Causes of hypertensive emergency

Causes of hypertensive emergency

Hypertensive emergency is defined as BP > 220/140 in the presence of target-organ damage.  Most cases of hypertensive emergency occur in patients with essential hypertension who have inadequate treatment of their hypertension or have discontinued their medications.  However there are many other causes of hypertensive emergencies:

1.  Renal parenchymal disease--acute glomerulonephritis, chronic pyelonephritis, tubulointerstitial nephritis

2.  Renovascular disease--fibromuscular dysplasia, polyarteritis nodosa, atherosclerosis

3.  Systemic disorders affecting kidneys-SLE, other vasculidities

4.  Endocrine causes--pheochromocytoma, Cushing syndrome, primary hyperaldosteronism (Conn's syndrome when caused by adrenal adenoma)

5.  Drugs--cocaine, amphetamine, ephedrine, diet pills, cyclosporine, clonidine withdrawal, oral contraceptives,

6.  Drug interactions--Monamine oxidase inhibitors when combined with tricyclic antidepressants, antihistamines, or tyramine-containing foods

7.  Pregnancy-related--preeclampsia/eclampsia

8.  CNS causes--CNS trauma, subarachnoid hemorrhage, ischemic and hemorrhagic stroke, spinal cord disorders

9.  Cardiovascular causes--coarctation of the aorta, acute aortic dissection

Classic teaching is that hypertensive emergency should be managed with IV agents to lower blood pressure by 20% within a few hours.  However, Tintinalli recommends treatment for hypertensive emergency should be stratified by diagnosis.  For example, in acute aortic dissection, SBP should be lowered to 100-120 range to reduce shearing forces on the vasculature.  In intracranial hemorrhage, SBP goal is < 160 to reduce chance of rebleeding.  In acute ischemic stroke, however, some degree of HTN is appropriate (maintain cerebral perfusion), but if fibrinolysis is planned, target BP is >185/110.  In acute renal failure, blood pressure reduction by no more than 20% is advised.  In acute sympathic crisis (cocaine, amphetamines, etc.), benzodiazepines can be administered for symptom relief.

References:
1.  Riaz K et al.  Emedicine:  Hypertension Treatment & Management.  Available at http://emedicine.medscape.com/article/241381-overview.  Accessed Jan. 10, 2012.
2.   From Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 7th Ed. Tintinalli, JE, Ed, et al.  New York: McGraw Hill, 2011: p. 442-445.