Regional myocardial protection: Use of a new method to compare cold potassium cardioplegia with hypothermic coronary perfusion

A new canine model was developed to compare two cardioplegic agents using each heart as its own control. Paired piezoelectric cyrstals were implanted into the left anterior descending and circumflex regions. The percentage of shortening (systolic shortening/end-diastolic segment length x 100) was assessed in each region on right-heart bypass over a range of cardiac outputs. During 100 minutes of ischemic arrest the left anterior descending and circumflex regions were perfused separately every 20 minutes with either cold buffered saline or cold KCl cardioplegia solutions. After recovery, the percentage of shortening after ischemic arrest was determined. The percentage of shortening in the region protected by KCl was unchanged (12.5 ± 5.0 to 13.0 ± 4.6%) after arreast, but was markedly decreased in the buffered saline region (11.3 ± 5.9 to 3.2 ± 4.9%) (p < 0.001, n = 6). This model should facilitate the comparison of two cardioplegic solutions.