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Efficacy and safety of repeated intravenous doses of ibutilide for rapid conversion of atrial flutter or fibrillation. Ibutilide Repeat Dose Study Investigators.

BACKGROUND: Currently available antiarrhythmic drugs have limited efficacy for acute termination of atrial fibrillation and flutter, especially if the arrhythmia is not of recent onset. The purpose of this multicenter study was to determine the efficacy and safety of repeated doses of intravenous ibutilide, a class III antiarrhythmic drug, in terminating atrial fibrillation or flutter. METHODS AND RESULTS: Two hundred sixty-six patients with sustained atrial fibrillation (n = 133) or flutter (n = 133), with an arrhythmia duration of 3 hours to 45 days, were randomized to receive up to two 10-minute infusions, separated by 10 minutes, of ibutilide (1.0 and 0.5 mg or 1.0 and 1.0 mg) or placebo. The conversion rate was 47% after ibutilide and 2% after placebo (P < .0001). The two ibutilide dosing regimens did not differ in conversion efficacy (44% versus 49%). Efficacy was higher in atrial flutter than fibrillation (63% versus 31%, P < .0001). In atrial fibrillation but not flutter, conversion rates were higher in patients with a shorter arrhythmia duration or a normal left atrial size. Arrhythmia termination occurred a mean of 27 minutes after start of the infusion. Of 180 ibutilide-treated patients, 15 (8.3%) developed polymorphic ventricular tachycardia during or soon after the infusion. The arrhythmia required cardioversion in 3 patients (1.7%) and was nonsustained in 12 patients (6.7%). CONCLUSIONS: Intravenous ibutilide given in repeated doses is effective in rapidly terminating atrial fibrillation and flutter and under monitored conditions is an alternative to current cardioversion options.

Aged↗

[Radiofrequency catheter ablation of type I atrial flutter].

PURPOSE: To verify the efficacy and safety of the creation of a barrier with radiofrequency (RF) in the tricuspid annulus and the vena cava ostium (TA-IVC). METHODS: Nine consecutive patients, 7 males, with age ranging from 36 to 76 years, with paroxysmal (7 patients) or permanent (2) type I atrial flutter (negative P wave in lead II, III and F) were submitted to RF ablation of TA-IVC istmo. One deflectable catheter with 4mm size tip was introduced into the right ventricle apex and pulled back to the inferior vena cava. When the atrial electrogram was detected the RF application was started. The RF was applied (20 watts during 60s) up to the proximity of inferior vena cava ostium. The end point was to stop atrial flutter. Then a vigorous atrial stimulation protocol, including isoproterenol infusion was used. In the next day, patients were submitted to transesophageal stimulation with the same protocol. RESULTS: Atrial flutter was interrupted in all patients (100%) with 4 to 28 (mean 16.7 +/- 7.7) applications. Eight patients (88.8%) with one session and 1 (11.1%) with two sessions. The mean time spent to stop the atrial flutter with one application was 30.5 +/- 18.5s. There were no complications. After a mean follow up of 3 +/- 1.6 month all patients (100%) are asymptomatic. Two of them are taking propranolol to control symptomatic atrial and ventricular ectopic beats. CONCLUSION: RF ablation of the TA-IVC istmo is efficient and safe in a short term follow up to interrupt and prevent re-induction and recurrence of type I atrial flutter.

Adult↗

Pharmacologic management of arrhythmias.

The role of antiarrhythmic drugs in the management of children with arrhythmias has changed due to the rapid development of radiofrequency ablation. Moreover, the release of new drugs and a better insight into the electrophysiologic mechanisms of arrhythmias have changed former patterns of drug management. However, because of lack of controlled trials, arrhythmia management in pediatrics is still mainly based on clinical studies and individual experience. Within these limitations, I attempt to give practical recommendations for the management of the different arrhythmias seen in children based on the latest developments in this area.

Adenosine↗

Efficacy of flecainide acetate for atrial arrhythmias following coronary artery bypass grafting.

