Type:
Educational Exhibit
Keywords:
Congenital, Complications, MR-Angiography, MR, CT, Paediatric, Cardiovascular system, Cardiac, Not applicable
Authors:
T. Balasko Josipovic, M. Mursic, I. Sjekavica, M. Hrabak Paar; Zagreb/HR
DOI:
10.26044/ecr2020/C-08430
Background
ccTGA is a rare acyanotic congenital heart defect that occurs in less than 0,5% of all congenital heart disease [1,2], also known as levo-transposition of the great arteries.
It is characterized by “double discordance” of atrio-ventricular and ventriculo-arterial connections Fig. 1, and often accompanied by other cardiovascular malformations - more than 90% of patients have associated anomalies like ventricular septal defect (VSD) Fig. 4 , left ventricular outflow tract (LVOT) obstruction and valve anomalies [3]. The discordant connections at both the atrioventricular and ventriculoarterial junctions result in pseudonormal physiology - hence the name congenital correction of the transposition [4]. With ccTGA, systemic venous return is pumped from the right atrium into the morphological left ventricle (LV), then through the pulmonary artery to the lungs. The pulmonary venous blood returns via the pulmonary veins through the left atrium into the morphological right ventricle (RV), then through the aorta. The coronary arteries in ccTGA are inverted [5] Fig. 6 .
- Clinical picture and natural course of ccTGA
A specific feature of ccTGA is its wide range of outcomes. Although the segmental arrangement of the cardiac components is abnormal, early symptoms depend on the presence of associated anomalies. In some infants the symptoms are instant - cyanosis if there is a VSD and pulmonary stenosis, both combined with a heart murmur during physical examination. As an adult, patients can present with bradycardia caused by a high-degree atrioventricular block. In rare cases with no associated malformations, some patients remain asymptomatic through childhood, until the anomaly leads to systemic atrioventricular (tricuspid) valvular regurgitation and failure of the systemic ventricle.
When a diagnosis of ccTGA is determined, it is not automatically an indication for surgical treatment, as long as the defect is isolated and the tricuspid valve function is normal. In the past, the preferred surgical approach was physiological that repairs the associated abnormalities, but after this repair, the RV remains the systemic ventricle and the progressive RV dysfunction is inevitable. Nowadays the anatomical repair is the first method of choice, making the morphologically LV the systemic chamber [6]. The decision to refer the patient for this complex surgery and when to do it is always difficult, especially in asymptomatic patients, so it should be based on multiple variables, such as the potential of the systemic RV to fail, the hemodynamic impact of the associated anomalies and severity of tricuspid valvar regurgitation [7].
Double switch operations have been developed to provide anatomic repair, thus securing cardiac function and prolonging life expectancy, with two procedures being most common: atrial switch - arterial switch and atrial switch - ventriculo-arterial switch (Rastelli) Fig. 8