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The relationship between the mitral annulus and left ventricular outflow tract
T Komoda1, R Hetzer, J Oellinger
1Department of Cardiovascular Surgery, German Heart Institute, Berlin, Germany.
ASAIO Journal (American Society for Artificial Internal Organs : 1992)
|December 5, 1997
Summary
Rigid mitral prostheses can cause dynamic left ventricular outflow tract (LVOT) obstruction by reducing the effective LVOT orifice size. Maintaining mitral annular (MVA) flexibility is crucial after mitral valve surgery to prevent this obstruction.
Area of Science:
- Cardiovascular Surgery
- Biomedical Engineering
- Cardiac Mechanics
Background:
- Mitral annular inflexibility from rigid prostheses is a known factor in dynamic left ventricular outflow tract (LVOT) obstruction post-mitral valve surgery.
- Understanding the geometric interplay between the mitral valve annulus (MVA) and the LVOT is essential for mitigating this complication.
Purpose of the Study:
- To elucidate the geometric relationship between the LVOT orifice and the MVA in normal subjects.
- To demonstrate how a rigid mitral prosthesis may lead to LVOT obstruction by assuming it follows posterior MVA (MVApost) motion.
Main Methods:
- Geometric analysis of the LVOT orifice and MVA in eight healthy individuals.
- Modeling prosthesis motion based on the MVApost during systole.
- Calculating the resultant obstruction rate at different time points in systole.
Main Results:
- The intersection between the LVOT orifice and the approximated plane of the MVApost (PI-MVApost) shifts apically during systole.
- This apical shift implies a reduction in the effective LVOT orifice size when a rigid prosthesis is present.
- Calculated obstruction rates increased progressively from 24.9% at 0 ms to 45.4% at 300 ms.
Conclusions:
- Rigid mitral prostheses can significantly reduce the effective LVOT orifice size, contributing to dynamic obstruction.
- Preserving MVA flexibility is vital to prevent LVOT obstruction following mitral valve interventions.