The Annals of Thoracic Surgery, Vol 40, 469-474, Copyright © 1985 by The Society of Thoracic Surgeons
Effects of varied cardioplegic perfusion pressure on myocardial preservation with critical coronary stenosis
MD Avery, J Ybarra, R Estrello, S Norris, JJ Ghidoni, JW Mack Jr, JK Trinkle and FL Grover
Inadequate delivery of cardioplegic solution distal to coronary artery
stenosis may result in increased injury during ischemic arrest. This study
was performed to determine the effects of cardioplegic perfusion pressure
on cardioplegia delivery and myocardial preservation in hearts with
critical coronary artery stenosis. Twenty dogs underwent 90 minutes of cold
potassium cardioplegic arrest with partial occlusion of the circumflex
coronary artery. Group 1 received cardioplegia at 50 mm Hg pressure, Group
2 at 90 mm Hg pressure, and Group 3 at 130 mm Hg pressure. It was found
that cooling rates were 5.4 degrees, 9.1 degrees, and 18.2 degrees C per
minute in the nonischemic area (p = 0.004) and 2.0 degrees, 4.5 degrees,
and 7.9 degrees C in the ischemic area (p = 0.008) in Groups 1, 2, and 3,
respectively. Total of cardioplegic solution flows were 86, 188, and 262 ml
per minute per 100 gm in Groups 1, 2, and 3, respectively (p = 0.001).
However, flow did not differ significantly between groups in the ischemic
area. Rate of rise of left ventricular (LV) pressure decreased
significantly in Groups 1 and 2 but not in Group 3 (p = 0.002). Other
measured variables did not differ significantly between groups, although LV
function curves showed less deterioration in the high-pressure groups. It
is concluded that higher cardioplegic perfusion pressure resulted in more
rapid cooling in normal and ischemic areas and slightly better preservation
of ventricular function as measured by some indexes. However, preservation
was generally good for each of the pressures for up to 90 minutes of
ischemia when the septum was consistently cooled to 10 degrees C.
