From the Guidelines
The murmur associated with Barlow's syndrome is a mid-to-late systolic click followed by a late systolic murmur, which is usually medium to high-pitched and loudest at the cardiac apex 1. This murmur is classically described as a high-pitched, crescendo-decrescendo sound that is best heard at the cardiac apex. The murmur occurs when the mitral valve leaflets prolapse back into the left atrium during ventricular contraction, causing mitral regurgitation. Some key characteristics of this murmur include:
- A high-pitched sound of short duration
- Variation in intensity and timing in systole according to LV loading conditions and contractility
- Occasional musical or honking quality
- Dynamic auscultation is often useful for establishing the diagnosis of MVP syndrome The timing and intensity of both the click and murmur can vary with physiologic maneuvers, such as standing or Valsalva maneuver, which decrease ventricular volume and cause the click and murmur to occur earlier in systole, while squatting or hand grip, which increase ventricular volume, delay the click and murmur 1. In the context of the provided options, the correct answer is:
- D. Midsystolic click, as it is the most closely associated with Barlow's syndrome, and the late systolic murmur that often follows it is a key characteristic of the condition.
From the Research
Barlow's Syndrome and Associated Murmur
- Barlow's syndrome, also known as mitral valve prolapse, is a condition where the mitral valve leaflets bulge back into the left atrium during systole 2, 3, 4, 5.
- The murmur associated with Barlow's syndrome is a mid-systolic click and late systolic murmur, which can be heard through auscultation 2, 3, 4.
- This murmur is caused by the prolapsing mitral valve leaflet(s) and can be distinguished from other causes of systolic clicks and mitral regurgitation murmurs by the characteristic movement of the click-murmur complex in systole with various hemodynamic interventions 2.
- The correct answer is D. Midsystolic click, as it is the murmur most commonly associated with Barlow's syndrome.
Other Options
- A. Graham steel murmur is associated with aortic regurgitation, not Barlow's syndrome.
- B. Carey coombs murmur is associated with rheumatic fever, not Barlow's syndrome.
- C. Austin flint murmur is associated with aortic regurgitation, not Barlow's syndrome.
Clinical Significance
- Barlow's syndrome can be diagnosed by echocardiography or by auscultation of the characteristic mid-systolic click and late systolic murmur 2, 3, 4.
- Patients with Barlow's syndrome may be asymptomatic or may experience symptoms such as chest pain, palpitations, dyspnea, or fatigue 2, 5.
- The prognosis for patients with Barlow's syndrome is usually excellent, but complications such as sudden death, infective endocarditis, and progressive mitral regurgitation can occur 2, 4.