Mitral annulus dynamics: determinants of left ventricular filling.
OBJECTIVE
To examine the influence of mitral annular dynamics on left ventricular filling.


METHODS
Twenty patients (mean age 64 +/- 6 years) with coronary artery disease and normal left ventricular function were studied by transesophageal echocardiography immediately before bypass grafting with the pericardium open. Pulmonary venous and transmitral velocities were recorded with pulsed wave Doppler. Mitral annulus position was derived by M-mode and its rate of change by digitisation of the records. From simultaneous high fidelity left atrial pressure, instantaneous power and its time integral work were derived.


RESULTS
In all patients the power curve was triphasic, being positive in both early and late diastole and negative during ventricular systole. Systolic annular work was related to pulmonary venous peak systolic velocities (r = 0.74, p < 0.001). The ratio of the early to late diastolic annular work correlated with the transmitral E/A ratio (r = 0.82, p < 0.0001) and early diastolic work was related to pulmonary venous peak diastolic velocities (r = 0.74, p < 0.001). Pressure-displacement curves of the annulus throughout the period of rapid ventricular filling were curvilinear with instantaneous stiffness increasing with distension. In addition all curves demonstrated a diastolic equilibrium point of zero stiffness.


CONCLUSIONS
Mitral annulus function, particularly when work and power are calculated, appear to be an important determinant of left ventricular filling. The underlying mechanics may also explain the variations in transmitral and pulmonary venous Doppler patterns seen in diseased states.
Carr-White
G S
GS
Department of Cardiology, Royal Brompton and Harefield NHS Trust, UK.
Gibson
D G
DG
D000368:Aged; D016275:Atrial Function / Q000502:physiology; D001783:Blood Flow Velocity; D003326:Coronary Circulation; D003327:Coronary Disease / Q000000981:diagnostic imaging / Q000503:physiopathology*; D017548:Echocardiography, Transesophageal; D006439:Hemodynamics; D006801:Humans; D008875:Middle Aged; D008943:Mitral Valve / Q000503:physiopathology*; D016277:Ventricular Function, Left / Q000502:physiology*