Importance of mitral valve second-order chordae for left ventricular geometry, wall thickening mechanics, and global systolic function

• Published in: Circulation (New York, N.Y.) N.Y.), 2004-09, Vol.110 (11), p.115-122
• Main Authors: RODRIGUEZ, Filiberto, LANGER, Frank, INGELS, Neil B, MILLER, D. Craig, HARRINGTON, Katherine B, TIBAYAN, Frederick A, ZASIO, Mary K, CHENG, Allen, LIANG, David, DAUGHTERS, George T, COVELL, James W, CRISCIONE, John C
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Biomechanical Phenomena; Blood and lymphatic vessels; Cardiology. Vascular system; Cardiovascular system; Chordae Tendineae - physiology; Chordae Tendineae - surgery; Diseases of the peripheral vessels. Diseases of the vena cava. Miscellaneous; Heart Rate; Heart Ventricles - diagnostic imaging; Heart Ventricles - physiopathology; Heart Ventricles - ultrastructure; Hemodynamics; Imaging, Three-Dimensional; Investigative techniques of hemodynamics; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Mitral Valve - diagnostic imaging; Mitral Valve - ultrastructure; Orthopedic surgery; Radiography; Sheep; Stress, Mechanical; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Systole - physiology; Torsion Abnormality; Ventricular Dysfunction, Left - etiology; Ventricular Dysfunction, Left - physiopathology; Ventricular Function, Left - physiology
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/01.cir.0000138580.57971.b4

Mitral valvular-ventricular continuity is important for left ventricular (LV) systolic function, but the specific contributions of the anterior leaflet second-order "strut" chordae are unknown. Eight sheep had radiopaque markers implanted to silhouette the LV, annulus, and papillary muscles (PMs); 3 transmural bead columns were inserted into the mid-lateral wall between the PMs. The strut chordae were encircled with exteriorized wire snares. Three-dimensional marker images and hemodynamic data were acquired before and after chordal cutting. Preload recruitable stroke work (PRSW) and end-systolic elastance (E(es)) were calculated to assess global LV systolic function (n=7). Transmural strains were measured from bead displacements (n=4). Chordal cutting caused global LV dysfunction: E(es) (1.48+/-1.12 versus 0.98+/-1.30 mm Hg/mL, P=0.04) and PRSW (69+/-16 versus 60+/-15 mm Hg, P=0.03) decreased. Although heart rate and time from ED to ES were unchanged, time of mid-ejection was delayed (125+/-18 versus 136+/-19 ms, P=0.01). Globally, the LV apex and posterior PM tip were displaced away from the fibrous annulus and LV base-apex length increased at end-diastole and end-systole (all +1 mm, P