Hypertrophic obstructive cardiomyopathy (HOCM) is a disease of the heart muscle. The main feature of HOCM is a thickening in the wall of the left ventricle. The disease cannot be cured and is occasionally accompanied by life-threatening symptoms. However, with appropriate treatment, those affected can lead a largely symptom-free life. You can find further information and selected HOCM specialists here.
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Brief overview:
- What is HOCM? A disease of the heart muscle that causes the wall of the left ventricle to thicken. This can lead to complications such as cardiac arrhythmias and heart failure.
- Symptoms: The symptoms depend on the degree and severity of the disease. They are basically similar to those of heart failure. Typical symptoms are A feeling of pressure in the chest, shortness of breath, reduced performance and cardiac arrhythmia.
- Cause: A genetic predisposition is often the cause of HOCM. The disease is therefore congenital.
- Diagnosis: After listening to the heart sounds, echocardiography, an ECG and cardiac catheterization confirm the diagnosis.
- Treatment: There is no cure. Medication and, if necessary, surgical and interventional procedures can alleviate the symptoms.
- Children: Genetic diagnostics can show whether a child has a genetic predisposition to HOCM. Children with HOCM must not take part in competitive sport as there is a risk of sudden cardiac death.
- Prognosis: If the disease remains untreated, in the worst case it can lead to sudden cardiac death. With appropriate treatment and monitoring, an almost normal life is possible.
Article overview
What is hypertrophic obstructive cardiomyopathy (HOCM)?
HOCM is a disease of the heart muscle. Alongside hypertrophic non-obstructive cardiomyopathy (HNCM), it is one of the hypertrophic cardiomyopathies (HCM). The obstructive form is significantly more common than the non-obstructive form, accounting for around 70 % of cases.
In HOCM, a constriction (obstruction) occurs in the area of the ejection tract in the left ventricle. From here, the blood from the ventricle passes through the aortic valve into theaorta and thus into the body.
The cause of the obstruction can be
- an enlargement and protrusion of the septum (interventricular septum) into the left ventricle and
- a pathological (abnormal) movement of the mitral valve (heart valve between the left atrium and left ventricle)
be.
In HCM, the heart wall of the left ventricle (heart chamber) is usually enlarged, occasionally also the right ventricle.
In the obstructive form, the septum (interventricular septum) is also enlarged (so-called septal hypertrophy). The septum then bulges into the left ventricle.
The mitral valve may also be affected. A suction pulls the mitral valve further into the ventricle due to the narrowing. This results in a malfunction of the mitral valve (so-called mitral valve insufficiency, also known as mitral regurgitation).
Comparison of a healthy heart with a heart affected by HCM © peterjunaidy | AdobeStock
What are the symptoms of HOCM?
The degree and severity of the symptoms depend on the severity of the disease. Basically, the heart is not able to pump enough blood into the circulation. The symptoms are therefore often based on the typical symptoms of chronic heart failure(cardiac insufficiency).
If the mitral valve no longer closes properly, blood can be forced back into the pulmonary circulation. This manifests itself, for example, in
- rapid fatigue,
- reduced performance and
- shortness of breath during exercise.
If there is already a dysfunction of the left atrium, atrial fibrillation may occur. However, those affected may also be symptom-free under certain circumstances, or their symptoms may only occur during physical exertion. This may be the case if the septal hypertrophy is only slightly pronounced and the atrium and mitral valve are not affected.
Angina pectoris (chest tightness) and fluid accumulation in the legs and lungs can also occur. If the brain is not supplied with sufficient oxygen, dizziness and syncope(loss of consciousness) can occur.
People with HOCM often feel tired and less productive than other people © leszekglasner | AdobeStock
HOCM leads to a thickening of the heart muscles. For this reason, they require more oxygen than a healthy heart. At the same time, the performance of the heart is reduced, which in turn leads to an undersupply of oxygen to the heart muscle.
This imbalance can lead to feelings of tightness and pressure in the chest(angina pectoris) of those affected. This chest pain can be felt both during exertion and at rest.
