Pathophysiology and clinical significance
Essential hypertension is highly prevalent in the population, its frequency increases with age, and its consequences include disability and death due to comorbid conditions. In Russia, this nosology remains underdiagnosed and undertreated, creating a major opportunity for the prevention of complications.
Blood pressure is determined by three parameters: cardiac output (depending on heart rate and left ventricular stroke volume), total peripheral vascular resistance (TPVR, depending on vessel lumen), and circulating blood volume (CBV, normally about 5 liters). Understanding these mechanisms dictates the choice of antihypertensive drugs: some affect heart rate and stroke volume, most affect TPVR, and diuretics reduce CBV.
In essential hypertension, the exact cause is unknown; discussed factors include imbalance of the vasomotor center, sympathetic nervous system activity, and vascular hyalinosis increasing vessel stiffness. The renin-angiotensin-aldosterone system plays a crucial role in increasing TPVR: the kidney releases renin in response to a drop in pressure, renin converts angiotensinogen (from the liver) into angiotensin I, which is converted to angiotensin II by angiotensin-converting enzyme. Angiotensin II increases TPVR and stimulates the production of aldosterone in the adrenal glands and antidiuretic hormone in the brain. The action of ACE inhibitors, angiotensin receptor blockers, and aldosterone receptor antagonists is based on this mechanism.
Diagnostic criteria and special forms
Russian clinical practice uses European criteria for arterial hypertension (American criteria are stricter, lowering the treatment threshold starting from 130 mmHg). According to the European classification, optimal, normal, high-normal blood pressure, and three grades of hypertension are distinguished.
A diagnosis is not established based on a single measurement—pressure fluctuates, therefore at least two office measurements, 24-hour ambulatory blood pressure monitoring (ABPM), or home blood pressure monitoring are used, with office measurement thresholds being higher than home ones.
Additionally, the following are distinguished:
- White-coat hypertension — elevated at clinic visits, normal at home;
- Masked hypertension — normal at clinic visits, elevated at home; suspected in high-normal blood pressure;
- Isolated systolic hypertension — only systolic pressure is elevated, characteristic of the elderly due to vascular wall stiffness.
Investigation of secondary hypertension
Secondary hypertension should be suspected in cases of: severe or resistant hypertension (more than three drugs without effect), sharply uncontrolled hypertension, onset before age 30 with a normal body mass index, rapid target organ damage (e.g., left ventricular hypertrophy or retinopathy at a young age), as well as electrolyte disturbances.
Red flags for targeted investigation:
- Renal symptoms, unexplained edema, bruits over renal arteries and aorta — renal artery stenosis;
- Episodes of headache and sweating — pheochromocytoma;
- Moon face, central obesity — Cushing's syndrome;
- Enlargement of acral body parts, coarsening of facial features — acromegaly;
- Exophthalmos — thyroid pathology;
- Loud snoring, daytime sleepiness — sleep apnea syndrome.
Screening involves the Epworth sleepiness scale and polysomnography (apnea), renal duplex ultrasound or CT angiography, creatinine, electrolytes (renal hypertension), 24-hour urinary metanephrines (pheochromocytoma), 24-hour urinary cortisol (Cushing's), TSH (thyroid gland).
Staging, risk stratification, and diagnosis formulation
To establish the stage of hypertension, target organ damage (vessels, kidneys, eyes, heart, brain) and the presence of associated clinical conditions are evaluated. Asymptomatic organ damage includes increased pulse pressure, decreased ankle-brachial index, hypertensive angiopathy, albuminuria, reduced glomerular filtration rate, and left ventricular hypertrophy. Associated clinical conditions include aortic dissection, atherosclerotic stenosis of brachiocephalic arteries greater than 50%, hypertensive retinopathy, pronounced albuminuria, myocardial infarction, angina pectoris, heart failure, myocardial revascularization, atrial fibrillation, stroke, and transient ischemic attack.
Staging algorithm (applied exclusively in Russian clinical practice): in the presence of an associated clinical condition — stage 3; in its absence, target organ damage and diabetes mellitus are assessed: neither present — stage 1, either one present — stage 2, both factors present — stage 3.
The risk group for stage 1 without risk factors is determined using the SCORE2 scale; in other cases, the risk table is used taking into account the stage and risk factors. The baseline evaluation for formulating a diagnosis includes ECG, echocardiography, complete blood count and urinalysis, glucose, creatinine, albumin-creatinine ratio (or 24-hour albuminuria), lipid profile, electrolytes, uric acid, TSH, and fundoscopy.
