This prevents the heart from pumping effectively, and it can cause sudden cardiac death if left untreated.
As the heart muscle, or myocardium, thickens, the muscle cells can also become disorganized. This can complicate the delivery of electrical signals through the muscle.
The heart muscle also becomes rigid, and this prevents the muscle from fully relaxing.
According to the American Heart Association (AHA), the disease occurs equally in men and women, and it can affect people of many ages, including infants. It is usually inherited, but can develop over time due to high blood pressure or aging.
The AHA notes that the condition affects up to 500,000 people in the United States. Fewer than 10 percent of these cases are among children under age 12 years.
It normally develops during childhood or young adulthood. Younger people with hypertrophic cardiomyopathy are likely to have a more severe form of the condition. It is also the most common reason for sudden cardiac arrest in young people, including athletes.
Symptoms and causes of hypertrophic cardiomyopathy
In atrophic cardiomyopathy, the heart muscle is thickened.
A person can suffer hypertrophic cardiomyopathy and never feel any symptoms, but possible symptoms are:
- Chest pain when under stress, known as angina
- Palpitations, or erratic heartbeat
- Shortness of breath
- Feeling faint or light-headed.
Symptoms can appear at any stage of a person's life, from the teenage years to middle age or older.
The exact cause of hypertrophic cardiomyopathy is not known, but appears to stem from is a genetic mutation.
Studies suggest that 50 percent to 60 percent of people with hypertrophic cardiomyopathy have a close relative with the disease.
The genetic cause of hypertrophic cardiomyopathy for people with no family history of the condition is known as de novo mutation.
There may also be non-genetic factors, but this has yet to be confirmed by research.
How is hypertrophic cardiomyopathy diagnosed?
To diagnose hypertrophic cardiomyopathy, the doctor will ask the patient about their medical history and their symptoms, and there will also be a physical exam.
A heart monitor can check the condition of the heart.
A number of tests can help to diagnose hypertrophic cardiomyopathy.
An electrocardiogram (ECG) will be carried out. Imaging tests that can help the doctor to identify the condition include an MRI scan, a chest X-ray, and an echocardiogram, which uses sound waves.
The heart will be evaluated for signs of valve leakage or obstruction, heart muscle thickness, chamber size, range of valve movement, flow of blood, and the extent of any obstruction.
Blood samples can help to identify specific gene mutations.
Monitoring how the body responds to exercise is a way of checking the heart's condition. Observation is carried out during or just after exercise or both.
A treadmill stress test monitors the heart rhythm, blood pressure, and breathing while the person is walking or running.
An oxygen consumption test measures the patient's use of oxygen, as they breathe into a mask during exercise. A thallium scan monitors the change in blood pressure, and an echocardiogram may be taken after exercise.
Cardiac catheterization involves inserting a soft, thin tube, called a catheter, into the groin or arm through a blood vessel.
The catheter will be guided to the left ventricle of the heart and the ascending aorta, to measure the pressure difference between them. In a person with hypertrophic cardiomyopathy, the pressures will differ.
Treatment options for hypertrophic cardiomyopathy
There is range of treatments for hypertrophic cardiomyopathy. The choice will depend on the risk to the patient and severity of the condition.
Medications can partially remove the obstruction and relax the heart muscles. These include anti-arrhythmia drugs and beta-blockers. The patient may also receive blood thinners such as warfarin, to reduce the risk of blood clots.
A procedure known as alcohol septal ablation involves the injection of alcohol into the artery that leads to the affected section of the heart. This causes a small, controlled heart attack, known as a localized myocardial infarction. The procedure can help to alleviate the symptoms and reduce the obstruction.
Defibrillator therapy can prevent cardiac death in patients at high risk. It monitors the heart rhythms and corrects any irregularities using tiny electric shocks.
Ventricular pacing, using a pacemaker, can help the left ventricle to contract. It is not consistently successful in all cases of hypertrophic cardiomyopathy.
Surgical myectomy is a complex, open-heart operation, in which a section of the overgrown muscle is removed, and any obstruction is cleared. Surgical myectomy has proven successful at treating hypertrophic cardiomyopathy, with a low mortality rate of less than 1 percent.
In some places, alcohol septal ablation has become the treatment of choice for hypertrophic cardiomyopathy, there has been some controversy about whether it should replace surgery for all patients.
Cardiac transplantation is also known as a heart transplant. This involves replacing the diseased heart with a healthy heart from a recently deceased donor. It is a last resort used when all other treatment methods have been unsuccessful.