This diagram shows the large and small circulation. It illustrates the problem of insufficient oxygen supply in HOCM © LuckySoul | AdobeStock
Cardiac arrhythmias can also occur. Those affected sometimes describe this as heart stumbling. In combination with general heart failure, they can lead to fainting spells or dizziness.
What are the causes of HOCM?
Genetic factors are among the main causes of hypertrophic obstructive cardiomyopathy. Most cases can be explained by errors in the genetic material. These lead to disorders in the formation of special proteins that are required to build certain muscle units.
Affected individuals can pass on such genetic defects directly to their offspring. For this reason, HOCM often runs in families. However, the disease can manifest itself differently in each offspring.
Examination and diagnosis of HOCM
During the patient consultation, the doctor will first ask about the patient's symptoms and medical history. If HOCM is suspected, the patient's family medical history is also relevant. If the disease has already occurred within the family, the risk of other family members developing the disease is also increased. The closer the family relationship, the higher the risk.
During the physical examination, the doctor looks for symptoms of cardiac arrhythmia and heart failure. He or she will also listen to the heart, as a flow noise is typical of hypertrophic obstructive cardiomyopathy. This murmur often intensifies during physical exertion.
Special examination methods are available to the doctor to confirm the diagnosis:
Ultrasound of the heart (echocardiography, also known as cardiac echo) is a radiation-free and risk-free ultrasound examination. Waves are emitted at high frequency, making the structures of the heart visible. The doctor can thus detect a thickened heart wall or a thickened heart muscle.
An electrocardiogram (ECG) measures and records the electrical activity of the heart. For a complete picture
- an ECG of the heart "at rest", i.e. without stress,
- a long-term ECG using a portable device over 24 or even 48 hours and
- an exercise ECG, for which the patient sits on an ergometer.
In the ECG history, HOCM patients show a specific rhythm disturbance or a permanently increased heart rate.
A thin tube is inserted into the heart by means of a cardiac catheterization. Instruments can be inserted through this tube for examination and treatment. This allows the doctor to assess the coronary arteries and also obtain tissue samples from the heart muscle. He then examines the tissue under a microscope so that he can make a reliable diagnosis.
An MRI (magnetic resonance imaging) uses a magnetic field to create high-resolution images of the heart. The examination is painless and does not involve harmful radiation.
The deflections and curves of an ECG give an indication of the type of disease © jimmyan8511 | AdobeStock
Treatment and specialists for HOCM
To date, hypertrophic obstructive cardiomyopathy cannot be cured. Doctors can only treat the symptoms, not the cause.
In general, it is advisable for those affected not to put excessive strain on the heart and to take it easy physically. Various treatment options are available to alleviate restrictive symptoms.
The first point of contact for HOCM patients is a specialist in heart disease, i.e. a cardiologist. The German Society of Cardiology has published a guideline for the diagnosis and treatment of HOCM, which you can access here.
The treatment chosen depends on the symptoms and their cause, for example
- the administration of medication (beta blockers or antiarrhythmic drugs) to regulate the heartbeat,
- the implantation of a defibrillator (ICD, "implantable cardioverter defibrillator") in the event of arrhythmia or the risk of sudden cardiac death, or
- the removal of muscle tissue in cases of severe septal hypertrophy.
Depending on the degree of severity, surgical or interventional procedures are also possible.
Transcoronary ablation of septal hypertrophy (TASH) is an important interventional procedure to eliminate HOCM. The underlying idea is to reduce the blood supply to the thickened tissue so that it shrinks again.
This goal is achieved during a cardiac catheterization procedure: the administration of ethanol into the corresponding coronary vessel creates an artificial infarction in the area of hypertrophy (thickening). This causes tissue to die and the thickening can regress. The treatment success rate is 88 %.
Drug therapy for HOCM
Drug therapy for hypertrophic obstructive cardiomyopathy (HOCM) aims to alleviate symptoms, reduce the risk of arrhythmias and support heart function. Here are some medications that are commonly used to treat HOCM:
- Beta-blockers: they reduce the heart rate and decrease the contractility of the heart muscle, which can alleviate obstructive hypertrophy. They also help to reduce the risk of arrhythmias.
- Calcium channel blockers: These drugs can help to lower the heart rate and reduce the contractility of the heart. They can also be helpful in controlling arrhythmias.
