salt-sensitive hypertension
Introduction
Introduction to salt-sensitive hypertension Salt-sensitive hypertension can be defined as an increase in blood pressure caused by relatively high salt intake. How much salt intake is an important environmental factor for hypertension, but the salt load or salt reduction between individuals in the population There are different blood pressure responses and there is a salt sensitivity problem. Salt sensitivity of blood pressure refers to an increase in blood pressure caused by relatively high salt intake. The salt sensitivity of blood pressure increases with age, especially in hypertensive patients. basic knowledge The proportion of illness: 0.02% Susceptible people: no special people Mode of infection: non-infectious complication:
Cause
Salt-sensitive hypertension
(1) Causes of the disease
Salt-sensitive individuals have a series of endocrine and biochemical metabolic abnormalities involving blood pressure regulation. Therefore, some people regard salt sensitivity as the intermediate genetic phenotype of hypertension. The salt-sensitized renin activity in circulating blood is generally low, but the so-called non-regulation Non-modulating salt-sensitive people have normal or elevated plasma renin levels, salt-sensitive people have abnormal metabolism of sodium and calcium, compensatory increase in blood circulation of natriuretic hormone levels, dysregulation of sympathetic nervous system, insulin resistance Increase, dysfunction of vascular endothelial function and renal sodium tendency.
(two) pathogenesis
1. The metabolic disorders of sodium are mainly manifested as:
1 The sodium content in the red blood cells is increased, and the sodium content in the red blood cells is further increased after the salt load;
2 After the salt load, the urinary sodium excretion reaction is delayed. Most studies believe that in the occurrence of human hypertension, the kidney affects blood pressure from at least three aspects, namely, the tendency of the kidney to retain sodium, the Goldblatt effect and the blood vessels secreted by the renal interstitial. The role of active substances, low renin levels, decreased renal sodium excretion after salt loading, and increased response to diuretics often suggest salt-sensitive sodium metabolism disorders;
3 accompanied by abnormal metabolism of potassium and calcium, the effect of potassium and calcium on sodium metabolism is mainly reflected in the interaction of renal excretion, sodium load will cause increased excretion of urinary calcium and urinary potassium, resulting in a lack of conditional potassium and calcium; Increasing potassium intake can promote sodium excretion and inhibit capacity expansion, which can prevent salt-mediated blood pressure elevation. There is a stable negative correlation between dietary calcium intake and blood pressure in most salt-sensitive people. The intake is low. Similarly, this type of hypertensive patients may exhibit an increase in urinary calcium relative or absolute excretion. Therefore, in the same situation of urinary sodium excretion, the amount of urinary calcium in hypertensive patients increases, and oral calcium helps to reduce this. Blood pressure in patients with hypertension
4 cell membrane sodium / lithium reversal rate of growth, sodium pump activity decreased, after a long-term follow-up of high blood pressure in adolescents and normal blood pressure control found that erythrocyte membrane Na-Li anti-transportation significantly increased, blood pressure with The increase in age has increased significantly.
2. Stress, blood pressure response enhances sympathetic nerve activity: salt and stress are considered to be two important environmental factors of hypertension, the interaction between them affects the occurrence and development of hypertension, salt-sensitive people in high salt or salt load There are often sympathetic activity enhancements, such as elevated plasma norepinephrine levels, changes in blood pressure circadian rhythms, nighttime blood pressure valleys, and nighttime low frequency components in heart rate variability, etc., in a laboratory environment, the human body Cardiovascular responses to stress are often assessed by the use of physical (somatic) or mental stimuli, such as cold-pressurization tests and psychostimulatory tests, which are mediated through the central -adrenergic, and cold-pressurization test. It mainly reflects the activity of peripheral -adrenergic nerves. Clinical observations show that the resistance of forearm vessels in salt-sensitive patients is significantly higher than that of salt-insensitive ones in cold-pressurization test. We have compared cold-pressurization and mental stimulation tests. Blood pressure and heart rate response in individuals with hypertension and normal blood pressure, it was found that the pressure-sensing effect of salt-sensing patients in cold-pressurization and mental stimulation tests was significantly greater than that of salt-insensitive Sensitive, salt-sensitive one of the possible mechanisms of stress-induced blood pressure response is due to membrane ion transport disorder, increased sodium content in vascular smooth muscle cells and partial depolarization of the cell membrane, eventually increasing intracellular free calcium and vascular smooth muscle compression The reaction of the substance increases.