Diagnosis structure: hypertensive disease → stage → hypertension grade (if blood pressure is elevated at the time of examination) → BP control status → risk factors or target organ damage → comorbid cardiovascular diseases, diabetes mellitus, chronic kidney disease → risk group → target BP.
Non-pharmacological and pharmacological treatment
For blood pressure up to grade 3, lifestyle modification may be recommended for 3–6 months: weight loss, the DASH diet (rich in fruits and vegetables, more effective than the Mediterranean diet for lowering pressure), sodium restriction, increased dietary potassium, alcohol cessation, aerobic, resistance, and isometric exercises. In terms of blood pressure reduction efficacy: weight loss > diet > physical activity > sodium and alcohol restriction.
Main drug groups:
- ACE inhibitors — reduce angiotensin II, provide nephro- and cardioprotection; side effects include cough and angioedema (due to bradykinin accumulation, which may appear and disappear months later); contraindicated in bilateral renal artery stenosis, hyperkalemia, and pregnancy;
- Angiotensin receptor blockers — similar effects without cough and edema; not combined with ACE inhibitors;
- Beta-blockers — indicated for CAD, CHF, atrial fibrillation, thyrotoxicosis, migraine; use with caution in asthma (cardioselective only), contraindicated in high-grade heart block and bradycardia; atenolol causes erectile dysfunction more frequently than others;
- Calcium channel blockers: dihydropyridines (amlodipine) dilate blood vessels, cause lower extremity edema; non-dihydropyridines (verapamil) decrease conduction and stroke volume, cause constipation, contraindicated in WPW syndrome with atrial fibrillation;
- Thiazide diuretics — indicated for isolated systolic hypertension, osteoporosis; contraindicated in gout and anuria, may cause hypokalemia and hyperglycemia;
- Aldosterone antagonists (spironolactone) — effective in resistant hypertension, primary hyperaldosteronism, CHF; risk of hyperkalemia and gynecomastia.
Target blood pressure is below 130/80 mmHg; for patients over 65 years and those with chronic kidney disease, it is below 140/80. The decision regarding the target level should be made jointly with the patient, taking quality of life into account. Initial therapy is a combination of two drugs (an ACE inhibitor or angiotensin receptor blocker plus a calcium channel blocker or diuretic); monotherapy is justified only in very elderly or young patients with mild blood pressure elevation.
Hypertensive crisis and emergency care
Hypertensive crisis is a blood pressure elevation above 180/120 mmHg. It is divided into uncomplicated crisis (without signs of acute target organ damage, manifested by nonspecific symptoms — headache, dizziness, epistaxis) and complicated crisis with target organ damage.
In an uncomplicated crisis, emergency blood pressure reduction is not required — maintenance therapy is adjusted, and investigation of secondary causes is considered. Signs of a complicated crisis requiring emergency intervention:
- Stroke (hemorrhagic or ischemic), hypertensive encephalopathy — headache, vomiting, confusion, seizures;
- Myocardial infarction — pain, sweating, pallor;
- Aortic dissection — back pain, asymmetrical limb pulses;
- Acute heart failure with pulmonary edema — dyspnea, moist rales;
- Acute kidney injury — decreased urine output, edema, microhematuria.
For intravenous blood pressure reduction, urapidil, nitrates, nitroprusside, and labetalol are used. In aortic dissection, blood pressure is rapidly reduced to 120 mmHg; in ischemic stroke, systolic blood pressure is not lowered below 180 mmHg due to the risk of impaired collateral blood flow.
Key points
- Blood pressure is determined by cardiac output, blood volume, and total peripheral resistance — the main groups of antihypertensive drugs target these exact links.
- In Russia, European criteria are used for diagnosis; the diagnosis is confirmed by at least two measurements, ABPM, or home monitoring.
- Secondary hypertension should be suspected in cases of resistant course, onset before age 30 without obesity, rapid target-organ damage, and red flags in the medical history.
- The stage of essential hypertension is determined by target-organ damage, associated clinical conditions, and the presence of diabetes mellitus.
- ACE inhibitors and angiotensin receptor blockers should not be combined with each other.
- Initial therapy is usually dual; the target blood pressure is below 130/80, and below 140/80 in elderly patients and those with CKD.
- Uncomplicated hypertensive crisis does not require emergency blood pressure reduction, whereas complicated crisis requires immediate intravenous therapy and hospitalization.
- In ischemic stroke, systolic blood pressure is not lowered below 180 mmHg in order to preserve collateral blood flow.