Invited Commentary: Morphological Variations in Tetralogy of Fallot and Their Impact in the Surgical Approach and Postoperative Evolution

Successful surgical repair of tetralogy of Fallot has been performed for the last five decades, with low mortality rates and very good results in the long-term evolution. Among the most prevalent postoperative late complications are pulmonary regurgitation with a frequency ranging from 36% to 70%¹ right ventricular dysfunction and arrhythmias. Pulmonary valvar replacement is usually indicated to mitigate the late complications and even to reduce the chance of sudden death in such patients.² However, there are many factors involved in postoperative right ventricular failure, including the presence of a transjunctional (also referred to as a transannular) patch, and preoperative myocardial remodeling under conditions of chronic hypoxia and cell hypertrophy. Farah et al³ showed that an increase in the myocardial content of fibrosis already present before surgery was associated with a compromise in the diastolic ventricular function in the postoperative period detected by echocardiography. The quality and extent of preoperative myocardial adaptation, thus, assumes particular importance in countries where referral to a tertiary center occurs after the optimal timing for surgical repair.

In the present issue of the World Journal for Pediatric and Congenital Heart Surgery, Chowdhury and coworkers ⁴ published their experience with the surgical treatment of patients with tetralogy of Fallot, collecting data from a huge number of cases over a period of 22 years. Their experience is impressive, with limited but relevant data of follow up and correlation with anatomical features observed during surgery. Perhaps the retrospective nature of these observational data does not reflect the totality of the morphological variations of the anomaly, as is the case for the majority of studies that have the same characteristics. The recognition of the position and borders of the ventricular septal defect is probably not difficult to report because careful defect closure is a fundamental step of the surgical repair in order to avoid damage to the atrioventricular conduction tissues. Other features, such as the degree of aortic overriding and relation of the aortic root to the right ventricle, usually cannot be easily defined. In the referenced work, the authors used an interesting criterion that was the surgical description of “closure of the septal defect” or “baffling to the aorta” to discriminate between less than a 50% degree of aortic overriding versus the presence of a double outlet right ventricle. This is also a compromise to accept that the diagnosis of tetralogy of Fallot does not exclude concomitance with double outlet ventriculoarterial connection. ⁵

A significant contribution of the work is the authors’ aim to correlate the phenotypic variations of tetralogy of Fallot found in the operating room with the early and late evolution. The morphological descriptions provided are excellent, serving as a guide to those who diagnose and those who repair the anomaly, especially regarding the details about the morphology of the ventricular septal defects. However, the same is not true for the evolutional aspects. In this specific regard, the lack of complete follow-up information is probably the consequence of the conditions found in a developing country. Recent publications have addressed the long-term follow up of repaired tetralogy of Fallot patients in developing and in Western countries,^1,6 addressing the role of pulmonary valvar regurgitation and of the presence of a transjunctional patch for right ventricular failure. In one of the cited publications, ¹ the time of follow-up and the degree of development of the pulmonary arteries could be predictive of the development of pulmonary valvar regurgitation.

It is somewhat surprising that in the Chowdhury series no case of severe pulmonary regurgitation was reported or the need for reoperation to repair this complication. However, as described by the authors, the late deaths in their cohort occurred in patients with transjunctional patch, pulmonary valvar regurgitation, and biventricular dysfunction. In addition, among those patients dying of ventricular arrhythmias, most were late presenters, which reinforces that the status of the myocardium at the time of surgery sums up the postoperative remodeling for the occurrence of late ventricular failure.

Considering the study limitations such as incomplete evaluation of the majority of survivors with magnetic resonance imaging to detect early hemodynamic alterations and increase in right ventricular volumes, the report of relevant anatomical variations in this huge series of tetralogy of Fallot patients still brings significant information for surgeons and medical imaging professionals.