Journal of cardiac surgery
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Randomized Controlled Trial Clinical Trial
Autotransfusion after coronary artery bypass surgery: is there any benefit?
Postoperative salvage autotransfusion of shed mediastinal blood, using the cardiotomy reservoir, is an inexpensive technique whose efficacy and safety are evaluated in this study. We randomized 75 consecutive patients into two groups. The autotransfusion group (n = 42) received autotransfusion after the completion of the coronary artery bypass grafting (CABG) until the drainage was < or = 50 mL per hour for 2 consecutive hours. ⋯ More febrile patients were seen in the autotransfusion group although not significantly more than the controls. The autotransfusion group received more red cells than the control group, but it lost more red cells in the mediastinal drains. In conclusion, the autotransfusion of shed mediastinal blood has not proved beneficial in reducing the postoperative requirements in homologous blood in patients undergoing coronary artery bypass grafting (CABG).
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Amrinone and dobutamine compare favorably in the treatment of chronic congestive heart failure. There is increasing evidence that amrinone alone or in combination with a catecholamine may be used with considerable success in treating patients who are difficult to wean from cardiopulmonary bypass or who have a low cardiac output syndrome after coronary artery bypass grafting surgery. Amrinone increases intramyocardial cyclic adenosine monophosphate and exerts positive inotropic activity in addition to being a potent vasodilator. ⋯ When compared with dobutamine as primary treatment for depressed myocardial function in patients being weaned from cardiopulmonary bypass after coronary artery bypass grafting surgery, it was more effective in achieving primary treatment objectives. Patients given dobutamine had a higher incidence of myocardial infarction, ventricular fibrillation, supraventricular tachyarrhythmias, sinus tachycardia, and hypertension compared to those given amrinone. It is concluded that amrinone compares favorably with dobutamine and may even be superior when used as primary treatment for treating myocardial depression in patients having coronary artery surgery supported by cardiopulmonary bypass.
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Traditionally, surgeons have attempted to minimize myocardial ischemic and reperfusion injury during cardiac procedures by optimizing cardioplegic solutions and modifying the conditions of reperfusion. New evidence suggests that in addition to these two strategies, surgeons may be able to induce myocardial resistance to ischemic injury, which permits immediate functional and metabolic recovery after cardiac operations. Although brief episodes of cardiac ischemia may be associated with mechanical and metabolic dysfunction ("stunning"), they have also been shown to protect against damage resulting from a subsequent prolonged ischemic episode. ⋯ Recent studies in surgical models of cardioplegic arrest and reperfusion have suggested that the preconditioned, arrested heart may have an increased tolerance to prolonged ischemia and improved functional recovery after reperfusion. The development of a pharmacological agent that induces the preconditioning effect may revolutionize cardioprotection for cardiac surgery. We will review the characteristics of preconditioning and data supporting the application of this natural protective capacity to reduce ischemic damage during cardiac procedures.
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Although myocardial ATP is essential for myocardial viability and ventricular function, it is a major source of free radical substrates for endothelial xanthine oxidase. Correlation between myocardial ATP and ventricular function has been hindered by the impact of ATP catabolites on ventricular function during reperfusion. ⋯ Despite severely reduced ATP levels, ventricular function significantly recovered to preischemic values only in the EHNA/NBMPR-treated groups. Selective blockade of purine release during reperfusion is cardioprotective against post-ischemic reperfusion mediated injury. It is concluded that nucleoside transport plays an important role in regulation of endogenous adenosine and inosine affecting the degree of myocardial injury or protection from reperfusion mediated injury.
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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.