Annals of internal medicine
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Randomized Controlled Trial Clinical Trial
Verapamil for control of ventricular rate in paroxysmal supraventricular tachycardia and atrial fibrillation or flutter: a double-blind randomized cross-over study.
The effectiveness of verapamil in controlling ventricular rate was evaluated in 20 patients with atrial fibrillation or flutter with a rapid ventricular response (Group 1) and 30 patients with paroxysmal supraventricular tachycardia (Group 2). In Group 1 low-dose verapamil (0.075 mg/kg body weight) decreased the mean ventricular rate from 146 to 114 beats/min (p < 0.01) compared to a decrease of 145 to 132 beats/min (p < 0.01) after placebo. In Group 2, 14 of 29 patients converted to sinus rhythm after low-dose verapamil, nine of 15 after high-dose verapamil (0.15 mg/kg body weight), and one of 24 after placebo (p < 0.01). We conclude that verapamil results in a clinically significant slowing of the ventricular response in atrial fibrillation or atrial flutter and is superior to placebo for conversion of paroxysmal supraventricular tachycardia to sinus rhythm.
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A 16-year-old boy had IIB von Willebrand's disease. The disorder is characterized by prolonged bleeding times; normal plasma levels of factor VIII-coagulant activity, factor VIII-ristocetin cofactor activity, and factor VIII-related antigen; abnormal (anodal) mobility of plasma factor VIII-related antigen on two-dimensional crossed immunoelectrophoresis; and enhanced binding of plasma factor VIII-related antigen to normal platelets in the presence of ristocetin. These variables were measured at time periods after an infusion of normal cryoprecipitate into the patient. ⋯ His bleeding times were normal after 24 hours and did not correlate with plasma levels of factor VIII-coagulation activity, factor VIII-ristocetin cofactor, factor VIII-related antigen, or the electrophoretic mobility of his plasma factor VIII-related antigen. These results imply that the abnormal factor VIII/von Willebrand factor multimers in the plasma of these patients can associate with normal factor VIII/von Willebrand factor multimers and delay the deposition of the normal multimers into subendothelial surfaces. This may require cryoprecipitate infusions 24 hours before elective surgical procedures.