Possible mechanism of late systolic mitral valve prolapse: systolic superior shift of leaflets secondary to annular dilatation that causes papillary muscle traction

Abstract

Progressive superior shift of the mitral valve (MV) during systole is associated with abnormal papillary muscle (PM) superior shift in late systolic MV prolapse (MVP). The causal relation of these superior shifts remains unclarified. We hypothesized that the MV superior shift is related to augmented MV superiorly pushing force by systolic left ventricular pressure due to MV annular dilatation, which can be corrected by surgical MV plasty, leading to postoperative disappearance of these superior shifts. In 35 controls, 28 patients with holosystolic MVP, and 28 patients with late systolic MVP, the MV coaptation depth from the MV annulus was measured at early and late systole by two-dimensional echocardiography. The PM tip superior shift was monitored by echocardiographic speckle tracking. MV superiorly pushing force was obtained as MV annular area × (systolic blood pressure − 10). Measurements were repeated after MV plasty in 14 patients with late systolic MVP. Compared with controls and patients with holosystolic MVP, MV and PM superior shifts and MV superiorly pushing force were greater in patients with late systolic MVP [1.3 (0.5) vs. 0.9 (0.6) vs. 3.9 (1.0) mm/m2, 1.3 (0.5) vs. 1.2 (1.0) vs. 3.3 (1.3) mm/m2, and 487 (90) vs. 606 (167) vs. 742 (177) mmHg·cm2·m−2, respectively, means (SD), P < 0.001]. MV superior shift was correlated with PM superior shift ( P < 0.001), which was further related to augmented MV superiorly pushing force ( P < 0.001). MV and PM superior shift disappeared after surgical MV plasty for late systolic MVP. These data suggest that MV annulus dilatation augmenting MV superiorly pushing force may promote secondary superior shift of the MV (equal to late systolic MVP) that causes subvalvular PM traction in patients with late systolic MVP. NEW & NOTEWORTHY Late systolic mitral valve prolapse (MVP) is associated with mitral valve (MV) and papillary muscle (PM) abnormal superior shifts during systole, but the causal relation remains unclarified. MV and PM superior shifts were correlated with augmented MV superiorly pushing force by annular dilatation and disappeared after surgical MV plasty with annulus size and MV superiorly pushing force reduction. This suggests that MV annulus dilatation may promote secondary superior shifts of the MV (late systolic MVP) that cause subvalvular PM traction.

Relations of Augmented Systolic Annular Expansion and Leaflet/Papillary Muscle Dynamics in Late-Systolic Mitral Valve Prolapse Evaluated by Echocardiography with a Speckle Tracking Analysis

“…A previous in- vestigation on late-systolic MVP has demonstrated that a systolic LV-LA pressure gradient on larger MV leaflets/ annulus can cause greater MV superiorly pushing force ( Figure 5), shifting MV leaflets superiorly, which secondarily tract PMs to shift superiorly. 6) Secondary PM traction has been confirmed by the disappearance of PM superior shift following surgical MV annuloplasty to reduce the MV annular area and MV superiorly pushing force. 6) Such abnormal pathophysiology does not develop in patients with holo-systolic MVP and only modest MV annular dilatation.…”

“…6) Secondary PM traction has been confirmed by the disappearance of PM superior shift following surgical MV annuloplasty to reduce the MV annular area and MV superiorly pushing force. 6) Such abnormal pathophysiology does not develop in patients with holo-systolic MVP and only modest MV annular dilatation. Results of the present study along with those of the previous studies suggest that augmented leaflet tissue distensibility, in addition to structurally large MV annulus, suggesting primary tissue fragility and leaflet tissue elongation, may further cause abnormal superior shift of PMs and contribute to systolic MV annular expan-sion in patients with MVP.…”

“…Systolic superior shift of PM tips was evaluated using the echocardiographic speckle tracking analysis, and details were described previously. 6) Briefly, in apical fourand two-chamber views with PM visualization, distances 1) between the PM tip and the fixed external reference point (ERP) around the cardiac apex ( Figure 3A, red points) and 2) between the MV annulus and ERP ( Figure 3A, blue points) were dynamically monitored using a twodimensional echocardiographic speckle tracking analysis in a commercially available software (free strain, Philips) ( Figure 3A-C). Measurements of medial and lateral PMs were averaged.…”

“…Systolic superior shift of PMs has been confirmed. 5,6) Systolic lengthening of MV leaflets has also been observed in patients with late-systolic MVP. 1) However, significant or clear tissue elongation of chordae is not expected because of its highly limited tissue distensi- bility.…”

Isolated Flailed P3 Scallop of the Mitral Valve Leaflet in the Setting of Newly Diagnosed Heart Failure With Preserved Ejection Fraction

“…An echocardiogram is a fundamental study required for the diagnosis of MVP with a flail leaflet and grading of mitral regurgitation (MR) severity [ 2 ]. A systolic billowing of any portion of the mitral leaflets of 2 mm or more above the annular plane in a long-axis view on echocardiogram is diagnostic for MVP [ 3 ]. MVP with a flail leaflet is a common cause of acute or sub-acute severe MR [ 4 ].…”