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HYPERTENSIONPathophysiologyDr. Zahoor Ali Shaikh
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Hypertension
1. Essential hypertension (90-95%) 2. Secondary hypertension (5-10%)
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Hypertension
•We will discuss pathophysiology of essential Hypertension.
•Although no cause is identified but 1. constitutional or inherent factors 2. life style or environmental factors
have been implicated.
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Essential Hypertension 1. Constitutional factors•Inborn risk factors or constitutional
factors▫Genetic factors e.g. liddles syndrome ▫Family H/O hypertension▫Fetal factors▫Race Black people are more prone to high blood pressure.▫Age related increase in blood pressure▫Insulin resistance
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Liddles syndrome
•Autosomal dominant - Genetic mutation at locus 16p13-p12 causing dysregulation of epithelial sodium
channel (ENaCl)•There is hypertension with low plasma
rennin and aldosterone and decrease potassium.
•There is abnormal kidney function with increased reabsorption of sodium and loss of potassium from renal tubule.
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Family H/O hypertension
•BP runs in families.•Children of hypertensive parents have
higher BP than children of normotensive parents.
Fetal factor•Babies born with low birth weight get
high BP.
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Insulin resistance
•It leads to hypertension, prediabetes, typeII diabetes, hyper lipidemia and obesity
•It is called insulin resistance or Metabolic syndrome.
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2. Life style risk factors
•Can contribute to the development of hypertension▫Increase salt intake – causes increase blood
volume, increase cardiac output, increase peripheral resistance
▫Increase alcohol consumption – systolic BP is affected more.
▫Stress – increase sympathetic activity
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Life style risk factors [cont]
•Obesity – lepton hormone derived from adipose tissue, causes increase sympathetic activity via hypothalamus▫There is research, supporting activation of
renin-angiotensin-aldosterone system by adipocyte derived angiotensinogen.
•Smoking
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We will discussSecondary hypertension•It is increase in blood pressure due to
another disease condition.•Occurs in 5-10% cases•Causes
▫Renal disease1. Glomerulonephritis2. Chronic pyelonephritis, 3. Polycystic kidney disease4. Diabetic nephropathy5. Renal artery stenosis
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Secondary hypertension [cont]
•Renal hypertension occurs due to decreased renal blood flow – increase renin – activation of renin- angiotensin -aldosterone mechanism
•Endocrine causes•Adrenal cortical disorder
▫Primary hyper aldosteronism or Conn's syndrome due to adenoma of renal cortex
▫Cushing’s syndrome
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Secondary hypertension
Endocrine cause (cont) • Pheochromocytoma – tumor of adrenal medulla- There is paroxysmal hypertension,
headache excessive sweating and palpitation – due to paroxysmal release of catecholamine (50% cases).
- Other patients of Pheochromocytoma may have sustained hypertension (50%cases)
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Secondary hypertension [cont]CVS causes•Coarctation of aorta
▫Narrowing of aorta in adult usually occurs just distal to origin of subclavian arteries
▫Large stroke volume is ejected into narrowed aorta which results in increase in systolic BP in upper parts of the body
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Secondary hypertension Coarctation of aorta (cont)
▫BP in lower extremities may be normal or low
▫Femoral pulses are weak▫Blood pressure in arms if 20 mm of Hg or
higher than in legs is suggestive of Coarctation of aorta
• Respiratory cause of secondary Hypertension Obstructive sleep apnea
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Drugs▫Oral contraceptives – Estrogen &
progesterone in contraceptive pills causes Na+ retention
▫common cause of secondary HT in young women
▫Women should check their blood pressure regularly when they are taking the pill
▫Steroids, Vasopressin ▫Cocaine ▫Amphetamine▫Erythropoietin
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Complications of hypertension
•Target Organ damage occurs due to long term effect of hypertension
•Organs affected are ▫Heart▫Eyes▫Kidney▫Blood vessels – increase risk of coronary
artery disease and stroke
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Hypertensive crises
•Situation when markedly increased blood pressure is accompanied by progressive target organ damage
•It is defined as diastolic BP greater than 120 mmHg
•Goal of initial treatment is partial reduction of BP to safe level, rather than to normal level
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•Malignant hypertension – when BP rises rapidly, diastolic BP more than 130mmHg. Unless treated, it may lead to death due to renal failure, heart failure or stroke.
•Severe hypertension is defined when blood pressure is more than 180/110 mmHg
•If diastolic blood pressure is more than 110 mmHg it should be treated urgently
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Hypertension in special population•High BP in pregnancy
▫Hypertension may complicate 5-10% of pregnancies
▫Causes may be Pre-eclamsia Eclampsia Gastational hypertension Chronic hypertension
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High BP in pregnancy
•Pre-eclampsia▫There is new onset of hypertension with
proteinuria▫Develops in last half of the pregnancy(after
20 wks) of pregnancy▫BP is more than 140 / 90 mmHg▫Cause:Decreased placental blood flow –
release of toxins which act on blood vessles
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IMPORTANT
•Blood pressure in pregnancy should be treated with safe anti hypertensive drugs, e.g.. Methyl dopa
•ACE inhibitors can cause injury or even death of fetus when given during second or third semester of pregnancy
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High BP in children and adolescents
•In children BP occurs in 1-3%•Reports are, BP is increasing in children•WHY???•Because of obesity, decrease physical
activity, increase uptake of salt and high caloric diet
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High BP in elderly
•BP increases with age•50% of people may be affected between
60 – 69 yrs.•Cause
▫Atherosclerosis – stiff large artery▫Increase peripheral resistance▫Decrease renal blood flow
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Orthostatic Hypotension or Postural hypotension•It is abnormal drop of BP on standing•Systolic BP drops more than 20 mmHg
and diastolic BP drops more than 10 mm Hg
•Person will feel dizziness and syncope•Take BP supine and standing position
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Causes of orthostatic/postural hypotension•Decrease blood volume e.g.. bleeding
peptic ulcer, gastroenteritis, diuretics•Drugs e.g.. Vasodilators•Ageing •Autonomic nervous system dysfunction
▫Peripheral neuropathy in diabetes mellitus ▫Stroke▫Parkinsonism with ANS failure
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