beta receptor hypersensitivity
Introduction
Introduction to -receptor hyperactivity receptor hyperthyroidism is a normal catecholamine secretion in the body and -receptor is oversensitive to its stimulation, resulting in increased heart rate, increased ventricular contractility and increased cardiac output, and -receptor resistance. The treatment of stagnation medicine is effective. It is generally believed that the central nervous system dysfunction causes the imbalance of autonomous (plant) nerves to induce onset under stress conditions such as overwork, high tension, and trauma. basic knowledge Sickness ratio: 0.0001% Susceptible people: no specific people Mode of infection: non-infectious Complications: heart failure
Cause
Causes of -receptor hyperactivity
Central nervous system dysfunction (30%):
The cause is not completely clear. It is generally believed that the central nervous system is dysfunctional, leading to an imbalance of autonomic (plant) nerves, which induces onset under stress conditions such as overwork, high tension, and trauma.
Pathogenesis (20%):
It is thought to be related to the excessive sensitivity of the cardiovascular system to catecholamine or sympathetic stimulation. The study confirmed that the patient's blood, urinary catecholamine levels are normal, after intravenous infusion of isoproterenol, tachycardia and hypertension, and other symptoms The stroke state is intensified, and the symptoms of the -blocker are rapidly improved. Therefore, it is indicated that the secretion of catecholamine is not increased, but the response of the cardiac receptor to catecholamine or sympathetic stimulation is increased or excessive. Sensitive.
Pathophysiology (15%):
Cardiac output depends on heart rate and stroke volume, which in turn depends on myocardial contractility, cardiac preload (venous return blood volume, ventricular dilatation) and cardiac afterload (peripheral vascular resistance), and is affected by sympathetic and parasympathetic nerves. Blood catecholamine and acetylcholine concentration and body temperature and other factors are regulated. Under normal factors, the cardiac output is constant at rest. The adult heart index is 2.6-4.0L/(min·m2), physical exercise, emotional excitement, and full meal. It can be increased after the hot and humid environment, but the change of the sleeping position has no effect.
This disease is oversensitive to the response of receptor to stimulation (catecholamine, sympathetic tone), resulting in increased myocardial contractility, accelerated cardiac conduction and shortened refractory period, peripheral vasodilation, resulting in increased cardiac output at rest, blood pressure rise High, peripheral resistance decreased, tachycardia, average systolic jet velocity accelerated, hemodynamics showed high power circulation, strong heart beat, right ventricular outflow tract increased, widened, blood pressure showed systolic hypertension And pulse pressure increased, and the average pressure is normal, the oxygen consumption is significantly increased, the myocardial relative ischemia and hypoxia, affecting the process of myocardial depolarization, causing ECG ST-T changes, due to beta receptor response allergy, when standing, nervous In the case of stress, the sympathetic tone is elevated, and when the catecholamine is increased, the performance of this high-power cycle is intensified, and cardiac output and heart rate are significantly increased. Conversely, when lying, vomiting, parasympathetic tone is increased or retarded. When the beta receptor reacts, the performance of the high power cycle is reduced or disappeared.
The persistence and development of high-powered circulation increases cardiac load, myocardial ischemia, and hypoxia, which can lead to high output heart failure. Because of sympathetic and parasympathetic imbalances, it is often accompanied by obvious mental symptoms, and even heat.
Prevention
Prevention of hyperthyroidism
It is very important to timely and correctly diagnose the -receptor syndrome.
1. Timely diagnosis and correct treatment can be completely cured and restored to health.
2. Timely diagnosis and avoiding misunderstanding of coronary heart disease, myocarditis, etc., can relieve the mental burden of patients in time.
Complication
Complications of -receptor hyperactivity Complications heart failure
Heart failure can occur on the severely ill side.
Symptom
Symptoms of -receptor hyperactivity Symptoms Symptoms of hand, foot, trembling, overwork, breathing, nausea, low fever, insomnia, anxiety
The disease can occur in all ages, age distribution 7 to 80 years old, 80% between 20 and 40 years old, more women than men, 3:1 to 6:1, most of the pre-existing mental factors, such as overwork , high tension, trauma, post-ill, etc., there are also some iatrogenic, a few without incentives.
Symptoms are diverse, mainly manifesting cardiovascular and neurological symptoms, chest tightness, palpitations, dizziness, fatigue, most common pain in the precordial area, long duration of chest pain, mostly stinging, followed by low fever, sweating, insomnia, limbs Hemp, consciously short, qi is not enough, sigh is comfortable, a few have a short "syncope", pharyngeal obstruction, when standing, nervous aggravation, lying, nausea, vomiting relieved, mild after an exhaustion, but work Generally unaffected, if there is heart failure, there will be a sitting breath.
There are anxiety in the signs, but most of the appearance is still good, the heart rate is as high as 90-100 times/min when resting, and the individual reaches 170 times/min, often changing with the body position, emotional, and increasing when standing or working. Or decreased during sleep, the normal adult heart rate difference is (8.23 ± 4.3) times / min, but the disease is up to (16.95 ± 9.18) times / min, the elderly with a long course of disease may have mild heart enlargement, palpation of the precordial area The heart beats strongly and fast, the first heart sound is auscultated, some have systolic jet-like clicks, the third and fourth heart sounds, the second sound splits, and the 1-3 grades of early and middle-stage murmurs can be heard to the sternum. The left edge of the 3rd, 4th intercostal space, the second intercostal space of the right sternal border and the external carotid artery are most obvious. After exercise, the systolic blood pressure can be slightly increased by 19-21 kPa, the pulse pressure is increased, and the water pulse is increased. , gunshots and capillary signs, can have hand and foot trembling and tendon reflex enhancement.
