Submitted on September 28, 2007
Accepted on February 11, 2008
The Progressive Nature of Chronic Mitral Regurgitation and the Role of Tissue Doppler derived Indices
Tomas G Neilan1*, Thanh-Thao Ton-Nu2, Yoshiaki Kawase2, Ryuichi Yoneyama2, Kozo Hoshino2, Federica del Monte3, Roger J. Hajjar3, Michael H. Picard4, Robert A. Levine5, and Judy Hung6
1 Cardiology, Massachusetts General Hospital, Boston, Massachusetts, United States
2 Medicine, MGH, 02139, Massachusetts, United States
3 Cardiovascular Research Center, Harvard Medical Shcool, USA, Charlestown, Massachusetts, United States
4 MGH
5 Massachusetts General Hospital, Cardiac Ultrasound Lab, VBK - 508, Boston, Massachusetts, United States
6 Medicine, MGH, 02114, Massachusetts, United States
* To whom correspondence should be addressed. E-mail: tneilan{at}partners.org.
The aim of the study was to determine whether severe mitral regurgitation (MR) is progressive, and whether tissue-Doppler (TD)-derived indices can detect early left ventricular (LV) dysfunction in chronic severe MR. Percutaneous rupture of mitral valve chordae was performed in pigs (n=8). Prior to (baseline), immediately post MR (Post-MR), and at 1 and 3 months after the creation of MR, cardiac function was assessed using conventional and TD-derived indices. The severity of MR was quantified using regurgitant fraction (RF) and effective regurgitant orifice area (EROA). In all animals, severe MR was created. On follow-up, the LV dilated progressively over time, while LV ejection fraction (EF) did not decrease. With the increase in LV dimensions, the forward stroke volume remained unchanged, while the mitral annular dimensions, EROA, and RF increased (EROA post-MR 41 ± 2 vs. 51 ± 2 mm2 at 3 months, p < 0.01). Peak systolic myocardial velocities, strain, and strain rate (SR) increased acutely after creation of MR, remained elevated at 1 month, but declined by 3 months (Anterior SR post-MR 2.9 ± 0.1 vs. 2.4 ± 0.2 s-1 at 3 months, p < 0.001). Therefore, in a chronic model of MR, serial echocardiographic assessment demonstrated that MR begets MR, and those TD-derived indices, which initially increased post-MR, decreased to baseline prior to any changes in LVEF.
