Hypertrophic cardiomyopathy is a genetic defect where the myocardium (heart muscle) thickens abnormally. Thickened myocardium can affect the heart’s electrical system, putting the patient’s life in danger through abnormal heart beats (arrhythmias) and rarely, sudden death.
In some cases, enlarged heart muscles are not able to relax between the beats, as it normally does, and thus it no longer receives oxygenated blood necessary for a normal development of cardiac activity.
In rare cases, thickened myocardium reduces the heart’s ability to pump blood effectively to the body.
Causes of Hypertrophic cardiomyopathy
Researchers found that genetic defects are the leading causes of hypertrophic cardiomyopathy. People who have a family history of hypertrophic cardiomyopathy are the most exposed to the disease and therefore have a lower life expectancy than the general population.
About 50% of the patients with hypertrophic cardiomyopathy have inherited the disease from their parents. In most cases remaining fetuses (medical name of unborn children) suffer genetic changes since the earliest stages of development in utero (in the womb). These mutations cause abnormal cardiac tissue.
Hypertrophic cardiomyopathy is transmitted autosomal dominant and is caused by mutations in genes encoding the cardiac sarcomere components (beta-myosin, myosin-binding protein C and troponin T).
In association of left ventricular hypertrophy of unknown cause with Wolf-Parkinson-White syndrome and preexcitation syndrome, were reported mutations in the gene encoding the gamma-2 subunit of AMP activated protein kinase.
Symptoms of Hypertrophic cardiomyopathy
However, if symptoms occur, usually manifesting by:
Breathing difficulties (dyspnea), to physical exercises;
Fatigue more often than usual;
Chest pain (angina);
Fainting (syncope) occurred during exercise;
Heart palpitations, rapid awareness and irregular heartbeat.
Sudden death may occur at the beginning of ventricular tachycardia (a type of fast heart beat) or may occur in other dangerous arrhythmias. The genetic factor is influencing the occurrence of sudden death in people with hypertrophic cardiomyopathy. Other risk factors that can cause sudden death include severe obstruction of the left ventricle, multiple episodes of fainting (syncope), repeated episodes of ventricular tachycardia and low blood pressure during exercise.
Although it can occur at any age, sudden death is more shocking when it occurs in young people and athletes. Although in mass media these tragic deaths are exaggerated, recent studies have shown that sudden death is increasingly rare (1% per year) than they thought.
Hypertrophic cardiomyopathy can be difficult to diagnose because symptoms do not always develop. The first step in diagnosing heart problems is a complete medical history and physical examination.
Family doctor will follow if there were cases of hypertrophic cardiomyopathy or other cardiac disease, if there were deceased relatives at a young age or of sudden deaths. In some cases, when young people die from a heart attack caused by hypertrophic cardiomyopathy, it is not detected because an autopsy is not always done.
During the examination the doctor will listen to your heart with a stethoscope and if he hears extra noises or abnormal (gallop or heart murmur), concludes that the structure of the heart is abnormal.
For a diagnosis and a treatment of the disease are made the following tests:
Electrocardiogram (EKG) measures the electrical activity of the heart during contraction or relaxation. An abnormal electrocardiogram may be the first sign of hypertrophic cardiomyopathy in people who have no other symptoms. ECG changes: left ventricular hypertrophy with repolarization abnormalities, pathological Q waves, left and right atrium dilatation.
Echocardiography is a type of ultrasound test that uses high frequency sound to create an image of the heart, which is seen on a screen. This examination is the best and easiest way to diagnose hypertrophic cardiomyopathy and its severity.
Echocardiography can be used to:
To assess how well it fills with blood the left lower chamber of the heart (left ventricle) when it expands and to measure the amount of blood pumped during contractions (ejection fraction);
Determining the normal functioning of heart valves;
Measuring the size of the heart;
Determine the thickness of the myocardium (heart muscle) and the wall separating the two lower chambers of heart (ventricular septum);
Measuring the degree of reduction in blood flow during contraction (systole) when the wall separating the two lower chambers of the heart is abnormally thickened.
Electrocardiography and echocardiography are the best diagnostic methods to detect hypertrophic cardiomyopathy. People who have a family history of sudden death, especially young athletes or those who are thinking to start an exercise program; you should consult a doctor to be tested for hypertrophic cardiomyopathy. These tests can help to evaluate a person’s passing out during strenuous efforts.
