Circulation
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Heparin rebound, the reappearance of anticoagulant activity after adequate neutralization with protamine, can lead to excessive postoperative bleeding after cardiac surgery. We investigated the mechanism of heparin rebound by using chemically modified heparin that lacks anticoagulant activity (low-affinity heparin) but that is able to displace protein-bound anticoagulantly active heparin. ⋯ Our findings demonstrate that heparin anticoagulant activity persists for up to 6 hours after surgery despite apparent protamine neutralization. The observation of the marked increase in plasma anti-factor Xa activity after the addition of low-affinity heparin suggests that after its administration, a large proportion of the heparin binds to plasma proteins and is incompletely removed by protamine. After protamine is cleared, the protein-bound heparin dissociates slowly and binds to anti-thrombin III to produce an anticoagulant effect.
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Despite the recent wide applicability of the bidirectional cavopulmonary shunt, there is limited reported experience in performing these shunts in infants 6 months or younger. ⋯ Early bidirectional cavopulmonary shunt in young infants has shown encouraging early results and provides improved oxygenation with low morbidity and mortality. We speculate that an early bidirectional cavopulmonary shunt on an elective basis may reduce the deleterious sequelae of chronic hypoxemia, long-term ventricular volume overload, and repeated palliative procedures, thus yielding a more suitable Fontan candidate.
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Acute occlusion after balloon coronary angioplasty is associated with an increased risk of angina, emergency coronary artery bypass grafting (CABG), myocardial infarction (MI), and death. Stents offer a way of restoring patency and avoiding these complications. ⋯ Coronary artery stenting for acute closure after PTCA relieves myocardial ischemia and provides an alternate means of treatment. This series includes early learning curve experience; 70% (67 of 96) of patients were spared emergency coronary artery bypass graft surgery when this adverse outcome occurred. Certain clinical and angiographic subsets are at increased risk for restenosis and future cardiac events.
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The purpose of this study was to assess the value of body surface mapping and the standard 12-lead ECG in localizing the site of origin of postinfarction ventricular tachycardia (VT) during endocardial pace mapping of the left ventricle. ⋯ These results demonstrate that application of the 62-lead instead of the 12-lead ECG during endocardial pace mapping enhances the localization resolution of this mapping technique and enables more precise identification of the site of arrhythmogenesis in the majority of compared postinfarction VT episodes.
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Comparative Study
Comparison of phasic blood flow velocity characteristics of arterial and venous coronary artery bypass conduits.
Coronary artery bypass conduits derived from internal mammary arteries show relative resistance to atherosclerosis and significantly improved long-term patency compared with saphenous vein grafts. Atherothrombotic occlusion of venous conduits has previously been correlated with lower flow rates measured intraoperatively. To quantitate coronary bypass conduit flow velocity, we examined the phasic blood flow velocity patterns by intravascular Doppler spectral analysis in patients during cardiac catheterization to test the hypothesis that resting systolic and diastolic phasic blood flow velocity patterns differ significantly between arterial and venous bypass conduits. ⋯ Patterns of resting phasic blood flow, as well as mean velocity and total velocity integral, differ significantly between internal mammary artery and saphenous vein bypass conduits. These differences may have implications regarding blood-vessel wall interactions, the development of degenerative graft disease, and long-term conduit patency.