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Home > What is Hypertrophic Cardiomyopathy > Diagnosis

How is Hypertrophic Cardiomyopathy Diagnosed?

Hypertrophic Cardiomyopathy may be suspected because of symptoms, a murmur or an abnormal ECG/EKG. An individual with the condition may present with any of the symptoms described previously. Because such symptoms could be caused by a large number of other conditions, further tests are necessary.

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, see figure 9. 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 electrocardiogram being performed.

ECG system

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, see figure 10. 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. Therefore ECHO provides a very thorough assessment of Hypertrophic Cardiomyopathy.

Echocardiogram being performed on a patient.

An echcardiogram is painless and non invasive.

Echocardiogram machine

Physical Examination

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.

MRI (Magnetic Resonance Imaging)

What is Magnetic Resonance Imaging (MRI)?

Magnetic resonance imaging or 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.
An MRI machine consists of a large circular magnet with an open horizontal tube running through the center of the magnet. Patients undergoing an MRI exam will lye flat on a table that will move the patient into the center of the magnet. In patients undergoing a cardiac MRI, the technician will often place a set of special cardiac coils over the chest. These coils act as “antennas” to pick up signal that is emitted from the heart during the examination. In addition, several ECG leads will be placed on the skin of the chest to monitor the heart rhythm. Depending on the type of MRI model, the patient may enter either head or foot first into the magnet. The average cardiac MRI examination will take one hour to complete. During this time, the patient will be instructed to undergo a series of pictures that require breath holds of roughly ten seconds (in order to minimize respiratory motion). Some additional pictures will be obtained while lying still and breathing freely. A significant number of cardiac MRI examinations will require the use of an intravenous contrast agent called gadolinium to help visualize certain changes in the heart muscle. Gadolinium is an FDA-approved contrast agent that is also used in a variety of different MRI examinations. If this information is required, gadolinium will be injected into a peripheral vein by a nurse during the examination.
A significant amount of complicated technology and physics are required to understand how an MRI machine is able to produce such detailed pictures. In short, MRI scanners use high magnetic fields, as well as pulses of radio waves to produce signal from a patients hydrogen atoms. These signals are captured by the MRI scanner and the computer system recreates the signal and converts the information into an image. These images can be viewed on a work station at the hospital or printed out on film.

Is MRI safe?

An MRI study utilizes radio waves to acquire pictures and therefore NO ionizing radiation is required (as opposed to a CT scan, cardiac catherization or X-ray which do require the use of ionizing radiation). As a result, MRI is a very safe test and no long term ill effects have been reported. Claustrophobia may be problematic in about 2% of patients but often a mild anxiolytic (prescribed by your doctor) prior to the test can prevent this from occurring. Patients with pacemakers, implantable cardiodefibrillators (ICD) or retained pacemaker leads cannot undergo an MRI examination. However, metallic implants such as hip prostheses, prosthetic heart valves, coronary stents and sternal sutures are not a problem.

MRI in Hypertrophic Cardiomyopathy

As MRI can provide tomographic high resolution pictures of the heart, it has recently become an important new test well suited for the assessment of the size and extent of left ventricular hypertrophy in HCM. In fact, recent studies have shown that a cardiac MRI may be better than an echocardiogram to reliably detect hypertrophy in areas such as the left ventricular anterolateral wall and apex. As a result, in some patients an echocardiogram may not be sufficient to confidently exclude a diagnosis of HCM and in that situation a cardiac MRI may be recommended.
In addition, because of its high spatial resolution a cardiac MRI may also be performed to define th precise extent of wall thickening. This information is crucial since the degree of left ventricular wall thickening that a patient has may change therapeutic recommendations. Cardiac MRI can also show if left ventricular outflow tract obstruction due to systolic anterior motion of the mitral leaflet (SAM) is present. In addition, for those patients who are going to undergo an invasive procedure such as alcohol septal ablation or surgical septal myectomy, a cardiac MRI can precisely define the cardiac anantomy prior to and following the procedure.
Finally, one area of current investigation involves the use of the intravenous contrast agent gadolinium. When gadolinium is injected into a vein, it is quickly taken up in areas of the heart where scarring or fibrosis may be present. After waiting approximately 10-20 minutes after the injection, more pictures are performed and areas where gadolinium is taken up in the heart will appear very bright relative to the dark areas of normal heart muscle. In the future, the amount of scarring detected by gadolinium may help determine which patients are more likely to experience arrhythmias or heart failure symptoms.