The Thoracic and cardiovascular surgeon
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Thorac Cardiovasc Surg · Oct 1993
Comparative StudyCoronary artery resistance and oxygen uptake during reperfusion: is there any difference between warm and cold cardioplegia?
To evaluate the effects of warm continuous versus cold intermittent blood cardioplegia on coronary blood flow patterns after prolonged cardioplegic arrest, nine pigs underwent cardiopulmonary bypass with 210 minutes of aortic cross-clamping. Antegrade blood cardioplegia was administered either cold intermittent (n = 4) or warm continuous (n = 5). During the first 30 minutes of reperfusion, there was decreased coronary blood flow with higher coronary vascular resistance in the cold group (mean +/- standard error; warm vs. cold: 30 min: flow: left anterior descending artery (LAD): 66 +/- 6 vs 36 +/- 4 ml/min, right coronary artery (RCA): 88 +/- 2 vs 61 +/- 4, p < 0.05, resistance: LAD: 33 +/- 3 vs 69 +/- 5 dyn.s.cm-5 x 10(3), RCA: 41 +/- 3 vs 58 +/- 8, p < 0.05). ⋯ Arterio-venous oxygen difference was higher in the cold group after 15 min (3.1 +/- 0.5 vs 4.8 +/- 0.3 ml O2/100 ml, p < 0.05) and 30 min (4.2 +/- 0.5 vs 6.2 +/- 0.7, p < 0.05) with equal values after 1 hour. During reperfusion there is reduced myocardial blood flow after cold intermittent blood cardioplegia. This may reflect superior myocardial protection with warm continuous cardioplegia.
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Thorac Cardiovasc Surg · Oct 1993
Protection of the ischemic immature heart--effect of perfusate reinfusion and composition.
We determined the influence of perfusate composition and reinfusion during ischemia upon myocardial protection in the immature rabbit heart. Isolated "working" hearts (n = 6 per group) from 7-10-day-old New Zealand White rabbits were perfused with Krebs bicarbonate buffer and function measured. Hearts were then arrested with 3 minutes cold (14 degrees C) perfusion with bicarbonate buffer (as hypothermia-alone group) or St. ⋯ There were no differences in post-ischemic creatine kinase leakage or myocardial water content between groups. These results suggest (i) that reinfusion itself, regardless of the composition of the perfusate, caused decreased recovery of function after an extended period of ischemia, and (ii) protection of the ischemic immature heart with St. Thomas' II solution remains inadequate and requires improvement.