hypertensive cardiomyopathy
Introduction
Introduction to hypertensive cardiomyopathy Hypertensive cardiomyopathy (hypertensive cardiomyopathy) refers to abnormal changes of left ventricular wall or left ventricular cavity caused by hypertension, severe cases of left ventricular hypertrophy, left heart cavity enlargement with diastolic, systolic cardiac insufficiency Cardiomyopathy, hypertensive cardiomyopathy is one of the major complications of hypertension. Myocardial interstitial fibrosis left ventricular hypertrophy In addition to myocardial hypertrophy, myocardial interstitial remodeling often occurs, and the lesion is progressive, which is a compensatory response to maintain left ventricular function, once collagen accumulation exceeds 20% Fibrosis occurs, and finally myocardial diastolic and systolic dysfunction and heart failure occur. The morphological changes of myocardial interstitial fibrosis are thickening of the original collagen. The new collagen is deposited in the myocardial interstitial which lacks collagen, and the collagen volume ratio increases. These changes lead to the destruction of the normal interstitial network structure and the occurrence of interstitial fibrosis. basic knowledge The proportion of the disease: the incidence of this disease in people with hypertension is about 0.01%-0.08% Susceptible people: no specific population Mode of infection: non-infectious Complications: heart failure, sudden death, arrhythmia
Cause
Causes of hypertensive cardiomyopathy
(1) Causes of the disease
Left ventricular wall hypertrophy and abnormal changes in the left ventricular cavity due to long-term hypertension have previously been considered a useful compensatory mechanism, but are now considered to be independent risk factors for increased cardiovascular morbidity and mortality.
(two) pathogenesis
1. Pressure and volume load increase According to Laplace's law, the stress of the wall is directly related to the product of ventricular cavity diameter and systolic pressure, and negatively correlated with the wall thickness. The pressure load increases the ventricular wall and sarcomere stress. Caused by centripetal cardiac hypertrophy, experiments have shown that volumetric load plays a large role in hypertensive cardiac hypertrophy.
2. Myocardial interstitial fibrosis Left ventricular hypertrophy In addition to myocardial hypertrophy, myocardial interstitial remodeling often occurs, and its pathology is gradual, which is a compensatory response to maintain left ventricular function, once collagen accumulation exceeds Fibrosis occurs at 20%, and finally myocardial diastolic and systolic dysfunction and heart failure occur. The morphological changes of myocardial interstitial fibrosis are thickening of the original collagen. The new collagen is deposited in the myocardial interstitial, which lacks collagen, and the collagen volume. The proportion increases, and these changes lead to the destruction of the normal interstitial network structure and the occurrence of interstitial fibrosis.
3. Renin-angiotensin-aldosterone system The renin-angiotensin-aldosterone system plays an important role in the development of cardiac hypertrophy. Angiotensin II can promote the hypertrophy of cardiomyocytes through the expression of fos oncogene. And protein synthesis, and can promote interstitial fibroblasts and smooth muscle cell proliferation and collagen synthesis, continuous intravenous injection of angiotensin II (200ng per minute) in normal rats, can cause renal hypertension and cardiac hypertrophy, application After adrenaline, it can cause rapid response of early response genes. After 30 minutes of intravenous epinephrine, c-fos gene mRNA can be increased by 15 times, c-Jun gene mRNA is increased by 3 times, egr gene mRNA is also increased, and normal after 2 hours. Adding norepinephrine to cardiomyocyte culture medium, the transcription of c-myc gene can be increased by 5 to 10 times, which can promote the expression of -actin gene.
Prevention
Hypertensive cardiomyopathy prevention
1. The most effective preventive measure for this disease is to prevent hypertension (including essential hypertension and various secondary hypertension).
2. Once high blood pressure is found, comprehensive measures should be taken to actively prevent complications.
Complication
Hypertensive cardiomyopathy Complications, heart failure, sudden cardiac arrhythmia
There may be complications such as heart failure, sudden death, and arrhythmia.
