From the Guidelines
Reducing the murmur of Hypertrophic Obstructive Cardiomyopathy (HOCM) can be achieved by increasing ventricular preload, decreasing contractility, or increasing afterload.
Mechanisms to Reduce Murmur
- Increasing ventricular preload can help reduce the murmur by decreasing the dynamic obstruction caused by systolic anterior motion (SAM) of the mitral valve 1.
- Decreasing contractility can also help reduce the murmur by reducing the force of contraction and subsequent obstruction 1.
- Increasing afterload can help reduce the murmur by decreasing the velocity of blood flow and subsequent obstruction 1.
Clinical Applications
- Beta blockers are commonly used to reduce contractility and heart rate, which can help decrease the murmur 1.
- Disopyramide can also be used to reduce contractility and help decrease the murmur, although its use is less common due to side effects 1.
- Avoiding provocative maneuvers such as standing, Valsalva strain, or exercise can also help reduce the murmur by avoiding increases in contractility and decreases in preload 1.
Important Considerations
- The management of HOCM should be individualized based on the patient's symptoms, physical examination, and echocardiographic findings 1.
- The use of medications such as beta blockers and disopyramide should be tailored to the patient's specific needs and monitored closely for efficacy and side effects 1.
From the Research
Reduction of Murmur in HOCM
The murmur of Hypertrophic Obstructive Cardiomyopathy (HOCM) can be reduced through various treatments, including:
- Nonsurgical septal reduction therapy (NSRT), which reduces left ventricular outflow tract (LVOT) obstruction and leads to symptomatic improvement 2
- Pharmacologic therapies, such as beta-blockers, calcium channel blockers, and disopyramide, which can help reduce the intensity of the murmur 3
- Surgical therapies, including septal myotomy/myectomy and mitral valve replacement, which can relieve LVOT obstruction and reduce the murmur 3, 4
- Alcohol septal ablation, which can reduce the LVOT gradient and improve symptoms 5
Mechanisms of Reduction
The mechanisms by which these treatments reduce the murmur of HOCM include:
- Widening of the LVOT diameter 2
- Thinning and akinesis of the septal base 2
- Decrease in the angle between LV systolic flow and the protruding mitral leaflets 2
- Decrease in peak acceleration rate and increase in the ratio of acceleration time to ejection time (AT/ET) 2
- Remodeling of the LVOT and changes in LV ejection dynamics 2
Factors Affecting Murmur Intensity
The intensity of the murmur in HOCM can be affected by various factors, including:
- Carotid sinus pressure, which can increase the intensity of the murmur due to decreased aortic pressure and impedance, increased contractility, and enhanced mitral valve systolic anterior movement 6