Knowledge brings us one step closer

Hypertrophic Cardiomyopathy, evident by the name alone, is a fairly complex condition of the heart. Below you will find information on HCM and its symptoms, as well as the diagnosis and treatment.

 

What is HCM

Symptoms

Diagnosis

Treatment

What is Hypertrophic Cardiomyopathy?

Hypertrophic Cardiomyopathy is a condition of the heart, usually genetic, that causes the heart muscle to become abnormally thick. This thickness can make it harder for the heart to pump blood, and may also affect the heart’s electrical system. In addition, a close examination of the cells of the heart muscle shows that these cells are also abnormally formed. Rather than a regular, parallel alignment of muscle cells, HCM causes the cells to form in a disorganized pattern, also known as “myocardial disarray.” This disarray means that the heart muscle also lacks it’s ordinary elasticity, further complicating the heart’s proper function.

Symptoms of Hypertrophic Cardiomyopathy

While there is no single symptom that confirms HCM or is unique to HCM, there are a number of symptoms that those with the disease most often experience. The lack of a defining symptom is one of the reasons that HCM often goes undiagnosed in young people. Many young athletes with HCM are incorrectly diagnosed with “exercise induced asthma,” since the shortness of breath they experience only appears upon exertion. If you or someone you know has been diagnosed with this form of asthma, ask your doctor about being screened for HCM. It is also important to remember that many people with HCM experience only mild symptoms and require little or no treatment to lead normal, active lives.

Shortness of Breath

Those with HCM may experience shortness of breath upon mild exertion, and sometimes even at rest. The severity of this shortness of breath can vary widely in individuals with HCM, as no two cases are the same. While many experience only mild exercise limitation, others may be significantly restricted in their activities.

Chest Pain

Chest pain is a common symptom in those with HCM. It is usually brought on by exertion and relieved by rest, but pain may occur at rest or during sleep and may persist. The cause of the pain is thought to be insufficient oxygen supply to the myocardium. In Hypertrophic Cardiomyopathy the main coronary arteries are usually normal, but the greatly thickened muscle demands an increased oxygen supply which cannot be met in some circumstances.

Palpitations

Palpitation is an uncomfortable awareness of the heart beat. People may occasionally feel an extra beat or a skipped beat and this is usually normal. Sometimes an awareness of the heart beating does suggest an irregular heart rhythm. In this case, palpitation may start suddenly, appear to be very fast and may be associated with sweating or light-headedness. The cause of such episodes should be determined and treated.

Light-Headedness and Blackouts

Persons with the condition may experience light-headedness, dizziness and more seriously, blackouts. Episodes may occur in association with exercise, with palpitations or without any apparent provocation. The reasons for these episodes are not always clear. They may be due to an irregularity of the heart beat, or fall in blood pressure. Episodes of light-headedness and certainly a blackout should be reported to one’s doctor and investigated.

Hypertrophic Cardiomyopathy Diagnosis

History and Physical Exam

The physician will first ask many questions about the patient’s history, including symptoms, prior tests and family history. This is very important so that the patient’s functional status can be determined. A physical examination concentrating on the heart will then be performed to determine information on the heart’s size and evidence of obstruction or valve leakage.

Blood Tests

These tests can be used to check for specific gene mutations. Hundreds of mutations have been uncovered in several genes. There is a tremendous interest in how specific mutations may impact the course of the disease. Because research is rapidly advancing, blood will also be stored so that further analysis can be done as new discoveries are being made. This may have important implications for first-degree relatives in the future.

Chest X-rays

These X-rays allow the heart size and position to be viewed.

Echocardiograms (“ECHO”)

This is a noninvasive sound wave imaging test that allows the physician to observe the heart as it is beating. It measures muscle thickness, degree of obstruction, chamber size, valve movement and blood flow. The test also determines pressures inside the heart chambers and major vessels. Medications that change the pressures inside the heart can be given during ECHO. This allows the physician to observe the change in the degree of obstruction when the heart is stressed.

