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Hypertensive Crisis

Mustafa Samir Smaisem

Hypertensive crises refer to clinical situations in which the blood   pressure is elevated and there is either acute( hypertensive   emergencies   )or impending end-organ damage hypertensive urgencie.Examples of impending end-organ damage include papilledema , shortness of  breath, and pedal edema.Historically ,hypertensive urgencies have been defined as diastolic blood pressures 120 mm Hg. It is important to remember ,however ,that the absolute blood pressure is not as critical as the degree and rate of increase from baseline blood pressure.

Epidemiology.:

Although approximately 60 million Americans have   hypertension  ,only 1% develop hypertensive crises.The typical patient whopresents with ahypertensive crisis is 40-50 years of age, male ,noncompliant with hypertensive therapy ,lacks primary care ,and uses illicit substances and/or alcohol. Any disorder that causes hypertension can give rise to a hypertensive crisis, but the most common cause is poorly controlled essential hypertension. Other etiologies include medications and antihypertensive withdrawal syndromes ,*illicit drugs,  renal  and  pregnancy-related  diseases,vasculitis   ,postoperative  hypertension , coarctation of the aorta, burns, and pheochromocytoma.

PATHOPHYSIOLOGY :

The pathophysiology of hypertensive crises is not. completely  understood. With mild-to- moderate elevations in blood pressure, arterial and arteriola vasoconstriction initially maintains tissue perfusion while preventing increased pressure from being transmitted to more distal vessels . With severe elevations in blood pressure( i.e < 180 /110 mm Hg,) this autoregulation fails, and increased pressure in capillaries leads to endothelial damage of the vascular wall ,causing fibrinoid necrosis and  perivascular  edema.  Fibrinoid necrosis obliterates the vascular lumen, resulting in organ damage.