The antiarrhythmic efficacy of intravenous flecainide and intravenous digoxin was assessed in 29 patients (26 men), aged 43 to 73 (63 +/- 7) years who developed atrial arrhythmias in the first 96 hours after coronary artery bypass grafting. Twenty-seven had atrial fibrillation and 2 had atrial flutter. Patients were entered into the study if the arrhythmia persisted for at least 15 minutes with a ventricular rate greater than 120 beats/min. Fifteen patients were randomized to flecainide (group 1) and 14 to digoxin (group 2). Flecainide was given as a bolus of 1 mg/kg over 10 minutes followed by an infusion of 1.5 mg/kg/hr for 1 hour and then 0.25 mg/kg/hr for the rest of the study period (24 hours). Digoxin was given as 3 bolus doses (0.5 mg followed after 6 and 12 hours by 0.25 mg). In both groups, 10 mg of verapamil was given intravenously after 45 minutes if the arrhythmia persisted with a mean ventricular rate greater than 100 beats/min. The antiarrhythmic efficacy was assessed by 24-hour Holter monitoring and frequent 15-second rhythm strips. Within 45 minutes control of arrhythmia, which was maintained for the rest of the study period, was achieved in 10 of 15 patients in group 1 and 2 of 14 in group 2 (p less than 0.01). Nine of 15 reverted to sinus rhythm in group 1 compared to 0 of 14 in group 2 and 1 of 15 remained in arrhythmia with a controlled ventricular rate in group 1 compared to 2 of 14 in group 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Reduction of radiation exposure time during catheter ablation with the use of pulsed fluoroscopy.

UNLABELLED: Prolonged exposure to radiation during radiofrequency catheter ablation implies a potential risk of radiodermatitis, neoplasm and genetic defects to the patient and to the operator-physician. The use of pulsed fluoroscopy is thought to reduce such a risk because the radiation dose decreases for the same period of time. The aim of the present study was to compare the radiation exposure time during pulse and continuous radiofrequency catheter ablation. METHODS: Procedures were divided according to the sort of fluoroscopy utilized and the last four cases of atrioventricular (AV) junction ablation, four of atrial flutter, five of atrial tachycardia, 16 of AV node reentrant tachycardia, 16 of AV tachycardia and 10 of ventricular tachycardia in which pulsed and continuous fluoroscopy were utilized were respectively separated into Group I (pulse fluoroscopy) and Group II (continuous fluoroscopy) with 55 patients in each group. Fluoroscopy was generated by the same device in the two groups. Continuous fluoroscopy used 2 mA and automatic kV adjustment (automatic brightness stabilizer) ranging from 70 to 110 kV. Pulsed fluoroscopy was set at 7 squares/s with 25 mA and automatic kV adjustment. Fluoroscopy time was registered by the fluoroscopy device counter. RESULTS: Procedure duration, success rate and complications did not differ between Groups I and II. Fluoroscopy time, however, was 4.4+/-4 min during pulsed fluoroscopy and 27+/-23 min during continuous fluoroscopy (p=0.001). CONCLUSION: During radiofrequency catheter ablation procedures, the use of pulsed fluoroscopy set at 7 squares/s, decreases the radiation exposure time by 80% as compared to continuous fluoroscopy without changing procedure duration and success rate.

Cardiac Catheterization↗

Aneurysm of the sinus of Valsalva: its natural history.

This case demonstrates that complications develop with aneurysm of the sinus of Valsalva. The aneurysm is diagnosed almost exclusively only after rupture. We feel that echocardiography provides a convenient means to follow cases of suspected aneurysms. A change in aortic root size may indicate imminent rupture. Fluttering of the anterior leaflet of the mitral valve would suggest aortic insufficiency, while an increase in right ventricular size coupled with paradoxical septal motion would strongly suggest a left-to-right shunt. Change in a murmur or in the aortic silhouette probably warrants cardiac catheterization. If rupture is suggested by clinical findings and corroborated by catheterization, surgery is indicated to prevent progressive cardiac failure.

Adult↗

Hemodynamic effects after conversion of arrhythmias.

