Hypertrophic cardiomyopathy is an inherited heart muscle disease. Medical science distinguishes between an obstructive and a non-obstructive form. Patients with the nonobstructive form are often asymptomatic for a long time or even for life.
What is hypertrophic cardiomyopathy?
The group of cardiomyopathies summarizes diseases of the heart muscle. Cardiomyopathies are associated with mechanical or electrical dysfunction of the heart. However, they are not necessarily associated with pathologically altered ventricles. Hypertrophic cardiomyopathy is also called hypertrophic familial cardiomyopathy. This disease is a congenital disease of the heart muscle. In addition to asymmetric thickening of the left ventricle, the disease involves dilatation of the ventricles. With a prevalence of 1:500, familial hypertrophic cardiomyopathy is a comparatively common heart disease. Inheritance is in the autosomal dominant mode. Two forms of the heart disease are distinguished: hypertrophic cardiomyopathy with dynamic obstruction and a form without dynamic obstruction. According to the World Health Organization (WHO) classification, all familial hypertrophic cardiomyopathies are classified as genetic primary cardiomyopathies. The disease was described by Liouville and Hallopeau in the mid-19th century. It has been recognized as a clinical entity since a description by Brock in the 20th century.
Causes
Hypertrophic cardiomyopathies are caused by genetic inheritance. More than 200 genetic defects on ten different genes are known as possible causes. The causative genes all code for proteins in the cardiac sarcomere. In more than 50 percent of cases, the genetic defect is in the structure of the so-called beta-myosin heavy chain. The resulting structural alterations of β-myosin and α-tropomyosin result from numerous point mutations of structural proteins in the sarcomere, such as myosinbinding protein C or troponin-T. Hypertrophic cardiomyopathy is therefore also called disease of the sarcomere. A majority of the point mutations affect the MYH7 gene locus on chromosome 14, resulting in a branching disorder of hypertrophied cardiomyocytes in the sarcomere. Due to increased lateral branching, the parallel arrangement is missing. The interstitium is remodeled in connective tissue. Phenotypic expression depends less on the individual mutation than on environmental factors and modifier genes. The disease is usually silent until 13 years of age.
Symptoms, complaints, and signs
One quarter of patients suffer from myocardial thickening of the left ventricle, which is located in the outflow tract. Thus, obstruction occurs during exercise but also at rest. This results in aortic stenosis with high pressure on the left ventricle. In about ten percent of patients, the obstruction is co-ventricular. Muscle thickening also causes muscle stiffness. The ventricle thus fills only to a limited extent during the flaccid phase and blood backs up into the veins of the lungs, causing shortness of breath. This phenomenon is known as diastolic heart failure. Muscle stiffness increases as the disease progresses due to forced pumping. A suction is created in the district of the narrowed outflow tract, also known as the Venturi effect. Thus, leakage in the sense of mitral regurgitation often occurs. Under stress, cardiac arrhythmias occur, which can cause brief loss of consciousness or even sudden cardiac death. Hypertrophic cardiomyopathy underlies many sudden deaths in young adults. Patients with the nonobstructive form are often asymptomatic. When symptoms are present, they are nonspecific symptoms such as shortness of breath, dizziness, or angina.
Diagnosis and disease progression
In diagnosing hypertrophic cardiomyopathy, the most important thing is to rule out reactive myocardial hypertrophy due to exercise (athlete’s heart) or due to hypertension. Diseases of the aortic valve should also be considered for differential diagnosis. Physical examination of the patient reveals a systolic that increases with exertion. This symptom can be observed during the Valsalva maneuver. The ECG ideally provides evidence of left ventricular hypertrophy by showing Q-spikes and repolarization dysfunction.On echocardiography, in addition to septal hypertrophy, displacement of the mitral valve leaflet can be observed, which constricts the outflow tract. The resting gradient in terms of a pressure jump between the left ventricle and the aorta is measured. Magnetic resonance imaging depicts atypical distribution patterns and may show patchy scars in the myocardium. It also allows visualization of flow acceleration and possibly evidence of past septal embolization. Cardiac catheterization measures pressure in the heart to determine myocardial stiffness. Molecular genetic testing confirms the diagnosis. Many asymptomatic patients have rather mild impairment and therefore a good prognosis. Forms with left ventricular outflow tract obstruction often progress to heart failure and therefore have a worse prognosis.
Complications
Complications of hypertrophic cardiomyopathy arise from the potential symptoms and consequences. For example, cardiac arrhythmias can become dangerous. In this case, it becomes necessary to take medications to treat the arrhythmias. In addition, the risk of sudden cardiac death, death from heart failure and stroke is comparatively high, making hypertrophic cardiomyopathy the most complicated and serious form of all cardiomyopathies. Sudden cardiac death occurs in one percent of cases and tends to affect younger patients. Symptoms usually run mildly, making the diagnosis of hypertrophic cardiomyopathy difficult. It can also be observed that there is a higher risk for family members affected by the same disease. In older affected individuals, heart failure plays a greater role as the most common complication. As the left outflow tract becomes increasingly strained, it can narrow as the disease progresses. This can cause the heart muscle to stiffen. A stiff ventricle results in atrial fibrillation, which affects 25 percent of patients. Endocarditis, an inflammation of the inner lining of the heart, can also occur as a secondary disease, spreading to the heart valves. Overall, hypertrophic cardiomyopathy is a non-curable disease, which in most cases runs its course without complications and has good chances of treatment. Life expectancy is not affected; this is the case only in severe disease progression.
