From the Guidelines
Hypertrophic obstructive cardiomyopathy (HOCM) is typically associated with a harsh crescendo-decrescendo systolic murmur due to systolic anterior motion (SAM) of the mitral valve with left ventricular outflow tract obstruction (LVOTO). This murmur is classically described as being heard best at the left lower sternal border and apex, and its intensity can range from 2/6 to 4/6. The murmur of HOCM has distinctive features that help differentiate it from other cardiac murmurs, including an increase with maneuvers that decrease ventricular volume (such as standing, Valsalva maneuver, or after premature ventricular contractions) and a decrease with maneuvers that increase ventricular volume (such as squatting or handgrip exercise) 1.
The pathophysiology behind this murmur is due to asymmetric septal hypertrophy causing dynamic left ventricular outflow tract obstruction. When ventricular volume decreases, the hypertrophied septum and the anterior mitral valve leaflet come closer together, worsening the obstruction and intensifying the murmur. The murmur may also be accompanied by a prominent S4 heart sound and, in some cases, a mitral regurgitation murmur due to associated mitral valve dysfunction. It is essential to seek the presence of outflow tract obstruction at rest and with provocative maneuvers when possible, such as the Valsalva maneuver or standing from the squatting position 1.
Key characteristics of the murmur associated with HOCM include:
- Harsh crescendo-decrescendo nature
- Heard best at the left lower sternal border and apex
- Intensity ranges from 2/6 to 4/6
- Increases with maneuvers that decrease ventricular volume
- Decreases with maneuvers that increase ventricular volume
- May be accompanied by a prominent S4 heart sound and/or mitral regurgitation murmur These features are crucial for differentiating the murmur of HOCM from other cardiac murmurs and for guiding further diagnostic and therapeutic approaches 1.
From the Research
Hypertrophic Obstructive Cardiomyopathy (HOCM) Murmur
- The type of murmur associated with HOCM is not explicitly stated in the provided studies.
- However, the studies discuss the mechanism of obstruction in HOCM, which involves dynamic left ventricular outflow tract (LVOT) obstruction caused by systolic anterior motion (SAM) of the mitral valve 2, 3.
- The murmur associated with HOCM is likely related to the turbulent flow caused by the obstruction of the LVOT, but the specific characteristics of the murmur are not described in the studies.
- The studies focus on the management and treatment of HOCM, including pharmacologic and surgical therapies, rather than the physical examination findings such as murmurs 4, 5, 6.