Dilated Cardiomyopathy

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What is dilated cardiomyopathy?

Dilated CMP
In dilated cardiomyopathy, the heart is enlarged and weaker than normal.

Dilated cardiomyopathy is a disease of the heart muscle. Here, the heart muscle becomes weak and as a result is not able to perform its function effectively. The size of the heart tends to become bigger and when it does so, the muscle becomes stretched and thinned out. Thinning of the heart muscle can make it weak.

One of the main problems that it is associated with dilated cardiomyopathy is that the heart is unable to pump blood effectively to all the vital organs. Due to this, patients start to experience different kinds of symptoms and can have problems with their health.

How common is dilated cardiomyopathy?

Dilated cardiomyopathy is more common in middle-aged men than in women. In women, the condition can affect them following menopause. There are no clear statistics on how common dilated cardiomyopathy is in the Indian population.

What causes dilated cardiomyopathy?

Many a time, the exact cause of dilated cardiomyopathy is not known. Some patients usually see their doctor because they have been feeling tired and increasingly breathless when they are performing day-to-day tasks. Some notice swelling in the legs as well.

Upon questioning, doctors often go through a detailed history to find out what the cause of the patient symptoms are. When a diagnosis of dilated cardiomyopathy is made, not every time is a cause identified. That being said, there are certain factors that can make the heart weak and can contribute to the development of dilated cardiomyopathy. The list below includes the common causes –

[list style=”check”] [li]Genetic factors (you can read more about genetic factors in this post)[/li] [li]Infections such as viral infections and some bacterial and fungal infections[/li] [li]Inflammation of the heart muscle (called myocarditis)[/li] [li]High blood pressure[/li] [li]High intake of alcohol over a number of years (called alcoholic cardiomyopathy)[/li] [li]Diabetes mellitus[/li] [li]A reduction in the blood flow to the heart muscle due to coronary artery disease[/li] [li]Exposure to certain kinds of toxins like Mercury and lead[/li] [li]Heart defects present from birth (called congenital heart defects)[/li] [li]Pregnancy (during the later stages or after delivery; this is a rare)[/li] [/list]

 Are there any risk factors for dilated cardiomyopathy?

Certain risk factors have most certainly been identified that can increase the chance of an individual developing dilated cardiomyopathy. Some of the common ones are listed below –

[list style=”check”] [li]Male gender[/li] [li]Age between 30 to 60 years[/li] [li]High blood pressure[/li] [li]High alcohol intake[/li] [li]Family history of dilated cardiomyopathy (read more)[/li] [li]Coronary artery disease and heart attacks[/li] [li]Cancer therapy with certain medications[/li] [li]Viral and bacterial infections[/li] [li]Obesity[/li] [li]Muscle inflammation (called myocarditis) due to viral infections or conditions such as lupus (which affect the immunity)[/li] [li]HIV infection[/li] [li]Drug abuse in particular cocaine use[/li] [/list]

Clinical symptoms and signs

An individual who has dilated cardiomyopathy typically complaints of increasing breathlessness when they attempt to perform daily tasks or go for short walks. Patients who were previously able to walk for 2 to 3 km regularly may find it difficult to walk short distances.

During the early stages, patients may only feel mild fatigue and tiredness. As the condition progresses, the breathlessness can become troublesome. Patients may notice increasing amount of swelling in the legs which is due to the accumulation of fluid under the skin.

In more severe cases, patients may notice breathlessness when they lie down in bed or may wake up in the middle of the night feeling breathless. Patients may also notice enlargement of their abdomen which is due to an accumulation of fluid within the abdomen.

The table below summarises the symptoms of dilated cardiomyopathy –

Symptoms of dilated cardiomyopathy

  1. Fatigue/tiredness
  2. Breathlessness at rest, when lying down and when walking or exercising
  3. Decreased exercise tolerance
  4. Swelling of the hands, feet, legs, abdomen and sometimes the face
  5. Decreased sleep as the patient may wake up feeling breathless in the middle of the night

How is dilated cardiomyopathy diagnosed?

A diagnosis of dilated cardiomyopathy is easily made by the cardiologist or treating physician through history and clinical examination. However, the doctor may order additional tests to confirm the diagnosis. These additional tests will guide the physician regarding the best course of management.

The commonly performed tests in treating dilated cardiomyopathy are listed below.

1. Blood tests

This will help determine if a patient has a low hemoglobin (anemia), an infection or whether there are any harmful toxins within the blood stream.

2. Electrocardiogram

Also called an ECG, this test will help determine if the electrical activity in the heart is normal. If any damage has been done to the heart muscle, the electrical activity will be abnormal and this can be seen clearly by the physician on an ECG.

3. Chest x-ray

The chest x-ray will help determine if there is any fluid accumulation in the lungs. It also helps visualise the shape and size of the heart . In dilated cardiomyopathy, the size of the heart is enlarged and this can be clearly seen on a chest x-ray. In addition, if there is any fluid on the lungs, it can be also clearly seen.

