Journal of cardiac surgery
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Depressed myocardial performance after cardiac surgery can be contributed to ischemic reperfusion injury (IRI) incurred during and following the cardiopulmonary bypass (CPB). Myocardial preconditioning (PC) achieved by brief ischemia and subsequent reperfusion appears to be a clinically useful method of improved cardiac protection during surgery involving CPB by retarding IRI. Based on animal studies, activation of cardiac adenosine (ADO) receptors prior to the prolonged ischemic period appears to mimic this PC phenomenon. ⋯ Based on these measurements, ADO pretreated patients had improved ventricular performance postoperatively. It also appears that ADO pretreatment results in lowered postoperative myocardial energy demand and less myocellular injury during CPB. To our knowledge, this is the first study to demonstrate that human myocardium can be hemodynamically improved with ADO pretreatment, and may be protected against IRI incurred during and following the CPB. We believe that a cardiac surgeon may now have the unique opportunity to confer myocardial protection during and after a cardiac surgical procedure.
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Measures of left ventricular (LV) contractility must be linear, load-independent, free of hysteresis, and sensitive to changes in inotropic state. These properties of measures of LV contractility have been assessed previously in animals, but never in man. Using a micromanometer and volume conductance catheter technology, we measured LV pressure and volume in 67 patients scheduled for CABG surgery. ⋯ Neither the slope nor the intercept of any of the three measures of contractility changed significantly with loading conditions. Heart rate demonstrated no physiologically significant baroreceptor-mediated changes during the perturbations. Comparing measures of LV function--ejection fraction (EF%), LV end-diastolic pressure (LVEDP), dP/dtMax-EDV, PLRSW, ESPVR, -dP/dtMax-EDV, and end-diastolic pressure-volume relationship (EDPVR)--in patients with a preoperative medical history of congestive heart failure (CHF), myocardial infarction (MI), and hypertension (HTN) demonstrated lower EF percent (62.4 +/- 16.7 vs 42.8 +/- 5.0 [p < 0.0002]) and lower ESPVR (2.27 +/- 1.98 vs 1.30 +/- 0.83 [p < 0.03]) in patients with a history of CHF.(ABSTRACT TRUNCATED AT 250 WORDS)
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Review Clinical Trial Controlled Clinical Trial
The management of temperature during cardiopulmonary bypass: effect on neuropsychological outcome.
Laboratory studies demonstrate that mild degrees of brain cooling (2 degrees C to 5 degrees C) confer substantial protection from ischemic brain injury, and that mild elevation of brain temperature can be markedly deleterious. During hypothermic cardiopulmonary bypass (CPB) patients are made hypothermic and then rewarmed at a time when they are exposed to neurological insults. Our studies show that during rewarming, peak brain temperatures near 39 degrees C often are achieved inadvertently. ⋯ We found patient acceptability and compliance were good. Sensitivity also seemed adequate in that 30% of patients were identified as having deteriorated at 1 week postoperatively compared to preoperatively, a result similar to that reported by others. Clinical trials of the efficacy of mild hypothermia in modulating brain injury in humans are needed before techniques of CPB can be designed to optimize neuroprotection.
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The value and utility of transesophageal echocardiography (TEE) in unstable cardiac surgical patients have been assessed; 119 TEE studies were performed and evaluated in the emergency setting. The studies were performed in the cardiac surgical intensive care unit (n = 62) and in the operating room (n = 57). There were 81 men and 38 women with a mean age of 58.2 years. ⋯ The average time to diagnosis was 11.2 minutes. No significant complications were noted. Our results suggest that TEE is highly diagnostic for most of the abnormalities responsible for hemodynamic instability in the perioperative period and facilitates decision making in cardiac surgical emergencies.
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Forty-three patients undergoing repair of a thoracoabdominal aortic aneurysm were monitored to evaluate spinal cord ischemia, as evidenced by somatosensory evoked potentials (SEPs). All patients were operated on using left heart bypass. In 34 patients (80%), staged clamping was used. ⋯ No relationship could be demonstrated between the extinction time, the recovery time, or the duration of loss of evoked potentials with postoperative neurological outcome. Intraoperative monitoring of SEPs is a good indicator of spinal cord ischemia, although we found a 5% incidence of false negatives. SEP monitoring offers an improvement in surgical strategy, and allows safer operations for thoracoabdominal aneurysms.