For echocardiography, early checks are recommended for children between 12 and 18 years who have a family history of hypertrophic cardiomyopathy and every five years thereafter. Additional tests are used for identification of hypertrophic cardiomyopathy in people who have no conclusive results to examinations with electrocardiogram and echocardiography. If hypertrophic cardiomyopathy is identified, doctors recommend checking every 12-18 months.
Chest radiography reproduces an image of the heart on a film using strong light rays that pass through the body. An X-ray can show the shape and size of the heart. In advanced stages of hypertrophic cardiomyopathy, radiography may reveal signs of pulmonary edema, lungs accumulating fluids.
Cardiac catheterization or coronary angiographies involve inserting a long, thin tube (catheter) through an artery or vein in the arm to the heart to measure the pressure in the heart chambers. Contrast substance can be injected through the catheter to see if the coronary arteries are blocked, how well the heart chambers pump is or if the heart valves are normal. Angiography can be done if the results are not conclusive echocardiograms.
Genetic testing can identify specific genes that are related to the disease. Many people with relatives suffering from hypertrophic cardiomyopathy wonder if they or their children should be tested genetically. Until now, the routine genetic testing is not considered practical because there are many abnormal genes that cause the disease. Genetic testing is currently used in a number of cases when specific genetic mutation has been identified in sick relative.
Treatment of Hypertrophic cardiomyopathy
Treatment – general things
Many people carry the gene for hypertrophic cardiomyopathy but do not develop symptoms. Doctors have not reached to a consensus on to or not to prescribe medication of this group of people. Some doctors believe that medication can improve cardiac function and prolong life in these cases. However, currently there are no studies that prove this.
If symptoms appear, treatment is recommended. Hypertrophic cardiomyopathy cannot be cured with medication, but they can be used to treat complications, including atrial fibrillation among them and heart attack.
Beta blockers. Beta blockers such as propranolol or atenolol are used frequently in people with dyspnea or chest pain. They lower the blood pressure, slow the heart rate, improve blood circulation, which helps to decrease symptoms and increase the power at physical exercises. They can even prevent or postpone the progression to heart failure caused by hypertrophic cardiomyopathy;
Calcium channel blockers. If no improvement is observed, after the administration of beta blockers, the physician will likely try a calcium channel blocker such as verapamil. These medicines also slow the heart rate and lowers the blood pressure. Your doctor may first try a calcium channel blocker and then move to a beta blocker, if results are not achieved. Typically, these drugs should not be used at the same time
Amiodarone. This is very powerful anti-arrhythmic medicines that is sometimes used to treat people suffering from hypertrophic cardiomyopathy, ventricular tachycardia or who are at high risk of sudden death. Research on continuous Amiodarone, but so far are not clearly proven that this medicine helps to prevent sudden death. Moreover, the longtime use of this medication can rather cause serious side effects on people.
Disopyramide. It is sometimes used, especially in episodes of fainting. This medication may decrease the force with which the heart contracts and reduce the number of abnormal heart rhythms. It helps to limit the symptoms of heart failure.
Atrial fibrillation occurs in 20% of people with hypertrophic cardiomyopathy. In atrial fibrillation, atrial abnormal electrical impulses cause the upper chambers of the heart (atrial fibrillation), which cause rapid and irregular beating of the ventricles, the heart’s main pump.
For most people, this aspect of atrial fibrillation itself is not a vital threat. However, for people suffering from hypertrophic cardiomyopathy, atrial fibrillation may increase the risk for the occurrence of other abnormal heart beats that can be life threatening. It also increases the risk of heart failure and myocardial infarction. For these reasons, most doctors treat seriously atrial fibrillation in people suffering from hypertrophic cardiomyopathy. Treatment usually comes down to the use of medications for rhythm controlling and / or cardiac electrical cardioversion to restore normal heart rhythm.
Anticoagulants are prescribed usually for people who suffer from atrial fibrillation. They help to protect against blood clots that develop in the heart. Blood clots are dangerous because they can escape and can spread into the bloodstream (embolism), which can cause a heart attack, stroke or blockage of blood flow to the hand or foot.
Most people suffering from hypertrophic cardiomyopathy, a cardiologist should be consulted to determine the risk of ventricular tachycardia, an abnormally fast heartbeat, which can cause sudden death. For those who fall into the category of risk advanced implantable cardio-defibrillator (ICD) appears to be the most effective treatment against sudden death. In a study of a large number of people suffering from hypertrophic cardiomyopathy with high risk of sudden death, ICD has identified ventricular tachycardia and restored normal heart beat for those suffering from life-threatening arrhythmia what they could.