3. Insulin resistance exists. Reaven compared blood insulin and triglyceride levels in salt-sensitive rats and normal rats. It was found that salt-sensitive rats had significant hyperinsulinemia and hypertriglyceridemia, and insulin resistance existed. Phenomenon, we monitored the dynamic changes of plasma insulin, blood glucose level and sugar load in 23 patients with normal blood pressure during the chronic salt load test. The peak plasma insulin levels and sugar load peaks in salt-sensitive patients during high salt load period. The blood glucose concentration was significantly increased, but there was no such change in the balanced diet and the low salt period. Nery Fuenmayor et al. observed similar results in hypertensive salt-sensitive patients. Why did salt-sensitive people have insulin resistance? Still not very clear.
4. Endothelial impaired performance Clinical observations show that acetylcholine-induced forearm vasodilation is reduced in salt-sensitive hypertensive patients, and has nothing to do with the presence or absence of salt load; we observed that salt-sensitive hypertensive patients and normal blood pressure The 24h urinary endothelin excretion of salt-sensitive patients was significantly lower than that of salt-insensitive patients; urinary endothelin excretion was negatively correlated with blood pressure, especially at nighttime blood pressure (r=-0.151).
Prevention
Salt-sensitive hypertension prevention
1. Reducing the intake of sodium in the diet The average salt intake in China is much higher than in other countries, and it is recommended to reduce the intake of sodium appropriately, especially in the north, reducing the daily salt intake to 100-150mmol, ie Reducing the intake of existing salt by 1/2 to 1/3 helps reduce the incidence of high blood pressure.
2. Salt-sensitive people should increase the intake of potassium and calcium, and prevent the increase of sodium due to dietary sodium intake. The appropriate amount of calcium and potassium supplements for children and adolescents can promote salt-sensitive children's urine sodium. Excretion, and significantly delay the growth of blood pressure in these children with age, according to our "Eighth Five-Year Plan" and "Ninth Five-Year Plan" for the 10 to 13-year-old primary school students and family units in the cardiovascular disease prevention and control area in Shaanxi Hanzhong area, blood pressure Primary prevention trials in older adolescents have shown that proper addition of potassium and calcium to the diet can significantly delay and prevent further increases in blood pressure with age or blood pressure.
Complication
Salt-sensitive hypertension complications Complication
Ventricular hypertrophy (ventricular septum and left ventricular posterior wall thickening), renal dysfunction and other complications may occur.
Symptom
Salt-sensitive hypertensive symptoms common symptoms left ventricular hypertrophy
Clinical features of salt-sensitive hypertension:
1. Blood pressure is obviously increased after salt load, and blood pressure is reduced after salt restriction or volume reduction. Salt-sensitive people have obvious pressure-increasing response to acute salt load or chronic salt load, while short-term administration of furosemide or chronic salt limitation Ingestion reduces blood pressure, which has been demonstrated in animal experiments and clinical observations and serves as a classic method for salt sensitivity determination.
2. The diurnal difference of blood pressure is reduced, the valley at night is shallow, and the salt load is more obvious.
3. Increased blood pressure stress response According to our observation of normal blood pressure and hypertensive salt sensitivity, the increase in blood pressure of salt-sensitive patients after mental stimulation test and cold-stress test is significantly higher than that of salt-insensitive patients, and continues Longer time.
4. Target organ damage occurs as early as the increase in urinary microalbumin excretion and relative increase in left ventricular mass.
According to our clinical observation, urinary microalbumin excretion in salt-sensitive hypertensive patients is significantly higher than that in salt-insensitive patients, and salt load will further increase it; salt-sensitive patients, regardless of hypertension or normal blood pressure, left ventricular mass index ( LVMI) was greater than salt-insensitive (P<0.01), and the detection rate of left ventricular hypertrophy (LVH) in hypertensive salt-sensitive patients was higher than that in salt-insensitive patients (24.3%:5.8%, P<0.05=.
5. There is insulin resistance, especially in the case of salt load, the plasma insulin level of salt-sensitive people is significantly higher than that of salt-insensitive ones, and the insulin sensitivity index is decreased.
Examine
Salt-sensitive hypertension check
Urinary microalbumin excretion increased.
How to determine the sensitivity of salt, up to now, there is no uniform, normative measurement method and criteria. The most widely used methods are acute salt load and chronic salt load.
