Cardiomyopathy

What is cardiomyopathy?


Cardiomyopathy is a serious disease in which the heart muscle becomes inflamed and doesn't work as well as it should. There may be multiple causes including viral infections.

Cardiomyopathy can be classified as primary or secondary. Primary cardiomyopathy can't be attributed to a specific cause, such as high blood pressure, heart valve disease, artery diseases or congenital heart defects. Secondary cardiomyopathy is due to specific causes. It's often associated with diseases involving other organs as well as the heart.

There are three main types of cardiomyopathy: dilated, hypertrophic and restrictive.

Symptoms

Some people who develop cardiomyopathy have no signs and symptoms during the early stages of the disease. But as the condition advances, signs and symptoms usually appear. Cardiomyopathy symptoms may include:

• Breathlessness with exertion or even at rest
• Swelling of the legs, ankles and feet
• Bloating of the abdomen due to fluid buildup
• Fatigue
• Irregular heartbeats that feel rapid, pounding or fluttering
• Dizziness, lightheadedness and fainting

No matter what type of cardiomyopathy you have, signs and symptoms tend to get worse unless treated. In certain people, this worsening happens quickly, while in others, cardiomyopathy may not worsen for a long time.

Causes
Most of the time, the cause of the cardiomyopathy is unknown. In some people, however, doctors are able to identify some contributing factors. Possible causes of cardiomyopathy include:

• Long-term high blood pressure
• Heart valve problems
• Heart tissue damage from a previous heart attack
• Chronic rapid heart rate
• Metabolic disorders, such as thyroid disease or diabetes
• Nutritional deficiencies of essential vitamins or minerals, such as thiamin (vitamin B-1), selenium, calcium and magnesium
• Pregnancy
• Excessive use of alcohol over many years
• Abuse of cocaine or antidepressant medications, such as tricyclic antidepressants
• Use of some chemotherapy drugs to treat cancer
• Certain viral infections, which may injure the heart and trigger cardiomyopathy
• Iron buildup in your heart muscle (hemochromatosis)

The three types of cardiomyopathy are:
  
1 Dilated cardiomyopathy 
2 Hypertrophic cardiomyopathy 
3 Restrictive cardiomyopathy

What is dilated (congestive) cardiomyopathy?

Dilated cardiomyopathy

This is the most common form. In it, the heart cavity is enlarged and stretched (cardiac dilation). The heart is weak and doesn't pump normally, and most patients develop heart failure. Abnormal heart rhythms called arrhythmias and disturbances in the heart's electrical conduction also may occur.

Blood flows more slowly through an enlarged heart, so blood clots may form. A blood clot that forms in an artery or the heart is called a thrombus. A clot that breaks free, circulates in the bloodstream and blocks a small blood vessel is called an embolus.

• Clots that stick to the inner lining of the heart are called mural thrombi.
• If the clot breaks off the right ventricle (pumping chamber), it can be carried into the pulmonary circulation in the lung, forming pulmonary emboli.
• Blood clots that form in the heart's left side may be dislodged and carried into the body's circulation to form cerebral emboli in the brain, renal emboli in the kidney, peripheral emboli or even coronary artery emboli.

A condition known as Barth syndrome, a rare and relatively unknown genetically linked cardiac disease, can cause dilated cardiomyopathy. This syndrome affects male children, usually during their first year of life. It can also be diagnosed later.  (For more information on Barth syndrome, visit the Barth Syndrome Foundation at http://www.barthsyndrome.org.

In these young patients the heart condition is often associated with changes in the skeletal muscles, short stature and an increased likelihood of catching bacterial infections. They also have neutropenia, which is a decrease in the number of white blood cells known as neutrophils. There are clinical signs of the cardiomyopathy in the newborn child or within the first months of life. These children also have metabolic and mitochondrial abnormalities.

How is dilated (congestive) cardiomyopathy treated?

A person with cardiomyopathy may suffer an embolus before any other symptom of cardiomyopathy appears. That's why anti-clotting (anticoagulant) drug therapy may be needed. Arrhythmias may require antiarrhythmic drugs. Therapy for dilated cardiomyopathy is often aimed at treating the underlying cause, however. If the person is young and otherwise healthy, and if the disease gets worse, a heart transplant may be considered.

When cardiomyopathy results in a significantly enlarged heart, the mitral and tricuspid valves may not be able to close properly, resulting in murmurs. Blood pressure may increase because of increased sympathetic nerve activity. These nerves can also cause arteries to narrow. This mimics hypertensive heart disease (high blood pressure). That's why some people have high blood pressure readings. Because the blood pressure determines the heart's workload and oxygen needs, one treatment approach is to use vasodilators (drugs that "relax" the arteries). They lower blood pressure and thus the left ventricle's workload.

What is hypertrophic cardiomyopathy?

