Hypertension: Definition, Diagnosis, and Treatment

• Hypertension (HTN) involves a chronic elevation in blood pressure greater than 140/90 mmHg.
• Most common cause of secondary HTN.
• Important to check eyes during examination of HTN patients.

Learning Objectives

• Define normal BP, elevated BP, Stage 1 HTN, Stage 2 HTN, and malignant HTN.
• Describe risk factors, presentation, diagnosis, course, and complications of essential HTN.
• Identify common drug classes for HTN treatment.
• Differentiate between HTN emergency and HTN urgency.
• Discuss common causes of secondary HTN

Determinants of Arterial Pressure

• Arterial pressure is determined by cardiac output and peripheral resistance.
• Cardiac output depends on stroke volume and heart rate.
• Peripheral resistance is influenced by vascular structure and function.

Renin-Angiotensin-Aldosterone Axis

• The renin-angiotensin-aldosterone system (RAAS) plays a key role in regulating blood pressure.
• Renin converts angiotensinogen to angiotensin I, which is then converted to angiotensin II by ACE.
• Angiotensin II acts on AT1 receptors to increase blood pressure and stimulate aldosterone release.
• Aldosterone increases sodium reabsorption in the kidneys, further raising blood pressure.

Hypertension (HTN)

• Etiology is unknown in 90-95% of patients with HTN (essential HTN).
• Genetic and environmental factors contribute to essential HTN.
• Consider secondary causes, especially in young patients or those developing HTN after age 50.

Classification of BP Elevation

• Normal: <120 systolic and <80 diastolic.
• Elevated: 120-129 systolic and <80 diastolic.
• Stage 1 HTN: 130-139 systolic or 80-90 diastolic.
• Stage 2 HTN: >140 systolic or >90 diastolic.

Epidemiology of HTN

• Affects 50-65 million people in the U.S.
• Affects >1 billion people worldwide.
• Underdiagnosed/undertreated in a third of cases.
• Prevalence of 36% in African Americans and 23% in Caucasians.
• Women have higher rates than men with increasing age.
• Prevalence increases with age, affecting 5% at 20 years, >50% at 60-69 years, and 75% at >=70 years.

Risk Factors for HTN

• Family history, advanced age, African-American race, obesity, inactivity, smoking, high salt intake, and high alcohol intake.
• Associated conditions include hyperinsulinemia, metabolic syndrome, and diabetes.

Essential HTN

• Chronic elevation with no definable cause.
• Represents 90-95% of HTN cases.
• Increased risks of MI, HF, stroke, and kidney disease.
• Risk of CVD doubles with each increase of 20 mm Hg systolic or 10 mm Hg diastolic.

Factors Influencing Essential HTN

• Salt sensitivity is observed in ~60% of hypertensive individuals.
• Low calcium intake may increase BP.
• Genes responsible for rare monogenic hypertensive syndromes have been identified.

Monogenic Hypertensive Syndromes

• Glucocorticoid-remediable HTN involves ectopic aldosterone production.
• Liddle's syndrome results from mutations in the epithelial sodium channel.
• Syndrome of apparent mineralocorticoid excess is caused by a defect in renal 11β-hydroxysteroid dehydrogenase.

Insulin Resistance and Hyperinsulinemia

• Mechanisms by which can increase arterial pressure:
• Renal sodium retention and increased sympathetic stimulation.
• Vascular smooth-muscle hypertrophy.
• Ion transport changes.
• May be a marker for another pathologic process.

Secondary Causes of Hypertension

• Chronic Renal Disease, Renovascular Disease are common.
• Endocrine disorders: Hyperthyroidism, Cushing's, primary aldosteronism, pheochromocytoma, acromegaly, hypercalcemia.
• Coarctation of aorta, Obstructive sleep apnea.
• Medications (oral contraceptives).

Drugs Potentially Contributing to HTN

• NSAIDs, herbal preparations, glucocorticoids, oral contraceptives, androgen use, adrenal steroid hormones.
• Stimulants such as sympathomimetics, street drugs, and OTC supplements.
• Immunosuppressants, erythropoietin analogs.

Target Organ Damage Caused by HTN

• Coronary artery disease, LVH, prior MI, Angina pectoris, Chronic heart failure.
• Transient ischemic attacks, nephropathy, peripheral vascular disease, retinopathy.

Approach to the Patient with HTN

• Most are asymptomatic.
• Severe HTN may cause headache, dizziness, palpitations, easy fatigability, and epistaxis.
• End-organ damage may be the initial presentation.

Physical Exam Findings in HTN

• Retinal arteriolar changes.
• Left ventricular lift, loud A2, S4.
• Clues to secondary HTN include Cushingoid appearance, thyromegaly, abdominal bruit, and delayed femoral pulses.
• Causes of systolic HTN include thyrotoxicosis, aortic regurgitation, systemic AV fistula.

Measurement of BP

• Seated quietly for 5 minutes with feet on the floor and arm supported at heart level.
• Use appropriate-sized cuff.
• Measure BP in both arms and a leg.
• Take at least 2 measurements.
• SBP is the point at which the first sound is heard; DBP is the point just before the disappearance of sounds.

