Overview: Hypertrophic cardiomyopathy is a heart disease characterized by cardiac muscle hypertrophy.
Hypertrophic cardiomyopathy is a heart disease characterized by hypertrophy of the myocardium, which mainly manifests itself as dyspnea, palpitations, chest pain, fainting, etc. It is an autosomal dominantly inherited heart disease and can be treated with medication and surgery.
Definition
Hypertrophic cardiomyopathy is a primary cardiomyopathy characterized by thickening of the left ventricular wall and is the most common hereditary heart disease.
It is the leading cause of sudden cardiac death in adolescents and athletes, and is most common between the ages of 10 and 35 years. Death due to heart failure is most common in middle-aged patients.
Classification
Classification according to the presence or absence of obstruction of the left ventricular outflow tract
According to the difference between the LV outflow tract and peak aortic pressure gradient (LVOTG) measured during echocardiography, it can be categorized as obstructive, nonobstructive, or insidious.
Obstructive: LVOTG ≥30 mmHg at quiet.
Non-obstructive: LVOTG normal at quiet, LVOTG <30mmHg during loaded exercise.
Occult: LVOTG normal at quiet, LVOTG ≥30mmHg during loaded exercise.
Classification according to the site of hypertrophy
Hypertrophic cardiomyopathy can be classified as apical hypertrophy, right ventricular hypertrophy and isolated papillary muscle hypertrophy.
Classification according to family history and hereditary pattern
Familial hypertrophic cardiomyopathy: the onset of family aggregation, accounting for 60% to 70%, mostly autosomal dominant inheritance.
Sporadic hypertrophic cardiomyopathy: hypertrophic cardiomyopathy without familial aggregation.
Incidence
Prevalence
According to the results of a survey conducted in nine provinces and cities (districts) from October 2001 to February 2002, the prevalence rate of the overall population was 0.16%, and the prevalence rate of males was higher than that of females (0.10%), which was estimated to be more than one million patients with hypertrophic cardiomyopathy in China.
The prevalence of hypertrophic cardiomyopathy in the general adult population in Europe and the United States is about 0.20%, and the prevalence in men is about three times higher than that in women.
Incidence rate
The incidence of hypertrophic cardiomyopathy in adults is 2.50/100,000 person-years in the United States (1989) and 4.14/100,000 person-years in Japan (2002), according to the results of studies in the United States (1989) and Japan (2002), respectively.
Causes
Causes
The disease is an autosomal dominant heart disease. 40% to 60% of hypertrophic cardiomyopathies in adolescents and adults are caused by mutations in the gene encoding myocardial sarcomeric proteins.
Between 5% and 10% are caused by other mutations or non-genetic diseases, including inborn metabolic disorders (e.g., glycogen storage disease, carnitine metabolism disease, lysosomal storage disease), neuromuscular disorders (e.g., Friedreich ataxia), mitochondrial disorders, Saki syndrome, systemic amyloidosis, and others.
In addition, 25% to 30% of the cases are of unknown etiology.
Pathogenesis
The pathogenesis of the disease is unclear.
Myocardial fiber contraction is impaired due to gene mutations, resulting in compensatory hypertrophy and diastolic dysfunction.
Genetic mutations may result in abnormal myocardial Ca2+ dynamics, which in turn increases intracellular Ca2+ concentrations in the myocardium and may ultimately lead to myocardial hypertrophy and cardiomyocyte disorders.
Symptoms
Main Symptoms
Exertional dyspnea
It is the most common symptom, present in more than 90% of symptomatic patients. Nocturnal paroxysmal dyspnea is less common.
Chest pain
1/3 of patients may have exertional chest pain, and some patients may have persistent chest pain at rest or after meals.
Palpitations
The incidence is 22.5%, which may be related to cardiac decompensation and arrhythmia.
Syncope or syncope with aura
Syncope occurs at least once in 15% to 25% of patients. Syncope with aura often occurs during exercise.
Sudden cardiac death
Most often caused by ventricular tachycardia (sustained or nonsustained), ventricular fibrillation, and atrioventricular block.
Other symptoms
Left ventricular dilatation
Left ventricular dilatation occurs in about 10% of patients with symptoms such as chest tightness, palpitations, shortness of breath, and dyspnea.
Complications
Atrial fibrillation
Most of the patients have no obvious symptoms. Those who have symptoms most commonly have palpitations, and may also have chest pain, dyspnea, limb weakness, dizziness, and blackouts (sudden darkness in front of the eyes).
Heart failure
Dyspnea, cough, sputum, hemoptysis, edema, and cyanosis of the skin and mucous membranes.
