Anatomic explanation of mobile systolic clicks: implications for the clinical and echocardiographic diagnosis of mitral valve prolapse

Identification of a High-risk Subgroup With Malignant Mitral Valve Prolapse Who Are Predisposed to Sudden Cardiac Death: A Review

Mitral valve prolapse (MVP) affects approximately 170 million people worldwide; however, phenotypically, there is a wide variety of heterogeneity. In particular subsets, the incidence of sudden cardiac death is calculated to be 998 per 100,000 person-years, which is significantly increased when compared with the general population of MVP patients. Individuals with high-risk features have been identified as young females with bileaflet MVP and electrocardiogram findings of frequent complex ectopy, ST-T wave changes, and inferior T wave inversions. Supplemental imaging modalities in this subgroup demonstrate redundant leaflets and chordae on 2-dimensional transthoracic echocardiography along with varying severity of mitral annular disjunction. Detailed morphologic assessment by 3-dimensional echocardiography provides a quantitative assessment of annular disjunction along with left ventricular longitudinal and basal circumferential strain patterns. Late gadolinium enhancement on cardiac magnetic resonance imaging identifies diffuse and isolated left ventricle fibrosis involving the fascicles and papillary muscles, which has been visualized in isolation during autopsy. Findings of this review propose that sudden cardiac death as a result of malignant arrhythmias arises from automaticity, complex ectopy, and reentry at the level of the fascicles and papillary muscles. The repetitive mechanical stress provides a nidus for the development of both micro- and macrofibrosis easily identified by late gadolinium enhancement on cardiac magnetic resonance imaging. Escalation to electrophysiology studies and early intervention could provide new targeted lifesaving therapies.

Morphofunctional Abnormalities of Mitral Annulus and Arrhythmic Mitral Valve Prolapse

Supplemental Digital Content is available in the text.

Background—

Arrhythmic mitral valve prolapse (MVP) is characterized by myxomatous leaflets and left ventricular (LV) fibrosis of papillary muscles and inferobasal wall. We searched for morphofunctional abnormalities of the mitral valve that could explain a regional mechanical myocardial stretch.

Methods and Results—

Thirty-six (27 female patients; median age: 44 years) arrhythmic MVP patients with LV late gadolinium enhancement on cardiac magnetic resonance and no or trivial mitral regurgitation, and 16 (6 female patients; median age: 40 years) MVP patients without LV late gadolinium enhancement were investigated by morphofunctional cardiac magnetic resonance. Mitral annulus disjunction (median: 4.8 versus 1.8 mm; P<0.001), end-systolic mitral annular diameters (median: 41.2 versus 31.5; P=0.004) and end-diastolic mitral annular diameters (median: 35.5 versus 31.5; P=0.042), prevalence of posterior systolic curling (34 [94%] versus 3 [19%]; P<0.001), and basal to mid LV wall thickness ratio >1.5 (22 [61%] versus 4 [25%]; P=0.016) were higher in MVP patients with late gadolinium enhancement than in those without. A linear correlation was found between mitral annulus disjunction and curling (R=0.85). A higher prevalence of auscultatory midsystolic click (26 [72%] versus 6 [38%]; P=0.018) was also noted. Histology of the mitral annulus showed a longer mitral annulus disjunction in 50 sudden death patients with MVP and LV fibrosis than in 20 patients without MVP (median: 3 versus 1.5 mm; P<0.001).

Conclusions—

Mitral annulus disjunction is a constant feature of arrhythmic MVP with LV fibrosis. The excessive mobility of the leaflets caused by posterior systolic curling accounts for a mechanical stretch of the inferobasal wall and papillary muscles, eventually leading to myocardial hypertrophy and scarring. These mitral annulus abnormalities, together with auscultatory midsystolic click, may identify MVP patients who would need arrhythmic risk stratification.

