Changes in left ventricular twist after mitral valve repair

Speckle tracking echocardiography for evaluation of myocardial functions before and after mitral valvuloplasty in dogs

Background

Myxomatous mitral valve disease (MMVD) is the most common acquired heart disease in dogs. Mitral valvuloplasty (MVP) addresses regurgitation, but the pre- and postoperative changes in myocardial function remain uncertain.

Objectives

This study evaluated myocardial motion before and after MVP using two-dimensional speckle-tracking echocardiography (2D-STE).

Animals

Eight client-owned dogs undergoing MVP for MMVD.

Methods

Myocardial deformation was assessed by 2D-STE before surgery and at 1- and 3-months post-surgery. Measurements included left ventricular global longitudinal strain (GLS), global circumferential strain (GCS), global radial strain (GRS), cardiac twist, and right ventricular free wall GLS (RVFW-GLS).

Results

Postoperative decreases were observed in left ventricular internal dimensions, left atrial size, and early diastolic myocardial velocity, with an increase in peak late diastolic velocity. LV-GLS decreased at 1 month (-14.4%) and 3 months (-16.3%) compared to preoperative values (-24.4%) (p = 0.0078, p = 0.015). GCS decreased at 1 month (-12.9%) and 3 months (-14.8%) compared to preoperative values (-21.7%) (p = 0.0078). GRS decreased at 1 month (27.7%) and 3 months (32.0%) compared to preoperative values (67.7%) (p = 0.0078). No significant changes were observed in RVFW-GLS. Peak systolic twist increased at 3 months (9.1° vs. 4.9°, p = 0.039). Peak systolic apical rotation showed an upward trend at 3 months (p = 0.109). Left ventricular twist was mildly affected by LVIDd, LVIDDN, and sphericity index (R 2 = 0.187, p = 0.034; R 2 = 0.33, p = 0.0029; R 2 = 0.22, p = 0.019).

Conclusions and clinical importance

Postoperative myocardial motion approached reference values, indicating significant improvement, particularly in left ventricular twisting motion. These findings highlight the positive impact of surgery on cardiac function in dogs with MMVD.

Mitral regurgitation severity correlates with symptoms and extent of left atrial dysfunction: Effect of mitral valve repair

PURPOSE

We aimed to assess the relationship between mitral regurgitation (MR) severity, symptoms, and left atrial (LA) structure and function, before and after mitral valve repair (MVR).

METHODS

Global peak atrial longitudinal strain (PALS) was evaluated in 37 patients with severe symptomatic MR and preserved left ventricular (LV) ejection fraction (60.4% ± 4.6%) before and 3 months after MVR and was compared with values from 30 age- and gender-matched controls.

RESULTS

Before surgery, PALS was worse in patients than in controls and indexed LA volume was greater (P < .0001 for both). After MVR, PALS deteriorated further and LA volume decreased (P = .001 and P = .05, respectively) as did LV ejection fraction, longitudinal strain (P = .05 and P < .001, respectively), and LV mass (P < .0001). Before surgery, LA volume correlated modestly with LV end-diastolic volume (R = 0.51; P = .01); effective regurgitant orifice area (EROA) correlated with PALS (R = -0.69, P < .001) and with LV longitudinal strain (R = 0.54, P = .01), and New York Heart Association class correlated with PALS (R = -0.69, P < .001), EROA (R = 0.69, P < .001), and LA volume (R = 0.51, P = .04). LA volume was the strongest predictor of global PALS reduction (P < .001), whereas global PALS was the main predictor of postoperative atrial fibrillation (AF) (P < .001).

CONCLUSIONS

In patients with severe MR, EROA correlate with symptoms and LA PALS, which itself predicts the occurrence of postoperative AF. Strain values were superior to 2D data for the prediction of postoperative AF.

Left ventricular twist mechanics in the context of normal physiology and cardiovascular disease: a review of studies using speckle tracking echocardiography

The anatomy of the adult human left ventricle (LV) is the result of its complex interaction with its environment. From the fetal to the neonatal to the adult form, the human LV undergoes an anatomical transformation that finally results in the most complex of the four cardiac chambers. In its adult form, the human LV consists of two muscular helixes that surround the midventricular circumferential layer of muscle fibers. Contraction of these endocardial and epicardial helixes results in a twisting motion that is thought to minimize the transmural stress of the LV muscle. In the healthy myocardium, the LV twist response to stimuli that alter preload, afterload, or contractility has been described and is deemed relatively consistent and predictable. Conversely, the LV twist response in patient populations appears to be a little more variable and less predictable, yet it has revealed important insight into the effect of cardiovascular disease on LV mechanical function. This review discusses important methodological aspects of assessing LV twist and evaluates the LV twist responses to the main physiological and pathophysiological states. It is concluded that correct assessment of LV twist mechanics holds significant potential to advance our understanding of LV function in human health and cardiovascular disease.

Left ventricular twist and shear in patients with primary mitral regurgitation

PURPOSE

To evaluate the relationship between left ventricular (LV) twist, shear, and twist-per-volume and the severity of mitral regurgitation (MR). Primary MR is a valvular disorder that induces LV dysfunction. There exist several measures of LV rotational mechanics, but it remains unclear which measure of LV dysfunction best accords with the severity of MR. We hypothesized that LV systolic twist-per-volume slope would decrease with increasing severity of MR because of both decreases in rotational mechanics and increases in stroke volumes.

MATERIALS AND METHODS

Normal subjects (n = 54), moderate MR patients (n = 29), and severe MR patients (n = 54) were studied. Magnetic resonance imaging (MRI) was performed on a 1.5T scanner and grid-tagged LV images were collected at the LV base and LV apex. Measures of LV rotational mechanics were derived from tagged images using Fourier Analysis of STimulated echoes (FAST).

RESULTS

Peak systolic twist-per-volume slope was significantly different for all pairwise comparisons (P < 0.0001) and compared to normal subjects (-0.14 ± 0.05°/mL) was decreased in moderate MR (-0.12 ± 0.04°/mL) and further decreased in severe MR (-0.07 ± 0.03°/mL).

CONCLUSION

Peak systolic twist-per-volume slope significantly decreased with increasing severity of MR and is therefore a suitable quantitative imaging biomarker for LV dysfunction in patients with MR.