Hypertension.  Learning objectives: at the end of this lesson the

student will be able to:

1. Define Hypertension. 2. List the etiologies of Hypertension. 3. Describe the different types of Hypertension. 4. Understand the epidemiology of Hypertension. 5. Understand the pathophysiology of Hypertension. 6. Identify the clinical manifestation of Hypertension. 7. Identity consequences of Hypertension. 8. Understand the diagnostic approach of

Hypertension. 9. Understand the management of chronic

hypertension and hypertensive crisis.

Definition:

Hypertension is defined as arterial blood pressure that exceeds 140/90mmHg at several determinations. This is an arbitrary definition because a diastolic pressure of even 85 mm Hg may be associated with increased cardiovascular morbidity and mortality.

• Hypertension is one of the most common diseases afflicting humans throughout the world. Because of the associated morbidity and mortality and the cost to society, hypertension is an important public health challenge.

• It is easily detectable, usually easily treatable, and often leads to lethal complications if left untreated

Hypertension is the most important modifiable risk factor for coronary heart disease, stroke, congestive heart failure, end-stage renal disease, and peripheral vascular disease.

Therefore, health care professionals must not only identify and treat patients with hypertension but also promote a healthy lifestyle and preventive strategies to decrease the prevalence of hypertension in the general population.

Epidemiology

Overall, approximately 20% of the world's adults are estimated to have hypertension in excess of 140/90 mm Hg. Some studies done in developed countries show almost 50 % of the population may have hypertension.

• The prevalence dramatically increases in patients older than 60 years.

• The prevalence is higher among balks than whites.

Classification

Because the risk to an individual patient may correlate with the severity of hypertension, a classification system is essential for making decisions about aggressiveness of treatment or therapeutic interventions.

BLOOD PRESSURE ( in mm Hg)

CATEGORY Systolic DiastolicOptimal <120 And <80Normal <130 And <85High-normal 130–139 Or 85–89

Hypertension

Stage 1 140–159 Or 90–99Stage 2 160–179 Or 100–109Stage 3 180 or N 110

Table III-7-1. Classification of blood pressure for adults and older children *

When systolic and diastolic blood pressure levels fall into different categories, the higher category should be selected to classify the individual's blood pressure status.

E.g. 160/92 mm Hg should be classified as stage 2 hypertension

174/120 mm Hg should be classified as stage 3 hypertension.

Isolated systolic hypertension is defined as systolic blood pressure 140 mm Hg or greater and diastolic blood pressure less than 90 mm Hg and staged approximately (e.g., 170/82 mm Hg is defined as stage 2 isolated systolic hypertension).

In addition to classifying stages of hypertension on the basis of average blood pressure levels, clinicians should specify the presence or absence of target organ damage and additional risk factors. This specificity is important for risk classification and treatment.

Optimal blood pressure with respect to cardiovascular risk is ≤ 120/80 mm Hg.

 Hypertension should be diagnosed based on the average of two or more readings taken at each of two or more visits after an initial screening.

The natural history of essential hypertension:

It evolves from occasional to established hypertension. After a long invariable asymptomatic period, persistent hypertension develops into complicated hypertension, in which target organ damage to the aorta and small arteries, heart, kidneys, retina, and central nervous system is evident.

• The progression begins with prehypertension in persons aged 10-30 years (by increased cardiac output) to early hypertension in persons aged 20-40 years (in which increased peripheral resistance is prominent) to established hypertension in persons aged 30-50 years, and, finally, to complicated hypertension in persons aged 40-60 years.

Etiologic Classification of Hypertension:

Hypertension may be classified as either essential or secondary.

I. Primary or essential hypertension (90-95%): Essential hypertension is diagnosed in individuals in

whom generalized or functional abnormalities may be the cause of hypertension but no specific secondary causes are identified.

The pathophyisoliogy of essential hypertension is multifactorial and highly complex. A number of factors modulate the blood pressure. These factors include humeral mediators, vascular reactivity, circulating blood volume, vascular caliber, blood viscosity, cardiac output, blood vessel elasticity, and neural stimulation.