Thromboembolism
Manifested by oliguria, dyspnea, coma, fainting, abdominal pain, diarrhea, etc.
Consultation
Recommendations
Hypertrophic cardiomyopathy in cardiovascular medicine.
Symptoms such as dyspnea, chest pain and palpitation after activity are recommended to consult the doctor promptly.
For repeat visits, please follow the doctor’s instructions and visit the doctor on time.
Preparation
Registration
You need to register at the hospital site or through official channels (e.g., the hospital’s official website, official app, 114 platform, etc.) before the outpatient consultation.
Emergency admissions can be made directly by registering. Pre-hospital emergency admissions generally do not need to register in advance, and can be made up in the course of treatment.
Preparation of documents
Prepare your medical card, social security card (medical insurance card) and other documents.
Bring your previous medical records, medical history, and echocardiogram report.
If you are taking medication, prepare a list of medications.
What questions the doctor may ask
When do the symptoms usually appear?
Have any tests been done? What are the results of the tests?
Is there any history of other medical conditions, medications, treatments, and any similar conditions in the family?
Questions you can ask your doctor
What tests are needed?
How to treat?
Can it be cured?
Is it hereditary?
What do I need to pay attention to on a daily basis?
Diagnosis
Diagnosis
Medical history
Family history of hypertrophic cardiomyopathy.
History of heart failure, heart transplantation, and implantable cardioverter-defibrillator pacemaker therapy.
Clinical manifestations
Symptoms
Dyspnea, chest pain, palpitations, syncope during/after activity, some patients are asymptomatic.
Signs
In patients with hypertrophic obstructive cardiomyopathy, a coarse jet systolic murmur can be heard in the 3rd to 4th intercostal space at the left edge of the sternum, which does not conduct to the neck, and the heart murmur can be enhanced by the aggravation of left ventricular outflow tract obstruction, e.g., cardiac tonic medication, when the patient changes from a squatting position to standing position, or when he or she is taking nitroglycerin with his or her mouth full.
The patient’s heart is usually not big, and the end stage shows that the left heart or the whole heart is obviously enlarged, and fine wet rales can be heard in both lungs when accompanied by left heart failure, and depressed edema of the lower limbs can be found when accompanied by right heart failure.
Electrocardiogram
The main manifestations are QRS wave left ventricular high voltage, T wave inversion and abnormal Q wave.
Precautions
Avoid strenuous exercise, emotional excitement, and remove electronic products from the body before the examination.
During the examination, expose the skin of the forehead, bilateral wrists and ankles, position yourself according to the doctor’s requirements, keep breathing evenly and avoid moving around.
Imaging
Echocardiography
Echocardiography can show the structure and movement status of the heart, and is the most important diagnostic tool in the clinic.
It is characterized by asymmetric hypertrophy of the ventricles without enlargement of the ventricular chambers. A diastolic septal thickness of 15 mm or more is the diagnostic threshold.
Under load, occult obstruction can be recognized.
Precautions
Expose the chest as requested by the physician before the examination.
A coupling agent will be applied to the skin at the examination site.
Maintain the position and avoid moving around during the examination as requested by the doctor.
The coupling agent can be wiped off with tissue paper after the examination.
Cardiac MRI
Examines the structure and function of the heart.
It can clarify the cause of the disease or rule out other diseases.
Precautions
Remove items containing metal, as well as electronic products and magnetic cards before the examination.
If you have medical devices such as steel plates or implantable pacemakers in your body, you should inform your doctor in advance.
Chest X-ray
It can show the size, shape, position and outline of the large blood vessels of the heart.
Ordinary chest X-ray heart shadow size can be normal or enlarged left ventricle.
Precautions: Remove jewelry or metal objects, such as necklaces, from the area to be examined and take off clothing made of metal before the examination.
Exercise stress test
A test that induces myocardial ischemia by increasing cardiac load through exercise, resulting in ischemic ECG changes. Exercise tolerance and cardiopulmonary function can be assessed at the same time.
The exercise plate test is commonly used and is usually performed before or more than 2 hours after a meal.
Intracardiac Catheterization
Intracardiac catheterization may show increased left ventricular end-diastolic pressure. In the presence of left ventricular outflow tract stenosis, there is a systolic pressure gradient between the ventricular cavity and the outflow tract, and ventriculography shows left ventricular deformation.
Grading
The New York Heart Association (NYHA) categorizes cardiac function in patients with heart disease into 4 classes based on the patient’s ability to live.
Class I: general physical activity is unrestricted.
Grade II: Mild limitation of general physical activity, palpitations and mild shortness of breath after activity, no symptoms at rest.
