Journal of the American College of Cardiology
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J. Am. Coll. Cardiol. · Dec 1990
Randomized Controlled Trial Multicenter Study Comparative Study Clinical TrialReduction in incidence of inducible ventricular tachycardia after myocardial infarction by treatment with streptokinase during infarct evolution.
The aim of this study was to determine whether intravenous streptokinase administered with or without oral aspirin to patients with evolving myocardial infarction reduces the inducibility of ventricular tachycardia at electrophysiologic study and thus the risk of sudden death in infarct survivors. Of 159 patients randomized at Westmead Hospital to the multicenter Second International Study of Infarct Survival (ISIS-2) after streptokinase and aspirin in acute myocardial infarction, 87 underwent electrophysiologic testing 6 to 28 days after infarction to determine their risk of subsequent ventricular arrhythmias (streptokinase 20 patients; aspirin 25 patients; streptokinase and aspirin 21 patients; both placebos 21 patients). Patients who underwent electrophysiologic testing had similar clinical characteristics to those of patients who did not. ⋯ During a mean follow-up period of 39 +/- 9 months, there were no spontaneous episodes of ventricular tachycardia, ventricular fibrillation or witnessed sudden death in the streptokinase-treated group compared with three such events in the placebo-treated group (p = 0.13). When compared with placebo therapy, intravenous streptokinase substantially reduced the incidence of inducible ventricular tachycardia in infarct survivors. No similar benefit was attributable to aspirin therapy.
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J. Am. Coll. Cardiol. · May 1990
Randomized Controlled Trial Clinical TrialInfective endocarditis, 1983-1988: echocardiographic findings and factors influencing morbidity and mortality.
The echocardiograms and clinical records of 70 patients with infective endocarditis seen between 1983 and 1988 were examined to evaluate the role of two-dimensional and Doppler echocardiography in the diagnosis of infective endocarditis and identify risk factors for morbidity and mortality. A blinded observer reviewed the echocardiograms for the presence and size of vegetations and the severity of the valvular regurgitation. Vegetations were identified in 54 (78%) of 69 technically satisfactory echocardiograms. ⋯ No patient with less than or equal to 1+ regurgitation (n = 8) died or required valve surgery for heart failure, but three of the eight patients did undergo surgery for mycotic aneurysm, recurrent embolism or paravalvular abscess. In patients without embolism before echocardiography, there was a trend toward a greater incidence of subsequent embolism in those with vegetations greater than 10 mm in size (26% [8 of 31] compared with 11% [2 of 18] with vegetations less than or equal to 10 mm) (p = 0.19). By multivariate analysis, risk factors for in-hospital death (n = 7) were an infected prosthetic valve (p less than 0.007), systemic embolism (p less than 0.02) and infection with Staphylococcus aureus (p = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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J. Am. Coll. Cardiol. · Nov 1989
Randomized Controlled Trial Clinical TrialRate-modulated cardiac pacing based on transthoracic impedance measurements of minute ventilation: correlation with exercise gas exchange.
The relation of pacing rate to physiologic variables of metabolic demand was examined in 10 consecutive patients with a minute ventilation-sensing, rate-modulating ventricular pacemaker implanted for complete heart block. All patients had paroxysmal (seven patients) or chronic (three patients) atrial fibrillation and were referred for catheter ablation of the atrioventricular junction. Treadmill exercise testing with measurement of expired gas exchange and respiratory flow was performed before ablation and 4 weeks after pacemaker implantation, with the pacemaker programmed to both the fixed-rate VVI and rate-modulating minute ventilation VVIR pacing modes in random sequence. ⋯ The mean exercise duration increased from 8.3 +/- 2.8 min in the fixed rate pacing mode to 10.2 +/- 3.4 min in the rate-modulating, minute ventilation mode (p = 0.0001). The maximal VO2 increased from 13.4 +/- 3.4 to 16.3 +/- 4.1 cc/kg per min (p = 0.0004). The maximal heart rate achieved in the minute ventilation pacing mode was 136 +/- 9.7 beats/min, similar to that observed in the patient's intrinsic cardiac rhythm before ablation (134.9 +/- 30.1 beats/min, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)
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J. Am. Coll. Cardiol. · Oct 1988
Randomized Controlled Trial Clinical TrialAcute elevation of blood carboxyhemoglobin to 6% impairs exercise performance and aggravates symptoms in patients with ischemic heart disease.
Acute exposure to carbon monoxide has the potential to impair exercise capacity in patients with ischemic heart disease. The effect of sufficient inhalation of this compound to gradually produce a level of 6% carboxyhemoglobin was studied in 30 nonsmoking patients with obstructive coronary artery disease and evidence of exercise-induced ischemia. After an initial training session, subjects were exposed to air or carbon monoxide on successive days in a randomized double-blind crossover fashion. ⋯ Both the level (62 +/- 2.4 versus 60 +/- 2.4%, p = 0.05) and change in left ventricular ejection fraction at submaximal exercise (1.6 +/- 1.6 versus -1.2 +/- 1.6%, p = 0.05) were greater on the air exposure day compared with the carbon monoxide day. The peak exercise left ventricular ejection fraction was not different for the two exposures (57 +/- 2.5% for both). These results demonstrate earlier onset of ventricular dysfunction, angina and poorer exercise performance in patients with ischemic heart disease after acute carbon monoxide exposure sufficient to increase blood carboxyhemoglobin to 6%.
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J. Am. Coll. Cardiol. · Mar 1988
Randomized Controlled Trial Comparative Study Clinical TrialSequential pulse defibrillation in humans: orthogonal sequential pulse defibrillation with epicardial electrodes.
A newly described sequential pulse technique, using four mesh electrodes positioned to approximate a true orthogonal system around the heart, was compared with a single pulse system using two of these same electrodes, which were located in positions that would be used for an automatic implantable defibrillator. The influence of electrode size was also assessed. The minimal energy necessary for defibrillation (defibrillation threshold) was determined intraoperatively in 21 volunteer patients undergoing accessory pathway ablation of Wolff-Parkinson-White syndrome. ⋯ Defibrillation thresholds were determined in three groups of patients: 1) those with four small mesh electrodes (6 cm2), 2) those with two small and two large (13 cm2) mesh electrodes, and 3) those with four large mesh electrodes. In all cases, the average minimal energy needed for sequential pulse defibrillation was less than that required for single pulse defibrillation in the same patients with the same electrodes (four small, 24.8 +/- 24.7 J single versus 6.7 +/- 8.3 J sequential; two small plus two large, 11.4 +/- 15.0 J single versus 2.7 +/- 1.4 J sequential; four large, 8.1 +/- 5.3 J single versus 3.9 +/- 2.6 J sequential). Using the 6 cm2 electrodes for single pulse defibrillation energies delivered at greater than 45 J in two patients failed to defibrillate the heart.(ABSTRACT TRUNCATED AT 250 WORDS)