Some factors that may contribute for the development of essential hypertension include:

1. Genetic predisposition: the exact mechanism has not been established

2. Environment: a number of environmental factors have been implicated

Dietary salt intake and Salt sensitivity Obesity Occupation Family size and crowding

3. Pregnancy-induced hypertension: Toxemia of pregnancy

II. Secondary causes of hypertension: In 5-10 % of patients with hypertension, the hypertension is secondary to an identifiable disorder.

A. Renal Hypertension (2.5-6%) a variety of renal diseases may be accompanied by hypertension

Renal parenchymal disease : Chronic pyelonephritis Acute and chronic glomerulonephritis Polycystic kidney disease Urinary tract obstruction Renin-producing tumorRenovascular hypertension (0.2-4%) Coarctation of aorta Vasculitis Collagen vascular disease

B. Endocrine (1-2%) • Oral contraceptives• Adrenocoritical

hypertension Primary aldosteronism Cushing syndrome Congenital adrenal

hyperplasia• Pheochromocytoma• Acromegally• Myxoedema• Thyrotoxicosis

C. Neurogenic : • Psychogenic • Increased

intracranial pressure • Acute spinal cord

sectionD. Drugs and toxins• Alcohol• Adrenergic

medications

Consequences of Hypertension (End organ /target organ damage)

Patients with hypertension die prematurely, the most common cause of death is heart disease, with stroke and renal failure also frequent, particularly in patients with retinopathy

1. Effects on the Heart : • Left ventricular hypertrophy as a

compensatory mechanism • Coronary artery disease /Ischemic heart

disease: Angina Pectoris Myocardial infarction which may lead to heart failure

2. Neurologic effects A. Retinal changes :i. Exudates: hard and soft exudatesii. Hemorrhages: dot and bloat hemorrhagesiii. Thickening of arterioles – copper wiring Æ silver

wiringiv. Abnormalities on arteriolo –venular crossings ( A/V

crossings )v. PapilledemaB. Central nervous system dysfunction i. Cerebrovascular disease Transient ischemic attacks : episodic dizziness ,

unilateral blindness , hemiparesis etc Stroke

Ischemic stroke : due to atherosclerosis of cerebral blood vessels

Hemorrhagic stroke: as a result of elevated arterial pressure and formation of vascular micro- aneurysms.

ii. Hypertensive encephalopathy: consists of severe hypertension, altered state of consciousness, increased intracranial pressure with papilledema and seizure. Focal neurologic deficits are not common.

3. Effects on the kidneys :

Arteriolosclerosis of the afferent and efferent arterioles and the glumerular capillary tuft impairs renal function. Patients may have proteinuria and microscopic hematuria and later on develop chronic renal failure.

Risk factors for an adverse prognosis in hypertension:

1. Black race2. Youth3. Male sex4. Smoking5. Diabetes mellitus6. Hypercholesterolemia7. Obesity8. Excess alcohol intake9. Evidence of end organ damage 

Approach to a patient with Hypertension:

Diagnosis of hypertension: is confirmed after an elevated blood pressure ≥ 140/90 mm Hg, properly measured, has been documented on at least 3 separate occasions (based on the average of 2 or more readings taken at each of 2 or more visits after initial screening).

An accurate measurement of blood pressure is the key to diagnosis.

• Several determinations should be made over a period of several weeks.

• At any given visit, an average of 3 blood pressure readings taken 2 minutes apart using a mercury manometer is preferable.

• Blood pressure should be measured in both the supine and sitting positions, auscultating with the bell of the stethoscope.

On the first visit, blood pressure should be checked in both arms and in one leg to avoid missing the diagnosis of coarctation of aorta or subclavian artery stenosis.

• As the improper cuff size may influence blood pressure measurement, a wider cuff is preferable, particularly if the patient's arm circumference exceeds 30 cm.

• The patient should rest quietly for at least 5 minutes before the measurement.

• Although somewhat controversial, the common practice is to document phase V (a disappearance of all sounds) of Korotkoff sounds as the diastolic pressure.

Patient evaluation: In evaluating a patient with hypertension the initial history, physical examination and laboratory should be directed at

1) Establishing pretreatment base line hypertension :2) Identifying correctable secondary caused of

hypertension3) Determining if target organ damage is present:

patients may have undiagnosed hypertension for years without having had their blood pressure checked. Therefore, a search for end organ damage should be made through proper history and physical examination.

