225Neglected unrepaired TGA with VSD, does CMR has a role?

Abstract

Introduction: Transposition of great arteries (TGA) with unrestrictive ventricular septal defect (VSD) should be surgically repaired early in life to avoid development of irreversible pulmonary vascular obstructive disease(PVOD).However, in developing countries late presentation of TGA with VSD is not uncommon. The management plan for those late presenting cases is still not clear due to lack of guidelines. Herewith we are presenting a neglected case of TGA with VSD and highlighting the CMR role in the management. Case report: A 13 year old female known to have TGA with subpulmonic VSD presented to our clinic with cyanosis (resting O2 saturation was 83% that dropped to 55% after 6 minute walking test) and dyspnea (NYHA III) that markedly worsened on sildenafil medication. Chest X-ray (CXR)was congested with cardiomegaly (Figure 1-A). Echocardiography showed TGA with large subpulmonic VSD, Dilated systemic right ventricle (RV) with mildly impaired systolic function & severe tricuspid regurge. Cardiac catheterization showed that pulmonary vascular resistance was 9 WU & dropped to 6 WU on 100% O2 inhalation Patient was referred for CMR to evaluate left ventricle (LV) volumes, mass & significance of intracardiac shunts through the VSD by calculation of Qp:Qs & check the pulmonary vascular bed reactivity. CMR was performed on 1.5 Tesla Scanner. CMR protocol included long & short axis Cine SSFP images to evaluate cardiac functions& mass as well as phase contrast cine for pulmonary & aorta flow evaluation. CMR confirmed the diagnosis of TGA with sub pulmonic VSD (Figure 1-B) Systemic RV was dilated &hypertrophied, with mildly impaired systolic function (EF = 45%, EDVI = 233, ESVI = 129 & SVI = 104ml\m). LV was dilated, with mildly impaired systolic function (EF = 44%, ED-VI = 182, ESVI = 102 & SVI = 80ml\m). Indexed LV diastolic mass was 66 g/m denoting conditioned LV. Pulmonary flow was 100 ml, while aortic flow was 30 ml then Qp: QS was 3.3 (Figure 1-C) that increased to 4.9 by 100% O2 inhalation denoting VSD is still shunting from left to right & pulmonary vascular bed is still reactive. Based on CMR data, patient though presenting late is still eligible for arterial switch operation. Patient had a smooth postoperative course&O2 saturation increased to 96%. Discussion(s): Though irreversible PVOD is expected in late presenters with unrepaired TGA with VSD. However, there is no clear cutoff point when PVOD will be developed. In our case, this 13 year old patient has a congested CXR with cardiomegaly & she became more symptomatic with use of sildenafil. CMR confirmed that LV is still conditioned & VSD is still shunting from left to right with reactive pulmonary vascular bed, these findings were against development of PVOD & encouraging definitive surgical repair with arterial switch in such age. Conclusion(s): CMR is a comprehensive tool to evaluate cardiac function and shunts which can help in decision making in complex congenital heart disease.