Elsevier

Cardiology Clinics

Volume 20, Issue 3, August 2002, Pages 395-404
Cardiology Clinics

Late problems in tetralogy of Fallot—recognition, management, and prevention

https://doi.org/10.1016/S0733-8651(02)00010-3Get rights and content

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Anatomy

The defect in TOF is due to antero-cephalad deviation of the outlet septum resulting in four features: (i) right ventricular outflow tract obstruction (RVOTO) which may be infundibular, valvar or (usually) a combination of both, with or without supravalvar or branch pulmonary artery stenosis; (ii) a nonrestrictive VSD; (iii) an overriding aorta (<50%), and (iv) consequent right ventricular hypertrophy (Fig. 1). The so-called pentalogy of Fallot also has an ASD. Accompanying features can include

Surgical repair

Most adults will have had surgery, either palliative or, more commonly, reparative by the time they present to the cardiologist. Rarely, an adult patient will present without previous operations. The focus of this article will be on the late outcome of adult patients after surgical repair of their tetralogy of Fallot.

Reparative surgery involves closing the VSD and relieving the RVOTO (Fig. 2). The latter may involve:

  • Pulmonary valvotomy (as in most instances the pulmonary valve is involved,

Late problems after surgical repair

The overall survival of patients who have had operative repair is excellent, provided the VSD has been closed, the RVOT obstruction has been relieved satisfactorily and severe PR, which may lead to RV dilation and RV dysfunction, is absent. A 32-to 36-year survival of 86% and 85% have been reported [2], [3]. Most adults with previous repair of tetralogy of Fallot lead a good quality of life [1], [2], [3]. Over 85% of patients after intracardiac repair are asymptomatic on follow-up. Symptoms do

Significant pulmonary regurgitation

Significant (PR) is almost always encountered when the transannular patch repair technique has been employed. PR is usually well tolerated if mild to moderate. Severe chronic PR, however, may lead to symptomatic RV dysfunction [9]. The severity of PR, and its deleterious long-term effects are augmented by co-existing proximal or distal pulmonary artery stenosis, or pulmonary artery hypertension. Until recently, the severity of PR has been difficult to quantify. Investigators have employed

Heart block

As a result of surgery, a right bundle branch block (RBBB) pattern is almost universal in patients who underwent repair of tetralogy of Fallot via a right ventriculotomy. Characteristically, the RBBB involves a short and narrow first part with a taller and broader second part of the QRS complex (Fig. 3). RBBB with left anterior hemiblock, so-called bifascicular block, is also common (approximately 15% of postoperative patients). Bifascicular block, when isolated, does not lead to complete heart

Pregnancy

The risk of pregnancy in repaired patients depends on the patient's hemodynamic status. The risk is low, approaching that of the general population, in patients with good underlying hemodynamics. In patients with significant residual RVOT obstruction, severe PR with or without tricuspid regurgitation and RV dysfunction, the increased volume load of pregnancy may lead to heart failure and arrhythmias [24]. Furthermore, LV dysfunction, usually due to previous volume overload, may be present. This

Significant pulmonary regurgitation

Relief of peripheral pulmonary artery stenosis may reduce the severity of PR [27]. Pulmonary valve implantation (with either a homograft or porcine bioprosthesis) may be necessary for severe PR or a grossly calcified pulmonary valve. It carries a low operative risk [12], [28] and leads to symptomatic improvement [28], [29], [30], [31].

Right ventricular dilation

Alleviation of peripheral pulmonary artery stenosis may lessen the degree of (PR) and, in turn, RV dilation. Timely PVR, before RV dilation and irreversible RV

Heart block

In patients with bifascicular block combined with late PR prolongation (PR > 0.20 msec), Holter or EPS is warranted as these patients may require pacing. Pacemaker implantation is mandatory in all cases of postoperative complete heart block and in true trifascicular block, confirmed by EPS.

Supraventricular arrhythmia

Patients presenting with sustained atrial flutter and/or atrial fibrillation, should undergo a thorough assessment of their hemodynamics and should have target residual hemodynamic lesions corrected (eg,

Pregnancy

All patients with repaired tetralogy should have specialist cardiologic counseling before conception and evaluation early in pregnancy. Fetal echocardiography is recommended at approximately 16 to 18 weeks' gestation.

Genetic counseling

Chromosome analysis is warranted due to the increased incidence of TOF in trisomy 21. The FISH test, to exclude 22qD should be considered.

Significant pulmonary regurgitation

Recent changes in the surgical technique [5], [6] with a less aggressive approach towards complete relief of RVOT obstruction and avoidance of a transannular patch will lessen the degree of PR.

Right ventricular dilation

The newer transatrial approach [5] (rather than transventricular) at the time of corrective surgery will lessen the degree of RV damage [35], [36]. Changes in the surgical technique with a less aggressive approach towards complete relief of RVOT obstruction with avoidance of transannular patches [5], [6]

Supraventricular arrhythmia

A surgical approach that would minimize atrial scars as well as avoid significant residual hemodynamic lesions causing RA dilation may lead to a lower incidence of atrial flutter and fibrillation in these patients.

Sustained ventricular tachycardia

A surgical approach that would minimize ventricular scarring as well as avoid significant residual hemodynamic lesions causing RV dilation may lead to a lower incidence of ventricular tachycardia [5], [35], [36].

Sudden cardiac death

High-risk patients for SCD (primary or secondary prevention) may benefit

Summary

Most adults with previous repair of tetralogy of Fallot lead unrestricted lives and are asymptomatic. Residual RVOT problems such as significant PR and/or RVOT obstruction however are common and often lead to gradual RV dilation and dysfunction with consequent supraventricular or ventricular arrhythmias. Hemodynamic causes for the tachyarrhythmia should be sought and corrected, and therapy directed towards suppressing the arrhythmia (antiarrhythmics, cryoablation or AICD) should be carried out

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