Accessory mitral valve tissue: an unusual cause of congenital mitral stenosis

Right Ventricular Outflow Tract Obstruction in Adults: A Systematic Review and Meta-analysis

Background

Right ventricular outflow tract obstruction (RVOTO) is a cause of hemodynamic instability that can occur in several situations, including cardiac surgery, lung transplantation, and thoracic surgery, and in critically ill patients. The timely diagnosis of RVOTO is important because it requires specific considerations, including the adverse effects of positive inotropes, and depending on the etiology, the requirement for urgent surgical intervention.

Methods

The objective of this systematic review and meta-analysis was to determine the prevalence of RVOTO in adult patients, and the distribution of all reported cases by etiology.

Results

Of 233 available reports, there were 229 case reports or series, and 4 retrospective cohort studies, with one study also reporting a prospective cohort. Of 291 reported cases of RVOTO, 61 (21%) were congenital, 56 (19%) were iatrogenic, and 174 (60%) were neither congenital nor iatrogenic (including intracardiac tumour). The mechanism of RVOTO was an intrinsic obstruction in 169 cases (58%), and an extrinsic obstruction in 122 cases (42%). A mechanical obstruction causing RVOTO was present in 262 cases (90%), and 29 cases of dynamic RVOTO (10%) were reported. In the 5 included cohorts, with a total of 1122 patients, the overall prevalence was estimated to be 4.0% (1%-9%).

Conclusions

RVOTO, though rare, remains clinically important, and therefore, multicentre studies are warranted to better understand the prevalence, causes, and consequences of RVOTO.

Accessory mitral valve tissue: anatomical and clinical perspectives

Mitral valve is a complex cardiac structure composed of several components to work in synchrony to allow blood flow into left ventricle during diastole and not to allow blood flow into left atrium during systole. Accessory mitral valve tissue (AMVT) was defined as existence of any additional part and parcel of valvular structure which has an attachment to normal mitral valve apparatus in left-sided cardiac chambers. AMVT may present itself in different clinical circumstances ranging from a silent clinical course to thromboembolic events, heart failure, left ventricular outflow tract obstruction, and severe arrhythmia. This article reviews the clinical perspectives of AMVT in terms of symptoms, diagnosis, and treatment, providing a new anatomical classification regarding the location of AMVT. Briefly type I refers to AMVT having attachments on the supra leaflets level, type II refers to attachments on the mitral leaflets, and type III refers to attachment below the mitral leaflets. Increased awareness and widespread use of echocardiographic techniques would increase recognition of AMVT in patients with heart murmurs but otherwise healthy and in those with left ventricular outflow tract obstruction or tissue which causes subaortic stenosis and with unexplained cerebrovascular events.

An Extremely Rare Cause of Mitral Regurgitation-Accessory Commissural Mitral Tissue with Anomalous Left Atrial Chordal Attachment

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Accessory mitral tissue and left atrial chordae are rare congenital abnormalities.

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Accessory mitral tissue can result in left ventricular outflow tract and mitral valve obstruction.

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This is the first case of lateral mitral accessory tissue with an associate anomalous chord.

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Transthoracic echocardiography may not be able to evaluate accessory mitral valve tissue.

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Removal of anomalous chordae affecting the mitral valve may be complicated.

Comparison of Modified With Classic Morrow Septal Myectomy in Treating Hypertrophic Obstructive Cardiomyopathy

This study aimed to compare the efficacy and safety of the classic Morrow septal myectomy with the modified procedure in treating hypertrophic obstructive cardiomyopathy (HOCM).A retrospective study was conducted to compare the outcomes of classic with modified Morrow septal myectomy in 42 patients treated from January 2005 to July 2011. Preoperative and postoperative ventricular septal thickness, left ventricular (LV) outflow tract velocity and gradient were measured echocardiographically.In both groups, the ventricular septal thickness, LV outflow tract velocity, and LV outflow tract gradient were significantly decreased after the operation. The modified Morrow procedure group, however, showed significantly greater reduction in these echocardiographic parameters than the classic procedure group. All patients in the modified procedure group were asymptomatic postoperatively with a postoperative transvalvular pressure gradient <30 mm Hg. In the classic procedure group, only 14 (87.5%) patients, however, were asymptomatic postoperatively with a postoperative transvalvular pressure gradient <30 mm Hg, and 2 patients still had severe LV outflow obstruction postoperatively.The modified Morrow septal myectomy is safe and effective in treating HOCM patients, and is superior to the classic procedure in reducing the LV outflow tract gradient and velocity, restoring normal anatomic atrioventricular size, and alleviating symptoms associated with HOCM.

Accessory mitral valve tissue: an updated review of the literature

Accessory mitral valve tissue (AMVT) is a rare congenital cardiac anomaly sometimes responsible for left ventricular outflow tract (LVOT) obstruction. It is diagnosed during both neonate-childhood and adult periods in patients usually symptomatic for dyspnoea, chest pain, palpitations, fatigue, or syncope. Nevertheless, AMVT is often an incidental finding. AMVT is most often associated with other cardiac and vascular congenital malformations, such as septal defects and transposition of the great arteries. Surgery is indicated only in cases of significant LVOT obstruction and in patients undergoing correction of other cardiac malformations or exploration of an intracardiac mass. Two-dimensional echocardiography, both transthoracic and transoesophageal, is considered the main imaging modality for AMVT diagnosis and patient follow-up. The recent introduction of three-dimensional echocardiography allows a more realistic characterization of this entity. We present three clinical cases in which AMVT was incidentally diagnosed during standard echocardiography and an updated review of the literature highlighting the usefulness of echocardiography for AMVT morphological and functional characterization as well as the most relevant clinical implications due to its discovery.