Ischemia-induced malcoaptation of scallops within the posterior mitral leaflet.
OBJECTIVE
The posterior mitral leaflet is divided into a variable number of scallops, and little is known about the role of scallopmalcoaptation in ischemic mitral regurgitation. The study aim was to assess whether acute ischemia in the posterolateral wall of the left ventricle would induce scallop separation that would contribute to mitral regurgitation.


METHODS
Radio-opaque markers were surgically placed in the left ventricle, around the mitral annulus, and at three sites along the posterior mitral leaflet edge in eight sheep. Three-dimensional marker coordinates were obtained by biplane videofluoroscopy at 60 Hz and 0.1 mm resolution before and during echocardiographically verified acute ischemic mitral regurgitation produced by balloon occlusion of the circumflex coronary artery.


RESULTS
During systole, the mean (+/-SD) distance between the central and anterolateral markers, both placed on the central scallop of the posterior mitral leaflet, was unaffected by ischemia (7.4+/-2.4 versus 7.4+/-2.5 mm; n = 8; p = NS). In contrast, the systolic distance between the central scallop marker and the posteromedial marker increased by 2.3+/-0.2 mm (p = 0.008) in three hearts with the posteromedial marker on the posteromedial scallop, compared with no separation (0.2+/-0.5 mm; p = NS) in five hearts with both the central and posteromedial markers on the central scallop itself. This result shows systolic separation of the central and posteromedial scallops during acute ischemic mitral regurgitation.


CONCLUSIONS
During acute left ventricular ischemia, the central and posteromedial scallops of the posterior mitral leaflet can fail to coapt during systole, potentially contributing to the mitral regurgitation observed.
Myrmel
Truls
T
Department of Cardiovascular and Thoracic Surgery, Stanford University School of Medicine, California, USA.
Lai
David T M
DT
Lo
Sidney
S
Timek
Tomasz A
TA
Liang
David
D
Miller
D Craig
DC
Ingels
Neil B
NB
Daughters
George T
GT
D000818:Animals; D002815:Chordae Tendineae / Q000503:physiopathology; D004195:Disease Models, Animal; D008297:Male; D008943:Mitral Valve / Q000503:physiopathology*; D008944:Mitral Valve Insufficiency / Q000209:etiology* / Q000503:physiopathology; D008945:Mitral Valve Prolapse / Q000209:etiology* / Q000503:physiopathology; D008955:Models, Cardiovascular; D009200:Myocardial Contraction / Q000502:physiology; D017202:Myocardial Ischemia / Q000150:complications* / Q000503:physiopathology; D009919:Orchiectomy; D012756:Sheep; D013318:Stroke Volume / Q000502:physiology; D018487:Ventricular Dysfunction, Left / Q000209:etiology / Q000503:physiopathology; D017725:Ventricular Pressure / Q000502:physiology