Circulation
-
Comparative Study
Precordial QT interval dispersion as a marker of torsade de pointes. Disparate effects of class Ia antiarrhythmic drugs and amiodarone.
Patients with a history of class Ia drug-induced torsade de pointes have been treated with chronic amiodarone without recurrence of torsade de pointes despite comparable prolongation of the QT interval. We hypothesized that in such patients, class Ia drugs cause nonhomogeneous prolongation of cardiac repolarization times, whereas amiodarone causes homogeneous prolongation of cardiac repolarization times. ⋯ An increase in regional QT interval dispersion during class Ia antiarrhythmic drug therapy is associated with torsade de pointes. Chronic amiodarone therapy in patients with a history of class Ia drug-induced torsade de pointes produces comparable maximum QT interval prolongation but does not increase QT interval dispersion. This characteristic may explain its apparent safe use in patients with a history of class Ia drug-induced torsade de pointes.
-
Comparative Study
Differences in vasomotor control between human gastroepiploic and left internal mammary artery.
Internal mammary artery grafts have a greater long-term patency rate than do saphenous vein grafts. This has in part been attributed to the difference in endothelial function of arterial and venous vessels. The use of the gastroepiploic artery in coronary artery bypass grafting has become popular recently because of its similarity to internal mammary artery. In this study, we compared the endothelial responses of gastroepiploic and left internal mammary arteries to vasoactive substances. ⋯ The resemblance of relaxations induced by metacholine and sodium nitrite in both gastroepiploic and left internal mammary arteries suggests a similar activation and behavior of the L-arginine pathway in both arteries. The difference in bradykinin-induced relaxations may reflect a prostaglandin metabolism in the gastroepiploic artery different from that in the left internal mammary artery. Furthermore, maximal metacholine-induced relaxation in rings of the left internal mammary artery shows an age dependency that was not observed in rings of the gastroepiploic artery.
-
Comparative Study
Global left ventricular performance and regional systolic function after suture annuloplasty for chronic mitral regurgitation.
In surgery for chronic mitral regurgitation, the mitral subvalvular apparatus, including annulus, may play an important role in preserving left ventricular (LV) performance. The suture annuloplasty for mitral regurgitation allows annular contraction of the mitral valve. The potential effects of suture annuloplasty on the postoperative LV performance have not been fully defined. ⋯ These data suggest that suture annuloplasty can provide more desirable postoperative LV systolic performance than conventional MVR by preserving both the contraction of the mitral annulus and the mitral valvular-ventricular interaction.
-
Thrombosis is a serious complication of heart valve replacement, and management is often difficult. In recent years, thrombolytic therapy has been used as the primary technique by some investigators. ⋯ Fibrinolytic treatment appears to be an attractive nonsurgical alternative for prosthetic heart valve thrombosis, but because of the risk of cerebral embolism, its use should be reserved for tricuspid valve thrombosis or critically ill patients with mitral or aortic valve thrombosis. The use of a fibrinolytic agent in cases of small, nonobstructive paravalvular thrombosis demonstrated with transesophageal echocardiography needs further studies.
-
From August 1982 to May 1991, 65 children (32 boys), 1 day to 14 years old, received extracorporeal membrane oxygenation (ECMO) 0-50 hours after cardiac surgery. Forty-four (67.7%) were weaned, with 23 (35.4%) survivors. ⋯ ECMO allows for myocardial recovery in the majority of patients with refractory postcardiotomy failure and permits some patients to survive who would not have otherwise.