Hypertension Lecture 1 PDF

Hypertension  Arterial BP is the pressure in the arterial wall measured in millimeters of mercury (mm Hg). Systolic pressure: the peak pressure exerted in the arteries when blood is pumped into them during ventricular systole. Diastolic pressure: the lowest pressure exerted in the arte...

Hypertension  Arterial BP is the pressure in the arterial wall measured in millimeters of mercury (mm Hg). Systolic pressure: the peak pressure exerted in the arteries when blood is pumped into them during ventricular systole. Diastolic pressure: the lowest pressure exerted in the arteries when blood is draining off into the vessels downstream during ventricular diastole. Pulse pressure: the difference between the systolic and diastolic pressure (normally= 40 mm Hg).  Hypertension: Persistent elevation in arterial blood pressure More than 140/90  EPIDEMIOLOGY Hypertension is widely prevalent and accounts for significant morbidity and mortality, as well as billions of dollars in direct and indirect costs. Worldwide prevalence of hypertension is estimated to include 1 billion individuals. There are an estimated 7 million deaths per year that may be related to the diagnosis of hypertension  Classification of Blood Pressure (BP) BP Classification Adult SBP (mm Hg) Adult DBP (mm Hg) Normal (normotensive) Less than 120 and less than 80 Prehypertension 120–139 or 80–89 Stage 1 hypertension 140–159 or 90–99 or both Stage 2 hypertension ≥160 ≥100 or both  Etiology The cause of hypertension is unknown in the majority of cases (primary hypertension), but for those with secondary hypertension, specific causes are indicated. Essential or primary hypertension: ~ 90% patients, hypertension results from an unknown pathophysiologic etiology. This form of hypertension cannot be cured, but it can be controlled. Secondary hypertension: A small percentage of patients have a specific cause of their hypertension; either concurrent medical conditions or are endogenously induced. If the cause can be identified, hypertension in these patients has the potential to be cured. Pseudohypertension White-Coat Hypertension and Masked Hypertension Resistant hypertension 6 Secondary cause of hypertension 7 Secondary cause of hypertension cont 8  Coarctation of the aorta Coarctation of the aorta is a birth defect in which the aorta, the major artery from the heart, is narrowed. The narrowing results in high blood pressure before the point of coarctation and low blood pressure beyond the point of coarctation. Most commonly, coarctation is located so that there is high blood pressure in the upper body and arms and low blood pressure in the lower body and legs. Symptoms can include localized hypertension, cold feet or legs, decreased exercise performance, and heart failure  Pheochromocytoma Pheochromocytoma is a rare tumor in part of the adrenal gland. In most cases, the tumors are not cancerous and do not spread to other parts of the body. But, in about 30 percent of cases, the tumors are cancerous. Most people with pheochromocytoma have hypertension because the tumor causes the adrenal gland to produce too much adrenaline or noradrenaline. Patients can have attacks of high blood pressure that occur in sudden, short bursts, or the high blood pressure can be more continuous and long lasting.  Renovascular disease Renovascular disease is a progressive condition that causes narrowing or blockage of the renal arteries or veins. It's the general term used for three disorders: renal artery occlusion, renal vein thrombosis, renal atheroembolism  Pathophysiology The pathophysiology of primary hypertension is heterogeneous, but ultimately exerts its effects through the two primary determinants of blood pressure: 1. cardiac output 2. and peripheral resistance. Multiple factors that control BP are potential contributing components in the development of essential hypertension. 1. humoral (i.e., the renin–angiotensin–aldosterone system [RAAS]) 2. vasodepressor mechanisms (Vascular Endothelial Mechanisms), 3. abnormal neuronal mechanisms, 4. defects in peripheral autoregulation, 5. and disturbances in sodium, calcium, and natriuretic hormones. most antihypertensives specifically target these mechanisms and components of the RAAS. 12 13 1- Humoral (role of the RAAS) 14 2. Neuronal Regulation Pathologic disturbances in any of the four major components of the neuroregulation system could conceivably lead to chronically elevated BP. These systems are physiologically interrelated: 1. autonomic nerve fibers 2. adrenergic receptors α1,α2, β1, β2 3. baroreceptors, through the ninth cranial nerve and vagus nerves 4. central nervous system: stimulation of certain areas within the central nervous system (nucleus tractus solitarius, vagal nuclei, vasomotor center, and the area postrema) can either increase or decrease BP 15 3. Vascular Endothelial Mechanisms: a deficiency in the local synthesis of vasodilating substances (prostacyclin and bradykinin, nitric oxide) or excess vasoconstricting substances (angiotensin II and endothelin I) 4. Electrolytes and Other Chemicals: Population-based studies indicate that high salt diets are associated with a high prevalence of stroke and hypertension. Some studies show that dietary calcium supplementation results in a modest BP reduction in patients with HTN. Potassium (Potassium depletion may increase peripheral vascular resistance?) 