The Annals of Thoracic Surgery, Vol 41, 70-74, Copyright © 1986 by The Society of Thoracic Surgeons
Left ventricular outflow tract obstruction with mitral valve replacement in small ventricular cavities
GK Jett, MD Jett, GR Barnhart, GL van Rijk-Swikker, M Jones and RE Clark
The inference that mitral valve replacement (MVR) may produce left
ventricular outflow tract (LVOT) obstruction has been made, but no
comparative hemodynamic studies with various types of prostheses have been
done. The purpose of the present study was to compare the gradients created
across the LVOT with MVR in young sheep with small left ventricular
cavities. Mitral valve replacement was accomplished using cardiopulmonary
bypass and hypothermic cardioplegic arrest. Five animals were used for each
of the following valves studied: 25-mm Ionescu-Shiley bovine pericardial
valve, 25-mm Hancock porcine aortic valve, 2M-6120 28-mm Starr-Edwards
ball-valve prosthesis, 25-mm Bjork- Shiley 60-degree flat tilting-disc
prosthesis, and 25-mm St. Jude Medical hemidisc valve. Gradients across the
LVOT were measured after MVR and then during infusion of isoproterenol
hydrochloride (0.05 micrograms/kg/min). Following MVR, only the
Starr-Edwards valve produced an LVOT gradient (32 +/- 23 mm Hg).
Substantial gradients after MVR were seen, however, with isoproterenol
administration with the Ionescu-Shiley (47 +/- 4 mm Hg), Hancock (13 +/- 8
mm Hg), and Starr-Edwards (65 +/- 30 mm Hg) valves but not with the
low-profile valves (Bjork-Shiley and St. Jude Medical). The results of the
present study demonstrate that MVR can produce LVOT obstruction. The
greatest degree of obstruction was with the high-profile mechanical and
bioprosthetic valves.