Systemic and coronary hemodynamic parameters were determined during an arrhythmia and immediately after a direct current transthoracic shock given in an attempt to convert the arrhythmia to a sinus mechanism. No anesthesia or drugs were administered between the two studies. 16 patients with atrial fibrillation converted to sinus rhythm and five did not. In two patients with atrial flutter and one with supraventricular tachycardia, the arrhythmia was corrected. The arrhythmia persisted in a single patient with ventricular tachycardia. Utilizing each patient as his own control, we compared statistically various hemodynamic parameters before and after the shock. In addition, the group of patients whose atrial fibrillation terminated was compared to the group treated in the same manner but in which the atrial fibrillation persisted. Pressures in the right side of the heart decreased in both groups so that the changes appeared to be caused by factors associated with the transthoracic direct current shock or the catheterization procedure. The differences between those with atrial fibrillation who converted to sinus rhythm as compared to those who did not were a decrease in heart rate, an increase in stroke volume, and an increase in cardiac efficiency. There was no immediate effect on the cardiac output or coronary blood flow.

Adult↗

Recent developments in cardiovascular drug therapy: treatment of atrial arrhythmias with new class III drugs and beyond.

Despite recent advances in non-pharmacologic approaches antiarrhythmic drugs still play a dominant role in the treatment of cardiac arrhythmias. Large randomized controlled clinical trials have pointed out the importance of a proper benefit to risk evaluation in various patient subsets. This led to a continuous decline in the use of sodium channel blockers due to their possible proarrhythmic effects particularly in patients with reduced left ventricular function and ischemic heart disease. On the contrary, beta-blockers and more complex class III compounds such as sotalol and amiodarone have been prescribed increasingly. However, side effects commonly observed boosted the development of agents with simpler ion channel-blockade and less adverse reactions. In this review newer so-called "pure" class III agents will be discussed. Their common mechanism of action is an antifibrillatory effect both on the atrial and ventricular level. Clinically, they are used in the chemical cardioversion and the prevention of atrial fibrillation or atrial flutter as well as for the maintenance of sinus rhythm after its successful restoration. This report contains a detailed analysis of the pharmacokinetics, results of clinical studies and implications regarding the use in daily practice for three distinct compounds: ibutilide, dofetilide and azimilide. As efficacy is still limited their current and future role in hybrid therapies combining drug therapy with alternative treatment modalities (catheter ablation, pacemakers and implantable cardioverter defibrillators) is discussed. In addition, an outlook for a future drug design implementing changes in electrically remodeled atrial tissue will be given.

Anti-Arrhythmia Agents↗

Pacing techniques in the treatment of tachycardias.

Pacemakers are playing an increasing role in the management of patients with tachycardia. Pacing to prevent tachycardia must be differentiated from pacing to terminate tachycardia. Pacing is of proven value in preventing ventricular tachycardia that occurs in the setting of complete heart block or the setting of drug-induced QT interval prolongation and may be valuable in some other patients with nonsustained ventricular tachycardia. Pacing termination has found its greatest use as an alternative to cardioversion in patients with atrial flutter, especially those with suspected digitalis toxicity or sick sinus syndrome or patients after cardiac surgery. Implanted pacemakers that can be activated by the patient are a promising area or investigation for the termination of tachycardias that are recurrent and debilitating despite medical therapy.

Arrhythmias, Cardiac↗

[Echocardiographic study following corrective surgery for transposition of the great arteries using a baffle].

Sixteen patients undergoing corrective surgery of transposition of the great arteries following Arcas' technique were studied by echocardiography. Mean age was 8.7 years, ranging from 2 to 25 years. The echocardiographic studies were performed between 6 months and 10 years after surgery (X: 5.6 years). Paradoxical movement of the interventricular septum, right ventricle dilatation, diastolic fluttering of the mitral valve and tricuspid incompetence are commonly recorded. Tricuspid insufficiency does not necessarily mean right ventricular disfunction in these patients. Due to the particular baffle shape, bidimensional echocardiographic recognition of superior cava vein obstruction is easy. In addition, the waves of cava veins showed a characteristic pattern with predominant diastolic wave, which is an argument against its obstruction. In conclusion, echo and Doppler studies are reliable means for an adequate follow-up of these patients.

Adolescent↗