Operação de Fontan: reflexões da evolução e perspectivas atuais

Abstract

Fontan, congenital heart diseases, surgery.As the Fontan operation 1 became the most frequently performed surgery in Pediatric Cardiology for the functional correction of many congenital heart diseases with singleventricle physiology, it started to be considered in relation to the most suitable maneuvers to minimize the complications that still challenge its management in the long term.Although the incidence of such complications has decreased mainly as from 1988 with the introduction of the total cavopulmonary technique 2 , we can still observe the occurrence of morbidity elements whose rates are disturbing and affect the evolution of this method.Because of the dynamics imposed on the new anatomic situation with the cavopulmonary connection which eliminates the pulsatile function of the right ventricle and establishes the slow venous flow through the venae cavae to the pulmonary arterial tree, the occurrence of complications resulting from congestive, electrical and thromboembolic aspects is thus facilitated.The congestive aspects are characterized by increased venous pressure, hepatomegaly, protein-losing enteropathy due to lymphangiectasia, lower-extremity edema, and ascitis.The electrical aspects concern both the decrease in sinus automatism and supraventricular arrhythmias such as extrasystoles, fibrillation, and paroxysmal tachycardias.The thromboembolic aspects, which start in the venous system and in venous-arterial junctions and conduit connections, are also related to the occurrence of several coagulation disorders caused by factors resulting from liver congestion.Pathogenic factors of these adverse elements are related to preoperative anatomic and functional aspects and that is why a more accurate analysis of these aspects is mandatory at the moment of the surgical procedure.In this setting, it is well timed to recall and mention the factors considered optimal for the surgical indication, which are mainly: preserved ventricular function close to normal, adequate pulmonary arterial tree with mean pressures below 15 mmHg and pulmonary resistance lower than 2U Wood, and also the presence of sinus rhythm responsive to stimuli 3 . Absence of atrioventricular and aortic regurgitation, of fistulae and systemic-pulmonary anastomotic vessels, in addition to myocardial hypertrophy are also included.These deleterious factors are effectively responsible for the mortality that occurs throughout time and which ranges, according to the expertise of each medical center, from 15 to 30% 15 years after the surgical procedure 3 . That is where death results from, mainly related to heart failure, arrhythmias, thromboembolism, and to protein-losing syndrome.Among the complications, those with the highest prevalence and repercussion are heart failure and arrhythmias, mainly in atriopulmonary 4-6 techniques, but also in cavopulmonary 7 procedures when performed in adulthood. These complications are less frequent in cavopulmonary connections with extracardiac conduits 8 than in intra-atrial lateral tunnel 7,9 . Other complica...