Barlow's syndrome

Overview

Barlow’s syndrome, also known as mitral valve prolapse (MVP)with redundant valve leaflets, is a condition where the mitral valve in the heart does not close properly. Specifically, one or both leaflets of the mitral valve bulge (prolapse) into the left atrium during systole (heart contraction). First described in detail by Dr. John Barlow in the 1960s, this syndrome is often benign but can be associated with mitral regurgitation, arrhythmias, and in rare cases, serious complications like infective endocarditis or stroke.

Causes

Barlow’s syndrome is caused by structural abnormalities in the mitral valve apparatus, particularly the thickening and redundancy of valve leaflets and elongation of chordae tendineae. The underlying causes may include:

• Genetic predisposition – MVP can run in families and may be part of inherited connective tissue disorders

• Myxomatous degeneration – weakening and thickening of the valve tissue due to excess mucopolysaccharides

• Marfan syndrome and Ehlers-Danlos syndrome – systemic conditions often associated with MVP

Symptoms

Many individuals with Barlow’s syndrome are asymptomatic and diagnosed incidentally. However, when symptoms are present, they may include:

• Palpitations – due to benign or significant arrhythmias

• Chest pain – typically non-cardiac in nature

• Fatigue and lightheadedness

• Shortness of breath, especially with exertion

• Syncope or near-syncope in some cases

• Midsystolic click and murmur on auscultation – a classic clinical finding

Diagnosis

Diagnosis of Barlow’s syndrome is made through a combination of clinical examination and imaging:

• Physical exam – may reveal a midsystolic click followed by a late systolic murmur

• Echocardiography (echo) – the gold standard for diagnosing MVP and assessing valve function

• Electrocardiogram (ECG) – may show nonspecific changes or arrhythmias

• Holter monitor – used to detect intermittent arrhythmias

• Cardiac MRI – occasionally used for more detailed structural analysis

Treatment

Treatment depends on the severity of the mitral valve prolapse and presence of complications such as mitral regurgitation or arrhythmias.

• No treatment is needed in asymptomatic individuals with mild prolapse and no regurgitation

• Beta-blockers – may help with palpitations and chest pain

• Antibiotic prophylaxis – previously recommended for dental or surgical procedures, but now only advised in specific high-risk cases

• Anticoagulation – if there is associated atrial fibrillation or thromboembolic risk

• Surgical repair or replacement – in severe cases with significant mitral regurgitation or valve dysfunction

Prognosis

The prognosis of Barlow’s syndrome is generally favorable in most individuals:

• Most patients remain asymptomatic or experience only minor symptoms throughout life

• Serious complications such as progressive mitral regurgitation, endocarditis, or sudden cardiac death are rare but possible

• Regular follow-up with echocardiography is essential to monitor valve function

• Excellent outcomes with timely surgical intervention in cases requiring mitral valve repair