Background: While it is understood that annular dilatation contributes to tricuspid regurgitation (TR), other factors are less clear. The geometry of the right ventricle (RV) and left ventricle (LV) may alter tricuspid annulus size and papillary muscle (PM) positions leading to TR.
Methods and results: Three-dimensional echocardiographic images were obtained at Emory University Hospital using a GE Vivid 7 ultrasound system. End-diastolic area was used to classify ventricle geometry: control (n=21), isolated RV dilatation (n=17), isolated LV dilatation (n=13), and both RV and LV dilatation (n=13). GE EchoPAC was used to measure annulus area and position of the PM tips. Patients with RV dilatation had significant (P≤ 0.05) displacement of all PMs apically and the septal PM and posterior PM away from the center of the RV toward the LV. Patients with LV dilatation had significant (P≤0.05) apical displacement of the anterior PM. Pulmonary arterial pressure (r=0.66), annulus area (r=0.51), apical displacement of the anterior PM (r=0.26), posterior PM (r=0.49), and septal PM (r=0.40), lateral displacement of the septal PM (r=0.37) and posterior PM (r=0.40), and tenting area and height (r=0.54, 0.49), were significantly (P≤0.05) correlated to the grade of TR. Ventricle classification (r=0.46) and RV end-diastolic area (r=0.48) also were correlated with the grade of TR. A regression analysis found ventricle classification (P=0.001), pulmonary arterial pressure (P≤0.001) annulus area (P=0.027), and apical displacement of the anterior PM (P=0.061) to be associated with the grade of TR.
Conclusions: Alterations in ventricular geometry can lead to TR by altering both tricuspid annulus size and PM position. Understanding these geometric interactions with the aim of correcting pathological alterations of the tricuspid valve apparatus may lead to more robust repairs.