Grade III: obvious limitation of general physical activity, no discomfort at rest, discomfort, palpitation, dyspnea with minor daily work, or previous history of heart failure.
Grade IV: severe limitation of general physical activity, inability to perform any physical activity, palpitations, dyspnea and other manifestations of heart failure at rest.
Differential Diagnosis
Cardiac Alterations in Athletes
Long-term exercise can cause the heart to undergo adaptive cardiac hypertrophic changes, manifested as symmetrical left ventricular hypertrophy. There is no family history of cardiomyopathy and genetic testing is negative. The heart can shrink and cardiac hypertrophy can be reduced 3 months after cessation of exercise.
Hypertensive heart disease
Prolonged hypertension can lead to cardiac hypertrophy, which manifests as elevated blood pressure, dyspnea, cough, and sputum. It can be identified by echocardiography and blood pressure examination.
Aortic stenosis
Aortic stenosis may present with dyspnea, angina and syncope. It can be identified by echocardiography.
Treatment
The goals of treatment include relieving clinical symptoms, improving cardiac function, slowing disease progression, and reducing death.
General treatment
Avoid exertion, agitation, and sudden exertion.
Strenuous exercise, stimulating recreational activities, and intense physical activity should be avoided.
Avoid drugs that enhance myocardial contractility and reduce cardiac load, e.g., digitalis, beta agonists, high-dose diuretics, arterial and venous vasodilators (nitrates).
Drug therapy
Treatment of left ventricular outflow tract obstruction
Beta-blockers
Can make myocardial contraction force weakened, reduce left ventricular outflow tract obstruction, reduce myocardial oxygen consumption, at the same time, can slow down the heart rate, improve the ventricular diastolic filling, thus improving the symptoms.
Commonly used drugs include metoprolol, bisoprolol, propranolol, atenolol and sotalol.
They can also be used in neonates and children with hypertrophic obstructive cardiomyopathy.
Non-dihydropyridine calcium channel blockers
Both reduce left ventricular outflow tract obstruction and improve ventricular diastolic filling and local myocardial blood flow.
Commonly used drugs include verapamil and diltiazem. Verapamil can also be used in children and adolescents with hypertrophic obstructive cardiomyopathy.
Propyzamide
is an antiarrhythmic drug with strong negative inotropic effects that inhibit myocardial contractility, slow the ejection rate, attenuate mitral regurgitation, and reduce left ventricular outflow tract obstruction.
Propyzamide is not recommended for use in children with hypertrophic obstructive cardiomyopathy.
Adverse reactions include dry eyes, dry mouth, delayed urination, urinary retention, and constipation.
Treatment of Combined Heart Failure
Patients with NYHA cardiac function class II to IV and ejection fraction (LVEF) ≥50% who do not have left ventricular outflow tract obstruction at rest and on stimulation should be considered for beta-blocker, verapamil, or diltiazem therapy to improve heart failure symptoms.
Patients with NYHA cardiac function II to IV and LVEF ≥50% who do not have LV outflow tract obstruction at rest and on stimulation should be considered for low-dose diuretic therapy to improve heart failure symptoms.
In patients without LV outflow tract obstruction and with LVEF <50%, treatment with β-blockers and angiotensin-converting enzyme inhibitors (ACEIs) may be indicated.
If ACEI is not tolerated, treatment with angiotensin II receptor antagonists (ARB) is indicated.
Small-dose loop diuretics or thiazide diuretics. They should be used in patients with hypertrophic obstructive cardiomyopathy who have symptoms (e.g., dyspnea, chest pain, palpitations, syncope, etc.) or with fluid retention to improve symptoms of dyspnea.
Combined atrial fibrillation treatment
In patients with permanent or persistent atrial fibrillation, beta-blockers and nondihydropyridines are recommended for heart rate control and the oral vitamin K antagonist warfarin for thromboembolism prevention.
In patients with recent episodes of atrial fibrillation, amiodarone may be used to maintain sinus rhythm.
Surgery
Percutaneous septal myocardial ablation
Indications
Patients who have been treated with strict medication for 3 months, whose basal heart rate is controlled at about 60 beats per minute, who have severe dyspnea or chest pain despite rest or light activity, who have had poor results or serious adverse effects of previous medication, and who have cardiac insufficiency (NYHA cardiac function class III-IV).
Transthoracic echocardiography and Doppler with LVOTG ≥ 50 mm Hg at rest or LVOTG ≥ 70 mm Hg after excitation.
Ventricular septum thickness ≥15 mm.
Postoperative complications
Bundle branch conduction block, incidence 50%, predominantly right bundle branch.
High or degree III AV block with an incidence of 2% to 10%.
Myocardial infarction.
