Hypertension in pregnancy is a pathological increase in blood pressure (BP) above the standard normal or characteristic for the patient indicators that occurred before conception or associated with gestation. Usually manifested by headaches, dizziness, tinnitus, shortness of breath, palpitations, fatigue. It is diagnosed by measuring blood pressure, ECG, EchoCG, ultrasound of the adrenal glands and kidneys, laboratory tests of blood and urine. Standard treatment involves the appointment of antihypertensive drugs (selective β1-adrenoblockers, α2-adrenomimetics, calcium antagonists, vasodilators) in combination with drugs that improve the work of the fetoplacental complex.
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Arterial hypertension (AH, arterial hypertension) is the most common cardiovascular disorder detected in the gestational period. According to WHO, hypertension is diagnosed in 4-8% of gestations, in USA, hypertensive conditions are found in 7-29% of pregnant women. In almost two-thirds of cases, hypertension is caused by pregnancy, pressure indicators stabilize for 6 weeks after delivery. Although physiological changes in the 1st trimester usually contribute to a decrease in blood pressure, hypertension that developed before gestation, without sufficient pressure control, often worsens the prognosis of pregnancy and its outcomes, therefore such patients need increased attention from medical personnel.
In 80% of pregnant women with high blood pressure, chronic arterial hypertension, which occurred before conception or manifested in the first 20 weeks of gestational age, is associated with the development of hypertension (essential hypertension). In 20% of women, blood pressure rises before pregnancy under the influence of other causes (symptomatic hypertension). The starting point for the exacerbation or onset of the disease in pregnant women is often an increase in the volume of circulating blood necessary to meet the nutritional and oxygen needs of both mother and fetus. The main prerequisites for the occurrence of chronic arterial hypertension are:
- Neurogenic disorders. According to most researchers, essential hypertension at the initial stages is a neurosis caused by the depletion of the mechanisms of higher nervous regulation against the background of constant stress, psychoemotional overstrain. Predisposing factors are considered to be hereditary burden, previously suffered kidney and brain diseases, excessive salt intake, smoking, abuse of alcoholic beverages.
- Symptomatic increase in vascular resistance. There are a number of diseases in which a change in hemodynamic parameters is associated with a violation of the structure of the vascular wall or the secretion of hormones regulating hemodynamics. Symptomatic hypertension in pregnant women often occurs against the background of chronic pyelonephritis, glomerulonephritis, polycystic kidney disease, diabetic nephropathy, renin-producing tumors, thyrotoxicosis, hypothyroidism, feverish conditions.
Hypertension detected after the 20th week of pregnancy (usually 3-4 weeks before delivery) is a functional disorder. It is caused by specific changes in hemodynamics and blood rheology associated with fetal gestation and preparation for childbirth. As a rule, the blood pressure level in such cases normalizes by the end of the 6th week of the postpartum period.
The initial link in the development of essential hypertension is a violation of the dynamic balance between the pressor and depressor systems of corticovisceral regulation, which maintain the normal tone of the vascular walls. An increase in the activity of the pressor sympathetic-adrenal and renin-angiotensin-aldosterone systems has a vasoconstrictive effect, which causes compensatory activation of the depressor system — increased secretion of vasodilator prostaglandins and components of the kallikrein-kinin protein complex. As a result of depletion of depressant agents, the lability of blood pressure increases with a tendency to its persistent increase.
Primary disorders at the cortical level, realized through secondary neuroendocrine mechanisms, lead to vasomotor disorders — tonic contraction of the arteries, which is manifested by increased pressure and causes tissue ischemia. At the same time, under the influence of the sympathoadrenal system, cardiac output increases. To improve the blood supply to the organs, the volume of circulating blood increases compensatorily, which is accompanied by a further increase in blood pressure. Peripheral vascular resistance increases at the level of arterioles, the ratio between electrolytes is disrupted in their walls, smooth muscle fibers become more sensitive to humoral pressor agents.
Through the swollen, thickened, and then sclerosed vascular wall, nutrients and oxygen penetrate worse into the parenchyma of internal organs, as a result of which various multi-organ disorders develop. To overcome the high peripheral resistance, the heart hypertrophs, which leads to a further increase in systolic pressure. Subsequently, the depletion of myocardial resources contributes to cardiodilation and the development of heart failure. With symptomatic hypertension, the starting points of the disease may be different, but subsequently unified pathogenesis mechanisms are included.
Additional pathogenetic factors of hypertension during gestation in hereditarily predisposed women may be insufficient synthesis of 17-hydroxyprogesterone by placental tissue, high vascular sensitivity to the action of angiotensins, increased production of renin, angiotensin II, vasopressin against the background of functional renal ischemia, endothelial dysfunction. A certain role is played by overstrain of corticovisceral regulation systems due to hormonal restructuring of the body, emotional experiences caused by pregnancy.
