Right and Left Atrial Function in Patients After Surgical Repair of Tetralogy of Fallot

Professor Cheung, Yiu Fai   (Principal Investigator)

24

2014-01-01

80000

Right and Left Atrial Function in Patients After Surgical Repair of Tetralogy of Fallot

atrial function, tetralogy of Fallot

Cardiovascular Research

201309176014

Small Project Funding

2013

Completed

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart defect. Although surgical repair can be performed with a high success rate in the present era, long-term cardiac functional abnormalities remain to be issues of concern. These include progressive pulmonary regurgitation (PR), right ventricular (RV) enlargement, RV and left ventricular (LV) dysfunction, and exercise intolerance. Recent studies demonstrated that ventricular dysfunction may predict impaired clinical status and have implications on long-term prognosis post TOF repair. Although the previous studies have focused on RV and LV functional assessment, the atrial function in patients after TOF repair has hitherto not been explored. The role of the atria in transforming the continuous venous return into the intermittent ventricular filling flow is important for optimal cardiac performance. The left atrium does not only serve as a simple passive conduit. It stores pulmonary venous return and acts as a reservoir during LV contraction and isovolumetric relaxation, and transfers both passively and actively blood into the left ventricle during diastole. The right atrium, on the other hand stores systemic venous return during RV contraction and isovolumetric relaxation, and transfers blood into the right ventricle during diastole. The relationship between ventricles and atria can hence be regarded characterized as an interactive one. Previous studies revealed LV enlargement to be a reliable predictor of adverse cardiovascular outcomes. The influence of different conditions on left atrial function such as aging, LV dysfunction, heart failure, and atrial fibrillation has further been investigated. In the context of TOF, dysfunction of the left and right ventricles may possibly affect functioning respectively of the left and right atria. Understanding of atrial function and atrioventricular interaction in repaired TOF patients has, however, been limited. Advances in imaging technology have enabled noninvasive evaluation of atrial function. The new speckle tracking echocardiography (STE) allows noninvasive frame by frame tracking of natural acoustic markers in the myocardium, hence allowing quantification of regional and global myocardial deformation in various directions. The application of STE in the quantification of regional and global LV and RV strain and strain rate has been reported. Recently, this technique has been increasingly applied to the assessment of left atrial (LA) function strain in patients with atrial fibrillation, hypertension, and heart failure, in whom LA deformation parameters may influence clinical management. The primary objective of the proposed study is to test the hypothesis that LA and right atrial (RA) function is impaired in the patients after surgical repair of TOF. The following issues would also be addressed in patients: 1) determinants of STE-derived indices of LA and RA deformation, 2) the relationship between LV diastolic function and LA deformation, 3) the relationship between RA and LV deformation and RV volume loading and function, and 4) potential RA-LA interaction.