Circulation
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Left ventricular outflow tract (LVOT) obstruction is a complication of Carpentier ring mitral valvuloplasty that may occur only when this procedure is used to correct mitral regurgitation attributable to myxomatous degeneration of the mitral valve. LVOT obstruction has not been observed among approximately 300 patients undergoing this procedure to correct mitral regurgitation attributable to other causes. Among 200 patients with degenerative mitral regurgitation who underwent Carpentier valvuloplasty, LVOT obstruction was found in 12 patients (6%). ⋯ The severity of the motion decreased, but still could be provoked, with amyl nitrite at late follow-up. Mitral regurgitation tended to recur at late follow-up. Despite the presence of LVOT obstruction and hemodynamic features resembling hypertrophic cardiomyopathy at late follow-up, none of the patients had left ventricular hypertrophy or asymmetric septal hypertrophy, and early postoperative functional class improvement was sustained.
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High-fidelity hemodynamic recordings of aortic and right atrial pressures and the coronary perfusion gradient (the difference between aortic and atrial pressure) were made in nine patients during cardiopulmonary resuscitation (CPR). Findings during conventional manual CPR were compared with those during high-impulse CPR (rate, 120 cycles/min with a shorter compression:relaxation ratio) as well as during pneumatic vest CPR with and without simultaneous ventilation and abdominal binding. Aortic peak pressure during conventional CPR averaged 61 +/- 29 mm Hg but varied widely (range, 39-126 mm Hg) among patients. ⋯ Abdominal binding had no significant hemodynamic effects. This evaluation of experimental resuscitation methods in humans shows that the high-impulse chest compression method augments aortic pressure over levels achieved during conventional CPR methods; however, the improvement in pressure is modest and may not be clinically important. Simultaneous ventilation as well as abdominal binding during CPR were associated with no benefit; in fact, simultaneous ventilation appears to adversely affect cardiac perfusion and, therefore, should not be used during clinical resuscitation.
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Coronary artery bypass grafting in pediatric patients provides a unique opportunity to evaluate the characteristics of graft material. Twelve pediatric patients with severe coronary artery involvement secondary to Kawasaki disease underwent coronary artery bypass grafting with internal mammary artery and autologous saphenous vein grafts. Eleven patients were boys and one was a girl; their ages ranged from 5 to 13 years (mean age +/- SD, 8.7 +/- 3.0 years). ⋯ Growth potential of the internal mammary artery graft provides a new demonstration of the viability and adaptability of this graft. We conclude that the internal mammary artery graft is a "live" conduit with potential for growth and adaptation. This growth potential may be the most important reason for its excellent long-term patency, which suggests that in situ internal mammary artery grafts are the graft of choice for pediatric coronary artery bypass grafting.
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Cyclic elevation of intrathoracic pressure can close the mitral valve during cardiac arrest in dogs.
Mitral valve closure during cardiopulmonary resuscitation may result from direct cardiac compression. An alternative hypothesis is that with a rise in intrathoracic pressure, mitral valve closure can occur but may be influenced by whether the lungs are inflated or deflated. To test this hypothesis, we placed a large-bore cannula into the thoraces of 11 dogs. ⋯ Thus, mitral valve closure, with concomitant retrograde pressure gradients, can be produced by intrathoracic pressure changes with accompanying lung deflation. With lung inflation alone, however, the mitral valve remains open, and there are no significant transmitral pressure gradients. We conclude that intrathoracic pressure changes can cause the mitral valve to close or to remain open, depending on how intrathoracic pressure is generated.