1. HYPERTENSION Pathophysiology Dr. Zahoor Ali Shaikh 1

2. Hypertension 1. Essential hypertension (90-95%) 2. Secondary hypertension (5-10%) 2

3. 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. 3

4. 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 4

5. 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. 5

6. 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. 6

7. Insulin resistance It leads to hypertension, prediabetes, typeII diabetes, hyper lipidemia and obesity It is called insulin resistance or Metabolic syndrome. 7

8. 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 8

9. 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 9

10. We will discuss Secondary hypertension It is increase in blood pressure due to another disease condition. Occurs in 5-10% cases Causes ▫Renal disease 1.Glomerulonephritis 2.Chronic pyelonephritis, 3.Polycystic kidney disease 4.Diabetic nephropathy 5.Renal artery stenosis 10

11. 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 11

12. 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) 12

13. 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 13

14. 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 14

15. 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 15

16. 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 16

17. 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 17

18. 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 18

19. 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 19

20. 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 20

21. 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 21

22. 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 22

23. 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 23

24. 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 24

25. 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 25

26. THANK YOU 26