Which conditions should be considered in apparent malignant hypertension?
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Which conditions should be considered in apparent malignant hypertension?
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@diane As many as 1% of patients with essential hypertension develop malignant hypertension, but the reason why some patients develop malignant hypertension whereas others do not is unknown. The characteristic vascular lesion is fibrinoid necrosis of arterioles and small arteries, which causes the clinical manifestations of end-organ damage. Red blood cells are damaged as they flow through vessels obstructed by fibrin deposition, resulting in microangiopathic hemolytic anemia.
In a retrospective study that evaluated hospital admissions data from the Nationwide Inpatient Sample for malignant hypertension, hypertensive encephalopathy, and essential hypertension, Polgreen et al found an increasing trend for malignant hypertension and hypertensive encephalopathy from 2000 to 2011, with a dramatic increase after 2007. [4] However, no corresponding dramatic increase was seen in morbidity for both conditions, which the investigators believed might have resulted from coding changes in diagnostic-related groups in 2007. Mortality declined significantly for patients with malignant hypertension but not for those with hypertensive encephalopathy.
Another pathologic process is the dilatation of cerebral arteries following a breakthrough of the normal autoregulation of cerebral blood flow. Under normal conditions, cerebral blood flow is kept constant by cerebral vasoconstriction in response to increases in BP. In patients without hypertension, flow is kept constant over a mean pressure of 60-120 mm Hg. In patients with hypertension, flow is constant over a mean pressure of 110-180 mm Hg because of arteriolar thickening. When BP is raised above the upper limit of autoregulation, arterioles dilate. This results in hyperperfusion and cerebral edema, which cause the clinical manifestations of hypertensive encephalopathy.