Enhanced inflammatory response to coronary angioplasty in patients with severe unstable angina

Annular geometry in patients with chronic ischemic mitral regurgitation: three-dimensional magnetic resonance imaging study

BACKGROUND

Although animal studies showed that annular remodeling may be related to the pathogenesis of chronic ischemic mitral regurgitation (CIMR), little was known in humans. A better understanding of the precise 3D geometry of the mitral valvular-ventricular complex in CIMR is needed to devise a better surgical technique. The purpose of the study was to elucidate mitral annular geometry in patients with CIMR using cardiac MRI.

METHODS AND RESULTS

Thirty-eight patients with previous inferior or posterior myocardial infarction were studied. With the 3D reconstruction of the mitral annulus and subvalvular apparatus from a series of longitudinal cine MRIs, end-systolic mitral annulus dimensions and 3D geometry were calculated. Patients were grouped by mitral regurgitation grade using echocardiography (> or =2+, n=15 versus < or =1+, n=23). Both septal-lateral and commissure-commissure mitral annular diameters were significantly greater in CIMR(+) patients (35+/-5 versus 30+/-4 mm, P=0.005; 46+/-6 versus 39+/-4 mm, P<0.001, respectively). The length of the fibrous annulus was significantly larger in CIMR(+) patients (28+/-3 versus 24+/-3 mm; P<0.001). The height of the annular "saddle horn" above a best-fit plane was lower in CIMR(+) patients (4.2+/-1.2 versus 6.0+/-1.8 mm; P=0.002), and the annular height to commissural width ratio was significantly lower in CIMR(+) patients (12+/-3 versus 21+/-5%; P<0.001).

CONCLUSIONS

Patients with CIMR had greater septal-lateral and commissure-commissure mitral annular dimension, larger intertrigonal distance, and flattened saddle shape of mitral annulus. These associated geometric alterations may be important in the pathogenesis of CIMR.

Ablation of mitral annular and leaflet muscle: effects on annular and leaflet dynamics

Mitral annular (MA) and leaflet three-dimensional (3-D) dynamics were examined after circumferential phenol ablation of the MA and anterior mitral leaflet (AML) muscle. Radiopaque markers were sutured to the left ventricle, MA, and both mitral leaflets in 18 sheep. In 10 sheep, phenol was applied circumferentially to the atrial surface of the mitral annulus and the hinge region of the AML, whereas 8 sheep served as controls. Animals were studied with biplane video fluoroscopy for computation of 3-D mitral annular area (MAA) and leaflet shape. MAA contraction (MAACont) was determined from maximum to minimum value. Presystolic MAA (PS-MAACont) reduction was calculated as the percentage of total reduction occurring before end diastole. Phenol ablation decreased PS-MAACont (72 +/- 6 vs. 47 +/- 31%, P = 0.04) and delayed valve closure (31 +/- 11 vs. 57 +/- 25 ms, P = 0.017). In control, the AML had a compound sigmoid shape; after phenol, this shape was entirely concave to the atrium during valve closure. These data indicate that myocardial fibers on the atrial side of the valve influence the 3-D dynamic geometry and shape of the MA and AML.

Paneth suture annuloplasty abolishes acute ischemic mitral regurgitation but preserves annular and leaflet dynamics

BACKGROUND

Ring annuloplasty, the standard treatment for ischemic mitral regurgitation (IMR), abolishes normal annular dynamics and freezes the posterior leaflet. We examined the impact of Paneth suture annuloplasty during acute IMR on motion of the mitral annulus and leaflets in an ovine model.

METHODS AND RESULTS

Eight sheep had radiopaque markers placed on the left ventricle, anterior mitral leaflet, posterior mitral leaflet, and mitral annulus. A Paneth suture annuloplasty that could be reversibly tightened was anchored to each fibrous trigone and externalized through the mid-lateral mitral annulus. Acute IMR was induced by proximal circumflex artery occlusion. Transesophageal echocardiography assessed the degree of IMR, and biplane cinefluoroscopy measured 3-dimensional marker coordinates before and during circumflex ischemia, and tightening of the Paneth suture. Paneth suture annuloplasty eliminated acute IMR, and reduced septal-lateral and commissure-commissure mitral annular dimensions. Tightening of the annuloplasty sutures, even beyond the degree necessary to eliminate mitral regurgitation (MR), did not reduce septal-lateral or commissure-commissure annular shortening, shortening of the muscular annular perimeter, annular flexion, or angular excursion of the anterior or posterior leaflets relative to ischemic conditions.

CONCLUSIONS

In contrast to ring annuloplasty, annular reduction sufficient to restore mitral competence during acute IMR can be achieved with a Paneth suture annuloplasty while simultaneously maintaining normal annular and leaflet dynamic motion. These findings should prompt additional investigation and design of repair methods that preserve the mobility of the mitral apparatus.

Geometric distortions of the mitral valvular-ventricular complex in chronic ischemic mitral regurgitation

BACKGROUND

Better understanding of the precise 3-dimensional geometric changes of the mitral valvular-ventricular complex in chronic ischemic mitral regurgitation (CIMR) is needed in order to devise better surgical repair techniques. We hypothesized that changes after inferior myocardial infarction would be different in hearts that developed CIMR compared with those that did not.

METHODS AND RESULTS

Twenty-four sheep underwent coronary snare and marker placement (annulus, papillary muscles, and anterior and posterior leaflets). After 8 days, cinefluoroscopy provided 3-dimensional marker data, and snare occlusion of obtuse marginal branches created inferior myocardial infarction, including the posterior papillary muscle. After 7 weeks, the 16 surviving animals were studied again and grouped by mitral regurgitation grade (>or= 2+, n=10 versus <or= 1+, n=6). End-systolic mitral annulus dimensions, components of papillary muscle and leaflet displacement, were calculated. After inferior myocardial infarction, total displacement of the posterior papillary muscle from the midseptal annulus ("saddle horn") was greater in CIMR(+) animals: 6.5+/-3.2 versus 3.1+/-2.7 (P=0.02), with the posterior papillary muscle moving more laterally (6.8+/-3.4 versus 2.5+/-3.5 mm, P=0.01). Increase in mitral annular septal-lateral diameter was greater in animals with CIMR (4.9+/-2.7 versus 2.3+/-2.0, P=0.02), and apical displacement of the posterior leaflet (PL) margin was also greater in the CIMR(+) group (1.7+/-1.0 versus 0.3+/-0.5, P=0.01).

CONCLUSIONS

The CIMR(+) group had greater septal-lateral annular dilatation, lateral posterior papillary muscle displacement, and apical PL restriction, indicating that these associated geometric alterations may be important in the pathogenesis of CIMR. Treatment of CIMR should address both annular septal-lateral dilatation and lateral displacement of the posterior papillary muscle.