Hypertrophic obstructive cardiomyopathy is a condition where portions of the heart muscle become thickened. This is often shortened to HOCM, pronounced "HO-come."
HOCM is also known as Idiopathic Hypertrophic Subaortic Stenosis (IHSS).
Classically with HOCM, the ventricular muscle becomes thickened, and especially the muscle near the aortic valve.
The thickened muscle bulges out into the pathway the blood takes out of the left ventricle and thru the aortic valve.
If the bulging obstructs the blood flow out of the left ventricle, the heart may struggle to pump effectively.
Patients may be asymptomatic if the heart is not struggling. Or patients may experience shortness of breath, chest pain, tiredness, and ankle swelling.
HOCM can (rarely) cause sudden death in young athletes.
HOCM is commonly inherited. It is often due to mutations in genes that relate to proteins in the heart muscle.
HOCM can usually be diagnosed with echocardiography. The echo may show thickening of the muscle in the septum, near the aortic valve. The echo may also show mitral valve leakage, if the bulging muscle is affecting the mitral valve.
Medications are usually the first therapy for HOCM. A beta-blocker such a metoprolol may be used.
A defibrillator may be placed if the patient has a lot of abnormal heart rhythms.
Sometimes, alcohol can be directed thru a catheter into the heart and into the bulging muscle. This creates a localized heart attack, which will result in the septum contracting into scar and thereby not causing as much obstruction.
Sometimes, surgery is needed to address HOCM. The surgery is called septal myectomy, or septal myomectomy.
Septal myectomy involves cutting the bulging muscle which is obstructing blood flow.
A sternotomy is used to access the heart and the septum.
The heart and lung machine is used. The section of septum is cut out. It is important not to cut the septum too deeply, or a hole may result in the septum.
It usually takes Dr. Pool about 3 hours to perform septal myectomy.
Often, HOCM is associated with leakage of the mitral valve (aka mitral regurgitation or MR). Often, performing the myectomy will change the blood flow out of the left ventricle in a way that reduces the MR. Sometimes, especially if a part of the mitral valve is broken, additional steps are taken to repair the mitral valve and make it not leak.