Hypertension - definitions, etiology and mechanisms
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hypertension, prehypertension, refractory hypertension, hypertensive urgencies and emergencies, hypertensive crisis, essential hypertension, secondary hypertension, etiology, mechanisms
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Hypertension - definitions, etiology and mechanisms
- 1. Hypertension –Definitions and Mechanisms Dr. Md.Toufiqur Rahman MBBS, FCPS, MD, FACC, FESC, FRCPE, FSCAI, FAPSC, FAPSIC, FAHA, FCCP, FRCPG Associate Professor of Cardiology National Institute of Cardiovascular Diseases, Sher-e-Bangla Nagar, Dhaka-1207 Consultant, Medinova, Malibagh branch Honorary Consultant, Apollo Hospitals, Dhaka and STS Life Care Centre, Dhanmondi drtoufiq19711@yahoo.com
- 2. Definition Blood pressure (BP) in human populations has a nor mal distribution. Accordingly,the definitions of "normal" BP and of va rious forms of hypertension are arbitrary, but are needed for practical reasons in the assessment and treatment of patients. Hypertension is defined as a systolic blood pressure (SBP) of 140 mm Hg or greater and/or a diastolic blood pressure (DBP) of 90 mm Hg or greater in persons not taking antihypertensive medication drtoufiq19711@yahoo.com
- 3. Pre Hypertension Those with a BP of 120- 139 mm Hg systolic and/or 80- 89 mm Hg diastolic areclassified as "prehypert ensive," now known to increase the risk of any CV event bytwo- to fourfold compared with a normal BP (<120 /80 mm Hg). drtoufiq19711@yahoo.com
- 4. Isolated systolic hypertension Ageing is associated with a progressive increase in systolic BP, a reduction indiastolic BP, and widening o f the pulse pressure. This is a reflection of a progressive reduction in the compliance, or stiffening, of large conduit arteries. "Isolated systolic hypertension" (ISH), the predominant form of hypertension in theelderly, is defined as a SBP of 140 mm Hg or greater in the presence of a DBP of 90mm Hg or lower. drtoufiq19711@yahoo.com
- 5. Essential, primary, or idiopathic hypertension "Essential, primary, or idiopathic hypertension," define d as high BP due neither tosecondary causes nor to a Mendelian (monogenetic) disorder, accounts for 90% of all cases. The term "primary hypertension" is preferred, since “ essentialhypertension" represents an archaic misunderstanding of pathophysiology, namely that hypertension is "essential" to maintain blood flow through severely narrowed resistance vessels. drtoufiq19711@yahoo.com
- 6. Secondary hypertension "Secondary hypertension" is high BP caused by an iden tifiable and potentiallycurable disorder. "Refractory or resistant hypertension" is defined as a BP of≥140/90 mm Hg despite three drugs of different classes at maximum approved doses, given for at least 1 month. "Spurious hypertension (pseudohypertension)" is artefactually elevated BP obtained by indirect cuff measurement over a rigid, oftencalcified, brachial artery. drtoufiq19711@yahoo.com
- 7. Whitecoat hypertension "White- coat hypertension" describes patients whose BP is high ( >140/90 mm Hg) inan office or clinic setting, with a normal daytime ambulatory pressure (<135/85 mmHg). This is a relatively benign condition with low risk of morbid events; however, the risk may increase with long- term followup (6 years or more). Antihypertensivemedication in white- coat hypertension patients may decrease clinic BP, but produces little or no change in ambulatory BP; thus, drug treatment may not confer substantial benefit.
- 8. Masked hypertension "Masked hypertension" is the mirror image of whitecoat hypertension. Here, theclinic BP is normal, but ambulatory or ho me measurements are high, andassociated with high risk. Although the prevalence of masked hypertension is low, perhaps only 6% of the normotensive population, the absolute number in the United States may approach 1518 million.
- 9. Hypertensive crisis "hypertensive crisis" encompasses both hyperte nsive urgency andhypertensive emergency. "Hypertensive urgency" is defined as DBP >120 mm Hg inthe absence of acute or rapidly wors ening targetorgan damage.
- 10. Hypertensive emergency "Hypertensive emergency" is defined as acute or rapidly worsening target- organdamage occurring in a hypertensive patie nt in association with elevated BP, but irrespective of the specific BP level attained. "Malignant hypertension" is ahypertensive emergency associated with papilledema, whereas " acceleratedhypertension" is a hypertensive emergency associated with retinal hemorrhages and exudates.
- 30. Summary Hypertension is very common in nearly all populations , and is a major independent risk factor for CVD. There is a graded relationship between BP and CV risk, with no apparent lower limit. BP targets are <130/80 mm Hg for those with diabetes , kidney disease, and coronary artery disease. The etiology of hypertension is multifactorial; monogenetic forms are rare. drtoufiq19711@yahoo.com
- 31. Summary Key elements in the etiology areactivation of neurohormonal systems (sympathetic nervous system, RAAS, ET); increased oxidative stress; altered cellular ion transport of sodium, potassium, and calcium; and abnormalities of endothelial function and vascular reactivity, large artery compliance, and small artery/ arteriolar resistance. The main target- organ effects and resultant CVD events are atherosclerotic vascular disease; MI, LV hypertrophy, atrial fibrillation, heart failure; stroke, encephalopathy, dementia, and renal failure. drtoufiq19711@yahoo.com