Systemic AV valve replacement in cTGA

Congenitally corrected transposition of the great arteries (CCTGA or cTGA) is a condition in which there is atrioventricular and ventricular arterial discordance so that the circulation is physiological. The right atrium connects to the morphological left ventricle, which in turn connects to the pulmonary artery so that systemic venous blood reaches the pulmonary circulation. The left atrium is connected to the morphological right ventricle which ejects to aorta, thereby ensuring that pulmonary venous drainage reaches the systemic circulation. Since the atrioventricular (AV) valves are a property of the ventricles, the systemic right ventricle in this case has a tricuspid valve. Hence it is prone for deformities affecting the tricuspid valve. In upto 70% cases of CCTGA, systemic AV valve (SAVV) may be displaced inferiorly, the Ebstein’s anomaly. This abnormal SAVV is an important cause for regurgitation rather than ventricular dilatation and dysfunction. SAVV was the only independent predictor of death in congenitally corrected transposition of the great arteries in certain series (Prieto LR, Hordof AJ, Secic M, Rosenbaum MS, Gersony WM. Progressive tricuspid valve disease in patients with congenitally corrected transposition of the great arteries Circulation 1998;98:997-1005). The prognosis becomes poor when SAVV replacement is delayed and the systemic ventricular ejection fraction falls significantly. Ten year survival after SAVV replacement was only about twenty percent when the pre operative systemic ventricular ejection fraction (SVEF) was below 44% in earlier studies (van Son JA, Danielson GK, Huhta JC, et al. Late results of systemic atrioventricular valve replacement in corrected transposition J Thorac Cardiovasc Surg 1995;109:642-652). In a recent series from Mayo Clinic, Mongeon F et al ( J Am Coll Cardiol, 2011; 57:2008-2017) it was found that late SVEF beyond one year was preserved in 63% of those who underwent surgery with SVEF of 40% or more while it was seen in only 10.5% of those who underwent surgery with SVEF less than 40%. An SVEF of 40% or less, subpulmonary ventricular systolic pressure of 50 mm Hg or more, atrial fibrillation and a poor NYHA class III or IV were the pre operative factors associated with late mortality. The authors recommend that SAVV replacement in those with cTGA and SAVV regurgitation should be recommended before the SVEF falls below 40% and the subpulmonary ventricular systolic pressure rises above 50 mm Hg.