Examine
Examination of -receptor hyperactivity
About half of the patients have a high basal metabolic rate and a reduced glucose tolerance.
1. Electrocardiogram sinus tachycardia, may have atrial or ventricular premature contraction, some patients have left ventricular high voltage, right atrial load aggravated, P wave shape high tip, electric axis right shift, V1 is rSr', Rs Types, II, III, aVF leads often have ST depression, T wave low level, biphasic or inverted, can also appear in I, aVL lead, the above changes are more significant or increased incidence when standing, after taking propranolol It returned to normal, and this change in the standing position disappeared. Sometimes the T wave changed greatly and returned to normal every few days.
2. The ECG exercise test may have a positive result.
3. X-ray examination of the heart shadow is more normal, the elderly patients will have enlarged heart shadow, and the lung field blood vessel texture can be increased.
4. The echocardiographic part may have an enlarged and widened right ventricular and right ventricular outflow tract.
5. Other inspections
(1) Isoproterenol test: intravenous infusion of isoproterenol 2 ~ 3g / min, before intravenous infusion, 2, 5, 8min after intravenous infusion measured heart rate, normal adult increased by 10 ~ 15 times / min, if increased by 20 ~ Above 30 times/min, the ST segment of the electrocardiogram decreased, the T wave was inverted, and the T-wave was inverted. The heart rate was restored within 5 minutes after the intravenous injection of propranolol 5 mg. The ECG changes were also restored, which was positive, but the age was large and the symptoms were severe. use.
(2) propranolol test: heart rate is fast, ECG has ST-T change to propranolol 20 ~ 40mg orally, after 30, 60, 120min for ECG, if ST segment returns to normal, T wave is inverted Biphasic or erect, or positive from low to normal, positive for both tests is considered to be consistent with beta receptor hyperactivity.
(3) Hemodynamic examination: stroke volume, heart index, average systolic blood spurting speed, peripheral resistance decreased.
(4) basal metabolic rate, high free fatty acids in the blood: occasionally decreased glucose tolerance test, blood catecholamine, 24h urinary vanillyl mandelic acid (VMA) were normal.
Diagnosis
Diagnosis and differentiation of -receptor hyperthyroidism
Diagnostic criteria
Diagnosis of typical symptoms is not difficult. Young people have palpitations, chest tightness, increased heart rate, anxiety, and symptoms disappear after taking beta blockers. Consider this disease, isoproterenol, propranolol test positive, helpful Diagnosis, the diagnostic criteria proposed by Frohlieh and Abe Jiuhong have certain reference significance:
1. Have circulatory system such as palpitations and anxiety and other mental symptoms, and exclude organic cardiovascular disease.
2. When the heart rate is above 90/min when quiet, standing, exercise and mental stimulation often increase the tachycardia.
3. Multiple stroke volume measurements, at least once over the normal range.
4. Symptoms and hemodynamics can be significantly improved after a small amount of propranolol.
It can be diagnosed if the above four items are met. The isoproterenol test is feasible for suspicious patients. For example, the heart rate and stroke volume increase significantly after infusion, and the original level can be diagnosed after propranolol.
Differential diagnosis
This disease is a common disease, but it is easily overlooked clinically and needs to be identified with the following diseases:
1. Hyperthyroidism due to palpitations, tachycardia, hyperhidrosis, insomnia, electrocardiogram changes in hyperthyroidism, similar to this disease, but the difference between the tachycardia and the vertical position is increased, with the emotional tension, the thyroid is not Large, no exophthalmia, normal thyroid function test, can be differentiated from hyperthyroidism.
2. Myocarditis This disease is more common in young people, because of heart palpitations, chest tightness, shortness of breath, ECG ST-T changes, premature contraction, and confusion with myocarditis, but this disease often has mental factors, heart sounds, hormones, rest Symptoms are not improved, and the effect on beta blockers is good, and the two can be identified.
3. Cardiac neurosis isoproterenol, propranolol can help diagnose this disease, can be identified with general neurosis.
4. Mitral valve prolapse due to both heart palpitations, chest pain, fatigue, dizziness, electrocardiogram ST-T changes, propranolol symptoms are relieved, it is easy to confuse, but the contraction of the middle and late clicks, echocardiography and drugs The test can distinguish the two.
5. Pheochromocytoma This symptom of catecholamine reaction is a pheochromocytoma of high catecholamineemia in the body, but by measuring 24h urinary vanillyl mandelic acid, adrenal computed tomography (CT) can help identify.
6. Coronary heart disease, especially with hypertension, also has large pulse pressure, strong pulse, abnormal ECG ST-T, positive performance of exercise test, but the symptoms of this disease are diverse, with body position, emotional relationship, tachycardia and exercise volume are not the same Adaptation, the symptoms of -blockers are relieved quickly, which helps to identify, but it should be noted that the two diseases can coexist at the same time, especially some patients with this disease will have coronary heart disease and hypertension at the same time.
7. Other causes of high power circulation such as anemia, arteriovenous fistula, pregnancy, beriberi, pulmonary heart disease, cirrhosis, carcinoid syndrome, have clear primary symptoms, not difficult to identify.
