The Annals of thoracic surgery
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Although the last decade has brought dramatic improvement in patient selection and postoperative management of adults and children undergoing advanced mechanical circulatory support, technological advances have been largely limited to the adult population. Intraaortic balloon pumps are technically feasible, but their efficacy has been questioned and their use has been limited in children. Over the last decade, extracorporeal membrane oxygenation has become the most commonly used method of mechanical circulatory support in children who have severe cardiac failure after cardiac operations. ⋯ Surprisingly, many of these patients did well with left ventricular support only. The overall children's survival rates in the myocardial recovery group are better than those in adults. However, current pediatric devices do not provide support for greater than a few weeks, making bridging to transplantation less feasible than in adults.
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Hypothermic total circulatory arrest (CA) is commonly used to facilitate repair of complex congenital heart defects. However, the "safe" period of CA remains to be defined. Extended periods of hypothermic total circulatory arrest may impair cerebral metabolism and cause ischemic brain injury. ⋯ Data were obtained before and immediately after CPB at 37 degrees C, and before and immediately after the experimental period at 18 degrees C. Parameters measured included cerebral blood flow by xenon 133 clearance, arterial and sagittal sinus blood gases, and cerebral metabolism. Hypothermic total circulatory arrest caused an impairment of cerebral metabolism that was directly proportional to CA duration (r2 = 0.73; p = 0.0001), and recovery of metabolic function after 60 minutes of CA improved more than 50% if the head was packed in ice.(ABSTRACT TRUNCATED AT 250 WORDS)
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Manual cardiopulmonary resuscitation is currently the standard treatment for cardiac arrest patients both in and out of the hospital. Accumulated experimental and anecdotal clinical evidence suggests enhanced survival in patients with extreme circulatory decompensation who have been emergently supported with portable cardiopulmonary bypass. Long-term survival is possible even when application is delayed, but early institution of support after cardiac arrest in selected patients offers the best survival advantages. ⋯ Machinery needed to perform emergency cardiopulmonary bypass is currently available in all hospitals with open heart surgery programs. Simple support is often therapeutic but can also serve as a bridge to definitive diagnostic and other therapeutic procedures. Commercial units are becoming more biocompatible and easier to use, making both wider application and more prolonged support likely in the future.
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Three myocardial protection techniques were studied in a canine model of acute myocardial ischemia with subsequent revascularization. Eighteen animals were randomly assigned to one of three treatment regimens: cold oxygenated crystalloid cardioplegia (CC), cold blood cardioplegia with modified reperfusate (CB), and continuous aerobic warm blood cardioplegia (WB) (n = 6 per group). Systemic hypothermic cardiopulmonary bypass (28 degrees C), antegrade arrest, and intermittent retrograde and antegrade delivery were used for the CC and CB groups. ⋯ Myocardial injury as assessed by ST segment elevation (millimeters) was less for the WB group (p = 0.03) (WB, 0.4 +/- 0.3; CB, 1.7 +/- 0.2; CC, 1.6 +/- 0.7). Countershocks necessary to restore sinus rhythm after cross-clamp removal were fewer in the WB group (p = 0.03) (WB, 0.8 +/- 0.3; CB, 4.0 +/- 1.2; CC, 5.5 +/- 1.5). In this model of acute global myocardial ischemia, continuous aerobic warm blood cardioplegia has important advantages over two widely used clinical hypothermic protection techniques.
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Eleven cardiac transplant candidates (all male; mean age, 43.3 years) with multiorgan (hepatic, pulmonary, and/or renal) dysfunction were sustained for prolonged periods (> 30 days) with the HeartMate (Thermo Cardiosystems, Inc, Woburn, MA) left ventricular assist device. We evaluated the effect of extended support on end-organ recovery and on the ultimate outcome of cardiac transplantation. In addition to cardiac failure, 9 patients had hepatic dysfunction, 8 had pulmonary dysfunction, and 6 had renal dysfunction (4 of whom required hemodialysis before left ventricular assist device support). ⋯ One patient who required hemodialysis underwent renal transplantation after cardiac transplantation and had complete recovery of renal function. In the current era of donor shortages, gravely ill patients can benefit from a strategy of prolonged left ventricular assist device support. This strategy has proved safe, has allowed for reversal of multiorgan dysfunction, and has produced healthier transplant candidates.