The Journal of thoracic and cardiovascular surgery
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J. Thorac. Cardiovasc. Surg. · Aug 1992
Myocardial oxygen consumption of fibrillating ventricle in hypothermia. Successful account by new mechanical indexes--equivalent pressure-volume area and equivalent heart rate.
We studied the effects of cardiac hypothermia on myocardial oxygen consumption of a fibrillating ventricle and evaluated whether myocardial oxygen consumption of a fibrillating ventricle in hypothermia can be accounted for by new mechanical indexes: equivalent pressure-volume area and equivalent heart rate in the isolated cross-circulated canine heart preparation. Equivalent pressure-volume area is the area that is surrounded by a horizontal pressure-volume line at the pressure of a fibrillating ventricle and the end-systolic and end-diastolic pressure-volume relations in the beating state in the pressure-volume diagram. Equivalent pressure-volume area is an analog of the pressure-volume area of a beating heart and has been proposed to be a measure of the total mechanical energy of a fibrillating ventricle. ⋯ The myocardial oxygen consumption-equivalent pressure-volume area relation during ventricular fibrillation in hypothermia was highly linear, with a correlation coefficient of 0.90 (mean). The relation between estimated and directly measured myocardial oxygen consumption values of a fibrillating ventricle in hypothermia was highly linear (r = 0.98), and the regression line (y = 0.80x + 0.48) was close to the identity line in the working range. Therefore we conclude that equivalent pressure-volume area is the primary determinant of myocardial oxygen consumption during ventricular fibrillation in hypothermia, and myocardial oxygen consumption of a fibrillating ventricle in hypothermia can be accounted for by the combination of equivalent pressure-volume area and equivalent heart rate as in normothermia.
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J. Thorac. Cardiovasc. Surg. · Aug 1992
Transient hypocalcemic reperfusion does not improve postischemic recovery in the rat heart after preservation with St. Thomas' Hospital cardioplegic solution.
We used the isolated perfused working rat heart to investigate the effects of transient hypocalcemic reperfusion after cardioplegic arrest with the St. Thomas' Hospital cardioplegic solution and 25 minutes of global normothermic (37 degrees C) ischemia. Hearts were reperfused (Langendorff mode) transiently (20 minutes) with solutions containing various concentrations of calcium; this was followed by 30 minutes of reperfusion with standard (1.4 mmol/L, the physiologic concentration) calcium buffer (10 minutes in the Langendorff mode and 20 minutes in the working mode). ⋯ Despite this, transient (10 minutes) hypocalcemic (0.5 mmol/L) reperfusion did not improve recovery. Finally, studies were undertaken with a longer duration of ischemia (40 minutes), and although recovery of cardiac output in the hypocalcemic group (0.5 mmol/L for 10 minutes) tended to be higher than in the control group (29.7% +/- 4.8% versus 18.5% +/- 4.9%, respectively), statistical significance was not achieved. We conclude that in these studies transient hypocalcemic reperfusion did not afford any additional protection over and above that afforded by cardioplegia alone.
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J. Thorac. Cardiovasc. Surg. · Aug 1992
Complete repair of total anomalous pulmonary venous connection in infancy.
From 1983 to 1990, 20 infants underwent complete repair of isolated total anomalous pulmonary venous connection. Twelve were male; ages ranged from 1 day to 240 days (mean 32 days). The abnormal anatomic connection was supracardiac in nine, cardiac in four, mixed in five, and infradiaphragmatic in two. ⋯ Postoperative arrhythmias occurred predominantly in patients with intracardiac drainage. All survivors (mean follow-up of 42 months) are in sinus rhythm, receiving no medications, and are growing and developing normally. Surgical correction of total anomalous pulmonary venous connection in infancy can be performed at low risk with good results after aggressive preoperative stabilization and postoperative management.