Electrocardiograms (ECG) and Holter Monitor

These are graphic records of the electrical activity in the heart that generates a heart beat. A 12-lead electrocardiogram provides information about the heart rhythm (taken over 10 seconds) and indirectly about the size of the heart. A Holter monitor is worn for 24 to 72 hours and records the heart rhythm over this entire period of time. In hypertrophic cardiomyopathy it is not uncommon to have irregular heart rhythms called arrhythmias. Some specific arrhythmias may predict future events.

Exercise Test (“TMET”)

Several exercise tests are available depending on the information the physician needs. An exercise test will help quantitate activity tolerance and screen for arrhythmias. The change in blood pressures during exercise also has implications for an individual’s prognosis.

With an O₂ consumption test, the patient will be asked to exercise while breathing into a mask so that the amount of oxygen that the body uses can be measured.

With a thallium scan, a harmless radioactive solution is injected into a vein during exercise and a camera is used to look at blood flow to the heart muscle.

ECHO can be done immediately after exercise to get a better understanding of how severe the obstruction may be under stress.

Heart Catheterization (“Angio” or “Cath”)

This invasive procedure is done in the hospital, but usually as an outpatient procedure. Thin flexible catheters are passed through a peripheral artery from the groin area into the chambers of the heart. The catheters are used to measure pressures inside the heart, deliver medications into the heart, and directly deliver dye into the heart chambers and vessels. The dye can be seen with X-ray imaging as it is moving through the heart and vessels and outlines any blockages in the arteries.

This test is also used to determine the heart’s response to a temporary pacemaker. Surprisingly, there is very little pain involved — it is usually just due to the numbing medication given at the start of the procedure. The patient is required to lie flat for several hours after the procedure to prevent bleeding from the puncture site.

Treatment for Hypertrophic Cardiomyopathy

While there is currently no cure for HCM, there are a number of treatments available that can improve heart function and improve the quality of life for those suffering from this disease.

Medication

Medications help relax the heart and reduce the degree of obstruction so the heart can pump more efficiently. Beta-blockers and calcium channel blockers are common families of drugs that are prescribed.

Myectomy (Surgery)

This is the surgical removal of a small amount of overgrown muscle from the heart wall, and is typically successful in relieving the symptoms of HCM.  It is considered in individuals with severe symptoms despite drug treatment, in whom the left ventricular outflow tract narrowing causes obstruction of the blood flow. Typically, if a person has an obstructive gradient greater than 50mm of mercury and is symptomatic and has failed drug therapy it is only then advised they consider this procedure. In this operation the surgeon removes a portion of the thickened muscle from the septum, thereby widening the outflow tract and relieving the obstruction. In rare cases, instead of a myectomy, the mitral valve is replaced with an artificial valve.  These are major operations which carry a definite risk and therefore are reserved for patients with severe symptoms and certain forms of HCM. It is imperative that the patient choose a center that is experienced in the surgical procedure and a surgeon with ample experience.

Septal Ablation

This is a new technique in which an alcohol solution is injected into an artery supplying the part of the thickened muscle that causes the obstruction. The result is a localized “heart attack” of this region of the heart muscle and will decrease the degree of obstruction.

While this procedure is relatively new, information from research studies suggests that its results are close to those of surgical myectomy. However, long-term safety issues need to be resolved, and not all patients have heart anatomy that would allow them to be candidates for septal ablation.

Automatic Implantable Cardioverter Defibrillator (AICD)

In some patients who are considered very “high risk,” an automatic implantable cardiac defibrillator (AICD) might be recommended. Through new advances in technology, this device can now be placed similar to a pacemaker. Usually, implantation is done in the hospital and requires a short overnight stay.

A small device is placed under the skin just below the collarbone and is connected to wire leads threaded through the vein into the heart chamber. The AICD monitors heart rhythms constantly. It can restore a normal heart rhythm using pacemaker functions and/or small electric shocks.

Periodically, outpatient surgery is required to change the battery in the device.  Also, quarterly check-ups are typically scheduled to ensure proper functioning of the device, and to monitor the heart rhythms recorded.