Cutting second-order mitral chordae in sheep caused global left ventricular dysfunction, significantly decreasing end-systolic elastance (0.98 vs 1.48 mm Hg/mL, P=0.04).
Does cutting second-order mitral chordae alter LV geometry and systolic function in a sheep model?
Cutting second-order mitral chordae causes global LV systolic dysfunction and alters LV geometry and local strain patterns, highlighting their importance for maintaining LV structure and function.
Absolute Event Rate: 0.98% vs 1.48%
p-value: p=0.04
BACKGROUND: 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. METHODS AND RESULTS: 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<0.05). Locally, subendocardial end-diastolic strains occurred: Longitudinal strain (E22) 0.030+/-0.013 and radial thickening (E33) 0.081+/-0.041 (both P<0.05 versus zero). Subendocardial systolic shear strains were also perturbed: Circumferential-longitudinal "micro-torsion" (E12) (0.099+/-0.035 versus 0.075+/-0.025) and circumferential radial shear (E13) (0.084+/-0.023 versus 0.039+/-0.008, both P<0.05). CONCLUSIONS: Cutting second-order chords altered LV geometry, remodeled the myocardium between the PMs, perturbed local systolic strain patterns affecting micro-torsion and wall-thickening, and caused global systolic dysfunction, demonstrating the importance of these chordae for LV structure and function.
Rodriguez et al. (Mon,) conducted a other in Left ventricular systolic function and mitral valvular-ventricular continuity (n=8). Cutting second-order "strut" chordae vs. Before chordal cutting (baseline) was evaluated on Global LV systolic function assessed by end-systolic elastance (E(es)) and preload recruitable stroke work (PRSW) (p=0.04). Cutting second-order mitral chordae in sheep caused global left ventricular dysfunction, significantly decreasing end-systolic elastance (0.98 vs 1.48 mm Hg/mL, P=0.04).
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