Death, with a treatment-related mortality rate of 1.2% to 4.0%.
Ventricular septal myocardial resection
Indications
Unsuccessful pharmacologic therapy and continued dyspnea or chest pain (NYHA cardiac function class II to IV) or other symptoms (e.g., syncope, syncope with aura); LVOTG ≥50 mm Hg at rest or after exercise provocation.
For some of the less severe symptoms (NYHA cardiac function class I), LVOTG ≥50 mmHg, but with moderate-to-severe mitral valve closure insufficiency, atrial fibrillation, or significant left atrial enlargement.
Postoperative complications
The risk of complete bundle branch block with myocardial resection is approximately 2%, and other complications include septal perforation, ventricular rupture, and aortic regurgitation.
Implantation of a permanent pacemaker
Reduction of left ventricular outflow tract obstruction and improvement of symptoms after installation of a pacemaker. It is indicated in the following cases.
Permanent pacemakers may be implanted in the presence of indications for pacemaker implantation, in some patients with resting or stimulated LVOTG ≥50 mm Hg, sinus rhythm and ineffective pharmacologic therapy, in those who are not candidates for percutaneous septal myocardial ablation or surgical septal septal resection, or who are at high risk for postoperative cardiac conduction block.
In addition, atrioventricular node ablation with permanent pacemaker implantation may be considered when pharmacologic control of ventricular rate is unsatisfactory in the presence of atrial arrhythmias.
Prognosis
Cure
After active treatment, most patients have mild symptoms and may have no obvious obstacles in their daily life, and their life expectancy is no different from that of normal people; while those who develop obvious symptoms or serious complications such as heart failure or sudden death have a poorer prognosis.
Harmfulness
A small number of patients progress to heart failure, and another small number develop atrial fibrillation and embolism.
The current literature reports an annual mortality rate of approximately 1% to 2% in adults with hypertrophic cardiomyopathy. Sudden cardiac death is the main cause of death in young people, whereas stroke and heart failure are the main causes of death in older people.
Daily
Daily management
Daily Management
Ensure adequate sleep and avoid late nights.
Avoid exertion.
Quit smoking and avoid passive smoking.
Exercise moderately, you may choose to play tai chi and so on. Or choose the exercise time and program according to the doctor’s requirements.
Pay attention to safety when exercising and avoid over-exercise.
Diet management
Avoid overeating, eat small and frequent meals, food should be soft and easy to digest.
Salt should be controlled at 2-3 grams per day, and intake of smoked, marinated and pickled food is strictly prohibited.
Avoid high-sugar foods, such as sugary drinks, snacks, and overly sweet fruits.
Avoid cholesterol-rich fatty meat, animal offal, fish roe, squid, cuttlefish, egg yolks, etc.
Increase protein, unsaturated fat, vitamins, minerals and dietary fiber in moderation. Choose fish and poultry, soy products, skimmed milk, egg whites, fresh fruits (fruits with low sugar content are appropriate), fresh vegetables and nuts.
Reduce the amount of refined rice and noodles, and choose corn, millet, white potatoes, yams and other alternatives to staple foods.
Strictly control the amount of fluids, which is 1,000 to 1,500 milliliters per day for adults, including dietary intake and infusion.
Abstain from alcohol.
Emotional management
Avoid adverse emotions such as tension, anxiety, anger and depression.
Stress can be relieved by listening to soft music, chatting with friends and relatives, reading books, watching movies and TV dramas with soothing dramas.
In severe cases, go to a formal psychological counseling institution for consultation and treatment.
Safety management
If dizziness and other discomforts occur, you should squat, sit or lie down immediately to avoid falling.
If you have mobility problems, you should choose crutches, walkers, wheelchairs, etc. to move around, or be assisted or pushed by family members.
Follow-up and review
For those with stable conditions, it is recommended to have checkups every 12 to 24 months, including 12-lead electrocardiogram, transthoracic echocardiography, and 48-hour ambulatory echocardiography; exercise load checkups every 2 to 3 years; and cardiac magnetic resonance imaging checkups every 5 years.
For those in sinus rhythm and with an internal diameter of the left atrium ≥45 mm, 48-hour ambulatory cardiographic testing is recommended every 6 to 12 months.
For patients with progressive disease, 12-lead electrocardiography and transthoracic echocardiography may be performed in a timely manner. Exercise stress testing is performed annually; exercise stress testing is performed every 2 to 3 years; and cardiac magnetic resonance imaging is performed every 5 years.
Prevention
The disease is mostly hereditary and there is no effective preventive measure. Those with a family history should have relevant examinations done in a timely manner and genetic testing done if necessary for early detection and intervention.