[Biatrial re-synchronization in the treatment of paroxysmal atrial fibrillation. 3- and 4-chamber pacemaker]. / Resincronización biatrial en el tratamiento de la fibrilación atrial paroxística. Marcapaso tres y cuatro cámaras.

The reason for multisite pacing is to correct atrial and ventricular electrical and mechanical asynchrony found in paroxysmal atrial fibrillation (PAF) and dilated cardiomyopathy. We report the first two cases in Mexico treated with biatrial pacing for PAF. The first was treated with a three chamber pacemaker and the other with a four chamber pacemaker. The first patient was a young man with uncontrolled ventricular rate in whom the atrioventricular conduction was modified with radiofrequency energy to control ventricular rate during atrial fibrillation. The second patient was a woman with corrected transposition of the great arteries, left ventricular ejection fraction (LVEF) of 30% and complete heart block. The pacing modalities were DDD for the first patient and DDDR for the second, both with sleep rate and auto mode switching. The atria were paced in right appendage and the left through the coronary sinus. PAF episodes were, found only in the first patient but were decreased in number and duration. The LVEF and functional class improved in the patient with biatrial and ventricular resynchronization. We conclude that biatrial pacing is effective in PAF.

[Trichamber pacing in dilated myocardiopathy. TTDR pacing?]. / Estimulación tricameral en la miocardiopatía dilatada. Modo de estimulación TTDR?

This article describes the first case in Mexico city that received a three chamber pacing system. A 40 year-old man with dilated cardiomyopathy with variant cardiac rhythm and bradycardia. The three leads were introduced by right subclavian approaches. The right chamber leads were placed in atrial's appendage and in the right ventricular outflow tract and the last one was placed in the great cardiac vein. The two ventricular lead were connected a Y-connector to the ventricular channel of a standard bipolar DDDR pacemaker. The right ventricular lead was connected to the distal pole (anode) and the left ventricular lead to the proximal pole (cathode). Eight days later, the patient's clinical status improved, his functional class improved from IV to II and his left ventricular ejection fraction increased from 30% to 35% by conventional ventriculography. In this type of patients the improvement in cardiac output is this result an of increase in left ventricular filling, reduced mitral and tricuspid regurgitation a better synchronization of ventricular contraction. Multisite pacing has added a mayor complexity to contemporary pacing and a modification of the standard pacer-maker code should be considered to accommodate multisite pacing. The letter in the first and second position might be T (three) or F (four) according to number of pacing chamber and also the letter "t" may be suitable to designate trigger in the third position. We conclude that implant of three chamber pacing in patients with dilated cardiomyopathy is technically feasible. An improvement in the patient's condition may be obtained and a modification in standard pacemaker code is necessary.