Contribution of mitral annular excursion and shape dynamics to total left ventricular volume change

Abstract

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 Ϯ 11 (means Ϯ 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-Dϩtime) 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 Ϯ 2 ml) represented 19 Ϯ 3% of the total LV stroke volume (52 Ϯ 12 ml). The AEV correlated strongly with LV stroke volume (r ϭ 0.73; P Ͻ 0.05). Peak MA area occurred during middiastole, and 91 Ϯ 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 THE MITRAL ANNULUS (MA) is a discontinuous fibrous ring and an essential component of the mitral valve/left atrial/left ventricular (LV) complex. It contributes to efficient valve closure as well as unimpeded LV filling (14,19,28,29). Many studies support the concept that the motion of the MA is dynamic throughout the cardiac cycle, yet the timing and extent of annular motion and shape variation remain incompletely understood (28,29). Assessment of the MA physiology has been important to the understanding of disorders of the mitral valve apparatus and LV dysfunction. The mechanisms of functional valve regurgitation in the setting of dilated cardiomyopathy and in the design of annuloplasty ring prostheses for valve repair (15,24,27) are two of many areas where MA physiology is a key issue.

Longitudinal Myocardial Contribution to Peak Systolic Flow and Stroke Volume in the Neonatal Heart

“…The link between D and SV is well known, but some controversies regarding absolute contribution exist (7)(8)(9)(10). In this study, the longitudinal contribution to PSF and SV was relative stable through both pharmacological and HR modulation and during modulation of the loading state of the ventricle.…”

Abnormalities of left ventricular long-axis function predict the onset of hypertension independent of blood pressure: a 7-year prospective study

“…Mitral annular excursion, which is due mainly to the contraction of the subendocardial layer of longitudinal fibers, accounts for approximately 19% of the total LV volume change in filling or emptying. 15,16 M-mode determined MAVPD evaluates the systolic function of the LV long-axis, is highly reproducible and simple to perform, 12 and correlates with LV ejection fraction. [17][18][19] Longitudinal systolic function assessed by M-mode echocardiography is decreased in hypertensives with left ventricular hypertrophy, whereas alterations in long-axis contraction occur early in HTN as assessed by tissue Doppler analysis.…”

The clinical anatomy of the mitral valve

“…Mitral annulus excursion toward the apex can be better evaluated by using the two-dimensional strain imaging technique (Hayashi et al, 2006). Mitral annular excursion (annular excursion volume) strongly correlates with left ventricular stroke volume (Carlhall et al, 2004). The rotation represents the torque movement while the complex three-dimensional modifications in shape are called folding of the annulus.…”