Symptoms of Enlarged Heart Demand Rapid Follow-Through

The heart muscle - known as the myocardium - performs a lot of heavy labor during our lifetimes. The daily workload: 100,000 expansions and contractions, and pumping of 2,000 gallons of blood.

Given the burdens faced by the heart, it understandably malfunctions under some circumstances. Enlargement of the heart muscle, called cardiomyopathy, is a relatively common disorder that demands treatment.

"The heart is basically a pumping muscle," says Bill Choi, MD, Professor of Medicine at the Medical College of Wisconsin, who practices at the Froedtert & The Medical College Emergency Department & Trauma Center. "If it gets weaker, it grows larger to compensate for remodeling." That enlargement is a sign that medical treatment is vitally necessary to prevent dire outcomes.

Types of Cardiomyopathy
There are two principle types of cardiomyopathy.

In dilated cardiomyopathy, the left ventricle of the heart's main pumping chamber loses force and becomes stretched and enlarged. Congestive heart failure can result. Also, abnormal heartbeats and fluctuations in the heart's electrical conduction can occur. Further, dilated cardiomyopathy increases the risk of blood clots that could potentially block circulation of blood to the brain, kidneys, or coronary artery.

This is the most common form of cardiomyopathy. While it does occur among people of all ages, it most frequently crops up among middle-aged males. Viruses most often prove to be the immediate trigger of dilated cardiomyopathy.

While the cause may prove to be elusive in some cases, "the dilated form of cardiomyopathy is always a direct insult to heart muscle right from the beginning," Dr. Choi observes.

"Dilated cardiomyopathy involves the muscle growing weaker and the ventricle getting dilated," explains Dr. Choi. "It's what we call a flabby heart," he notes.

In hypertrophic cardiomyopathy, the heart muscle thickens, especially in the outflow tract of the left ventricle. "The muscle becomes thicker in the left ventricle, which has more power, but it now can't pump the blood out as efficiently as before," says Dr. Choi. The thickening of the muscle shrinks the pumping chamber and its capacity to distribute blood, and the heart may stiffen in addition to undergoing outflow obstruction.

This form of cardiomyopathy generally has a hereditary basis, with abnormal genes creating a predisposition to the disorder. Over half of those with the hypertrophic form have a hereditary link to the disorder.

Hypertrophic cardiomyopathy has a more severe impact upon those who have had the condition since childhood. However, it can occur among people of any age. Most disturbingly, young people may show virtually no symptoms of the disorder and the first symptom can happen as a sudden death.

Warning Signs
Cardiomyopathy triggers a set of what Dr. Choi calls "five cardinal symptoms" that should be taken seriously:

1. Dizziness, light-headedness, and fainting due to obstruction
2. Dyspnea - water stagnating in lungs, resulting in breathlessness after only mild exertion or even while resting
3. Edema - mild swelling of the feet and ankles caused by fluid buildup
4. Angina - chest pain
5. Palpitations or other signs of an irregular heartbeat

The symptoms may vary depending on the precise location of obstructions created by the thickened heart muscle, says Dr. Choi. "The sites of the obstruction determine the symptoms," he notes.

If symptoms are present, heart specialists can conduct a battery of tests, including an echocardiogram (also called ECG or EKG), to check for the existence of muscle thickening and to determine the exact size of the heart chamber.

Primary and Secondary Causes
A variety of conditions may contribute to enlargement of the heart and poor functioning of the organ. When the cause cannot be attributed to a single specific factor such as heart defects, valve disease, or high blood pressure, the cardiac hypertrophy is classified as "primary." It usually becomes apparent as the wall of the heart chamber thickens.

When there is a specific, identifiable cause, the cardiac hypertrophy is considered "secondary" because it is often linked to conditions other than heart problems. For instance, in patients with hypertension, heart muscle can thicken to pump out the blood against high pressure, but eventually dilate the chamber as it fails to compensate.

Here are some of the conditions that can contribute to cardiac hypertrophy (or dilatation of the heart):

• High blood pressure over a prolonged period of time
• Thyroid disorders or diabetes, which hamper metabolism
• Other heart defects, including valve problems, tissue damage from a heart attack, or a chronically high heart rate
• Heavy use of alcohol over many years
• Nutritional deficiencies of critical vitamins and minerals, including selenium (vital to the heart's electrical functioning), thiamin, calcium, and magnesium
• Abuse of cocaine
• Overuse or unmonitored use of certain antidepressants
• Some chemotherapy drugs used to treat cancer, especially adriamycin
• Pregnancy

HIV has become an important factor in dilated cardiomyopathy in two ways. First, it can introduce a viral infection directly into the heart. Second, it can lower the body's immunity to viruses.

A third form of cardiomyopathy, known as the restrictive variety, is relatively rare and usually the result of another disease, such as sarcoidosis - in which inflammation causes lumps of cells, called granulomas, in organs - or amyloidosis, which causes abnormal protein formation in body tissue.

Treatment Options
The initial stages of treatment for all types of cardiomyopathy typically involve eliminating any secondary causes of hypertrophy, along with making changes in diet and lifestyle.

Reducing salt intake and adopting a sensible regimen of regular exercise are considered vital forms of treatment.

For dilated cardiomyopathy, anti-clotting drug therapy is often needed to prevent emboli (blood clots) from forming. Arrhythmia - irregular heartbeats - are another frequent symptom, and can be treated with anti-arrhythmic drugs.

If the heart has become significantly enlarged, arteries might narrow, causing high blood-pressure. In this case, one treatment is to use drugs called vasodilator that relax narrowed, inflexible arteries and increase blood flow.

In the case of hypertrophic cardiomyopathy, the most common treatments include drugs such as beta blockers or calcium channel blockers, which help heart muscle relax and pump out more blood.

Anti-arrhythmic drugs might be used to prevent irregular heartbeats that could lead to cardiac arrest.

Pacemakers and defibrillators are another course of treatment, which may be necessary when patients have persistent irregular heartbeats. For many patients, a combined pacemaker/defibrillator is a lifesaver that can improve heart function and prevent sudden cardiac death.

A new non-surgical procedure, still considered experimental, is called "alcohol ablation." This consists of injecting alcohol into a heart artery with the aim of destroying the excess heart muscle. This procedure normally results in chest pain and could disrupt normal heart rhythms. In this case a pacemaker would need to be installed.

When non-surgical procedures fail to halt the damage caused by cardiomyopathy, a variety of surgical options may be considered.

Like many other serious medical conditions, the precise roots of cardiomyopathy are still unclear after decades of medical advances, says Dr. Choi. In particular, the hereditary nature of hypertrophic cardiomyopathy continues to perplex and fascinate researchers.

"We as human beings are survivors over many millions of years, and everything has a purpose for survival," he points out. "But why exactly we inherited this remains unclear."

Some of the information in this article was provided by the National Institutes of Health and the American Heart Association.

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.