Fourteen patients with atrial flutter (AFL) and rapid atrial tachycardia (AT) (8 AFL type I, 2 AFL type II and 4 AT) were treated with endocavitary atrial pacing (EAP). In 10 patients no antiarrhythmic agent was during this study and in 4 patients digoxin and/or verapamil was administered before. Conversion to sinus rhythm was successfully achieved in 7 patients, 50% (4 AFL type I and 3 AT). Primary success rate (return to sinus rhythm either immediately or after < 10 min of atrial fibrillation) was 71% (5/7) (2 AFL type I and 3 AT); delayed success (conversion to sinus rhythm in > 10 min, but < 24 h) was observed in 2 cases (29%) with AFL type I. At five patients AFL was converted in stable atrial fibrillation (4 AFL type I and 1 AFL type II). EAP failed to terminate the arrhythmia in 1 patient with uncommon AFL (type II) and 1 case with AT. EAP included single extrastimuli, coaction, single decremental atrial extrastimuli and incremental atrial pacing (burst) during AFL or AT. In conclusion, EAP is a method with few complications and has efficacy for converting AFL and rapid AT sinus rhythm or to atrial fibrillation.

Adult↗

PubMedDate not supplied

The monophasic action potential: a simple in vivo model to evaluate the effects of antiarrhythmic drugs at atrial level.

Monophasic action potential (MAP) represents an extracellular recording of electrical potentials variations produced simultaneously by several cells. Even if it does not represent the real cellular action potential, monophasic action potential generally reproduces with accuracy that aspect, being useful especially in the assessment of myocardial repolarisation phases. Monophasic action potential recording was performed with a quadripolar catheter designed by Franz; the quality of recordings was good and the procedure is safe. In clinical electrophysiology, monophasic action potential may be helpful in the study of certain aspects that cannot be evaluated adequately by standard electrophysiological techniques. The study was performed on six patients, in drug-free state. The duration of monophasic action potential at 90% of repolarisation and the atrial effective refractory period, at three basic cycle lengths (600, 500 and 400 msec) were determined. Both monophasic action potential duration at 90% of repolarisation and the atrial effective refractory period shortening at short cycle length and a linear correlation between these two parameters were seen. We conclude that the correlation between monophasic action potential duration and the effective atrial refractory period may be a simple and useful model to characterise in vivo the electrophysiologic profile of antiarrhythmic drugs.

Action Potentials↗

PubMedDate not supplied

The efficacy of sublingual verapamil in controlling rapid ventricular rate in chronic atrial fibrillation.

The efficacy of sublingual verapamil (Verapabene, 40 mg) in acute control of high ventricular rate was assessed in 20 patients with chronic atrial fibrillation (AF) of ischemic origin (class NYHA II and III). The effect on irregularity of the rhythm was also studied using time domain parameters of heart rate variability. Four ECG recordings (before, and at 10, 30 and 60 minutes after the administration), of 10 minutes each, were performed in every patient in basal conditions. The parameters were compared using paired t-test and Wilcoxon's test. Mean heart rate became significantly lower (p = 0.0064) after 10 minutes, and reached progressively the lowest value after 60 minutes (from the initial 112.9 beats/min to 90.6 beats/min, after 60 minutes, p < 0.0001). The irregularity parameters (SDNN--from 114.7 ms to 148.6 ms, rMSSD--from 152 ms to 205.9 ms) and the NNmin interval (from 353 ms to 404.5 ms) increased significantly after 30 and 60 minutes (p < 0.0001), but the frequency corrected irregularity (coefficient of variability) remained unchanged (p > 0.4). Sublingually administered verapamil proved to be an efficient alternative in acute control of rapid ventricular rate in AF. The method has the advantage to be applicable by a properly instructed patient itself.

Administration, Sublingual↗

PubMedDate not supplied

Peculiar atrial fibrillation in patients working with electric current.

During a period of 20 years, 8 patients with atrial fibrillation, without other cardiac abnormalities, resistant to electroconversion, but successfully defibrillated with quinidine, were examined. All were males, aged 40 to 50 years, working with electric current and exposed for many years to frequent electric shocks. The authors consider that chronic exposure to electric current induces a special form of atrial fibrillation, resistant to electric conversion. The inefficiency of the electroshock therapy in such cases might be explained by the increase of transthoracic impedance consecutive to repeated electrocutions.

Adult↗

PubMedDate not supplied

[The Deitz-Marques phenomenon after right atrial electric stimulation].

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Adult↗