The traditional division of hypertensive conditions into primary and symptomatic, systolic and diastolic, mild, moderate and severe during pregnancy should be rationally supplemented with a classification based on the criteria of the time of occurrence of the disease and its connection with gestation. In accordance with the recommendations of the European Society for the Study of Arterial Hypertension, the following forms of arterial hypertension are distinguished, determined in pregnant women:
- Chronic hypertension. Pathological increase in blood pressure was diagnosed before gestation or during its first half. It is noted in 1-5% of pregnancies. Usually, the disease becomes persistent and persists after childbirth.
- Gestational hypertension. Hypertensive syndrome is detected in the second half of pregnancy (more often after the 37th week) in 5-10% of patients with previously normal blood pressure. Blood pressure is completely normalized by the 43rd day of the postpartum period.
- Preeclampsia. In addition to signs of arterial hypertension, proteinuria is observed. The protein level in the urine exceeds 300 mg/l (500 mg/day) or with a qualitative analysis of a single serving, the protein content meets the “++” criterion.
- Complicated pre-existing hypertension. In a pregnant woman who suffered from hypertension before childbirth, after 20 weeks of gestation, an aggravation of arterial hypertension is detected. Protein begins to be detected in the urine in concentrations corresponding to preeclampsia.
- Unclassified AG. A patient with elevated blood pressure was admitted under the supervision of an obstetrician-gynecologist at a time that does not allow classifying the disease. Information about the previous course of the disease is insufficient.
The severity of clinical symptoms depends on the level of blood pressure, the functional state of the cardiovascular system and parenchymal organs, hemodynamic features, rheological characteristics of blood. The mild course of the disease may be asymptomatic, although more often pregnant women complain of the periodic occurrence of headaches, dizziness, noise or ringing in the ears, increased fatigue, shortness of breath, chest pain, palpitations. The patient may feel thirst, paresthesia, cold extremities, visual disturbances, increased urination at night. Night sleep often worsens, unmotivated anxiety attacks appear. It is possible to detect small blood impurities in the urine. Sometimes there are nosebleeds.
Arterial hypertension in pregnancy can be complicated by gestosis, fetoplacental insufficiency, spontaneous abortions, premature birth, premature detachment of the normally located placenta, massive coagulopathic bleeding, stillbirth. The high frequency of gestosis in pregnant women with hypertension (from 28.0 to 89.2%) is due to the general pathogenetic mechanisms of disorders of vascular tone regulation and kidney function. The course of gestosis, which occurred against the background of arterial hypertension, is extremely severe. It is usually formed at 24-26 weeks, is characterized by high therapeutic resistance and a tendency to re-development in subsequent pregnancies.
The risk of premature termination of gestation increases with the aggravation of hypertension and averages 10-12%. During pregnancy and during childbirth, cerebral circulation is more often disrupted in women with high blood pressure, the retina peels off, pulmonary edema, multiple organ and kidney failure, and HELLP syndrome are diagnosed. Hypertension is still the second most common cause of maternal mortality after embolism, which, according to WHO, reaches 40%. Most often, the immediate cause of a woman’s death is DIC-syndrome caused by bleeding during premature placental abruption.
The detection of complaints characteristic of hypertension in a pregnant woman and an increase in blood pressure with a single tonometry is a sufficient reason for prescribing a comprehensive examination that allows to clarify the clinical form of pathology, determine the functional viability of various organs and systems, identify possible causes and complications of the disease. The most informative methods for diagnosing hypertension in pregnancy are:
- Measurement of blood pressure. Determination of blood pressure indicators using a tonometer and a phonendoscope or a combined electronic device reliably detects hypertension. To confirm the diagnosis and identify circadian rhythms of pressure fluctuations, if necessary, its daily monitoring is performed. The diagnostic value is an increase in systolic pressure to ≥140 mm Hg, diastolic pressure to ≥90 mm Hg.
- Electrocardiography and echocardiography. Instrumental examination of the heart is aimed at assessing its functional capabilities (ECG), anatomical and morphological features and pressure in the cavities (EchoCG). With the help of these methods, the severity of hypertension is assessed on the basis of data on myocardial hypertrophy, focal pathological changes that occur during overloads, possible violations of conduction and heart rate.
- Ultrasound of the kidneys and adrenal glands. A significant part of cases of symptomatic hypertension is associated with impaired secretion of components of the vasopressor and depressor systems in the kidneys and adrenal glands. Ultrasound examination makes it possible to detect tissue hyperplasia, focal inflammatory and neoplastic processes. Additional ultrasound of the renal vessels reveals possible violations of blood flow in the organ.
- Laboratory tests. In the general analysis of urine, red blood cells and protein can be determined. The presence of leukocytes and bacteria indicates a possible inflammatory nature of changes in the renal tissue. To assess the functional capabilities of the kidneys, Rehberg and Zimnitsky tests are performed. Diagnostically significant indicators are potassium, triglycerides, total cholesterol, creatinine, renin, aldosterone in blood plasma, 17-ketosteroids in urine.
