[Usefulness of exercise test in programming dual chamber pacemakers]. / Utilidad de la prueba de esfuerzo en la programación de los marcapasos bicamerales.

Prospectively, we studied 42 patient to evaluate the usefulness of treadmill exercise to programme pacemaker DDD in relation to the functioning upper frequency (relation between block frequency of pacemaker and the upper rate frequency). We excluded patient who had no treadmill exercise test after implant pacemaker. During stress 7 (17%) patient presented AV conduction 1:1 (group I); 16 (38%) second degree AV block type Wenckebach (group II); 14 (33%) second degree AV block 2:1 (group III); and 5 (12%) showed inhibition of the pacemaker by intrinsic activity (group IV). Block frequency of the pacemaker in group I and II was superior in regard of the upper rate frequency, 156.85 +/- 22.16 vs 141.43 +/- 20.82 and 135.25 +/- 11.54 vs 121.25 +/- 5.9, respectively. In group III and IV, it was lower, 120.36 +/- 15.31 vs 138.57 +/- 13.29 and 121.0 +/- 7.38 vs 142.0 +/- 14.39. The comparative analysis of the block frequency of the pacemaker in relation with the upper rate frequency showed statistically significant differences (p < 0.05) between groups I and II, and between the group I and III. The appearance of second degree AV block 2:1 is nonphysiologic, is rather due to an abrupt falling in the cardiac output. This phenomenon is able to be predicted and corrected by programming with the use the telemetry with parameters as the AV delay, as well as upper rate frequency and post-ventricular refractory atrial period.

[Ablation using radiofrequency in the treatment of ventricular tachycardia]. / Ablación con radiofrecuencia en el tratamiento de la taquicardia ventricular.

We performed radiofrequency catheter ablation in 14 consecutive patients with Ventricular Tachycardia (VT) 10 of which had healthy hearts, one patient with ischemic heart disease, one with arrhythmogenic dysplasia, one with dilated cardiomyopathy, and one with congenital heart disease. The localization of the VT was: 10 in the left posterior fascicular region, 3 in the right ventricular outflow tract (RVOT), and one patient with ischemic heart disease with the substrate in the left ventricular apex. All of them with VT refractory to pharmacological management, using an average of 2.7 drugs per patient. After all patients underwent Electrophysiological Study (EPS), an intracavitary mapping was performed, in order to locate the arrhythmogenic substrate. Later on, the RF ablation was performed, delivering an average of 15 pulses, using 40 Watts, and an average time of 25 sec. per pulse. The procedure was successful in 60% of the fascicular VT, with a 16% of recurrence; 100% of success with those originated in the RVOT with no recurrence; in the ischemic patient we achieved primary success, but with recurrence, a second session was successful with no recurrence up to date. No major complications occurred in this group. Those patients which showed no success required the use of antiarrhythmic drugs. The total success of the series is 71.4% with 10% recurrence, and no mortality.