The Annals of thoracic surgery
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Between 1990 and 1992, 346 consecutive patients underwent coronary artery bypass procedures. Ninety-eight patients (group A) from 1990 served as historical controls, and 248 patients (group B) from 1991 to 1992 served as a prospective, consecutive cohort for statistical comparison. The two groups varied in the type of myocardial protection used: intermittent cold crystalloid cardioplegia was used in group A and continuous warm blood cardioplegia in group B. (Two patients in group A received intermittent cold blood cardioplegia, and these 2 patients are grouped with the crystalloid group for the sake of convenience. ⋯ Group B patients were less likely to have development of complex postoperative arrhythmias. Ventricular fibrillation at unclamping was noticeably rare (2.0% in group B versus 84% in group A; p < 0.05). The average group B heart resumed sinus rhythm 72 seconds after declamping.(ABSTRACT TRUNCATED AT 250 WORDS)
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Biography Historical Article
In memoriam: Nina S. Braunwald, 1928-1992.
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The pH management that provides optimal organ protection during hypothermic circulatory arrest is uncertain. Recent retrospective clinical data suggest that the pH-stat strategy (maintenance of pH at 7.40 corrected to core temperature) may improve brain protection during hypothermic cardiopulmonary bypass with a period of circulatory arrest in infants. The impact of alpha-stat (group A) and pH-stat (group P) strategies on recovery of cerebral high-energy phosphates and intracellular pH measured by magnetic resonance spectroscopy (A, n = 7; P, n = 5), organ blood flow measured by microspheres, cerebral metabolic rate measured by oxygen and glucose extraction (A, n = 7; P, n = 6), and cerebral edema was studied in 25 4-week-old piglets undergoing core cooling and 1 hour of circulatory arrest at 15 degrees C. ⋯ Brain water content postoperatively was less in group P (0.8075) than in group A (0.8124) (p = 0.05). These results suggest that compared with alpha-stat, the pH-stat strategy provides better early brain recovery after deep hypothermic cardiopulmonary bypass with circulatory arrest in the immature animal. Possible mechanisms include improved brain cooling by increased blood flow to subcortical areas, improved oxygen delivery, and reduction of reperfusion injury, as well as an alkaline shift in intracellular pH with hypothermia in spite of a stable blood pH.
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Gastrointestinal damage occurs in 0.6% to 2% of patients after cardiopulmonary bypass (CPB), and carries a mortality of 12% to 67%. The incidence of subclinical gastrointestinal damage may be much greater. We examined the effects of nonpulsatile, hypothermic CPB on intestinal absorption and permeability in 41 patients. ⋯ The permeation of 3-O-methyl-D-glucose and D-xylose returned to normal levels 5 days after CPB, but that of L-rhamnose remained significantly below pre-CPB values at 6.6% +/- 0.5% (p = 0.004). However, the permeation of lactulose increased after CPB (from 0.35% +/- 0.04% to 0.59% +/- 0.1%; p = 0.018), and the lactulose/L-rhamnose gut permeability ratio increased markedly (from 0.045 +/- 0.04 to 0.36 +/- 0.08; normal = 0.06 to 0.08; p = 0.004). Patients who had a CPB time of 100 minutes or more had a greater increase in gut permeability (p = 0.049).(ABSTRACT TRUNCATED AT 250 WORDS)