Left ventricular outflow tract obstruction with mitral valve replacement in small ventricular cavities

Area of Science:

• Cardiovascular Surgery
• Biomedical Engineering
• Hemodynamics

Background:

• Left ventricular outflow tract (LVOT) obstruction post-mitral valve replacement (MVR) is a concern.
• Comparative hemodynamic data for different prosthetic valves are limited.

Purpose of the Study:

• To compare LVOT gradients across various prosthetic mitral valves in a sheep model.
• To assess the hemodynamic impact of MVR in small left ventricles.

Main Methods:

• Mitral valve replacement (MVR) performed in young sheep using cardiopulmonary bypass.
• Hemodynamic gradients measured across LVOT with five different prosthetic valves (Ionescu-Shiley, Hancock, Starr-Edwards, Björk-Shiley, St. Jude Medical).
• Measurements taken post-MVR and during isoproterenol infusion.

Main Results:

• The Starr-Edwards valve produced a significant LVOT gradient post-MVR.
• Isoproterenol administration increased LVOT gradients with Ionescu-Shiley, Hancock, and Starr-Edwards valves.
• Low-profile Björk-Shiley and St. Jude Medical valves did not result in substantial LVOT obstruction.

Conclusions:

• Mitral valve replacement (MVR) can lead to left ventricular outflow tract (LVOT) obstruction.
• High-profile mechanical and bioprosthetic valves are associated with greater LVOT obstruction.
• Low-profile valve designs may mitigate LVOT obstruction risk.