Circulation
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Comparative Study
Neutralization of low molecular weight heparin by polybrene prevents thromboxane release and severe pulmonary hypertension in awake sheep.
Protamine reversal of heparin anticoagulation in patients is occasionally associated with life-threatening acute pulmonary hypertension. In a sheep model, we evaluated the effect on this adverse cardiopulmonary reaction of modifying the type of heparin (low molecular weight heparin compared with unfractionated heparin) and the type of heparin antagonist (polybrene compared with protamine). Protamine reversal of low molecular weight heparin (LMWH) and polybrene reversal of unfractionated heparin induced more than a 10-fold increase of plasma thromboxane B2 levels, a threefold increase of pulmonary vascular resistance and pulmonary artery pressure, and a 25% decrease of PaO2. ⋯ Anti-Xa activity increased to more than 3 IU/ml 4 minutes after LMWH anticoagulation (p less than 0.01) but was only partially neutralized by polybrene. Various polyanion-polycation complexes that are formed when heparin anticoagulation is reversed induce thromboxane release and acute pulmonary vasoconstriction in awake sheep. Reversal of LMWH anticoagulation with polybrene does not elicit this adverse reaction.
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A successful outcome of an arterial switch operation (ASO) for dextro-transposition of the great arteries (D-TGA) depends in large part on the transfer of the coronary arteries to the neoaorta without distortion or narrowing. However, the origins and distribution of the coronary arteries are quite variable in D-TGA; therefore, the entire experience with ASO at the Children's Hospital in Boston was reviewed. From 1983 through November 1989, 314 patients underwent surgery for D-TGA with the intent to perform an ASO. ⋯ Single right coronary artery was found in 14; 12 had ASOs with three CA deaths (25%); and two had Senning operations. One late death was due to diffuse narrowing of the single right coronary artery. Single left coronary artery occurred in 11 patients, and seven had ASO with no early but one late "sudden" death, whereas four had Senning operations.(ABSTRACT TRUNCATED AT 250 WORDS)
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Comparative Study Clinical Trial
Diabetic patients have abnormal cerebral autoregulation during cardiopulmonary bypass.
We tested the hypothesis that insulin-dependent diabetic patients with coronary artery bypass graft surgery experience altered coupling of cerebral blood flow and oxygen consumption. In a study of 23 patients (11 diabetics and 12 age-matched controls), cerebral blood flow was measured using 133Xe clearance during nonpulsatile, alpha-stat blood gas managed cardiopulmonary bypass at the conditions of hypothermia and normothermia. In diabetic patients, the cerebral blood flow at 26.6 +/- 2.42 degrees C was 25.3 +/- 14.34 ml/100 g/min and at 36.9 +/- 0.58 degrees C it was 27.3 +/- 7.40 ml/100 g/min (p = NS). ⋯ Arteriovenous oxygen saturation gradients and oxygen extraction across the brain were calculated from arterial and jugular bulb blood samples. The increase in arteriovenous oxygen difference between temperature conditions in diabetic patients and controls was significantly different (p = 0.01). These data reveal that diabetic patients lose cerebral autoregulation during cardiopulmonary bypass and compensate for an imbalance in adequate oxygen delivery by increasing oxygen extraction.
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Stimulated skeletal muscle grafts have been proposed as a means to reinforce ventricular wall in the treatment of severe myocardial failure. Latissimus dorsi cardiomyoplasty was performed in 11 patients with advanced heart failure due to cardiomyopathy who were in New York Heart Association (NYHA) class III or IV despite maximal medical therapy. There were no operative deaths. ⋯ At 6 months of follow-up, all the above values remained essentially unchanged. Furthermore, nonsustained ventricular tachycardia was abolished without specific medical therapy in four patients. Thus, cardiomyoplasty improves left ventricular function, reverses congestive heart failure, and may improve long-term survival in severe cardiomyopathies.