Symptom
Symptoms of hypertensive cardiomyopathy common symptoms heart failure dyspnea hypertensive arrhythmia palpitations apex beats diffuse pulmonary congestion myocardial stunning
1. Symptoms and signs
(1) Compensatory phase of cardiac function: This stage often lacks obvious symptoms. When physical examination or other diseases are diagnosed and treated, hypertension and hypertensive cardiomyopathy are found. If accompanied by arrhythmia, there may be a feeling of palpitations, and the heart is normal or slightly Expanded to the lower left, the apex beats powerfully, and there is a sense of lift.
(2) Restricted cardiac dysfunction stage: clinical manifestations, signs similar to restrictive cardiomyopathy.
(3) stage of systolic heart dysfunction: this stage manifests as symptoms of congestive heart failure, gradually increased dyspnea, organ hypoperfusion, heart enlargement to the left, pulmonary congestion signs.
Examine
Examination of hypertensive cardiomyopathy
1. ECG can be normal, left ventricular hypertrophy and strain, RV5 SV1 is greater than 4.0mV (male), RV5 SV1 is greater than 3.5mV (female), ST segment of R wave dominant lead can be moved down, or T The wave is inverted and the electric axis is left.
2. The left ventricular margin of the chest X-ray film is full, round and blunt, and can also be enlarged to the left.
3. Echocardiography
(1) M-mode echocardiography:
1 chamber interval and left ventricular posterior wall thickness increase: ventricular septum and left ventricular posterior wall showed uniform symmetry thickening, when the interventricular septum and left ventricular posterior wall absolute thickness greater than 12mm, can diagnose left ventricular hypertrophy.
2 left ventricular myocardial weight increase: the determination of myocardial weight is an important index to evaluate cardiac hypertrophy. In the past, only the actual value of myocardial weight can be understood through autopsy. In recent years, a large number of clinical studies have shown that the myocardial obtained by echocardiography The weight value is highly correlated with autopsy results. Therefore, the American Society of Echocardiography recommends using the following formula to calculate myocardial weight and myocardial weight index.
Left ventricular weight (g) = 0.8 × [1.04 × (left ventricular reduced diameter left ventricular sac diameter left ventricular mean diameter)] 3 0.6.
Left ventricular mass index (g/m2) = left ventricular weight / body surface area.
The normal left ventricular mass index was 135 g/m2 for men and 125 g/m2 for women.
(2) Two-dimensional echocardiography: left ventricular long axis, short axis section showed left ventricular wall hypertrophy, left ventricular hypertrophy with centripetal hypertrophy, a few irregular irregular hypertrophy, centripetal hypertrophy ventricular septum and left ventricle The wall is symmetrical hypertrophy, the irregular type is asymmetrical hypertrophy between the ventricular septum and the posterior wall of the left ventricle, the left ventricular cavity is normal or slightly reduced, the amplitude of the wall motion is enhanced, and the left atrium can be slightly increased. Echocardiographic measurement of left ventricular myocardium thickness is more accurate than M-mode echocardiography, and heart failure during systolic dysfunction, as well as enlargement of the left atrium and left ventricle.
(3) Doppler echocardiography: early systole is hyperdynamic, the peak velocity of aortic blood flow is increased, the stroke volume is normal, the ejection fraction is normal, and the mitral blood flow spectrum often has different abnormal changes. When left ventricular hypertrophy and diastolic compliance decline, left ventricular filling resistance increases. In order to maintain cardiac output, the main compensatory mechanism is to increase atrial filling pressure, which is characterized by left ventricular isovolumic diastolic prolongation, E peak peak velocity. Decrease, acceleration time, deceleration time, prolonged duration of diastole, peak peak velocity of A peak, and decreased E/A ratio, reflecting impairment of left ventricular diastolic function.
Diagnosis
Diagnosis and diagnosis of hypertensive cardiomyopathy
diagnosis
According to the medical history, clinical manifestations, laboratory examination and diagnosis is not difficult to determine.
Differential diagnosis
Need to be differentiated from hypertrophic cardiomyopathy, restricted cardiomyopathy, other heart disease, differential diagnosis combined with age of onset, history, clinical manifestations, comprehensive analysis of laboratory tests, echocardiography can provide a basis for diagnosis.
