Journal of cardiac surgery
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We evaluated cerebral metabolism during retrograde cerebral perfusion (RCP) and circulatory arrest during profound hypothermia, and also investigated the effects of perfusion pressure on RCP. Twenty-four adult mongrel dogs were placed on cardiopulmonary bypass and cooled to a nasopharyngeal temperature of 20 degrees C. At this temperature, hypothermic circulatory arrest (HCA; n = 6), and RCP with a perfusion pressure of 10 mmHg (RCP10; n = 6), 20 mmHg (RCP20; n = 6), and 30 mmHg (RCP30; n = 6) were carried out for 60 minutes. ⋯ In the RCP30 group, the water content of cerebral tissue was significantly higher than in other groups. In the RCP20 group, temperature was maintained in a narrow range, oxygen consumption and carbon dioxide excretion could be observed, there was no excess lactate, and ATP and energy charge were significantly higher than in the HCA group. In conclusion, RCP can provide adequate metabolic support for the brain during circulatory arrest, and a perfusion pressure of 20 mmHg is most appropriate for RCP.
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Current surgical techniques in operations on the thoracic aorta frequently require exclusion of the cerebral circulation for varying periods. During these periods, hypothermic circulatory arrest (HCA), selective cerebral perfusion (SCP), and retrograde cerebral perfusion (RCP) can be used for cerebral protection. Hypothermia is the principle component of these methods of protection. ⋯ Present clinical data do not allow separation of its protective effect from that of HCA alone. Recent modifications in the application of HCA include monitoring of cerebral O2 extraction, and selective use of supplemental SCP to limit arrest times to less than 50 minutes, or RCP to prevent embolic strokes, as indicated. These changes appear to have reduced the overall mortality, the severity of embolic strokes, and stroke-related mortality.
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Case Reports
Coronary artery bypass in systemic lupus erythematosus using total autogenous arterial bypass.
A 63-year-old man with systemic lupus erythematosus (SLE) underwent coronary artery bypass grafting using only arterial grafts, the left internal thoracic, and the right gastroepiploic arteries. This is the first report of coronary artery bypass grafting in a patient with SLE using the gastroepiploic artery.
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Closure of a persistent ductus arteriosus through a median sternotomy on cardiopulmonary bypass in a 24-year-old man resulted in a tear of the descending aorta below the ductus. The repair of the aortic injury was attempted with deep hypothermia and low arterial flow, which resulted in massive air embolism of the aorta, the central arteries, and the arterial line. Air was expelled by reverse and perfusion by connecting the arterial line to the venous cannula in the superior vena cava. The patient was discharged from the hospital without neurological consequences.
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Comparative Study
Stunned myocardium following prolonged cardiopulmonary bypass: effect of warm versus cold cardioplegia in the canine model.
"Stunned myocardium" is defined as the prolonged but transient postischemic contractile dysfunction of viable myocardium that has been salvaged by reperfusion. This phenomenon, although first characterized in the experimental canine model of coronary artery occlusion/reperfusion, also occurs following transient global ischemia. Moreover, despite the superb cardioprotection conferred by administration of cold cardioplegia during aortic cross-clamping, stunned myocardium is a well-recognized sequela of prolonged cardiopulmonary bypass. ⋯ Direct comparison of LV function between the two groups was confounded by a profound decrease in afterload in dogs that received cold cardioplegia. However, incorporation of systemic vascular resistance as a covariate revealed that LV function following bypass was modestly depressed at approximately 85% of baseline values, and that continuous administration of warm cardioplegia did not prevent this hypokinesis. Thus, in our canine model: (1) morphological injury and LV dysfunction induced by 3 hours of aortic cross-clamping is subtle; and (2) continuous retrograde infusion of warm blood cardioplegia during the cross-clamp period failed to preclude myocardial stunning following prolonged cardiopulmonary bypass.