Hypertrophic cardiomyopathy

In this condition, the muscle mass of the left ventricle enlarges or "hypertrophies."

In one form of the disease, the wall (septum) between the two ventricles (pumping chamber) becomes enlarged and obstructs the blood flow from the left ventricle. The syndrome is known as hypertrophic obstructive cardiomyopathy (H.O.C.M.) or asymmetric septal hypertrophy (A.S.H.). It's also called idiopathic hypertrophic subaortic stenosis (I.H.S.S.).

Besides obstructing blood flow, the thickened wall sometimes distorts one leaflet of the mitral valve, causing it to leak. Hypertrophic cardiomyopathy is the most common inherited heart defect, occurring in one of 500 individuals. Close blood relatives (parents, children or siblings) of such persons often have enlarged septums, although they may have no symptoms. This disease is most common in young adults.

In the other form of the disease, non-obstructive hypertrophic cardiomyopathy, the enlarged muscle doesn't obstruct blood flow.

The symptoms of hypertrophic cardiomyopathy include shortness of breath on exertion, dizziness, fainting and angina pectoris. (Angina is chest pain or discomfort caused by reduced blood supply to the heart muscle.) Some people have cardiac arrhythmias. These are abnormal heart rhythms that in some cases can lead to sudden death. Often an implanted cardioverter defibrillator (ICD) is needed to shock the heart to restart a normal heart rhythm and prevent sudden dealth. The obstruction to blood flow from the left ventricle increases the ventricle's work, and a heart murmur may be heard.

How is hypertrophic cardiomyopathy treated?

The usual treatment involves taking a drug known as a beta blocker (such as propranolol) or a calcium channel blocker. If a person has an arrhythmia, an antiarrhythmic drug may also be used. Surgical treatment of the obstructive form is possible in some cases if the drug treatment fails.

Alcohol ablation is a type of nonsurgical treatment for hypertrophic obstructive cardiomyopathy. It involves injecting alcohol down a small branch of one of the heart arteries to deaden the extra heart muscle. This allows the extra heart muscle to thin out without having to cut it out surgically.

What is restrictive cardiomyopathy?

Restrictive cardiomyopathy

This is the least common type in the United States. The myocardium (heart muscle) of the ventricles becomes excessively "rigid," so it's harder for the ventricles to fill with blood between heartbeats. A person with restrictive cardiomyopathy often complains of being tired, may have swollen hands and feet, and may have difficulty breathing on exertion. This type of cardiomyopathy is usually seen in the elderly and may be due to another disease process.

Tests and diagnosis

Your doctor will conduct a physical examination, take a personal and family medical history, and ask when your symptoms occur — for example, whether exercise brings on your symptoms. If your doctor thinks you have cardiomyopathy, you may need to undergo several tests to confirm the diagnosis. These tests may include:

• Chest X-ray. An image of your heart will show whether it's enlarged.
• Echocardiogram. An echocardiogram uses sound waves to produce images of the heart. Your doctor can use these images to examine the size of your heart and its motions as it beats.
• Electrocardiogram (ECG). In this noninvasive test, electrode patches are attached to your skin to measure electrical impulses from your heart. An ECG can show disturbances in the electrical activity of your heart, which can detect abnormal heart rhythms and areas of injury.
• Cardiac catheterization and biopsy. In this procedure, a thin tube (catheter) is inserted in your groin and threaded through your blood vessels to your heart, where a small sample (biopsy) of your heart can be extracted for analysis in the laboratory. Pressure within the chambers of your heart can be measured to see how forcefully blood pumps through your heart. Pictures of the arteries of the heart can be taken during the procedure (coronary angiogram) to ensure that you do not have any blockage.
• Cardiac magnetic resonance imaging (MRI). Cardiac MRI is an imaging technique that uses magnetic fields and radio waves to create images of your heart. Cardiac MRI is often used in addition to echocardiography, particularly if the images from your echocardiogram aren't helpful in making a diagnosis.
• Blood tests. One blood test can measure B-type natriuretic peptide (BNP), a protein produced in your heart. Your blood level of BNP rises when your heart is subjected to the stress of heart failure, a common complication of cardiomyopathy.
  A variety of other blood tests may be done, including those to check your kidney function and look for anemia and thyroid problems. Your iron level may be measured. Having too much may indicate an iron overload disorder called hemochromatosis. Accumulating too much iron in your heart muscle can weaken it and cause cardiomyopathy.
  
