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Effects of various periods of cold potassium cardioplegic arrest upon myocardial contractility and metabolism

1980; Elsevier BV; Volume: 28; Issue: 4 Linguagem: Inglês

10.1016/0022-4804(80)90093-1

1095-8673

Frederick L. Grover, John G. Fewel, Kenton P. Schrank, John J. Ghidoni, Kit V. Arom, J. Kent Trinkle,

Fuel Cells and Related Materials

A maximal “safe” period of cardioplegic arrest has not been documented. Twenty-five dogs were therefore subjected to 1, 2, and 3 hr of potassium cardioplegic arrest (Groups I, II, and III), using 200 ml at 20-min intervals of D5 0.2 NS with 20 mEq KCl and 6 mEq NaHCO3/500 ml at 0–4°C. Results: Myocardial temperature decreased to 13°C after each cardioplegic infusion. Left ventricular pressure volume curves did not decrease significantly in Group I, but did in Group II, from 204 ± 20 mm Hg with 10-ml volume to 140 ± 8 (P < 0.03). Group III decreased from 117 ± 9 with 5-ml volume to 60 ± 3 (P < 0.0004), from 160 ± 11 with 10-ml volume to 108 ± 6 (P < 0.004), and from 181 ± 17 with 15-ml volume to 127 ± 9 (P < 0.03). Cardiac output was less in Group III than in Groups I and II 60 min after bypass [44 ± 10 vs 76 ± 8 ml/min/kg (P < 0.08)]. Myocardial ATP was significantly less in Group III than Group I 15 min after reperfusion and 60 min after bypass, being 2.25 ± 0.35 and 2.95 ± 0.81 vs 5.18 ± 0.85 and 5.68 ± 0.60 μmoles/g (P < 0.05). Myocardial lactate increased from 3.65 to 8.55 ± 0.81 μmoles/g at 60 min of cardioplegia, 9.36 ± 0.67 at 2 hr, and 12.01 ± 2.0 at 3 hr. Myocardial glycogen decreased through the cardioplegic period and remained depressed in Group III 30 min after bypass, being 488 ± 124 mg%, as compared to 901 ± 130 in Group I (P < 0.05). Conclusions: Hearts subjected to 1 and 2 hr of potassium cardioplegia showed relatively little hemodynamic or metabolic derangement, as compared to those subjected to 3 hr of cardioplegia.