Ventricular resynchronization through biventricular cardiac pacing for the treatment of refractory heart failure in dilated cardiomyopathy

Abstract

Objective -The biventricular pacing (BVP) approach has good results in the treatment of congestive heart failure (CHF) in patients (pts) with disorders of intraventricular conduction. Methods -We have applied BVP to 28 pts, with left ventricular pacing using minitoracotomy in 3 pts and the transvenous aproach via coronary sinus in 25 pts. The mean duration of the QRS complexes wasHeart failure is currently considered a public health problem. In 1997, it accounted for 3.58% of all admissions in the Brazilian public health system, corresponding to 36.95% of the hospitalizations due to cardiocirculatory problems, with mortality of 6.39%, and a cost to the Brazilian government of 3 billion reais 1 . In the USA, from 1970 to 1994, the rate of hospitalizations due to heart failure tripled in patients aged 45 to 65 years, and increased 4 times in those over the age of 65 years 2 . Despite the great progress in the medicamentous treatment of heart failure, many patients have dilated cardiomyopathy refractory to this type of therapy, with a poor prognosis and a very poor quality of life. Of the nonpharmacological procedures indicated for this type of patient, cardiac transplantation, despite its limitations, remains the gold standard, because other options, such as cardiomyoplasty and Batista's surgery, have results that are somewhat controversial. At the beginning of the '90s, Hochleitner et al 3 proposed for the first time artificial cardiac pacing (dual-chamber pacemaker with a short atrioventricular interval) as a treatment for refractory heart failure, with encouraging acute results; these results, however, proved catastrophic within a short period of follow-up 4,5 . At the beginning of the '90s, Xiao et al 6,7 studied the effects of intraventricular conduction disorders of the myocardial function in patients with dilated cardiomyopathies and showed that the larger the QRS, the longer the time required for contraction and relaxation of the fibers, impairing myocardial function. Bakker et al 8 were the first to report ventricular resynchronization through permanent biventricular pacing using DDD pacemakers with a bifurcated lead in the ventricular exit; the right ventricle was stimulated by anodic current through a conventional endocardial electrode, and the left ventricle by cathodic current through an epimyocardial electrode. In the first half of the '90s, Cazeau et al 9 in the classical study with a 4-chamber pacemaker started the era of left ventricular pacing through the coronary sinus. Since then, ventricular resynchronization through biventricular pacing has shown