How is Hypertrophic Cardiomyopathy Diagnosed?
How is it Diagnosed?
HCM is diagnosed primary with imaging of the heart with an echocardiogram and in some cases a cardiac MRI. Genetic testing is used for those with a knowingly diagnosed person in the family.
It is not uncommon to see people diagnosed with asthma, anxiety attacks, panic attacks or some forms of depression, only to find that the underlying cause of the symptoms is HCM.
Electrocardiogram or ECG (EKG)
An ECG records the electrical signals from the heart and is performed by placing electrodes on the chest, wrist and ankles. In Hypertrophic Cardiomyopathy the ECG usually shows an abnormal electrical signal due to muscle thickening and disorganization of the muscle structure. In a minority of patients (approximately 10%) the ECG may be normal or show only minor changes. ECG abnormalities are also not specific to Hypertrophic Cardiomyopathy and may be found in other heart conditions. An EKG takes just a few minutes and the test is read by a cardiologist.
Echocardiogram or ECHO
Currently, the diagnosis of Hypertrophic Cardiomyopathy is made by an ultrasound scan of the heart called an “echocardiogram” or ECHO. Like the ECG this is an entirely safe test. An ECHO produces a picture of the heart. Excessive thickness of the muscle can be easily measured. Additional equipment called “Doppler” ultrasound can produce a color image of blood flow within the heart and measure the heart’s contraction and filling. Turbulent flow can be detected. During the test the entire heart is measured including the walls, valves and other structures within the heart. Therefore ECHO provides a very thorough assessment of Hypertrophic Cardiomyopathy. An ECHO should not be rushed, they can take between 20 minutes and one hour to complete.
Note: Limited echocardiography or “two minute ECHOS” have not been proven to rule in or out HCM.
In the majority of patients with Hypertrophic Cardiomyopathy, the physical examination is unremarkable and the abnormalities may be subtle. Most patients have forceful or jerky pulse and a forceful heart beat, which can be felt on the left side of the chest. Both of these reflect the thickened, strongly contracting heart. However, the most obvious abnormality on physical examination is a heart murmur, which is present in 30 – 40% of patients. In some patients the simple maneuver of squatting can help to bring out a murmur.
Cardiac Magnetic Resonance Imaging (CMR or MRI)
In some patients the walls of the heart are not easy to measure and additional screening with Magnetic Resonance Imaging, MRI may prove helpful. MRI is a diagnostic procedure that produces detailed pictures of the human body. The quality of the images produced by an MRI are excellent, often superior to all other imaging tests. MRI technology has been used since the early 1980’s to help physicians obtain pictures of a variety of organs including the brain, spine, muscles, liver and kidney. Recently, with advanced technology it is now possible to acquire high quality, reliable pictures of the heart throughout the entire cardiac cycle. As a result, more patients are now undergoing MRI for the evaluation of a variety of cardiac problems.
Maron, B.J. and Salberg, L. Hypertrophic Cardiomyopathy: For patients, their families and interested physicians. Blackwell Futura: 1stedition 2001,81 pages; 2ndedition 2006, 113 pages; 3rdedition pending publication 2014
Gersh, B.J., Maron, B.J., Bonow, R.O., Dearani, J.A., Fifer, M.A., Link, M.S., et al. (2011). 2011 ACCF/AHA guidelines for the diagnosis and treatment of hypertrophic cardiomyopathy. A report of the American College of Cardiology Foundation/American Heart Asociation Task Force on practice guidelines. Journal of the American College of Cardiology and Circulation, 58, e212-260.