Randomized, prospective comparison of four burst pacing algorithms for spontaneous ventricular tachycardia.

"Less aggressive" burst stimulation is more effective in terminating spontaneous monomorphic ventricular tachycardia with a lesser acceleration rate. Higher ventricular tachycardia cycle length and use of 91% coupling interval were independent predictors for pacing termination.

Intravenous amiodarone in treatment of recent-onset atrial fibrillation: results of a randomized, controlled study.

OBJECTIVES: This study was designed to determine the efficacy of intravenous amiodarone in the management of recent-onset atrial fibrillation. BACKGROUND: The optimal approach for acute atrial fibrillation has not been established. Amiodarone is a unique antiarrhythmic agent with activity in both supraventricular and ventricular tachyarrhythmias, but its value for the restoration of sinus rhythm in patients with recent-onset atrial fibrillation has not been demonstrated. METHODS: Sample size was calculated to detect a 25% increase in reversion rate with amiodarone with a statistical power of 80%. One hundred consecutive patients with recent-onset (<1 week) atrial fibrillation and not taking antiarrhythmic agents were randomized to receive either intravenous amiodarone, 5 mg/kg body weight in 30 min followed by 1,200 mg over 24 h, or an identical amount of saline. Both groups received intravenous digoxin, 0.5 mg initially, followed by 0.25 mg at 2 h and 0.25 mg every 6 h thereafter, to complete 24 h while the ventricular rate was >100 beats/min. Amiodarone and digoxin blood levels were determined. Both groups were homogeneous regarding underlying heart disease, time from onset to treatment, initial ventricular rate and left atrial size. RESULTS: By the end of the 24-h treatment period, 34 patients (68%, 95% confidence interval [CI] 53% to 80%) in the amiodarone group and 30 (60%, 95% CI 45% to 74%) in the control group had returned to sinus rhythm (p = 0.532). Mean times (+/-SD) of conversion were 328 +/- 335 and 332 +/- 359 min, respectively (p =0.957). Among patients who did not convert to sinus rhythm, treatment with amiodarone was associated with a slower ventricular rate (82 +/- 15 beats/min in the amiodarone group vs. 91 +/- 23 beats/min in the control group, p = 0.022). After restoration of sinus rhythm, atrial fibrillation recurred during a 15-day follow-up period in 4 (12%) of 34 patients (95% CI 3% to 27%) in the amiodarone group and in 3 (10%) of 30 (95% CI 2% to 26%) in the control group (p = 0.861). CONCLUSIONS: Intravenous amiodarone, at the doses used in this study, produces a modest but not significant benefit in converting acute atrial fibrillation to sinus rhythm.

Limitations of head-up tilt test for evaluating the efficacy of therapeutic interventions in patients with vasovagal syncope: results of a controlled study of etilefrine versus placebo.

OBJECTIVES: This study assessed the efficacy of oral etilefrine (10 mg three times a day) in preventing a positive response to head-up tilt testing. BACKGROUND: Previous reports have suggested that oral etilefrine can be effective either in preventing a positive response to head-up tilt testing or in reducing syncopal recurrences in patients with vasovagal syncope. Up to now most studies assessing drug therapy in these patients have been uncontrolled. METHODS: This was a randomized double-blind crossover study of etilefrine versus placebo in 30 consecutive patients with syncope and a baseline positive head-up tilt test. After the first test, patients had no treatment for 3 days and were randomized to receive etilefrine or placebo for 4 additional days. They underwent tilt testing under treatment and again after 3 days of washout; they then received the alternative treatment for 4 days, and a third test was performed. RESULTS: Head-up tilt test results were negative in 13 (43%) patients with etilefrine and 15 (50%) with placebo (p = NS). Therefore, the statistical power of the study was only 10%. The rate of positive responses decreased with repeated testing irrespective of the assigned treatment: A positive response was obtained during the second head-up tilt test in 20 patients (10 with placebo, 10 with etilefrine) but in only 12 during the third (7 with etilefrine, 5 with placebo) (p < 0.05). CONCLUSIONS: Oral etilefrine (10 mg three times a day) was not superior to placebo in preventing a positive response to head-up tilt testing. Despite a low statistical power, the high rate of negative response with placebo (50%) suggests that controlled trials are needed to assess the real efficacy of any treatment in patients with vasovagal syncope.

[The usefulness of transesophageal echocardiography in the diagnosis of a free-floating thrombus in the left atrium]. / Utilidad de la ecocardiografía transesofágica en el diagnóstico de un trombo libre en aurícula izquierda.

The case of a patient with mitral prosthesis who had arterial embolism is presented. The transoesophageal echocardiogram showed a floating thrombus in the left atrium which had not been detected by transthoracic echocardiography. The usefulness of transesophageal echocardiography in the diagnosis of this pathology is emphasized.

[Usefulness of peridural anesthesia in surgery on a patient with Wilms' tumor and arterial hypertension]. / Utilidad de la anestesia peridural en la cirugía de un paciente con tumor de Wilms e hipertensión arterial.

We report an anesthetic technique to control hypertension in a Wilms' tumor in stage I in a 25-month-old child weighing 10 kg. He was treated with actinomycin D and vincristine during 4 weeks before surgical resection, developing inadequate ADH secretion due to vincristine. General anesthesia was used, with atropine, thiopental and atracurium as muscular relaxant. Systemic intraoperative anesthesia with narcotics was not given. A catheter was placed in the epidural space, with entrance through L3-L4 and its extreme in L1. Radiological control of the distal end of the catheter was carried out with iohexol before the administration of two 0.3% bupivacaine doses without adrenaline of 3 ml each, and intraoperative normal blood pressure was achieved. It was concluded that combined superficial general anesthesia techniques, associated with continuous epidural blockade, can be useful to control hypertension in Wilms' tumor.