Surgical Management for Systolic Anterior Motion (SAM) of the Mitral Valve in Obstructive Hypertrophic Myopathy

The Spectrum of Mitral Regurgitation in Lung Transplant Recipients: A Systematic Review

Mitral regurgitation (MR) in lung transplant (LTx) recipients is a rare but complex cardiopulmonary phenomenon. The overlap between symptoms of MR and post-LTx complications, such as primary graft dysfunction, complicates its diagnosis and management. This systematic review aims to characterize the incidence, pathophysiology, presentation, and management of MR in LTx patients. We conducted a literature search in PubMed, Web of Science, Scopus, and Embase. The search yielded 133 studies, of which 11 were included. Data regarding MR development, clinical presentation, echocardiographic findings, and management strategies were extracted and analyzed. Perioperative MR, occurring during or immediately post-LTx, was frequently attributed to the systolic anterior motion of the mitral valve (MV) occurring in the setting of hypovolemia and/or inotrope usage. Later postoperative MR, on the other hand, was associated with reverse ventricular remodeling and mitral annular dilation, although some variability in the literature was present. Preexisting MR or ventricular dysfunction, elongated MV leaflets, and bilateral LTx procedure appeared to be risk factors for MR development. Management was dependent on the timing of MR and its pathophysiology, where systolic anterior motion-related MR was treated with medical therapy, whereas postoperative MR often required MV interventions. In conclusion, the diagnosis of MR in LTx patients is complicated by its symptomatic overlap with other post-LTx complications. Echocardiographic monitoring in patients with preexisting MR, regardless of severity, is essential for early identification and management. Further research is needed to better understand the underlying mechanisms and refine management strategies for MR in this population.

Feasibility of 4D-flow CMR for haemodynamic characterization in hypertrophic cardiomyopathy after septal myectomy with and without anterior mitral valve leaflet extension

OBJECTIVES

The common surgical treatment in patients with obstructive hypertrophic cardiomyopathy is septal myectomy. This involves resection of a segment of the myocardial septum and can be performed with and without concomitant anterior mitral valve leaflet extension (AMVLE). While both approaches have satisfying clinical outcomes, there is a lack of data regarding the added value of concomitant AMVLE. In particular, their impact on postoperative haemodynamics remains unexplored. Therefore, we conducted a study to assess the feasibility of utilizing four-dimensional-flow cardiac magnetic resonance imaging (4D-flow cardiac magnetic resonance imaging (CMR)) to investigate postoperative haemodynamic differences among both surgical approaches.

METHODS

In this feasibility study, nine subjects underwent 4D-flow CMR evaluation, including three patients who underwent isolated myectomy, three patients with myectomy + AMVLE and three healthy controls. Primary end-points were aortic wall shear stress, left ventricular outflow tract (LVOT) peak velocity and peak kinetic energy in the LVOT and ascending aorta.

RESULTS

Results showed that patients who underwent myectomy with concomitant AMVLE exhibited (i) lower aortic wall shear stress (-21.2%), (ii) lower LVOT peak velocity (-6.3%), (iii) higher kinetic energy in the LVOT (+10.8%) and (iv) lower kinetic energy in the ascending aorta (-28.8%) compared to patients who underwent isolated myectomy.

CONCLUSIONS

Patients undergoing additional AMVLE exhibited a better trend towards the haemodynamic reference values from healthy controls compared to patients undergoing isolated myectomy. Our findings underscore the feasibility of 4D-flow CMR to assess postoperative haemodynamic differences in hypertrophic cardiomyopathy patients undergoing different surgical approaches. This highlights the potential of 4D-flow CMR to compare surgical strategies based on postoperative haemodynamics.

CLINICAL REGISTRATION NUMBER

Dutch National Medical Ethics Committee, registration number 2022.0078.

Posterior Papillary Muscle Suspension for Treating Systolic Anterior Motion in Hypertrophic Obstructive Cardiomyopathy

Systolic anterior motion of the anterior mitral leaflet can persist after ventricular septal myectomy for obstructive hypertrophic cardiomyopathy, resulting in residual pressure gradients and mitral regurgitation. However, additional procedures for systolic anterior motion involving mitral valve leaflet suturing and resection may lead to future valve disease. Therefore, we adopted posterior papillary muscle suspension, a subvalvular procedure for functional mitral regurgitation, to treat systolic anterior motion without directly intervening in the mitral valve leaflets. Papillary muscle suspension toward the posterior mitral annulus moved the papillary muscles away from the interventricular septum and successfully eliminated the systolic anterior motion and midventricular pressure gradient. In terms of avoiding direct mitral interventions, this procedure is a viable option for systolic anterior motion, especially in cases of very mild mitral regurgitation.

Mitral Valve Prolapse in Obstructive Hypertrophic Cardiomyopathy

Obstructive hypertrophic cardiomyopathy (oHCM) and mitral valve (MV) prolapse (MVP) are the 2 conditions which could cause symptomatic heart failure and sudden cardiac death. The clinical characteristics and surgical outcomes of patients with oHCM and MVP have not been well reported. From April 2012 to February 2018, 84 patients with oHCM (28 patients with MVP and 56 gender- and age-matched patients without MVP) who underwent septal myectomy at our institution were enrolled in this study. Information on clinical characteristics and outcomes was obtained from electronic medical records and follow-up surveys. Compared with those without MVP, patients with MVP were more symptomatic (New York Heart Association class III to IV; 96% vs 77%), more often moderate-to-severe mitral regurgitation (86% vs 48%), atrial fibrillation (39% vs 11%) and higher incidence of nonsustained ventricular tachycardia (44% vs 15%). Twenty (71%) had MV repair and 8 (29%) had MV replacement. Compared with patients without MVP, those with MVP had a longer postoperative hospital stay (10.9 ± 6.4 vs 7.8 ± 2.8 days). None of the 84 study patients died during hospital or follow-up. At the most recent echocardiographic evaluation, left ventricular outflow tract gradient significantly decreased from 69.7 ± 35.4 millimeters of mercury to 7.3 ± 5.1 millimeters of mercury and the degree of mitral valve regurgitation improved from grade 2.43 ± 0.69 to grade 0.5 ± 0.69. In conclusion, MVP occurs rarely in oHCM, and was related to atrial fibrillation, ventricular arrhythmia and mitral regurgitation. Mitral valve surgery in combination with myectomy is effective and safe for patients with oHCM and MVP, relieving substantially left ventricular outflow tract gradients and mitral regurgitation.

Mitral Valve in Obstructive Hypertrophic Cardiomyopathy: Abnormalities, Management and Controversies

Obstructive hypertrophic cardiomyopathy (obstructive HCM) is a hereditary disease characterized by septal hypertrophy and dynamic left ventricular outflow tract (LVOT) obstruction. Other than septal hypertrophy, mitral valve abnormalities are also quite common in patients with obstructive HCM, which may contribute to systolic anterior motion (SAM) of the mitral valve and LVOT obstruction. Surgical myectomy is the standard treatment to achieve anatomic correction of obstructive HCM, but controversies remain on whether and how the mitral valve procedures should be performed at the same time. In this review, we first described the mitral valve abnormalities in patients with obstructive HCM and their surgical corrections, we then explained the controversies based on current clinical studies, and we finally made a brief introduction on our surgical strategy and results.