- Disopyramide: An antiarrhythmic drug commonly used to treat symptomatic obstructive hypertrophy by reducing the force of contraction of the heart and alleviating obstructive symptoms.
- ACE inhibitors or angiotensin II receptor blockers (ARBs): These medications can help lower blood pressure and reduce the strain on the heart by dilating the blood vessels.
- Diuretics: They can be used to treat heart failure and reduce fluid retention in the body, which can relieve the symptoms of HOCM.
- Antiarrhythmic drugs: Certain antiarrhythmic drugs can be used to control irregular heartbeats and reduce the risk of life-threatening arrhythmias.
The choice of medication and its dosage depends on
- the patient's individual situation
- the severity of the symptoms and
- the presence of concomitant diseases
diseases. The therapy is often determined in close cooperation with a cardiologist and monitored regularly to achieve the best results.
Children with HOCM
HOCM is a congenital disease, so it can manifest itself in infancy. However, it is rarely diagnosed in infancy, but usually only in adolescence.
In symptom-free children in families in which HCM occurs, genetic diagnostics can be carried out. It shows whether the child is a carrier of a genetic mutation responsible for the disease. If this is the case, the child should be monitored more closely.
In children with HOCM, obstruction of the left ventricular outflow tract can increase as a result of physical activity (for example during school and recreational sports). This can lead to rapid exhaustion and shortness of breath, but also to fainting.
Children with HOCM become exhausted more quickly and are tired more often than children with a healthy heart © famveldman | AdobeStock
HOCM carries the risk of sudden cardiac death. Therefore, children with hypertrophic obstructive cardiomyopathy must not participate in competitive sports or isometric muscle exercise. Isometric muscular exertion is muscular exertion without movement, i.e. the pure tensing of muscles.
Sudden cardiac death in particular, which can also occur during sporting activity as described, is a serious complication. It is therefore very important that children are correctly diagnosed at an early stage and the risk of sudden cardiac death is determined.
The risk is higher if children have
- have had cardiac arrhythmias and fainting spells, and
- septal hypertrophy,
- an enlarged atrium and/or
- an enlarged heart wall of the left ventricle
are present.
Implantation of a defibrillator (known as an ICD) can then reduce the risk of sudden cardiac death.
Prognosis for HOCM
Hypertrophic obstructive cardiomyopathy does not necessarily have to be accompanied by symptoms. On the other hand, life-threatening cardiac arrhythmias can also occur as a complication. If HOCM remains undetected, the disease is one of the most common causes of sudden cardiac death.
If left untreated, this disease kills around
- about six percent of affected children and adolescents and
- about one percent of adults.
Athletes are particularly frequently affected.
Early detection and treatment of HOCM can mitigate many of the risks and symptoms of the disease.
With optimal treatment, nothing stands in the way of a normal life expectancy. However, the affected person's ability to work depends on the severity of the disease and their personal condition.
References
- Amboss (2020) Hypertrophe Kardiomyopathie (HCM). https://next.amboss.com/de/article/_S05Xf?q=hypertrophe%20kardiomyopathie
- Batzner A et al. (2019) Hypertrophe obstruktive Kardiomyopathie. Dtsch Arztebl Int 116: 47-53; DOI: 10.3238/arztebl.2019.0047
- Dittrich S et al. (2012) Primäre Kardiomyopathien. LL 28 Leitlinie Pädiatrische Kardiologie. Deutsche Gesellschaft für Pädiatrische Kardiologie. http://www.kinderkardiologie.org/fileadmin/user_upload/Leitlinien/18%20LL%20Primaere%20Kardiomyopathien.pdf
- Miron A et al. A Validated Model for Sudden Cardiac Death Risk Prediction in Pediatric Hypertrophic Cardiomyopathy. Circulation 2020; DOI: 10.1161/CIRCULATIONAHA.120.047235
- Sieverding L. (2015) Kardiomyopathien bei Kindern und Jugendlichen. In: Hoffmann G., Lentze M., Spranger J., Zepp F. (eds) Pädiatrie. Springer Reference Medizin. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-54671-6_206-1