Definition and Overview

Restrictive cardiomyopathy (RCM) is a condition that restricts heart movement. It causes the muscles of the ventricles to become stiff. This prevents the ventricles from filling with enough blood. Thus, even when the heart pumps efficiently, the amount of blood that circulates the body is still reduced.

RCM is one type of cardiomyopathy, a term that refers to a group of diseases that affects the heart muscle. RCM often occurs due to the presence of scar tissue in the heart muscle.

The condition can be mild, moderate, or severe. Mild and moderate cases often do not cause worrying symptoms. However, when left untreated, the condition can progress and could lead to heart failure.

RCM patients may be candidates for a heart transplant in most severe cases. RCM is rare. But of all the types of heart muscle diseases, it has the poorest prognosis. It is one of the most common causes of sudden cardiac death.

Causes of Condition

In many cases, the cause of RCM is unknown. However, it can be genetic and can run in families. In up to 30% of diagnosed patients, there is a family history of RCM. Another known cause is the build-up of scar tissue, abnormal proteins, or iron in the heart muscle. Certain cancer treatments, such as radiation therapy and chemotherapy can also cause the condition. Sarcoidosis, a disease that causes inflammation of body tissues, is also linked to RCM.

Key Symptoms

RCM often does not cause symptoms until it progresses. When this happens, signs like fatigue and shortness of breath will start to show. Other symptoms include fainting and feeling dizzy. A persistent cough and abnormal heartbeats are also very common.

In children, the first symptoms of the condition seem to be related to lung problems. They often present with asthma or chronic lung infections. Others have fluid build-up in their hands, legs, face, and feet. Some also have excess fluid in their abdomen and an enlarged liver. Most of these patients are seen by respiratory specialists or gastroenterologists first. They are often referred to heart specialists when the results of their x-ray show abnormalities in their heart.

Who to See and Treatment Available

Restrictive cardiomyopathy can be difficult to diagnose because its symptoms are not very specific. This means that they can also be caused by other conditions. This is a cause for concern because RCM puts the patient at risk of sudden cardiac death.

The diagnosis of RCM involves the review of the patient’s medical history and a physical exam. It also involves the use of a chest x-ray, echocardiography (ECG), and imaging tests. These include magnetic resonance imaging (MRI) and computed tomography (CT) scan. Doctors also order a complete blood count, blood gas analysis, and liver function tests.

If more information is needed to make a definite diagnosis, the doctor may elect to order additional tests. These may include cardiac catheterisation. This test is used to assess the structure and function of the heart. It is performed by advancing a catheter into the organ. In patients with RCM, this test will show significantly elevated pressures when the heart relaxes. In rare cases, this test may be followed by a cardiac biopsy. This test involves removing a sample tissue of the heart muscle for further study. Results of the test can confirm or rule out possible causes of the condition. These include the build-up of abnormal proteins and iron in the heart muscle.

There is no cure for RCM. Available treatments are used to improve its symptoms. Depending on the severity of symptoms, patients may be placed under medical therapy. Common medications prescribed are those that make the smooth muscle of blood vessels more relaxed. Drugs that reduce the risk of blood clots and make the heartbeat stable are also often prescribed. Other medications used include diuretics and calcium channel blockers. In some patients, medications can adequately manage the condition and prevent it from getting worse.

It is important for patients to make regular follow-ups with a heart specialist. They will need to undergo periodic tests to confirm that their condition is not progressing. The doctor will also assess how they respond to treatment. Doctors may need to make adjustments from time to time to achieve better treatment outcomes. Patients are also advised to make healthy lifestyle changes. Some are advised against certain types of exercises and competitive sports.

Because patients are at risk of sudden cardiac arrest, doctors may recommend implantable cardioverter defibrillator (ICD). These are small, battery-powered devices implanted just under the skin. They are designed to keep track of the heart rate. They deliver electric shocks if they detect abnormal heart rhythms.

In most severe cases, a heart transplant may be needed. This procedure involves replacing the diseased heart with a healthy heart from a deceased donor. This procedure can extend the lives of RCM patients.

References:

  • Gonzalez-Lopez E, Gallego-Delgado M, Guzzo-Merello G, et al. Wild-type transthyretin amyloidosis as a cause of heart failure with preserved ejection fraction. Eur Heart J. 2015 Oct 7. 36 (38):2585-94.

  • Lindenfeld J, Albert NM, Boehmer JP, et al, for the Heart Failure Society of America. HFSA 2010 Comprehensive Heart Failure Practice Guideline. J Card Fail. 2010 Jun. 16(6):e1-194.

  • Sasaki N, Garcia M, Ko HH, Sharma S, Parness IA, Srivastava S. Applicability of published guidelines for assessment of left ventricular diastolic function in adults to children with restrictive cardiomyopathy: an observational study. Pediatr Cardiol. 2015 Feb. 36 (2):386-92.

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