HTN Laboratory Screening

• Serum creatinine, BUN, UA
• Serum K (measured off diuretics).
• CXR.
• ECG(LVH suggests chronicity of HTN)
• Usual screening including CBC, glucose, lipid levels, calcium, uric acid.
• TSH if thyroid disease suspected

Imaging Studies

• CXR can show rib notching or indentation of distal aortic arch in coarctation of aorta.
• Echocardiography indicates stage II or long standing untreated stage I HTN.

Ambulatory BP Monitoring

• Diagnosing white coat HTN in absence of target organ injury
• Evaluating refractory HTN and circadian patterns of BP
• Determining relationship between BP and such symptoms as dizziness and visual changes

HTN Further Workup

• Further workup indicated for specific diagnosis if screening tests are abnormal or BP is refractory to antihypertensive therapy.
• Renal artery stenosis: captopril radionuclide scan, renal duplex US, Magnetic resonance angiography, renal arteriography.
• Cushing's Syndrome: dexamethasone suppression test
• Pheochromocytoma: 24-h urine collection for catecholamine's, metanephrine and vanillylmandelic and/or measurement of plasma metanephrine
• Primary hyperaldosteronism: depressed plasma renin activity and hypersecretion of aldosterone, both of which fail to change with volume expansions

Clues to Secondary HTN

• Much less common than essential or idiopathic HTN 5-10%
• Always consider a secondary correctable form of HTN, especially in pts aged < 30 or those who become hypertensive after 55
• BP is poorly controlled despite multiple medications
• They are likely compliant with medications, do not add dietary sodium & do not take medications such as steroids, contraceptives, NSAIDs, OTC cold remedies
• Use of birth control pills or glucocorticoids
• Paroxysms of HA, sweating, or tachycardia (pheochromocytoma)
• History of renal disease or abdominal traumas(renal HTN)

Symptoms Suggesting Secondary HTN

• Polyuria, polydipsia, and muscle weakness secondary to hypokalemia in patients with primary aldosteronism
• Weight gain and emotional lability in patients with Cushing's syndrome
• Episodic headaches, palpitations, diaphoresis, and postural dizziness in patients with a pheochromocytoma
• Use of medications (e.g., OCP, Glucocorticosteroids, decongestants, NSAID's, cyclosporine)
• History of renal disease or abdominal trauma(renal HTN)
• Daytime somnolence and snoring (sleep apnea)

Secondary Hypertension

• Renal Artery Stenosis (Renovascular Hypertension)
• Due to either atherosclerosis (older men) or fibromuscular dysplasia(young women)
• Presents with recent onset of HTN refractory to usual antihypertensive therapy
• Abdominal bruit is present in > 50% of cases
• Hypokalemia due to activation of the renin-angiotensin-aldosterone system may be present
• Renal Parenchymal Disease
• Elevated serum creatinine and/or abnormal urinalysis containing protein, cells, or casts

Coarctation of the Aorta

• Presents in children or young adults(including 35% of pts with Turner Syndrome)
• Constriction is usually present in aorta at origin of left subclavian artery
• Exam shows diminished, delayed femoral pulsations.
• Systolic murmur loudest at left infrascapular region
• Most common site of coarctation is just distal to origin of L SCA, so circulation to head & arms is not affected.
• Collateral circulation develops through internal mammary & Intercostal arteries
• Pulse waves in distal aorta & its branches are impaired

Pheochromocytoma

• A catecholamine-secreting tumor typically of the adrenal medulla or extraadrenal paraganglion tissue.
• Presents as paroxysmal or sustained HTN in young to middle-aged persons
• Sudden episodes of headache, palpitations, and profuse diaphoresis are common
• Associated findings include chronic weight loss, orthostatic hypotension, and impaired glucose tolerance
• Diagnosis is suggested by elevated plasma metanephrine level or urinary catecholamine metabolites in a 24-h urine collection; the tumor is then localized by CT or MRI

Hyperaldosteronism

• Due to aldosterone-secreting adenoma or bilateral adrenal hyperplasia
• Depressed plasma renin activity & hypersecretion of aldosterone, both of which fail to change with volume expansion
• Suspect when hypokalemia is present in a hypertensive patient off diuretic

HTN Treatment Goals

• Reduce CVD & renal morbidity & mortality.
• Treat to BP < 140/90 or BP < 130/80 in patients with DM or chronic kidney disease.
• Achieve SBP goal especially in persons > 50 years of age.
• In persons > 50 years of age, SBP >140 is a more important CVD risk factor than is DBP.
• Start with lifestyle modifications, control of other arteriosclerosis contributing risk factors.

Beneficial Lifestyle Modifications

• Weight reduction(goal BMI < 25 kg/m2)
• Sodium restriction
• Diet rich in fruits, vegetable, and low fat diary products
• Regular exercise
• Moderations of alcohol consumption

Lifestyle Modifications

• DASH (Dietary Approaches to Stop Hypertension) diet: high in K and low in saturated and total fat.
• Encourage fewer servings of red meat, sweets, sugar-containing beverages.
• Increase in potassium and/or calcium intake may be helpful.
• Modest sodium restriction:
• Weight loss: BMI <25 kg/m²
• Sodium Restriction: < 6 g NA per day
• Significant benefits for salt-sensitive hypertensive patients