Circulation
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Skeletal muscle grafts can be used to mechanically assist the failing heart. In 13 mongrel dogs, latissimus dorsi muscle was preconditioned in situ for 6-8 weeks. Biopsy samples of the muscles were obtained for histochemical analysis. ⋯ Thus, chronic stimulation of skeletal muscles induces fiber transformation and increases resistance to fatigue and force development. Cardiomyoplasty, on the other hand, improves ventricular function in the presence of acute heart failure. This surgical technique represents an alternative method of treatment for advanced myocardial failure.
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Dispatcher-delivered telephone instruction in cardiopulmonary resuscitation (CPR) has been proposed to increase rates of bystander CPR in cases of out-of-hospital cardiac arrest. We tested the efficacy of a previously developed CPR message using a recording mannikin in a high stress, simulated cardiac arrest scenario. Community volunteers were unaware they would perform CPR until immediately before each trial. ⋯ Because of the time required for telephone instruction, groups A and B started chest compressions a mean of 4.0 minutes after collapse compared with 1.2 minutes for group C (p less than 0.0001). We found that the previously untrained volunteers of group A performed CPR of an overall quality comparable to that performed by previously trained members of group C. Group A performed chest compressions significantly better than group C (p less than 0.02) but had greater problems performing effective ventilations.(ABSTRACT TRUNCATED AT 250 WORDS)
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Among 48 consecutive patients with pretransplant pulmonary vascular resistance (PVR) greater than 4 Wood units, 38 patients underwent orthotopic heart replacement (OHT), and the remaining 10 received a graft in a heterotopic position (HHT). The OHT recipients were smaller (63 vs. 73 kg, p less than 0.05) and received a larger donor heart (donor-recipient, 109% vs. 79%, p less than 0.001) with a shorter graft ischemic time (108 vs. 139 minutes, p less than 0.05) than HHT recipients, reflecting patient selection and surgical complexity. Comparison between the hospital survivors and nonsurvivors identified the selection of HHT and graft ischemic time in excess of 150 minutes as potent risk factors. ⋯ The higher the preoperative PVR value, the more substantial the reduction observed, resulting in normalization of PVR for all survivors. The incidence of early graft failure was similar between the groups, but HHT recipients frequently developed pulmonary complications and infection, resulting in a 30% hospital survival in contrast to 71% in OHT recipients (p less than 0.05). The results suggest that transplant candidates with pulmonary hypertension might better be treated by OHT with an oversized, on-site, viable donor heart than by HHT.
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A method is presented for maintaining aortic flow by mechanical means during intractable cardiac arrest. A spherical balloon was inserted into the left ventricle while the usual intra-aortic balloon was introduced into the thoracic aorta. Ventricular fibrillation was induced by direct current. ⋯ The intraventricular balloon capacity varied from 40 to 110 ml (six dogs weighing 16-24 kg) while the intra-aortic balloon capacity was 20 ml. An optimal pumping rate of 75 beats/min maintained an aortic flow of 0.9-1.5 ml/beat/kg and a mean pressure into the brachiocephalic trunk of 110 +/- 12.5 mm Hg (mean +/- SD). These experimental data indicate that an easily applied mechanical device system (needing no extracorporeal circulation) may be used to bridge the time between intractable cardiac arrest and implantation of an artificial heart or transplantation.