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Hemodynamic determinants of the mitral annulus diastolic velocities by tissue Doppler
S F Nagueh1, H Sun, H A Kopelen
1Department of Medicine, Baylor College of Medicine, Houston, Texas, USA. sherifn@bcm.tmc.edu
Insights
Left ventricular relaxation and preload influence early mitral annular diastolic velocity (Ea). Late diastolic velocity is determined by left atrial pressure changes, left atrial relaxation, and left ventricular end-diastolic pressure.
Area of Science:
- Cardiology
- Physiology
- Biomedical Engineering
Background:
- Mitral annular (MA) diastolic velocities are valuable indicators of left ventricular (LV) diastolic function.
- The specific hemodynamic factors influencing these velocities remain incompletely understood.
Purpose of the Study:
- To elucidate the hemodynamic determinants of MA diastolic velocities using tissue Doppler imaging.
- To investigate the relationship between MA velocities and parameters of LV diastolic function and loading conditions.
Main Methods:
- Measurements of left atrial (LA) and LV pressures were performed in mongrel dogs using Millar catheters.
- Tissue Doppler imaging recorded MA diastolic velocities, alongside conventional transmitral flow.
- Hemodynamic conditions were manipulated via fluid administration, caval occlusion, and pharmacological agents (dobutamine, esmolol) to alter preload, afterload, and relaxation.
Main Results:
- Early diastolic velocity (Ea) showed a significant correlation with the transmitral pressure gradient in most dogs.
- Ea strongly correlated with LV relaxation (tau and LV -dP/dt) and minimal LV pressure.
- Late diastolic velocity correlated positively with LA dP/dt and LA relaxation, and inversely with LV end-diastolic pressure.
Conclusions:
- Left ventricular relaxation, minimal pressure, and preload are key determinants of early diastolic mitral annular velocity (Ea).
- Late diastolic velocity is influenced by left atrial pressure dynamics, left atrial relaxation, and left ventricular end-diastolic pressure.
Objectives:
Our goal was to identify the hemodynamic determinants of the mitral annulus (MA) diastolic velocities by tissue Doppler.
Background:
The MA diastolic velocities are promising indexes of left ventricular (LV) diastolic function. However, their hemodynamic determinants have not yet been evaluated.
Methods:
Ten adult mongrel dogs underwent left atrial (LA) and LV pressure measurements by Millar catheters while tissue Doppler was applied to record the MA diastolic velocities at the septal and lateral comers. Conventional transmitral flow was also obtained. Left atrial and LV pressures were modified utilizing fluid administration and caval occlusion, whereas dobutamine and esmolol were used to change LV and LA relaxation. Left ventricular filling pressures were altered during different lusitropic states to evaluate for the possible interaction of preload and LV relaxation on the early diastolic velocity (Ea).
Results:
In the majority of dogs, a positive significant relation was observed between Ea and the transmitral pressure gradient (r = 0.57, p = 0.04). The Ea had strong correlations with tau (r = -0.83, p < 0.001), LV -dP/dt (r = 0.8, p < 0.001) and minimal LV pressure (r = -0.76, p < 0.01). However, there was no relation between Ea and the transmitral pressure gradient in experimental stages where tau >50 ms. Furthermore, the late diastolic velocity at both corners of the MA had significant positive relations with LA dP/dt (r = 0.67, p < 0.01) and LA relaxation (r = 0.73, p < 0.01) but an inverse correlation with LV end-diastolic pressure (r = -0.53, p = 0.01).
Conclusions:
Left ventricular relaxation, minimal pressure and preload determine Ea while late diastolic velocity determinants include LA dP/dt, LA relaxation and LV end-diastolic pressure.