Subaortic Stenosis Produced by an Accessory Mitral Valve: The Role of Echocardiography

Abstract

Subaortic stenosis caused by an accessory mitral valve is an exceedingly rare finding. We report the case of an asymptomatic 14-year-old patient, in whom transthoracic echocardiography revealed an accessory mitral valve in the left ventricular outflow tract, producing mild subaortic stenosis. Except for an aneurysm of the interventricular septum, with no shunt, there were no other anomalies. Transesophageal echocardiography provided details about the morphology and location of the accessory valve. Being asymptomatic and having only a mild gradient, antibiotic prophylaxis for infective endocarditis and follow-up were recommended. After 2 years the patient is asymptomatic, with a similar echocardiographic gradient.

Accessory Mitral Valve Tissue Causing Severe Left Ventricular Outflow Tract Obstruction in a Post-Senning Patient with Transposition of the Great Arteries

“…5 In the majority of cases there is severe LVOT obstruction, with a median LVOT gradient of more than 50 mmHg. 2,6 Other types of left ventricular mass, like tumors or vegetations, can produce similar findings on echocardiography. However, these lesions more often originate from cardiac muscle (tumors), or build-up on the low-pressure side of a heart valve (vegetations), 3 and do not have a leaflet-like appearance.…”

Accessory mitral valve without subaortic obstruction of left ventricular outflow tract in a middle-aged male

“…Owing to the existence of other types of left ventricular masses such as tumours (myxomas and papillary fibroelastomas) or vegetations that can produce similar echocardiographic appearances, AMV should be considered in the differential diagnosis of a cardiac mass 3 4 8. Echocardiography especially TEE, is a valuable diagnostic tool for recognising the nature, morphology and attachment point of a mass in the LVOT in a patient with an asymptomatic murmur 3 4 8 9.…”

“…Echocardiography especially TEE, is a valuable diagnostic tool for recognising the nature, morphology and attachment point of a mass in the LVOT in a patient with an asymptomatic murmur 3 4 8 9. It provides us with significant information to make diagnosis without the use of an invasive approach such as cardiac catheterisation 4.…”

“…It provides us with significant information to make diagnosis without the use of an invasive approach such as cardiac catheterisation 4. During the past decade, the number of reports of AMV has significantly increased as a result of the availability of echocardiography 3 4 8. In addition to amiodarone prophylaxis for recurrent episodes of ventricular tachycardia, we recommended a conservative approach including periodic echocardiographic follow-up for early identification of any changes that might warrant surgery.…”

Dynamic mild subaortic left ventricular obstruction caused by an accessory mitral valve attached to the anterior mitral valve in a young pregnant woman

“…In conclusion in patients without rest and only an exertional mild LVOTO and no other cardiac malformations, prophylactic removal of mitral accessory tissue excision is not required; antibiotic prophylaxis for endocarditis can be indicated 6 and a regular follow up is recommended to identify any progression in LVOTO entity. …”