16  The Concept of White Coat and Masked Hypertension 200 Masked HTN: people who are truly hypertensive but Home/Ambulatory SBP 180 in whom the diagnosis is True missed by office BP Masked HTN hypertensive measurements. 160 White-coat HTN: BP may 140 be elevated in the office 135 but not on ambulatory BP 120 True White Coat HTN mmHg Normotensive 100 100 120 140 160 180 200 Office SBP mmHg  Pseudohypertension Pseudohypertension is when blood pressure measurements are elevated but the blood pressure is actually normal. Pseudohypertension is not very common, and it is almost always found in older patients (WHY?) Pseudohypertension is usually suspected in cases where: – The blood pressure reading is very high over time, but the patient has no signs of organ damage or other complications – Attempting to treat the measured high blood pressure causes symptoms of low blood pressure (dizziness, confusion, decreased urine output) While a finger blood pressure meter or other similar devices may provide some useful data in cases of suspected pseudohypertension, the only way to confirm the diagnosis is by directly measuring the intraarterial blood pressure. This is done inserting a needle directly into a small artery. 18  Classification of BP – JNC7+8 The following definitions were suggested in 2003 by the seventh report of the Joint National Committee (JNC 7) and reaffirmed in 2013 by JNC 8, and are based upon the average of two or more properly measured readings at each of two or more visits after an initial screen It includes four categories: normal, prehypertension, stage 1 hypertension, and stage 2 hypertension. 19  Hypertensive crises Hypertensive crises are clinical situations where BP values are very elevated, typically greater than 180/120 mm Hg. Hypertensive crisis can be divided into: 1. Hypertensive emergencies are extreme elevations in BP that are accompanied by acute or progressing target-organ damage. 2. Hypertensive urgencies are high elevations in BP without acute or progressing target-organ injury. 20  Cardiovascular Risk and Blood Pressure Risk of stroke, myocardial infarction, angina, heart failure, kidney failure, or early death from a CV cause are directly correlated with BP. Starting at a BP of 115/75 mm Hg, risk of CV disease doubles with every 20/10 mm Hg increase. Even patients with prehypertension have an increased risk of CV disease. Treating patients with hypertension with antihypertensive drug therapy provides significant benefits. 21  Cardiovascular Risk and Blood Pressure SBP is a stronger predictor of CV disease than DBP in adults older than 50 years of age and is the most important clinical BP parameter for most patients. Patients with Isolated systolic hypertension (DBP values less than 90 mm Hg and SBP values >140 mm Hg) have higher pulse pressure values. In these patients pathophysiologic changes in their arterial vasculature are consistent with aging. These changes decrease the compliance of the arterial wall and ↑ risk of CV morbidity and mortality. 22  Diagnostic Considerations Hypertension is called the silent killer because most patients do not have symptoms. The primary physical finding is elevated BP. The diagnosis of hypertension cannot be made based on one elevated BP measurement. The average of two or more measurements taken during two or more clinical encounters is required to diagnose hypertension 23  Diagnostic Evaluation of BP Diagnostic procedures aim at: 1. establishing blood pressure levels; 2. identifying secondary causes of hypertension; 3. evaluating the overall cardiovascular risk by searching for other risk factors, target organ damage and concomitant diseases or accompanying clinical conditions. The diagnostic procedures comprise: – repeated blood pressure measurements – medical history (family and clinical) – physical examination – laboratory and instrumental investigations. 24  1- Measuring blood pressure In general the diagnosis of hypertension should be based on multiple blood pressure measurements (2) , taken on separate occasions (2-3) over a period of time, although in particularly severe cases the diagnosis can be based on measurements taken at a single visit. Blood pressure can be measured by a mercury sphygmomanometer or other non-invasive devices (auscultatory or oscillometric semiautomatic devices). office-based BP measurements are considered the gold standard values that guide antihypertensive drug therapy. Correct BP measurements require that the clinician listen through a stethoscope that is placed over the brachial artery for the appearance of the five phases of the Korotkoff sounds 25 26  Recommendations for measuring BP Patients should refrain from nicotine or caffeine ingestion for 30 minutes and be seated with the lower back supported in a chair and with their bare arm supported and resting near heart level. Feet should be flat on the floor (with legs not crossed). Measuring BP in the supine or standing position may be required under special circumstances (suspected orthostatic hypotension, volume depletion, or dehydration). The measurement environment should be relatively quiet and provide privacy. Measurement should begin only after a 5-minute period of rest. A properly sized cuff (pediatric, small, regular, large, or extra large) should be used.  