4) Determining whether other cardiovascular risk factors are present 

5) Assessing factors that may influence the type of therapy or be changed adversely by therapy

Clinical symptoms and History:  Most patients with hypertension have

no specific symptoms and are identified only in the course of physical examination

If patients develop symptoms, the they may be attributable to The elevated BP itself or The end organ damage associated with

hypertension or The underlying secondary disease

Some of the symptoms may be

Headache: though popularly considered symptom of high BP, it is a characteristic of only sever hypertension. Such headaches are localized to the occipital region and present when the patient awakens in the morning but subsides spontaneously after several hours

Dizziness , palpitation , easy fatigability and impotence Symptoms referable to vascular diseases or evidences

of target organ damage include Epistaxiis , hematuria Retinal changesÆblurring of vision Cerebrovascular damages : Transient ischemic attacks Æ

episodes of weakness or dizziness or Stroke may occur ( hemorrhagic or ischemic )

Cardiovascular damages : chest pain /angina pectoris or myocardial infarction which may cause dyspnea due to heat failure

Pain due to dissecting aorta

Predisposing factors for hypertension

Strong family history of hypertension Age : secondary hypertension often develops before the

age of 35 or after 55

Associated cardiovascular risk factors: • Cigarette smoking • Lipid abnormality or hypercholesterolemia, • Diabetes mellitus • Family history of early deaths due to cardiovascular

diseases • Alcoholism. • Obtain a history of over-the-counter medication

use, current and previous unsuccessful antihypertensive medication trials

Physical Examination:

General appearance: Round face and truncal obesity suggests Cushing syndrome Muscular development in the upper extremities out of the

proportion of the lower extremities suggests coarctation of the aorta

Proper measurement of blood pressure Compare the BP and pulses in the two upper extremities

and in supine and standing position A rise in diastolic pressure when the patient goes from

supine to standing position is most compatible with essential hypertension while a fall in BP in the absence of antihypertensive medications suggests secondary hypertension.

Funduscopic evaluation of the eyes

Palpation of all peripheral pulses should be performed

A careful cardiac examination Abdominal examination:

 

Diagnostic workup 

Laboratory investigations: Unless a secondary cause for hypertension is

suspected, only the following routine laboratory studies should be performed: CBC and Hematochrite Urinalysis including microscopy , protein , blood and ,

glucose Fasting blood glucose Serum electrolytes : serum K+ Lipid profile (total cholesterol, low-density lipoprotein

[LDL] and high-density lipoprotein [HDL], and triglycerides).

Serum creatinine, uric acid, ECG

Imaging Studies:

Echocardiography: to detect LVH Special studies to screen for Secondary

hypertension: should be requested only when secondary hypertension is strongly suspected.

Renovascular disease : ultrasound and Doppler flow study

Pheochromocytoma : 24 hrs urine assay of metanehprines and catecholamine

Cushing’s syndrome: overnight dexamethason suppression test or 24 hrs urine cortisol

Primary aldosteronism: plasma aldostrone Thyrotoxicosis or Myxoedema : Thyroid function test

( TSH , T3 and T4 )

Therapy of Hypertension

Indication for treatment: Patients with a diastolic pressure >90mm Hg or

systolic pressure > 140 mm Hg repeatedly Isolated systolic hypertension (systolic BP > 160

with diastolic BP < 89 mmHg) if the patient is older than 65 years.

Goal of therapy : • Reducing the diastolic BP to < 90 mmHg

and systolic BP < 150mmHg.

1. General measures : non pharmacologic therapy

A. Sodium restriction: intake not more than 100 mmol/d (2.4 g sodium or 6 g sodium chloride).

B. Lifestyle modifications.1. Weight reduction in obese patients2. Limitation of alcohol intake : alcohol potentiates the

action of catecholamines and may exacerbate hypertension3. Regular physical exercise: increase aerobic activity (30-45

min most 4. days of the week).5. Maintain adequate intake of dietary potassium,

calcium and magnesium for general health. ( healthy diet like fruits, vegetables, etc)

6. Stop smoking7. Reduce intake of dietary saturated fat and cholesterol

2. Pharmacologic therapy.

A. Diuretics : are often the first line drugs , and reduce extra cellular fluid volume

Thiazide diuretics : are more effective anti-hypertensive agents than loop diuretics