1. Acute salt load test was first reported by American scholar Lufl in 1977 for clinical research. The basic method is: intravenous infusion of 2000ml saline as sodium load period within 4h, and low salt diet (10mmol/d) 3 days after sputum. Under the daily oral furosemide, 40mg, once every 8 hours for the sodium reduction period, observe the increase in the average blood pressure before and after the infusion of normal saline and the average blood pressure reduction after salt reduction to determine whether the salt is sensitive The specific criteria are: the average blood pressure at the end of the salt load is 5mmHg or the average blood pressure at the end of the salt reduction period is 10mmHg, which is judged as salt sensitive, and less than the upper value is not sensitive to salt. The middle between them, the Italian scholar Ferrucck, Galletti, etc. (1997) improved the above method, the salt reduction, shrinking time was changed to 1 day, the dietary sodium intake was still 10mmol / d, fur The sami dose was changed to 37.5 mg.
Oral at 8am, 2pm and 8pm, respectively. The blood pressure at 8 o'clock in the morning was measured as salt reduction and blood pressure after contraction. It is believed that this method can accurately predict the blood pressure response after limiting salt intake in most patients. In the clinical and primary epidemiological investigations, the above method was further modified, and the volume of the systolic saline was immediately transferred to the venous saline load to immediately take 40 mg of furosemide, and the blood pressure change after 2 hours was monitored. The increase and the sum of the mean blood pressure reduction at the end of 2 hours after taking furosemide 15mmHg were judged as salt-sensitive. According to our comparison with the modified acute venous saline load and the chronic salt load test, The salt sensitivity detection rate was 100%.
2. Chronic salt load test Most scholars use a combination of high-salt diet and low-salt diet to determine salt sensitivity. The daily salt load in high-salt diet is based on the dietary habits of different populations, from 180mmol to 1600mmol. Etc., salt load time varies from 1 week to several weeks. We have carried out a chronic salt load test on 23 normal blood pressure volunteers. On the basis of a 3-day balanced diet, the salt intake was 393 mmol per day for 1 week. In the 7-day low-salt period, the daily salt intake is 51mmol. According to Sullivan's recommended standard, the average blood pressure during the high-salt diet is >5mmHg compared with the balanced diet and/or the average blood pressure reduction during the low-salt diet is 10mmHg. It was judged to be salt sensitive; those who did not exceed this value were salt-insensitive. We found that the blood pressure of the salt-sensitive patients in the chronic salt load test was significantly increased on the sixth day of the high-salt diet; It appears faster, 89% of salt-sensitive people on the third day.
The literature shows that the detection rate of salt-sensitive people in normal blood pressure groups ranges from 15% to 42%; the high-pressure population is 28% to 74%, and the detection rates of salt-sensitive individuals of different races and populations are different, and The salt sensitivity of blood pressure increases with age, especially in patients with hypertension. In the past few years, the authors have used oral saline load, acute venous saline load combined with furosemide sodium, suffocation and chronic salt load to treat different populations. Salt sensitivity determination (Table 3), as can be seen from Table 3, nearly 60% of the tested hypertensive patients were salt-sensitive. Among normal blood pressure, adults were 28.57%, and adolescents were 33.33%. The high detection rate may be related to the high proportion of family history of hypertension in selected subjects; in those with positive family history of hypertension, including hypertension and normal blood pressure, the detection rate of salt sensitivity is 65% in adults. In 45% of adolescents, this result indicates that the ratio of salt-sensitive people in the Han population in northern China is relatively high, especially those with a positive family history of hypertension.
3. The stress response of blood vessels increased the increase of blood pressure after the mental stimulation test and the cold compression test was significantly higher than that of the salt-insensitive ones, and the duration was long.
Diagnosis
Diagnostic identification of salt-sensitive hypertension
diagnosis
According to its clinical characteristics and auxiliary examination, it can diagnose salt-sensitive hypertension. Salt-sensitive hypertension can be divided into two types: regulating type and non-regulating type.
1. Salt-sensitive regulated hypertension increases salt intake or salt load blood pressure, while blood pressure is reduced by restriction or contraction; plasma renin activity is low, and response to salt is slow; serum free calcium level is low, Reducing sodium intake or increasing potassium and calcium intake can help lower blood pressure.
2. Non-regulated salt-sensitive hypertension is a type of hypertension that is the opposite of low-renine type. It is called non-regulated because of the lack of sodium-mediated response of target tissue to angiotensin II. Hypertensive plasma renin activity levels are elevated or normal; there is hereditary renal sodium deficiency.
Differential diagnosis
Need to be differentiated from primary and various secondary hypertension.
