The American journal of cardiology
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During the 3-month blind treatment period there were 40 deaths in the metoprolol group compared with 62 deaths in the placebo group (p = 0.024). During the first year (after 3 months the 2 groups were treated similarly) there were 64 deaths in the metoprolol group vs 93 in the placebo group (p = 0.017) and during 2 years 92 patients died in the metoprolol group vs 120 in the placebo group (p = 0.043). The relative incidence of different causes of death did not differ significantly between the 2 treatment groups, indicating that metoprolol reduced all causes of death to the same extent as its effect on overall mortality.
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Entrainment was attempted during electrophysiologic evaluation of 8 patients with atrioventricular (AV) nodal reentrant tachycardia. Entrainment could be performed while pacing from the high right atrium in 35 of 35 episodes, from proximal coronary sinus in 9 of 21 episodes and from distal coronary sinus in 10 of 20 episodes. The minimal rates required were 8 to 40 beats/min faster than those of the tachycardias. ⋯ Moreover, termination of tachycardia apparently was a function of the pacing site. In some episodes, either because of a proximity effect or because of a preferential input into the upper common pathway, coronary sinus pacing terminated the tachycardia at slower rates or with fewer stimuli than high right atrial pacing. Thus, patients with drug-resistant AV nodal reentrant tachycardias may benefit from recently introduced pacing techniques for termination of tachycardia through entrainment.
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A pericardial effusion is easily recognized by echocardiography, but the diagnosis of cardiac tamponade by echocardiography is controversial. Recently, several reports have indicated that right ventricular (RV) or right atrial (RA) diastolic collapse represent highly specific and sensitive signs of a hemodynamically significant pericardial effusion. This report evaluates the pathophysiologic significance of these findings in 3 patients. ⋯ Increases in wall stiffness of chamber pressures may prevent diastolic collapse in the setting of tamponade. Conversely, extremely low intracardiac pressures may allow diastolic collapse to occur in the absence of overt cardiac tamponade. The extent and timing of the RA or RV collapse, rather than its mere occurrence, are important in the diagnosis of cardiac tamponade by echocardiography.
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A device for temporary external DDD pacing was developed using a modified permanent pulse generator, and temporary atrial and ventricular electrode catheters were inserted pervenously. The atrial lead was a J type and the ventricular lead had a remote anode in the superior vena cava. With a special clamp and appropriate connectors the permanent DDD pulse generator provided unipolar external DDD pacing. ⋯ Eight patients benefited from temporary DDD pacing and 7 had permanent DDD pacemakers implanted. In 1 patient, atrial fibrillation developed, 2 patients had brief episodes of ventricular lead displacement and another required reprogramming because of loss of ventricular capture. Results suggest that the device is applicable for a clinical trial of DDD pacing before possible permanent implantation when attempting to improve cardiac output or control arrhythmias.
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Comparative Study
Sources of variability in the radionuclide angiographic assessment of ejection fraction: a comparison of first-pass and gated equilibrium techniques.
Measurements of ejection fractions (EF) determined by first-pass and gated equilibrium radionuclide angiography are widely believed to be equivalent. To compare these measurements in a large group of patients over a wide range of EF values, left ventricular (LV) and right ventricular (RV) EFs at rest were measured in 135 consecutive patients who underwent the 2 methods of radionuclide angiography within 1 hour: first-pass upright with a multi-crystal camera in the anterior projection and gated equilibrium supine with a single-crystal camera in the left anterior oblique projection. The population included 18 normal patients and 117 patients with various cardiac and pulmonary disorders. ⋯ However, in the latter group, the correlation remained good in the 15 patients with cardiomegaly due to aortic or mitral regurgitation (r = 0.80). Inter- and intraobserver error was similar for both methods. In contrast, there was a poor correlation between first-pass and gated equilibrium RVEF, with the first-pass values higher than the gated equilibrium values (0.51 +/- 0.11 vs 0.43 +/- 0.11, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)