Barlow syndrome is mitral valve prolapse (also known as "click murmur syndrome"), the most common heart valve abnormality, affecting 5-10% of the world population. Most patients have no symptoms and require no treatment. However, the condition can be associated with fatigue and/or palpitations. The mitral valve prolapse can often be detected by a doctor during examination of the heart and can be confirmed with anechocardiogram. Patients are usually given antibiotics prior to any procedure which might introduce bacteria into the bloodstream, including dental work and minor surgery.
Causes: The underlying problem with the valve is a degeneration of the tissue causing the leaflets to become stretched and enlarged. This redundant tissue bulges into the atrium, preventing the valve from closing properly. The exact reason for this tissue change is not known, but it is associated with the tissue degenerative disorders. Functional MVP can occur with completely normal valve leaflets: this is found in conditions of abnormal papillary muscle function due to myocardial ischaemia, and in dilated cardiomyopathy. Patients with hypertrophic cardiomyopathy are also at risk. Symptoms Most patients do not experience symptoms. However, when they do the symptoms include: • Fatigue ï Migraine ï Dizziness ï Panic attacks ï Low blood pressure when lying down ï Shortness of breath ï Palpitations ï Chest pain that is not angina However, these non-specific symptoms are not reliable indicators of the condition. When the doctor listens to the heart, a murmur may be heard. This is caused by irregular blood flow through the valve. A click may also be heard, thought to be due to the snapping of the anchoring “ropes” – the chordea – as the valve billows and then is suddenly held taut. This is much like the snapping taut of the sails on a boat. These sounds are often transient or absent, and might only be detected by an experienced cardiologist. If there are problems with the function of the left ventricle, the patient may experience shortness of breath and troublesome irregularities of heart rhythm. Barlow’s syndrome may result in severe dysfunction of the mitral valve, leading to what is called mitral regurgitation (MR), a leaking, or incompetent valve. Mitral regurgitation means that blood flows back into the left atrium during contraction rather than moving forwards into the aorta as it should do. About 25% of people with Barlow's syndrome also suffer from lax joints, and a high arched palate in the mouth (these patients may also have a degree of Marfan's syndrome), and other abnormalities of their skeleton such as scoliosis, a funnel chest and a straight back.
Treatment: Individuals with mitral valve prolapse, particularly those without symptoms, often require no treatment. Those with mitral valve prolapse and symptoms of dysautonomia (palpitations, chest pain) may benefit from beta-blockers (e.g., propranolol). Patients with prior stroke and/or atrial fibrillation may require blood thinners, such as aspirin or warfarin. In rare instances when mitral valve prolapse is associated with severe mitral regurgitation, mitral valve repair or surgical replacement may be necessary. Mitral valve repair is generally considered preferable to replacement. Current ACC/AHA guidelines promote repair of mitral valve in patients before symptoms of heart failure develop. Symptomatic patients, those with evidence of diminished left ventricular function, or those with left ventricular dilatation need urgent attention.
Statistics: The relationship of VO2max (ml O2 • kgFFM−1 • min−1) and the metabolic syndrome score was of borderline significance after adjusting for age, sex, physical activity, and measurement error (β = −0.58, P = 0.06). The magnitude of the association between physical activity (kJ • d–1 • kgFFM−1) and the metabolic syndrome was more than three times greater than for VO2max (standardized β = −1.83, P = 0.0042). VO2max, however, modified the relationship between physical activity energy expenditure and metabolic syndrome (P = 0.036). 19 patients were identified, 9 were male, with the corrected QT interval (QTc) ranging from 460-619ms. Mode of presentation included syncope (n=9), ventricular tachycardia (n=2), convulsion (n=1) and as incidental finding (n=7). Pathogenic mutations were identified in 9 patients (LQT1=3, LQT2=4, LQT3=1, LQT5=1), likely pathogenic mutations in 2 (LQT2), unclassified variants in 2, and no mutation in 6. Patients with pathogenic and likely pathogenic mutations had significantly longer mean QTc than those without such mutations (p=0.046). Twenty-five children were enrolled and 68% of children were neurologically abnormal at an average follow-up of 59 months. A wide range of abnormalities and outcomes was seen. Speech and language difficulties were present in 64% including autistic spectrum disorder. Cranial nerve abnormalities were present in 20%. Visual deficits and epilepsy compounded learning difficulties in 25% of survivors. Consent for follow-up was more likely to be obtained where the perpetrator was known.