Hypertension.pdf

Hypertension Prof.Udaya Ralapanawa MBBS,MD(Col),MRCP(UK),FRCP(London),FRCP(Edin ),FCCP Professor in Medicine Consultant Physician Overview of presentation ⚫ Introduction to hypertension ⚫ Presentation to primary care ⚫ Measurement of BP/other parameters ⚫ When to manage ⚫ How to manage ⚫ Upd...

Hypertension Prof.Udaya Ralapanawa MBBS,MD(Col),MRCP(UK),FRCP(London),FRCP(Edin ),FCCP Professor in Medicine Consultant Physician Overview of presentation ⚫ Introduction to hypertension ⚫ Presentation to primary care ⚫ Measurement of BP/other parameters ⚫ When to manage ⚫ How to manage ⚫ Update of recent evidence Introduction to hypertension ⚫ Hypertension is not a disease but a risk factor (modifiable) ⚫ Lowering BP decreases risk of stroke, coronary events, cardiac failure & renal impairment. ⚫ HP is undiagnosed and undertreated (140 or DBP >90 persistently (last 3 readings) Prevalence and Incidence ⚫ More than 25% of world adult population is already hypertensive. ⚫ 29% of adult US population ⚫ By 2025 1.56 billion ⚫ Related to body mass index ⚫ High prevalence in African Americans ⚫ 5% of pediatric population; prevalence increases with age ⚫ Strong positive relationship between blood pressure and risk of CVD events Prevalence and Incidence ⚫ In Sri Lanka prevelence of HT 18.8% in male & 19.3% in female ⚫ Only 22% of diagnosed HT are adequately controlled. ⚫ Only 6-15% of diagnosed HT are adequately evaluated for risk factors for CVD & target organ damage Pathophysiology ⚫ Blood pressure is a function of cardiac output multiplied by peripheral resistance ⚫ Affected by diameter of blood vessel ⚫ Atherosclerosis decreases diameter, increases blood pressure  Determinants of Blood Pressure 1. Blood volume 2. Vascular resistance to pressure 3. Heart stroke volume i Ps-DZ, 2009 o Ps-DZ, 2009  Vascular Resistance Viscosity of blood Width of vessels—(constriction or dilation)—controlled by muscle tone in vessel walls  Regulation of Blood Pressure 1. Sympathetic nervous system (SNS)—responds immediately; SNS innervated tissues contract or dilate vascular bed 2. Renin-angiotensin system—retains Na and H2O to increase blood volume; constricts blood vessels; increases aldosterone 3. Kidneys—respond to renin-angiotensin system; aldosterone and antidiuretic hormone (ADH) are sent out as needed Homeostatic Control of Blood Pressure ⚫ Short term —Sympathetic nervous system —Vasoconstriction —Vasodilation ⚫ Long term —Fluid volume —Renin-angiotensin system Renin-Angiotensin Cascade Redrawn from Guyton AC: Textbook of medical physiology, ed 8, Philadelphia, 1991, WB Saunders.  Hypertension-Aetiology 1. 90% HTN is essential HTN (cause unknown; perhaps prenatal impacts?) 2. 10% HTN is secondary to other diseases Causes of Secondary Hypertension With Clinical Indications Common causes Renal parenchymal disease Renovascular disease Primary aldosteronism Obstructive sleep apnea Drug or alcohol induced Uncommon causes Pheochromocytoma/paraganglioma Cushing’s syndrome Hypothyroidism Hyperthyroidism Aortic coarctation (undiagnosed or repaired) Primary hyperparathyroidism Congenital adrenal hyperplasia Mineralocorticoid excess syndromes other than primary aldosteronism Acromegaly Risk factors for Hypertension Algorithm content developed by John Anderson, PhD, and Sanford C. Garner, PhD, 2000. Presentation of hypertension to primary care ⚫ Usually asymptomatic ⚫ May be found on routine screening/incidental. ⚫ Headache/visual disturbance. ⚫ Symptoms end organ damage: LVH, TIAs CVA,MI, angina, renal impairment, PVD, retinopathy. Measurement 1.Screening ⚫ British Hypertension Society suggest all adults should have BP measured every 5 years. ⚫ If BP ‘high normal’ (SBP 130-139 mmHg DBP 85-89) BP check annually. ⚫ Screen any patient with known renal, atherosclerotic disease, diabetes as part of routine follow up. Is accurate BP measurement important? Is accurate BP measurement important? ⚫ Elevated BP is a common finding & asymptomatic till target organ damage develops. ⚫ Elevated BP confers substantial risk of cardiovascular disease. ⚫ Incidence of cardiovascular events in people with high BP can be reduced with drugs Rx. ⚫ Detecting & treating high BP before onset of target organ damage is cost effective. Is accurate BP measurement important? ⚫ Underestimating BP denies large no. of people access to potentially lifesaving & morbidity preventing therapy. ⚫ Overestimating BP substantially increase no. of people with inappropriate diagnostic labels & therapy. ⚫ ?Diagnosing & initiating Rx for HT can cause psychosocial harm to pt. Should we recommend home self-measurement?(HSM) ⚫ The “white coat effect can raise BP in excess of 20/10mmHg in upto 40% pts. ⚫ Consider HSM of BP to avoid over diagnosis due to white coat effect. Should we recommend ambulatory BP monitoring?(ABPM) ⚫Consider ABPM for evaluating of pts with suspected # white coat HT # apparent drug resistance # episodic HT # Hypotensive symptoms on antihypertensive Rx How would we define hypertension? Ps-DZ, 2009  Categories of BP in adults*:2020 ISH BP Category SBP DBP Normal