Iv. Mayer et al., Reversal of increased diastolic stiffness in mitral stenosis after successful balloon valvuloplasty, J HEART V D, 8(1), 1999, pp. 47-56
Background and aim of the study: Abnormal passive elastic properties have b
een reported in patients with severe mitral stenosis and have been attribut
ed to either: (i) chamber atrophy due to unloading; (ii) myocardial fibrosi
s; (iii) right and left ventricular (LV) interaction; or (iv) internal rest
rictions due to the rigid mitral valve apparatus. The study aim was to eval
uate the effect of percutaneous mitral balloon valvuloplasty (PMV) on passi
ve elastic properties in 19 patients with severe mitral stenosis. Ten patie
nts with normal coronary arteries and LV function served as controls.
Methods: LV high-fidelity pressure measurements and simultaneous biplane LV
angiograms were obtained before and after PMV (n = 11). The constant of ch
amber stiffness (b; ml(-1)) was calculated from the diastolic pressure-volu
me relationship and the constant of myocardial stiffness (beta) from the di
astolic stress-strain relationship. The time constant of relaxation (T; ms)
was calculated from the LV pressure decay during isovolumic relaxation. Re
gional ejection fraction (radial axis system) was determined in six regions
of the right anterior oblique (RAO) and left anterior oblique (LAO) angiog
raphic projections. Results: Mitral valve area was increased from 1.0 to 2.
2 cm(2) after PMV, whereas diastolic pressure gradient was reduced from 14
to 4 mmHg. Global LV ejection fraction (EF) was slightly reduced (57% versu
s 63%; p<0.05) before valvuloplasty and normalized thereafter. Regional EF
increased significantly (p<0.05) in the posterolateral region of the LAO pr
ojection after intervention. Myocardial stiffness was increased before, and
decreased significantly after balloon valvuloplasty (from 16 to 11; p<0.05
). The rate of relaxation and chamber stiffness remained unchanged.
Conclusions: Myocardial stiffness is increased in patients with mitral sten
osis, but normalized after successful PMV. The improvement in passive elast
ic properties after valvuloplasty can be explained by the mobilization of t
he subvalvular apparatus with an improvement in regional LV function.