Malignant Hypertension
Feature
Disease Facts
Synonyms
A severe form of acute hypertension that results in the abrupt rise in the blood pressure (diastolic pressure often over 120 mmHg).
Epidemiology
Relatively uncommon (incidence - 3/10,000/year in United States. Occurs in 1 - 5% of patients with a history of hypertension. Most common in younger adults, especially African American men. Occasionally occurs in women with toxemia of pregnancy and patients with renal or collagen vascular disorders. High risk in patients with acute renal failure or renal hypertension due to renal artery stenosis.
Age, Sex, Race
More common in middle age and younger individuals. Most common in men and blacks. Malignant hypertension occurs more commonly in males, African Americans, and those with a history for hypertension.
Etiology
and
Pathogenesis
Precise etiology unknown. Very high levels of renin, angiotensin, and aldosterone occur. Renal vessels are highly susceptible to damage from elevated blood pressure, including vascular necrosis, endothelial cell damage, platelet thrombi and inkavascular coagulation. These events produce ischemia and promote the release of more renin, aggravating the cycle. Acute renal failure can develop, and multiple organs, including the brain, eyes, blood vessels, heart, and kidneys can sustain damage.
Clinical
Presentation
Acute development of hypertension with diastolic pressures > 120 mm. Severe headaches, nausea/vomiting, visual impairment, convulsions, changes in mental status, chest pain, shortness of breath, weakness, and other symptoms may occur. Physical examination may reveal papilledema, retinal bleeding, or retinal infarction. A chest X-ray may reveal pulmonary congestion.
Laboratory
Features
No specific laboratory assays. BUN and creatinine are increased in patients with azotemia, and metabolic acidosis may be present. Urinalysis reveals marked proteinuria , microscopic hematuria, and protein casts. Renin and aldeosterone levels are increased.
Anatomic
Pathology

Gross - Swollen kidney with "flea-bitten" surface due to multiple small hemorrhages. Foci of infarction appear as pale areas. Cut surface reveals widened cortex with very sharp corticomedullary demarcation.
LM - Occlusive arteriolar changes, primarily affecting interlobular and arcuate arteries. Earliest change is intimal edema. Later, more specific changes include (1) Fibrinoid necrosis of arterioles (`'necrotizing arteriolitis") - eosinophilic granular change in vessel walls with fibrin deposition and inflarnmatory infiltrate, (2) hyperplastic arteriolitis - intimal thickening by proliferation of elongated, concentrically arranged cells and collagen ("onion-skin pattern), (3) necrotizing glomerulitis: Necrotic glomeruli infiltrated with neutrophils with thrombosed capillary loops, and (4) ischemic atrophy and infarction distal to vessel lesions.
Clinical
Course
and
Prognosis
Malignant hypertension is a medical emergency. About 75% of patients survive survive 5 years with aggressive treatment, and 50% recover baseline renal function. The disease is fatal in two years or less if untreated, largely from non-renal complications. Major complications include acute renal failure, stroke, cerebral edema, stroke, seizures, intracerebral hemorrhage, coma, heart attack, blindness, pulmonary edema, etc.
Treatment
Hospitalization for blood pressure control with nitroprusside, nitroglycerin, diazoxide, hydralazine, or other anti-hypertensive agents followed by oral anti-hypertensive medications to maintain blood pressure control. Good prognosis if treated promptly. Severe and life threatening complications if undiagnosed or untreated.
References
and
Web Links
Web Links - General Information

Health Central - http://www.healthcentral.com/mhc/top/000491.cfm
Primary Care Lecture Series - http://uhs.bsd.uchicago.edu/~dliebovi/Internlectures/htm
NOAH - http://noah.cuny.edu/heart_disease/ushc/highblood.html

Web Links - Gross and Microscopic Images

NKF - http://www.ajkdjournal.org/atlas/34/1/atlas34_1.htm
Tulane U - http://www.tmc.tulane.edu/classware/pathology/medical_pathology/mcpath/gr_renal/Renal21.html
Tulane U - http://www.tmc.tulane.edu/classware/pathology/medical_pathology/mcpath/gr_renal/Renal22.html
WebPath - http://www-medlib.med.utah.edu/WebPath/RENAHTML/RENAL034.html
WebPath - http://www-medlib.med.utah.edu/WebPath/RENAHTML/RENAL035.html
Urbana Atlas - http://www.med.uiuc.edu/PathAtlasf/framer3/legends/jpegimages/V3271.html