essays 22 - arterial hypertension - essential hypertension. secondary (symptomatic) hypertension, etiology, pathogenesis

define arterial hypertension

sustained elevation of systemic arterial blood pressure with systolic pressure >/= 130 mmHG and/or diastolic pressure >/= 90 mmHg (measured on at least two separate occasions)

what is essential hypertension

• essential hypertension is hypertension with no single identifiable cause, It accounts for 90-95% of cases. Its etiology is multifactorial

risk factors for arterial hypertension

• family hsitory

• age (incidence increased with age)

• high salt intake

• obesity

• stress

• hypercholesterolemia

• sedentary lifestyle

what is secondary hypertension due to, give etiologies

• is due to an identifiable underlying disease. this accounts for 5-10% of all cases

• etiology:

• renal = chronic kidney disease, renal artery stenosis

• endocrine = cushings disease (increased cortisol), conn syndrome (primary hyperaldosteronism → Na+ retention)

• cardiovascular = coarctation of aorta (congenital narrowing of the aorta)

• neurologic = increased intracranial pressure, sleep apnoea

• drug induced = oral contraceptives, corticosteroids, cocaine, NSAIDs

pathogenesis of hypertension (general mechanism)

• increased cardiac output = due to sympathetic nervous system overactivity → increased heart rate and stroke volume = increased BP

• increased systemic vascular resistance = caused by persistent vasoconstriction and vascular remodelling of small arteries/arterioles (hypertrophy and thickening of smooth muscle)

• intravascular volume expansion = renal sodium and water retention, largely mediated by RAAS activation (aldosterone)
  - RAAS activation
  - aldosterone promotes sodium and water reabsorption → increasing plasma volume
  - increased plasm volume → increased circulating blood volume
  - increased venous return → increased stroke volume
  - increased BP

• altered vascular regulation = imbalance between vasodilators (decreased nitric oxide, prostacyclin) and vasoconstrictors (increased angiotensin II, endothelin)