Dose: Hydrochlorothiazide 25 mg PO daily and may be increased gradually

Side effects: hypokalemia, hyperuricemia, hyperglycemia Contraindcation: Gout Potassium-sparing diuretics (e.g. Spironolactone ) :

is a competitive inhibitor of aldosteron and may be used in primary hyperaldosteronism (as an additional therapy in combination with thiazide diuretics)

Dose: 25-50 mg PO 2 to 4 times daily

B. β-adrenergic blocking agents reduce cardiac output and rennin release • β-blockers : Propanolol , Metoprolol , Labetolol

, Carvidolol , Atenolol Doses: Propranolol 20 mg PO /day to Maximum

of 120 mg PO 4X/day Metoprolol: 25 – 150 mg PO BID Atenolol: 25-100

mg PO/day Side effects: bronchospasm, bradycardia,

worsening of heart failure, impotence, depression Contraindication: Asthma, peripheral vascular

disease (severe)

C. Centrally acting agents

These agents inhibit sympathetic out flow from the CNS. • Methyldopa : 250 mg -1000 mg PO BID , TID or QID Side effects: postural hypotension, depression,

gyneacomastia.

D. Vasodilators: dilate arteriols and arteries, reducing peripheral vascular resistance which inturn reduces high blood pressure.

• Hydrallazine : Oral 10-75 mg PO QID Paraneteral: 10-50 mg IV or PO every 6 hours. Side effects: – headache, lupus erythromatosis like

syndrome• Minoxidil : 2.5 -40 mg PO BID Side effects: Orthostatic hypotension

E. Calcium channel blockers: by modulating calcium release in smooth muscles,

calcium channel blockers reduce smooth muscle tone, resulting vasodilatation. Dihydropyridines: Nifedipine, Felodipine, Amlodipine

Non dihydropyridines : Diltiazime, and Verapamil

Doses: Nifedipine: 30 – 90 mg PO daily Amlodipine: 2.5 -10 mg PO daily Side effects : Dihydropyridines: headache ,

tachycardia , GI disturbance Non dihydropyridines have cardio depressant effect and their use may be problematic in CHF patients

Contraindication: Heart block, heart failure

F. ACE inhibitors: Inhibit the conversion of angiotensin I to angiotensin II (a potent

vasoconstrictor). By doing so ACE inhibitors reduce peripheral resistance. In addition they reduce aldosteron production, reducing the retention of sodium and water. Captopril , Nezapril , Enalapril , Fosinopril , Ramipril.

Doses: Captopri : 12.5 -75 mg PO BIDEnalapril: 2.5-40 mg dailySide effects: Cough, Leucopenia, angioedema, hyperkalemia.Contraindicated in: Bilateral renal artery stenosis, Renal failure.G. Angiotensin receptor blockers: they block the

angiotensin system without causing some of the annoying side effects of ACE inhibitors such as cough. Losartan: 25-50 mg once or twice daily

Side effects: hypotension

Hypertensive crisis Is defined as severe hypertension characterized by diastolic blood

pressure greater than 130 mmHg. Blood pressure elevation to such degree can cause vascular damage, encephalopathy, retinal hemorrhage, renal damage and death. 1 –2% of the hypertensive population develop this complication. It is categorized into two:

• Hypertensive Emergency in which there is acute impairment of an organ system (CNS,

CVS, Renal). In these conditions, the blood pressure should be lowered aggressively over minutes to hours.

• Hypertensive Urgency in which BP is high and there is potential risk but not yet caused

acute end-organ damage. These patients require BP control over several days to weeks.

Diagnosis: A diastolic pressure of 130 mmHg, funduscopic finding of papilledema, change in neurologic and mental status and abnormal renal sediments are the hallmarks of hypertensive

Approach to patients with hypertensive crisis:

• Rapid assessment of the patient with brief history and targeted physical examination (of the CNS, CVS , retina ),

• Laboratory investigations : o CBC o Urinalysis o Renal function test o ECG Treatment “treats the patient, not the number”

General measures: Initial considerations: look if the patient is in a stressful

situation .Place the patient in a quiet room and reevaluate after initial interview, some patient’s BP lowers below a critical level after relaxation.

How to measure a

Blood pressure