Due to the risk of sudden death, it is important for people with hypertrophic cardiomyopathy to avoid activities too demanding and intense physical exercise. Around 50% of sudden deaths in people with hypertrophic cardiomyopathy occur during or after intense physical activity. See your doctor about physical exercises and what physical activities are safe.
Prolonged activity in hot weather is not recommended, because dehydration can worsen the symptoms at people with hypertrophic cardiomyopathy.
Once started the medication, most people will have to continue it for the rest of their lives.
People who suffer from this disease who are on medical or dental interventions often are given antibiotics to prevent heart infections (endocarditis).
Treatment it the conditions gets worse
Medicines for heart failure may be used if hypertrophic cardiomyopathy progresses.
An operation called myectomy or myomectomy is recommended for people if the medication does not help to reduce the symptoms of heart failure (NYHA class III and IV) due to hypertrophic cardiomyopathy. In this surgery, a thickened portion of the heart muscle is removed. Often the muscle that is in excess is found in the septum that separates the ventricles. An increased septum can intervene in the left ventricular function and limit blood flow out of the heart. Studies show that this surgery causes a decrease of symptoms and increased ability for physical activity in case of 70% of patients over the next five years or more.
A pacemaker can be surgically implanted in order to enhance the activity of the heart pumping. Wires from the pacemaker are placed in the atria and ventricles. Because the pacemaker controls both chambers of the heart, is called atrioventricular pacing. It is more likely that these dual pacemakers be beneficial for persons over 65 years for which surgery is not an option.
Heart transplantation is an optional treatment available for a small number of people who suffer from serious and terminal cardiomyopathy. This procedure involves a surgical removal of the diseased heart and replaces it with a healthy heart donated by a deceased recently. There are a limited number of donor hearts. Moreover, the criteria for eligibility for a transplant are very specific.
A non-surgical septal reduction method is a new procedure in the treatment of people with hypertrophic cardiomyopathy. When the surface edges of the heart that separates the right chamber of the heart to the left (septum) becomes too thick, it causes obstruction of the left ventricle, which prevents normal pumping. Thickened septum is reduced in size by injecting alcohol into the coronary artery supplying the heart with blood. Alcohol destroys a part of the heart muscle that forms the thickened septum, thereby reducing obstruction and improving the pumping power of the left ventricle. The advantages of this procedure are to avoid major surgery and long recovery because alcohol can be administered through a catheter during a cardiac catheterization procedure. After this procedure is required implantation of a permanent pacemaker.
Studies show that this procedure reduces the symptoms and increases the life quality over several years. However, long-term effects have not been studied yet. Experts recommend that this complex procedure to be done in a medical center where the staff has enough experience in its use.
Outpatient treatment (at home)
Due to the risk of sudden death, it is important for people with hypertrophic cardiomyopathy to avoid strenuous activities and strenuous exercises. Approximately 50% of sudden deaths in people with hypertrophic cardiomyopathy occur during or after strenuous activities. Ask your doctor about the level of difficulty of the physical exercises and what type of activities are safe. Because the dehydration can worsen the symptoms at people suffering from this disease, prolonged activity in hot weather is not recommended.
The following recommendations for care are also important:
Avoid alcohol. Drinking alcohol for a long period of time increases the risk of cardiomyopathy in some people.
Good hydration (if you do not have heart failure or another condition that requires limiting fluid intake).
Daily weighing. People with heart failure can quickly accumulate large amounts of fluids, so it is necessary to balance daily.
An increase in weight from 1.36 kg to 1.81 kg in two days may be a sign of heart failure and should call your doctor.
It is recommended to follow medical advice for regular examinations to monitor your health condition.
Because some people with hypertrophic cardiomyopathy are at high risk of sudden death, is a good idea for the family to learn cardiopulmonary resuscitation techniques.
Atrial fibrillation (irregular atria beats) is the most common complication of hypertrophic cardiomyopathy. This abnormal rhythm of the atria interacts with the normal function of the heart pump. This may form thrombi (blood clots) that can break and migrate into the bloodstream (systemic embolism). They can cause heart attack, stroke, or stopping blood flow to an arm or leg.
Heart failure may develop if this disease progresses, so that the lower chambers of the heart (ventricles) are no longer able to pump enough oxygenated blood and nutrients for the body’s needs. Common symptoms include fluid retention (edema) in the legs, knees and feet; breathing problems when lying down or making effort; and increased nighttime urination.