Hypertrophic cardiomyopathy is characterized by hypertrophy of the myocardium. It can be divided into obstructive and non-obstructive hypertrophic cardiomyopathy according to the presence or absence of obstruction of the left ventricular outflow tract. Hypertrophic cardiomyopathy is not a terrible disease, but it develops slowly and has a good prognosis.
Etiology
1.Heredity
There can be multiple cases in a family, suggesting a genetic link. It has long been believed that the cause of hypertrophic cardiomyopathy is related to genetics and belongs to autosomal dominant inheritance. Clinically there is a clear family history of genetic only about 30%-55%, while the other 40%-50% but no genetic family history.
2. Endocrine disorders
Pheochromocytoma patients with coexisting hypertrophic cardiomyopathy are more common, and intravenous injection of large amounts of norepinephrine in humans can cause myocardial necrosis. Animal experiments, intravenous injection of catecholamines can cause myocardial hypertrophy. Therefore, it is believed that hypertrophic cardiomyopathy is caused by endocrine disorders.
Clinical manifestations and identification of symptoms
The clinical manifestations of hypertrophic cardiomyopathy vary due to complex intrinsic factors, including diastolic insufficiency, outflow tract obstruction, mitral valve closure insufficiency, and arrhythmias. The clinical presentation is markedly heterogeneous and complexly variable.
When angina pectoris is present, it needs to be differentiated from coronary artery disease and angina pectoris.
Examination
1.X-ray examination
The size of the heart is normal or enlarged. The size of the heart is proportional to the pressure step difference between the heart and the left ventricular outflow tract, and the larger the pressure step difference is, the larger the heart is. The left ventricular hypertrophy of the heart is predominant, the aorta is not widened, the pulmonary artery segment is not obviously prominent, pulmonary stasis is mostly light, and mitral valve calcification is common.
2.Electrocardiogram
Due to cardiac ischemia, myocardial repolarization abnormalities, ST-T changes are common, left ventricular hypertrophy and left bundle branch conduction block are also more common, Q waves may appear due to septal hypertrophy and myocardial fibrosis, and various types of arrhythmias are often present in this disease.
3.Echocardiography
It is an important non-invasive diagnostic method.
4.Cardiac catheterization and cardiovascular angiography
On cardiac catheterization, there is a pressure step difference between the left ventricle and the left ventricular outflow tract, and the end-diastolic pressure of the left ventricle is increased. In cardiac angiography, when the septal muscle hypertrophy is obvious, the ventricular cavity can be seen to have narrow crack-like changes, which is meaningful for diagnosis.
Diagnosis
Clinically, this disease should be considered when the patient has left ventricular hypertrophy and there are no other factors that can be found to promote left ventricular hypertrophy such as hypertension and aortic stenosis. The diagnosis can be made based on the etiology, clinical manifestations and laboratory tests.
Treatment
Hypertrophic cardiomyopathy develops slowly and has a good prognosis. Due to arrhythmias, cardiac events can occur, and care should be taken to avoid overwork and excessive mental stress. β-blockers and calcium antagonists can reduce myocardial contractility, reduce left ventricular outflow tract obstruction, and improve left ventricular diastolic function.
Surgical treatment: If the outflow tract obstruction is >60 mmHg, and drug treatment is ineffective, surgical treatment can be performed. Hypertrophic muscle resection can be performed. In cases with severe mitral valve insufficiency, mitral valve replacement can be performed.
The natural history of hypertrophic cardiomyopathy is particularly complicated and variable because of the complications of combined atrial fibrillation, concurrent coronary artery disease, endocarditis, and left ventricular systolic insufficiency.