) of blood potassium
cardioplegia solution was maintained throughout the arrest period.
Measurements of myocardial metabolism, ventricular function, regional blood
flow, and ultrastructure were carried out before arrest and 30 minutes
after final unclamping. Analysis of the data revealed no significant
benefit of one method over another, with the exception that adenosine
triphosphate level was least preserved with intermittent unclamping and
reperfusion. Because continuous perfusion techniques are more cumbersome
than multidose reinjection, and intermittent aortic crossclamping lengthens
total cardiopulmonary bypass time, we favor the simplest approach,
multidose reinjection during a single uninterrupted period of aortic
crossclamping.