Ambulatory and self blood pressure monitoring Either of these may be warranted in patients with suspected white coat hypertension (without hypertension-related target-organ damage) to differentiate white coat from essential hypertension. They may be helpful in patients with: – apparent drug resistance, – hypotensive symptoms while on antihypertensive therapy, – episodic hypertension, – autonomic dysfunction, /and – to identify "nondippers" whose BP does not decrease by >10% during sleep and which may portend increased risk of BP-related complications 28  As a comparison, the normal upper limit for BP in most patients is: – 140/90 mm Hg for office-based measurement, – ABPM Twenty-four-hour average BP − Normotension is defined as a BP less than 130/80 mmHg, and hypertension is defined as a BP greater than or equal to 130/80 mmHg Daytime (awake) BP − Normotension is defined as a BP less than 135/85 mmHg, and hypertension is defined as a BP greater than or equal to 135/85 mmHg Nighttime (asleep) BP − Normotension is defined as a BP less than 120/70 mmHg, and hypertension is defined as a BP greater than or equal to 120/75 mmHg – 135/85 mm Hg for self-BP measurements. Note: – the threshold for acceptable values is lower than that obtained during office-based measurements 29  Main indications for ambulatory BP monitoring are for patients in whom the diagnosis of hypertension or response to therapy is unclear from office visits. Further indications include suspected syncope or hypotensive disorders, evaluation of vertigo, and dizziness.  Ambulatory BP monitoring is also important for avoiding overtreatment in the elderly with white-coat hypertension and also to ensure diagnosis and treatment of those with masked hypertension  Ambulatory BP is a better predictor of risk than clinic or office BP measurement in older patients with isolated systolic hypertension 30 Resistant HTN Resistant hypertension is defined as that in which patients fail to attain their BP goal while treated with a three-drug regimen that utilizes full (maximum) antihypertensive doses, one of which is a diuretic. 31  Diagnostic algorithm for high Blood Pressure including Office, ABPM and Home Blood Pressure Measurement In the absence of end-organ Hypertension Visit 1 Hypertensive BP Measurement, damage, the diagnosis of History and Physical Urgency / Emergency mild hypertension should examination not be made until the blood pressure has been Hypertension Visit 2 Target Organ Damage measured on at least three or Diabetes Yes Diagnosis of HTN to six visits, spaced over a or Chronic Kidney Disease or BP ≥ 180/110? period of weeks to months. No BP: 140-179 / 90-109 Clinic BPM ABPM (If available) HBPM  Diagnostic algorithm for high Blood Pressure including Office, ABPM and Home Blood Pressure Measurement BP: 140-179 / 90-109 Clinic BP ABPM (If available) HBPM Hypertension visit 3 ≥ 160 SBP or Diagnosis ≥ 135 ≥ 100 DBP of HTN Awake BP Awake BP < 135/85 SBP or ≥ < 135/85 and ≥ 135 SBP or DBP 85 < 160 / 100 ABPM or HBPM 24-hour ≥ 85 DBP or or < 130/80 Or 24-hour ≥ 130 SBP or Hypertension visit 4-5 ≥ 80 DBP ≥ 140 SBP or Diagnosis ≥ 90 DBP of HTN Continue to Diagnosis Continue to Diagnosis follow-up of HTN follow-up of HTN Continue to < 140 / 90 follow-up In the absence of end-organ damage, a patient should not be labeled as having hypertension unless: the blood pressure is persistently elevated after three to six visits over a several month period; hypertension is revealed by 24-hour ambulatory monitoring; or the average of home blood pressure readings taken in the morning and evening daily for seven days is elevated.  Clinical Evaluation (Cont’d) Once it has been determined that the patient has persistent hypertension, an evaluation should be performed to ascertain the following information: – To determine the extent of target organ damage. – To assess the patient's overall cardiovascular risk status. – To rule out identifiable and often curable causes of hypertension. 34  Hypertension-Associated Complications Atherosclerotic Vascular Disease: 1. Coronary artery/heart disease Myocardial infarction [MI] Acute coronary syndromes Chronic stable angina 2. Carotid artery disease: Ischemic stroke Transient ischemic attack 3. Peripheral arterial disease 4. Abdominal aortic aneurysm Other forms of CV disease – Left ventricular dysfunction (heart failure) Chronic kidney disease 35  Risk factors for hypertension-associated complications Hypertension Advanced age Cigarette smoking – Males > 55 yrs Obesity (BMI >30 kg/m2) – Females > 65 yrs Physical inactivity Family history of premature Dyslipidemia atherosclerotic vascular disease Diabetes mellitus – Males < 55 yrs Kidney disease – Females < 65 yrs Microalbuminuria or estimated GFR < 60 ml/min These are considered major CV risk factors that increase the likelihood of developing hypertension-associated complications, not hypertension. BMI, body mass index; CV, cardiovascular; GFR, glomerular filtration rate. 36  Benefits of Lowering BP Why treat HTN? – 35-40%  in stroke morbidity and mortality – 20-25%  CAD events – 21%  vascular mortality – 52%  in CHF – 35%  in LVH 37 Goal BP and initial drug therapy 38 39 40 41 42 43 44 45  Recommendations for Management of Hypertension (JNC8) Recommendation 1 In the general population aged ≥60 years, initiate pharmacologic treatment to lower blood pressure (BP) at systolic blood pressure (SBP) ≥150 mm Hg or diastolic blood pressure (DBP) ≥90 mm Hg and treat to a goal SBP