- Direct ophthalmoscopy. During the examination of the fundus, characteristic hypertensive changes are revealed. The lumen of the arteries is narrowed, the veins are dilated. With prolonged hypertension, vascular sclerosis is possible (symptoms of “copper” and “silver wire”). Pathognomonic for the disease is considered arteriovenous intersection (Salus-Gunn symptom). The normal branching of blood vessels is disrupted (a symptom of “bull horns”).
Taking into account the high probability of fetoplacental insufficiency, it is recommended to conduct studies that allow monitoring the functional capabilities of the placenta and fetal development — ULTRASOUND of uteroplacental blood flow, fetometry, cardiotocography. During pregnancy, differential diagnosis of hypertension is carried out with kidney diseases (chronic pyelonephritis, diffuse diabetic glomerulosclerosis, polycystic fibrosis, developmental abnormalities), encephalitis, brain tumors, aortic coarctation, nodular periarteritis, endocrine diseases (Itsenko-Cushing syndrome, thyrotoxicosis). The patient is recommended to consult a cardiologist, neurologist, urologist, endocrinologist, oculist, according to indications — a neurosurgeon, oncologist.
The main therapeutic task in the management of pregnant women with hypertension is an effective reduction in blood pressure. Antihypertensive drugs are prescribed with blood pressure values of ≥ 130/90-100 mm Hg, exceeding the normal systolic pressure for a particular patient by 30 units, diastolic pressure by 15, detecting signs of fetoplacental insufficiency or gestosis. Hypertension therapy, if possible, is carried out with a monopreparation in a minimum dosage with a chronotherapeutic approach to taking medications. Medicines with a prolonged effect are preferred. To reduce blood pressure during gestation, it is recommended to use the following groups of antihypertensive drugs:
- α2-adrenomimetics. The agents of this group connect with the α2 receptors of sympathetic fibers, preventing the release of catecholamines (adrenaline, norepinephrine) – mediators with a vasopressor effect. As a result, the total peripheral resistance of the vascular bed decreases, the contractions of the heart are reduced, which as a result leads to a decrease in pressure.
- Selective β1-adrenoblockers. The drugs affect the beta-adrenoreceptors of the myocardium and smooth muscle fibers of the vessels. Under their influence, the strength and heart rate are mainly reduced, electrical conductivity in the heart is suppressed. A feature of selective beta-adrenergic receptor blockers is a decrease in oxygen consumption by the heart muscle.
- Blockers of slow calcium channels. Calcium antagonists have a blocking effect on slow L-type channels. As a result, the penetration of calcium ions from the intercellular spaces into the smooth muscle cells of the heart and blood vessels is inhibited. The expansion of arterioles, coronary and peripheral arteries is accompanied by a decrease in vascular resistance and a decrease in blood pressure.
- Myotropic vasodilators. The main effects of antispasmodics are a decrease in tone and a decrease in the contractile activity of smooth muscle fibers. Peripheral vascular dilation is clinically manifested by a drop in blood pressure. Vasodilators are effective for relieving crises. Usually vasodilators are combined with medications of other groups.
Diuretics, angiotensin receptor antagonists, ACE blockers are not recommended for the treatment of hypertension of the gestational period. Complex drug therapy of high blood pressure during pregnancy involves the appointment of peripheral vasodilators that improve microcirculation in the fetoplacental system, metabolism and bioenergetics of the placenta, protein biosynthesis.
The preferred method of delivery is natural childbirth. With good blood pressure control, a favorable obstetric history, and a satisfactory condition of the child, gestation is prolonged to full-term terms. During childbirth, hypotensive therapy continues, adequate analgesia and prevention of fetal hypoxia are provided. To shorten the period of exile, according to indications, a perineotomy is performed or obstetric forceps are applied. With high therapeutic refractoriness, the presence of serious organ complications (heart attack, stroke, retinal detachment), severe and complicated gestosis, deterioration of the child’s condition, childbirth is carried out ahead of schedule.
Prognosis and prevention
The outcome of gestation depends on the severity of the hypertensive syndrome, the functional state of the fetoplacental complex and target organs, and the effectiveness of antihypertensive treatment. Taking into account the severity of the disease, specialists in the field of obstetrics distinguish 3 degrees of risk of pregnancy and childbirth. With mild hypertension with signs of hypotensive effect of gestation in the first trimester (risk group I), the prognosis is favorable. In pregnant women with mild and moderate hypertension without a physiological hypotensive effect in the early stages (risk group II), more than 20% of gestations are complicated. With moderate and severe hypertension with a malignant course (risk group III), more than half of pregnant women have complications, the probability of having a full-term baby decreases sharply, and the risk of perinatal and maternal mortality increases.
To prevent hypertension, women planning pregnancy are recommended to reduce excess weight, treat the detected somatic and endocrine pathology, and avoid stressful situations. Pregnant patients with hypertension are considered to be at high risk for follow-up and specialized treatment by a therapist with at least 2-3 examinations during the gestational period.