Circulation
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Despite the recent wide applicability of the bidirectional cavopulmonary shunt, there is limited reported experience in performing these shunts in infants 6 months or younger. ⋯ Early bidirectional cavopulmonary shunt in young infants has shown encouraging early results and provides improved oxygenation with low morbidity and mortality. We speculate that an early bidirectional cavopulmonary shunt on an elective basis may reduce the deleterious sequelae of chronic hypoxemia, long-term ventricular volume overload, and repeated palliative procedures, thus yielding a more suitable Fontan candidate.
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Heparin rebound, the reappearance of anticoagulant activity after adequate neutralization with protamine, can lead to excessive postoperative bleeding after cardiac surgery. We investigated the mechanism of heparin rebound by using chemically modified heparin that lacks anticoagulant activity (low-affinity heparin) but that is able to displace protein-bound anticoagulantly active heparin. ⋯ Our findings demonstrate that heparin anticoagulant activity persists for up to 6 hours after surgery despite apparent protamine neutralization. The observation of the marked increase in plasma anti-factor Xa activity after the addition of low-affinity heparin suggests that after its administration, a large proportion of the heparin binds to plasma proteins and is incompletely removed by protamine. After protamine is cleared, the protein-bound heparin dissociates slowly and binds to anti-thrombin III to produce an anticoagulant effect.
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Surgical treatment of discrete and tunnel subaortic stenosis. Late survival and risk of reoperation.
Although membranectomy, with or without septal myotomy or myectomy, has been the accepted method for treatment of fixed subaortic stenosis, controversies remain regarding operative methods and uncertainties regarding recurrence of subaortic obstruction and development of aortic insufficiency after repair. ⋯ Our results support the use of myectomy in conjunction with membranectomy for discrete subaortic stenosis. For restenosis and tunnel obstruction, more complete relief of subaortic stenosis by extended resection or a modified or classical Konno-Rastan procedure may improve late survival and reduce the incidence of recurrent subaortic stenosis and late aortic valve insufficiency.
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Dynamic cardiomyoplasty is a relatively new surgical procedure proposed for treatment of severe myocardial failure. Limited clinical experience suggests that this procedure reverses congestive heart failure, improving the long-term survival. ⋯ Our detailed evaluation of left ventricular mechanics demonstrates that cardiomyoplasty has significant multiple beneficial effects on dilated myopathic heart.
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Comparative Study
The effects of warm versus cold blood cardioplegia on endothelial function, myocardial function, and energetics.
Recent interest in the use of normothermic blood cardioplegia is based on theoretical advantages over the traditional method of hypothermic myocardial protection. This study was designed to compare the effects of warm and cold blood cardioplegia on left ventricular functions and energetics and coronary responsiveness. ⋯ For 30 minutes of aortic cross-clamp time, continuous warm cardioplegia did not provide any benefit over a single injection of cold cardioplegia in coronary endothelial and smooth muscle function, myocardial function, and energetics.