When should you go to the doctor?
Abnormalities of the heart rhythm should be examined by a doctor. If there is a feeling of pressure in the upper body, an internal heaviness, or if there are problems with breathing, a doctor is needed. Disturbances in respiratory activity, shortness of breath or interruptions in breathing must be clarified immediately by a physician. There is a risk of undersupply of the organism, which can lead to multiple organ failure. Since hypertrophic cardiomyopathy can lead to sudden cardiac death without medical treatment, a visit to the doctor is recommended at the first irregularities of cardiac activity. If there is palpitations, increased blood pressure, sleep disturbances or inner restlessness, a doctor should be consulted. In case of chest pain, reduced performance or rapid exhaustion, investigations should be initiated to clarify the cause. If disturbances of consciousness set in or unconsciousness occurs, the affected person requires an emergency physician. An ambulance service must be alerted and first aid measures must be initiated. In case of dizziness, unsteadiness of gait or disturbances of attention, a check-up visit to a physician is recommended. A general feeling of illness or persistent malaise must be examined and treated. If the symptoms increase, a visit to the doctor is indispensable. If emotional problems set in with the physical irregularities, a doctor is needed.
Treatment and therapy
Although hypertrophic cardiomyopathy is not curable to date, it can now be treated symptomatically to good effect. Therefore, the prognosis improves the earlier the diagnosis is made. Conservative treatment measures include drugs such as beta-blockers to down-regulate the left ventricle. Antiarrhythmic drugs reduce cardiac arrhythmias. Patients are advised to avoid competitive sports and sports with sudden maximum stress. Interventional measures may include catheter treatment of septal hypertrophy.This treatment is performed by transcoronary ablation of septal hypertrophy or percutaneous transluminal septal myocardial ablation. Through cardiac catheterization, the ramu interventricularis anterior is closed with a balloon. When the gradient in the outflow tract drops, pure alcohol is chased through the balloon and induces a circumscribed infarct in the obstructing district. This reduces the obstruction. Another possible treatment procedure is endocardial radiofrequency ablation of septal hypertrophy. Cardiac catheter-directed radiofrequency ablation treats cardiac arrhythmias. Electrical energy is delivered to the right ventricle of the septum through a cardiac catheter in the area of obstruction. Thus, scarring reduces the gradient in the outflow tract of the left ventricle. An invasive treatment option is transaortic subvalvular myectomy. This cardiac surgery removes muscle tissue from the outflow tract of the left ventricle through the aortic valve. Supportive measures are also available to patients with hypertrophic cardiomyopathy. For example, a defibrillator may be implanted to treat arrhythmias.
Prevention
Hypertrophic cardiomyopathy cannot be prevented because the disease has an underlying genetic cause.
Follow-up care
Follow-up options for hypertrophic cardiomyopathy focus primarily on regular checkups to ensure that blood pressure is properly adjusted. Depending on the symptoms, the physician may extend this diagnosis or shorten the intervals between examination appointments. In some cases, patients have access to specialized physicians who offer corresponding consultation hours. In the long-term course of follow-up, a stable course should take place, which the treating physician is responsible for monitoring. If necessary, a new adjustment of the medication is necessary to avoid a worsening. However, in hereditary patients with dilated left ventricle, the risk of sudden cardiac death increases. Sufferers should refrain from excessive physical exertion and should also be careful when exercising. If they overload themselves, the risk increases sharply. If physical exertion is unavoidable, patients should not stop abruptly, but allow it to subside gradually. However, the usual everyday activities are generally not a problem and do not cause discomfort. So those affected do not have to give up swimming, traveling and light activities. If other surgical or dental procedures are necessary, the responsible physician must take the necessary precautions to protect the patient and minimize the risk.
Here’s what you can do yourself
In everyday life, the main thing is to avoid situations that are physically demanding. Depending on the usual physical stress tolerance of the affected person, this may include intensive sports activities and competitive situations such as a soccer match or playing top-level sports. Heavy physical work should also be avoided. This is especially true if they involve heavy pushing and shoving. However, if a physically stressful situation does occur, it is best not to stop it abruptly, but to let it come to an end slowly. However, most everyday activities, as well as traveling or swimming, are perfectly possible for otherwise symptom-free sufferers. Sexual activities within a normal framework are unproblematic with normal everyday stress. To prevent the development of further heart disease, patients should refrain from smoking. It is also recommended to eat a diet rich in vegetables and fruits and to consume only small amounts of cholesterol-containing foods with animal fats as well as meat. All stress factors should also be reduced. Those affected can also find help in self-help groups and Internet forums.
