The Canadian journal of cardiology
-
Clinical Trial Controlled Clinical Trial
The inefficacy of intravenous propafenone for rate control in atrial fibrillation.
The antiarrhythmic agent propafenone has been reported to prolong atrioventricular node conduction and may be suitable for rate control in atrial fibrillation (AF). To evaluate this, 10 patients (seven men and three women aged 29 to 67 years, mean +/- SD 48 +/- 14) were given intravenous propafenone during AF in both the supine and upright positions. Intracardiac catheters measured local electrograms from the high right atrium and right ventricular apex during AF. ⋯ In contrast, propafenone markedly increased the mean atrial cycle length (136 +/- 35 versus 226 +/- 39, P < 0.001). The mean ventricular cycle length reverted to baseline after tilt (447 +/- 103 ms) while the mean atrial cycle length decreased but not to baseline levels (170 +/- 21 ms). The authors conclude that intravenous propafenone is generally inadequate for rate control in AF, especially in the upright position.
-
Penetrating chest trauma is the most common cause of acute cardiac tamponade. Clinical recognition of this potentially life threatening condition may be difficult despite well described physical signs. Failure to repair the injury causing acute cardiac tamponade may result in sudden decompensation with poor clinical outcome. Emergent use of two-dimensional echocardiography can be an extremely valuable tool in evaluating the presence of cardiac tamponade and directing subsequent clinical management.
-
Comparative Study
Heparin monitoring during coronary intervention: activated clotting time versus activated partial thromboplastin time.
Activated clotting time (ACT) and activated partial thromboplastin time (APTT) are used for monitoring heparin therapy during coronary angioplasty. The purpose of this study was to determine which parameter is more useful clinically, and to assess the correlation between ACT and APTT. The authors measured these parameters at fixed intervals (0, 15, 30, 60, 150 and 240 mins) following intravenous heparin administration (12,500 +/- 3100 U) during coronary intervention in 39 patients. ⋯ There were no abrupt closures in the study patients. It was concluded that subthreshold ACTs with high APTTs occur frequently, suggesting the improved suitability of ACT for intraprocedural monitoring of anticoagulation status. If one accepts the minimum amount of anticoagulation for prevention of thrombosis to be that which produces an ACT of greater than 300 s, then an APTT of greater than 90 s does not predict adequate anticoagulation.
-
This overview summarizes the pathophysiology of acute myocardial infarction and reviews existing strategies for secondary prevention of myocardial infarction. The review also examines the complex interactions among lipids and the hemostatic/fibrinolytic systems to delineate the importance of lipid reduction as a secondary prevention measure. ⋯ Atherosclerotic plaque rupture with occlusive thrombus formation is integral to the pathophysiology of acute myocardial infarction. Beta-blockers, acetylsalicylic acid, warfarin, and angiotensin-converting enzyme inhibitors are useful agents for secondary prevention. The myriad deleterious effects of hyperlipidemia that promote a prothrombotic and antifibrinolytic vascular milieu serve to elucidate the importance of lipid reduction as an additional secondary prevention measure.