Optimal Myocardial Protection with Fluosol Cardioplegia

An oxygenated perfluorocarbon cardioplegic solution was examined, utilizing a blood-perfused canine model. Twenty-one animals were divided into three equal groups, and each animal received Fluosol cardioplegia at one of three infusion temperatures: 20°C, 10°C, or 4°C. All hearts underwent 90 minutes of ischemia, during which time 150 ml of the cardioplegic solution was infused every 30 minutes. Myocardial oxygen and carbon dioxide tensions (PmO₂ and PmCO₂) were monitored continually using mass spectrometry, and myocardial oxygen consumption was calculated with each cardioplegic injection. The mean increase in PmO₂ was 7.1 ± 0.9 mm Hg with 20°C Fluosol infusions, 31.1 ± 4.7 mm Hg with 10°C Fluosol injections, and 22.2 ± 4.7 mm Hg with infusions of 4°C Fluosol. Average myocardial oxygen consumption, expressed as cubic centimeters of oxygen per 100 gm of left ventricle (wet weight), was 21.2 ± 0.5 with 20°C Fluosol, 22.8 ± 1.3 for 10°C Fluosol, and 19.6 ± 1.0 for 4°C Fluosol. Mean myocardial temperatures with infusions of 20°C, 10°C, and 4°C solutions were 21.4 ± 0.1°C, 16.9 ± 0.4°C, and 15.9 ± 0.5°C, respectively. After 45 minutes of reperfusion, maximum rate of rise of left ventricular pressure, expressed as percentage of preischemic control, was 70.9 ± 3.9% for 20°C Fluosol, 90.9 ± 3.2% for 10°C Fluosol, and 90.4 ± 2.3% for 4°C Fluosol (p < 0.005, 20°C versus 10°C, 4°C Fluosol). In addition, the 10°C and 4°C Fluosol hearts had essentially normal structure by light and electron microscopy. These data demonstrate that Fluosol cardioplegia results in near optimal myocardial protection when infused at cold temperatures (4°C to 10°C). The increases in intramyocardial oxygen and myocardial oxygen consumption with each injection demonstrate that there is enhanced oxygen delivery and utilization, which may account for the improved functional recovery observed in these hearts.