4. Echocardiogram

This is an ultrasound scan of the heart that can study the structure and function of the heart muscle and the valves. In dilated cardiomyopathy, the echocardiogram will reveal a thin, poorly moving heart muscle which is not functioning optimally.

Normally, the heart pumps out around 50 to 60% of the blood that it gets from the rest of the body. This is known as the ejection fraction. In dilated cardiomyopathy, this ejection fraction can be significantly reduced below 50%. An echocardiogram helps determine the ejection fraction and movement of the heart muscle.

5. Holter recording

In some patients with dilated cardiomyopathy, the electrical activity of the heart may be rather irregular. This is reflected on clinical examination as an irregular pulse. In patients who have an irregular rhythm, a Holter recording is performed. This is basically a heart monitor that is fitted for a period of 24 hours and records the variation in the heartbeat over that period of time. It provides valuable information regarding how the heart is contracting and can guide treatment effectively.

6. Exercise stress test

This is a test that determines whether the heart is able to work under stressful conditions. The test is described in detail elsewhere. Not all patients with dilated cardiomyopathy will require this test and the decision to perform it is made on a case-by-case basis.

7. Coronary angiography

This test is described in detail elsewhere. In dilated cardiomyopathy, there may not be a need to perform this test. However, if a reduction in blood supply to the heart muscle is thought to be the cause of dilated cardiomyopathy, then performing this test will be certainly of value.

8. Genetic screening

This is a rarely performed test in India. Instead of performing detailed genetic analysis which can be rather costly, patients who have dilated cardiomyopathy may want to have the rest of their blood relatives checked out for the same condition. It can be easily done through echocardiography alone.

Treatment of dilated cardiomyopathy

First and foremost, all patients who have dilated cardiomyopathy must make drastic changes to their lifestyle as advised by the doctor. Below are some of the simple measures that one can try to adopt.

Lifestyle changes

  • Stop smoking
  • Stop alcohol intake
  • Maintain a healthy body weight
  • Exercise regularly (after seeking advice from a medical professional)
  • Eating a healthy diet rich in protein and wholegrain foods and low in fats, sugar and salt. Patients who have diabetes must avoid eating rice and rice-based products along with sugary items. It is always worthwhile seeing a dietician regarding the right diet.

Medical therapy

There are a number of different drugs that are available to treat dilated cardiomyopathy. Patients often require a combination of these drugs so that they can protect the heart safely and effectively.

The commonly used drugs are listed briefly below –

1. Angiotensin converting enzyme (ACE) inhibitors (Ramipril, Perindopril)

These drugs lower the blood pressure and reduce the amount of work that the heart must do to pump blood effectively to the body. In addition, it improves the flow of blood to the heart muscle itself.

You can read more about these drugs here.

2. Angiotensin II receptor blockers (Candesartan)

These are drugs that are used in patients who do not tolerate ACE inhibitors. These drugs also increase the blood supply to the heart muscle and lower the blood pressure.

You can read more about these drugs here.

3. Beta-blockers (Carvedilol, Bisoprolol, Metoprolol)

These drugs slow down the heart rate by blocking the actions of adrenaline on the heart. By doing so, they reduce the amount of work that the heart has to do, along with reducing the amount of oxygen that the heart demands.

Read more about beta blockers here.

4. Diuretics (Furosemide, Bumetanide, Aldactone, Spironolactone, Metolazone)

These heart medications help get rid of any excess fluid in the body. They work by pushing the kidneys to allow more water to pass through them. They are extremely useful in managing patients with heart failure. Patients taking this drug tend to go to the toilet to pass urine more often than normal.

Read more about diuretics here.

5. Digoxin (Lanoxin)

This is a commonly prescribed drug in heart failure and in atrial fibrillation. This drug slows down the heart rate, increases the blood flow through the heart and increases the strength with which the heart contracts.

Read more here.

Surgical Therapy

Patients who suffer from advanced cases of dilated cardiomyopathy may require form of surgical treatment. The available surgical treatments include –

1. Cardiac resynchronisation therapy

In dilated cardiomyopathy, the left and the right side of the heart may not beat in synchrony with each other. It is believed that this can be a contributing factor in the degree of heart failure and how much exercise a patient is able to perform.

In cardiac resynchronisation therapy, a pacemaker called a bi-ventricular pacemaker is inserted into the heart. This pacemaker improves the ability of the heart the contract efficiently. In addition, it can also help patients who have slow heart rates or irregular heart rhythms. Patients who have cardiac resynchronisation therapy notice a significant improvement in their symptoms and in their ability to perform day-to-day activities and exercise.

Read more about cardiac resynchronisation therapy here.

2. Implantable cardioverter defibrillators (ICD)

These are special devices that are placed in patients with dilated cardiomyopathy who may have life-threatening irregular heartbeats. This device constantly monitors the way the heart is beating. If any life-threatening heart rhythms are detected, the device will deliver a small electric shock that will restore normal rhythm.

You can read more about ICDs here.

3. Heart transplant

In special circumstances, patients with dilated cardiomyopathy may be considered for a heart transplant operation. Unfortunately, this is extremely expensive and not all patients are suitable for this procedure.

You can read about heart transplants here.

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