Safety and efficacy of low-energy cardioversion of 500 patients using two different techniques.

AIM: To present some safety and efficacy issues of low-energy internal cardioversion of chronic atrial fibrillation from 500 consecutive procedures performed with two different techniques, using either two single-coil catheters, or a single twin-coil catheter. METHODS AND RESULTS: Low-energy internal cardioversion was carried out in 368 patients by means of two defibrillation catheters: the former was positioned in the right atrium and the latter either in the left pulmonary artery (212 patients), or in the distal coronary sinus (156 patients). In the remaining 132 patients, a single twin-coil catheter was positioned with the distal coil either in the pulmonary artery (75 patients) or in the coronary sinus (57 patients), while the proximal coil was in the right atrium. The external defibrillator delivered truncated biphasic shocks (6/6 ms, tilt 50%), with a voltage of 10-400 V. In 283 patients (57%) external cardioversion had been unsuccessfully tried before low-energy internal cardioversion. After a total of 1118 shocks, the overall success rate was 92.2% (91.3% with two catheters and 94.7% with the single catheter); the success rate was 93.4 and 91.3% with the coronary sinus and the pulmonary artery approach, respectively. The mean energy used was 6.5 +/- 3.4 J (voltage: 320 +/- 45 V); no difference was found between the twin catheter (6.3 +/- 3.1 J) and the single catheter approach (6.9 +/- 3.7 J), while the coronary sinus configuration required a significantly lower energy than the pulmonary artery configuration (5.6 +/- 2.9 vs 7.2 +/- 3.8 J, P < 0.05). The duration of the current atrial fibrillation episode was the only clinical characteristic statistically different between the 461 successfully cardioverted patients and the 39 failures (295 vs 727 days, P < 0.01). No complication was recorded during or after the delivery of the therapy; no procedure had to be terminated because of patient's intolerance. CONCLUSIONS: Low-energy internal cardioversion is a safe and effective procedure for converting chronic atrial fibrillation, confirmed by this large multicentre experience. The newly available twin-coil catheter seems to achieve a slightly better success rate compared with the traditional two-catheter technique, and is associated with the same safety profile.

Critical analysis of the vectorcardiogram's reliability in the quantitative diagnosis of old myocardial infarction.

The purpose of this work is to verify if the vectorcardiogram (VCG) can be used for the quantification of old myocardial infarction (OMI). 50 cases of acute myocardial infarction were studied by mean of seriate determination of MB-CK isoenzyme and Sobel Index (SI); 4 weeks later, Frank's VCG was recorded. The studied cases did not show any conduction disturbances or other electrical abnormalities besides the sign of OMI. The 50 cases were divided into two groups according to the site of the necrosis: Group A, including 27 cases of inferior and/or posterior infarction and Group B, including 23 cases of septal and/or anterior infarction. On the VCG records, the variables related to OMI and to the general shape of ventricular depolarization and repolarization were measured. The electrical variables and the SI were compared by means of the methods of linear regression and of principal components analysis. No significant correlations were detected. Therefore, we conclude that the VCG is useless in the quantitative assessment of OMI; that such terms as "extensive, localized" and so on, at present widely used in electro- and vector-cardiography, are misleading if based only on surface electrical records obtained at distance from the acute phase of infarction and should therefore be avoided; that the work is consistent with the hypothesis that the electrical pattern of OMI could depend mainly upon peripheral intraventricular conduction disturbances.