The mechanisms, diagnosis and management of mitral regurgitation in mitral valve prolapse and hypertrophic cardiomyopathy

Valvular disease is a frequent cardiac pathology leading to heart failure and, ultimately, death. Mitral regurgitation, defined as the inability of the two mitral leaflets to coapt, is a common valvular disease and a self sustained pathology. A better understanding of the mitral valve histological layers provides a better understanding of the leaflet and chordae changes in mitral valve prolapse. Mitral valve prolapse may occur in myxomatous degenerative abnormalities, connective tissue disorders or in sporadic isolated cases. It is the most common mitral abnormality of non-ischemic cause leading to severe surgery-requiring mitral regurgitation. In addition to standard echocardiographic investigations, newly implemented three-dimensional techniques are being used and they permit a better visualisation, from the so-called ‘surgical view’, and an improved evaluation of the mitral valve. Hypertrophic cardiomyopathy is the most frequent inherited myocardial disease caused by mutations in various genes encoding proteins of the cardiac sarcomere, leading to a marked left ventricular hypertrophy unexplained by other comorbidities. The pathological echocardiographic hallmarks of hypertrophic cardiomyopathy are left ventricular hypertrophy, left ventricular outflow tract obstruction and systolic anterior motion of the mitral valve. The systolic anterior motion of the mitral valve contributes to the development of mitral regurgitation and further narrows the left ventricular outflow tract, leading to more severe symptomatology. Cardiac magnetic resonance imaging accurately measures the left ventricular mass, the degree of diastolic function and it may also be used to distinguish phenotypic variants. The clinical outcome of patients with these pathologies is mostly determined by the selected option of treatment. The purpose of surgical correction regarding mitral valve involvement is to restore valvular competence. Surgery has proven to be the only useful treatment in preventing heart failure, improving symptomatology and reducing mortality. Our approach wishes to enhance the understanding of the mitral valve’s involvement in hypertrophic cardiomyopathy and mitral valve prolapse from genetic, haemodynamic and clinical perspectives, as well as to present novelties in the grand field of treatment.

Diastolic Function Evaluations by Tissue Doppler Imaging in Patients With Mitral Valve Prolapse

Background

Tissue Doppler imaging (TDI) is a new echocardiographic imaging technique that is believed to be superior to older conventional techniques in assessing abnormalities of cardiac function in many conditions affecting the heart. There are very limited data regarding the role of TDI in evaluating patients with mitral valve prolapse (MVP). Current study evaluates diastolic function in patients with MVP by this method.

Methods

From November 2009 to April 2011, one hundred and ten adults matched for age and sex and without structural heart disease were studied in two groups, with and without MVP, at Madani Heart Center, Tabriz, Iran. TDI was performed at the basal-lateral wall and S, E, E’, A, and A’ velocities, as well as the E/A and E’/A’ ratios were measured. Mitral annular systolic velocity and early diastolic (E’) velocities were measured lateral corner of mitral valve in apical 4-chamber view.

Results

Patients with MVP had higher left atrium volume (42.31 ± 10.47 vs. 35.19 ± 9.15 cm3; P < 0.001) and deceleration time (186.70 ± 26.00 vs. 176.89 ± 20.36 ms; P = 0.03). Diastolic dysfunction, although seemed more prevalent in MVP group (14.54%) than normal subjects (5.45%), the difference was not statistically significant between groups (P = 0.11).

Conclusion

Left atrial volume and deceleration time of mitral valve inflow was significantly higher in MVP which could be indicative of early stages of diastolic dysfunction in patients with MVP. However, larger follow-up studies are required to evaluate clinical significance of our findings in these patients.

Mitral valve prolapse

Mitral valve prolapse is a common valvular abnormality that is the most common cause of severe non-ischaemic mitral regurgitation in the USA. The overall prognosis of patients with mitral valve prolapse is excellent, but a small subset will develop serious complications, including infective endocarditis, sudden cardiac death, and severe mitral regurgitation. We present a comprehensive review of mitral valve prolapse, examining normal mitral anatomy, the clinical and echocardiographic features of mitral valve prolapse, and the pathophysiology and genetics of the disorder. We discuss the contemporary management of both asymptomatic and symptomatic prolapse, with particular attention to the timing and technique of surgical repair. We conclude that echocardiography is the method of choice for diagnosing mitral valve prolapse, that clinical and echocardiographic features can predict which patients with prolapse are at highest risk for complications, and that mitral valve repair is the treatment of choice for symptomatic prolapse.

Three-dimensional echocardiography of intracardiac masses

We describe two cases in which three-dimensional echocardiography provided unique anatomical data. This information enhanced the diagnostic power of two-dimensional echocardiography by improving confidence in interpretation and by providing distinctive spatial insights.