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Mitral annular (MA) excursion during diastole encompasses a volume that is part of total left ventricular (LV) filling volume (LVFV). Altered excursion or area variation of the MA due to changes in preload or inotropic state could affect LV filling. We hypothesized that changes in LV preload and inotropic state would not alter the contribution of MA dynamics to LVFV. Six sheep underwent marker implantation in the LV wall and around the MA. After 7-10 days, biplane fluoroscopy was used to obtain three-dimensional marker dynamics from sedated, closed-chest animals during control conditions, inotropic augmentation with calcium (Ca), preload reduction with nitroprusside (N), and vena caval occlusion (VCO). The contribution of MA dynamics to total LVFV was assessed using volume estimates based on multiple tetrahedra defined by the three-dimensional marker positions. Neither the absolute nor the relative contribution of MA dynamics to LVFV changed with Ca or N, although MA area decreased (Ca, P < 0.01; and N, P < 0.05) and excursion increased (Ca, P < 0.01). During VCO, the absolute contribution of MA dynamics to LVFV decreased (P < 0.001), based on a reduction in both area (P < 0.001) and excursion (P < 0.01), but the relative contribution to LVFV increased from 18 [+ or -] 4 to 45 [+ or -] 13% (P < 0.001). Thus MA dynamics contribute substantially to LV diastolic filling. Although MA excursion and mean area change with moderate preload reduction and inotropic augmentation, the contribution of MA dynamics to total LVFV is constant with sizeable magnitude. With marked preload reduction (VCO), the contribution of MA dynamics to LVFV becomes even more important. diastolic function; inotropic augmentation; mitral annular excursion; preload reduction; regional left ventricular filling properties

Contribution of mitral annular excursion and shape dynamics to total left ventricular volume change. Am J Physiol Heart Circ Physiol 287: H1836-H1841, 2004. First published June 17, 2004; 10.1152/ajpheart.00103.2004.--The mitral annulus (MA) has a complex shape and motion, and its excursion has been correlated to left ventricular (LV) function. During the cardiac cycle the annulus' excursion encompasses a volume that is part of the total LV volume change during both filling and emptying. Our objective was to evaluate the contribution of MA excursion and shape variation to total LV volume change. Nine healthy subjects aged 56 [+ or -] 11 (means [+ or -] SD) years underwent transesophageal echocardiography (TEE). The MA was outlined in all time frames, and a four-dimensional (4-D) Fourier series was fitted to the MA coordinates (3-D + time) and divided into segments. The annular excursion volume (AEV) was calculated based on the temporally integrated product of the segments' area and their incremental excursion. The 3-D LV volumes were calculated by tracing the endocardial border in six coaxial planes. The AEV (10 [+ or -] 2 ml) represented 19 [+ or -] 3% of the total LV stroke volume (52 [+ or -] 12 ml). The AEV correlated strongly with LV stroke volume (r = 0.73: P < 0.05). Peak MA area occurred during middiastole, and 91 [+ or -] 7% of reduction in area from peak to minimum occurred before the onset of LV systole. The excursion of the MA accounts for an important portion of the total LV filling and emptying in humans. These data suggest an atriogenic influence on MA physiology and also a sphincter-like action of the MA that may facilitate ventricular filling and aid competent valve closure. This 4-D TEE method is the first to allow noninvasive measurement of AEV and may be used to investigate the impact of physiological and pathological conditions on this important aspect of LV performance. annular physiology; ventricular long-axis function; echocardiography; three dimension; four dimension

Rapid early diastolic left ventricular (LV) filling requires a highly compliant chamber immediately after systole, allowing inflow at low driving pressures. The transmural LV deformations associated with such filling are not completely understood. We sought to characterize regional transmural LV strains during diastole, with focus on early filling, in ovine hearts at 1 week and 8 weeks after myocardial marker implantation. In seven normal sheep hearts, 13 radiopaque markers were inserted to silhouette the LV chamber and a transmural beadset was implanted into the lateral equatorial LV wall to measure transmural strains. Four-dimensional marker dynamics were obtained 1 week and 8 weeks thereafter with biplane videofluoroscopy in closed-chest, anesthetized animals. LV transmural strains in both cardiac and fiber-sheet coordinates were studied from filling onset to the end of early filling (EOEF, 100 ms after filling onset) and at end diastole. At the 8 week study, subepicardial circumferential strain ([E.sub.CC]) had reached its final value already at EOEF, while longitudinal and radial strains were nearly zero at this time. Subepicardial [E.sub.CC] and fiber relengthening ([E.sub.ff]) at EOEF were reduced to 1 compared with 8 weeks after surgery ([E.sub.CC]:0.02 [+ or -] 0.01 to 0.08 [+ or -] 0.02 and [E.sub.ff]:0.00 [+ or -] 0.01 to 0.03 +-0.01, respectively, both P Keywords: diastolic strain, early filling, myocardial mechanics, postoperative period, transmural heterogeneity