Systemic AV Valve Replacement in cTGA

Systemic AV valve replacement in cTGA

Congenitally corrected transposition of the great arteries is a condition in which there is atrioventricular and ventriculo 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 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 congenitally corrected transposition of the great arteries, systemic AV valve may be displaced inferiorly, the Ebstein’s anomaly. This abnormal systemic AV valve is an important cause for regurgitation rather than ventricular dilatation and dysfunction. Systemic AV valve regurgitation was the only independent predictor of death in congenitally corrected transposition of the great arteries in certain series [1]. The prognosis becomes poor when systemic AV valve replacement is delayed and the systemic ventricular ejection fraction falls significantly.

Ten year survival after systemic AV valve replacement was only about twenty percent when the preoperative systemic ventricular ejection fraction was below 44% in earlier studies [2]. In a series from Mayo Clinic [3], it was found that late systemic ventricular ejection fraction beyond one year was preserved in 63% of those who underwent surgery with systemic ventricular ejection fraction of 40% or more while it was seen in only 10.5% of those who underwent surgery with systemic ventricular ejection fraction less than 40%.

A systemic ventricular ejection fraction 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 preoperative factors associated with late mortality. The authors recommend that systemic AV valve replacement in those with congenitally corrected transposition of the great arteries and systemic AV valve regurgitation should be recommended before the systemic ventricular ejection fraction falls below 40% and the subpulmonary ventricular systolic pressure rises above 50 mm Hg.

References

1. 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.
2. 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.
3. Mongeon FP  et al. Congenitally corrected transposition of the great arteries ventricular function at the time of systemic atrioventricular valve replacement predicts long-term ventricular function. Am Coll Cardiol, 2011; 57:2008-2017.