  Treatments and drugs
  The overall goals of treatment for cardiomyopathy are to manage your signs and symptoms, prevent your condition from worsening, and reduce your risk of complications. Treatment varies by which of the major types of cardiomyopathy you have.
  Dilated cardiomyopathy 
  
  
  If you're diagnosed with dilated cardiomyopathy, your doctor may recommend medications, surgically implanted devices or a combination of both. The medications you may be prescribed include:
  • Angiotensin-converting enzyme (ACE) inhibitors to improve your heart's pumping capability, such as enalapril (Vasotec), lisinopril (Zestril, Prinivil), ramipril (Altace) and captopril (Capoten).
  • Angiotensin receptor blockers (ARBs) for those who can't take ACE inhibitors, such as losartan (Cozaar) and valsartan (Diovan).
  • Beta blockers to improve heart function, such as carvedilol (Coreg) and metoprolol (Lopressor, Toprol XL).
  • Digoxin (Lanoxin). This drug, also referred to as digitalis, increases the strength of your heart muscle contractions. It also tends to slow the heartbeat. Digoxin reduces heart failure symptoms and improves your ability to live with cardiomyopathy.
  • Diuretics. Often called water pills, diuretics make you urinate more frequently and keep fluid from collecting in your body. Commonly prescribed diuretics for heart failure include bumetanide (Bumex) and furosemide (Lasix). The drugs also decrease fluid in your lungs, so you can breathe more easily. One diuretic, spironolactone (Aldactone), may also be helpful in treating scarring of your heart tissue.
  Another option for some people with dilated cardiomyopathy is a special pacemaker that coordinates the contractions between the left and right ventricles (biventricular pacing). In people who may be at risk of serious arrhythmias, drug therapy or an implantable cardioverter-defibrillator (ICD) may be options. An ICD is a small device — about the size of a box of matches — implanted in your chest to continuously monitor your heart rhythm and deliver electrical shocks when needed to control abnormal, rapid heartbeats. The device can also work as a pacemaker.
  Hypertrophic cardiomyopathy
  
  
  Your doctor may recommend beta blockers to relax your heart, slow its pumping action and stabilize its rhythm. These medications include Lopressor or calcium channel blockers, such as verapamil (Calan, Isoptin). Medications are often the preferred treatment for hypertrophic cardiomyopathy.
  If medications don't work, you may need surgery or a medical device to treat your condition. Options include:
  • Septal myectomy. 
  • This is an open-heart operation in which the surgeon removes part of the thickened, overgrown heart muscle wall (septum) that separates the two bottom heart chambers (ventricles). Removing part of this overgrown muscle improves blood flow and reduces mitral regurgitation. Myectomy is used if medications don't relieve symptoms. Most people who have symptoms and undergo myectomy have no further symptoms. This type of surgery is available only in medical centers that specialize in the treatment of hypertrophic cardiomyopathy.
  • Septal ablation. 
  • Also called septal alcohol ablation, this is a treatment in which a small portion of the thickened heart muscle is destroyed by injecting alcohol through a catheter into the artery supplying blood to it. There are possible complications with this procedure, including heart block — a disruption of the heart's electrical system — which requires implantation of a pacemaker. The long-term success of this procedure isn't yet known, but it's becoming more commonly used.
  • Pacemaker implantation.
  •  A pacemaker is a small electronic device inserted under your skin that sends electrical signals to your heart to monitor and regulate your heartbeat. Surgery to implant the pacemaker is usually performed during local anesthesia and typically takes less than three hours. Pacemaker implantation is generally not as effective as surgical options, but it's sometimes used in older people who want to avoid more invasive procedures.
  • Implantable cardioverter-defibrillator (ICD). 
  • This is a pager-sized device implanted in your chest like a pacemaker. An ICD continuously monitors your heartbeat. If a life-threatening arrhythmia occurs, the ICD delivers precisely calibrated electrical shocks to restore a normal heart rhythm. A small number of people with hypertrophic cardiomyopathy are at risk of sudden cardiac death because of abnormal heart rhythms. In these high-risk individuals, many doctors recommend the implantation of an ICD.
  Restrictive cardiomyopathy
  
  
  Treatment for restrictive cardiomyopathy focuses on improving symptoms. Your doctor will recommend you pay careful attention to your salt and water intake and monitor your weight daily. Your doctor may also recommend you take diuretics if sodium and water retention becomes a problem. You may be prescribed medications to lower your blood pressure and control fast or irregular heart rhythms.
  Many of the medications that doctors prescribe for cardiomyopathy may have side effects. Be sure to discuss these possible side effects with your doctor before taking any of these drugs.
  Heart transplant 
  
  
  If you have severe cardiomyopathy and medications can't control your symptoms, a heart transplant may be an option. Because of the shortage of donor hearts, even people who are critically ill may have a long wait before having a heart transplant. In some cases, a mechanical heart assist device can help critically ill people as they wait for an appropriately matched donor. These devices, known as ventricular assist devices (VADs), can help blood circulate through your heart for months, or even years. A VAD may allow you to live outside the hospital while you wait. In some people who aren't candidates for a heart transplant, VAD therapy could be a long-term treatment option.