Multi-detector computed tomography in the assessment of tetralogy of Fallot patients: is it a must?

Abstract

Background: Tetralogy of Fallot (TOF) accounts for 10% of all CHD. It classically consists of ventricular septal defect (VSD), aortic overriding, right ventricular outflow tract (RVOT) obstruction, and RV hypertrophy. There are many anatomic variants, associated intracardiac and extracardiac anomalies that must be taken into consideration when imaging and planning the surgical procedure needed. Multi-detector computed tomography (MDCT), with its high spatial and temporal resolution, has a pivotal role in the evaluation of complex anatomical findings in both unrepaired and repaired TOF patients. Main body: Though MDCT has a limited role in the initial diagnosis of TOF, it is particularly important when there is a question about anatomy of pulmonary arteries (PAs) (whether sizable, hypoplastic, or atretic), presence of major aorto-pulmonary collaterals (MAPCAs) and presence of additional VSDs. Additionally, MDCT is crucial in the diagnosis of different anatomical variants of TOF. TOF patients with absent pulmonary valve classically have hugely dilated PAs which raise an important question about the degree and severity of airways compression. This question can be accurately answered by MDCT. TOF with double-outlet RV (DORV) has variable degrees of aortic override which can be assessed by MDCT. An atrio-ventricular septal defect (AVSD) is seen in about 13% of TOF cases and typically occurs in patients with Down syndrome. MDCT can assess the size and extent of inlet VSD and size of both ventricles (balanced or unbalanced AVSD). Coronary artery anomalies are common and important association. MDCT can identify the presence of a major coronary artery crossing the RVOT, a left anterior descending (LAD) from RCA, or a dual LAD. The clinical importance of these anomalies is its susceptibility to injury during ventriculotomy incision required for TOF repair necessitating changing the usual approach of surgery. Patients with reduced pulmonary blood flow undergo a systemic to pulmonary shunt. MDCT can assess the patency of the shunt, stenotic, or occluded segments. In surgically repaired TOF patients, MDCT can identify the sequalae and long-term complications including residual RVOT obstruction, conduit stenosis, RVOT patch aneurysm, RVH, and aortic root dilatation.Conclusion: MDCT is a safe and reliable imaging modality that provides accurate assessment of anatomical variants and associated anomalies of TOF.

The Nakata index and McGoon ratio: correlation with the severity of pulmonary regurgitation after the repair of paediatric tetralogy of Fallot

“…However, the Nakata index was lower in patient with shunt history. The complete repair of TOF is recommended between 3 months and 1 year old, and palliative procedures such as systemic to pulmonary shunts are indicated in some patients due to small or hypoplastic pulmonary arteries [ 16 ]. Although the overall results of palliation with systemic to pulmonary shunt in TOF patients are favorable, it is possible that the palliation with a modified Blalock–Taussig shunt leads to an increase in the incidence of hypoplasia or distortion of the pulmonary arteries [ 17 ] and the hypoplasia or stenosis of the pulmonary arteries can be determinants of the postoperative pulmonary regurgitation [ 7 ].…”

Detection of Coronary Artery and Aortic Arch Anomalies in Patients with Tetralogy of Fallot Using CT Angiography

“…Invasive angiography is sometimes needed to establish the diagnosis and to provide detailed anatomy and hemodynamic characterization. As a good alternative to invasive cardiac catheterization, multi-detector computed tomography (MDCT) with high spatial and temporal resolution plays an important role in the evaluation of complex anatomical findings [ 3 ].…”