A hypertensive emergency is very high blood pressure with potentially life-threatening symptoms and signs of acute damage to one or more organ systems (especially brain, eyes, heart, aorta, or kidneys). It is different from a hypertensive urgency by this additional evidence for impending irreversible hypertension-mediated organ damage (HMOD). Blood pressure is often above 200/120 mmHg, however there are no universally accepted cutoff values. Signs of organ damage will be discussed below. Signs and symptoms
Symptoms may include headache, nausea, or vomiting. Chest pain may occur due to increased workload on the heart resulting in inadequate delivery of oxygen to meet the heart muscles metabolic needs. The kidneys may be affected, resulting in blood or protein in the urine, and acute kidney failure. People can have decreased urine production, fluid retention, and confusion.Other signs and symptoms can include:
Chest pain
Abnormal heart rhythms
Headache
Nosebleeds that are difficult to stop
Dyspnea
Fainting or the sensation of the world spinning around them (vertigo)
Severe anxiety
Agitation
Altered mental status
Abnormal sensationsThe most common presentations of hypertensive emergencies are cerebral infarction (24.5%), pulmonary edema (22.5%), hypertensive encephalopathy (16.3%), and congestive heart failure (12%). Less common presentations include intracranial bleeding, aortic dissection, and  pre-eclampsia or eclampsia.Massive, rapid elevations in blood pressure can trigger any of these symptoms, and warrant further work-up by physicians. Physical exam would include measurement of blood pressure in both arms.
Laboratory tests to be conducted include urine toxicology, blood glucose, a basic metabolic panel evaluating kidney function, or a complete metabolic panel evaluating liver function, EKG, chest x-rays, and pregnancy screening.The eyes may show bleeding in the retina, an exudate, cotton-wool spots, scattered splinter hemorrhages, or swelling of the optic disc called papilledema. Causes
Many factors and causes are contributory in hypertensive crises. The most common cause is patients with diagnosed, chronic hypertension who have discontinued anti hypertensive medications.Other common causes of hypertensive crises are autonomic hyperactivity such as pheochromocytoma, collagen-vascular diseases, drug use particularly stimulants, cocaine and amphetamines and their substituted analogues, monoamine oxidase inhibitors or food-drug interactions, spinal cord disorders, glomerulonephritis, head trauma, neoplasias, preeclampsia and eclampsia, hyperthyroidism and renovascular hypertension. People withdrawing from medications such as clonidine or beta-blockers have been frequently found to develop hypertensive crises. It is important to note that these conditions exist outside of hypertensive emergency, in that patients diagnosed with these conditions are at increased risk of hypertensive emergencies or end organ failure. Pathophysiology
The pathophysiology of hypertensive emergency is not well understood. Failure of normal autoregulation and an abrupt rise in systemic vascular resistance are typical initial components of the disease process.Hypertensive emergency pathophysiology includes:
Abrupt increase in systemic vascular resistance, likely related to humoral vasoconstrictors
Endothelial injury and dysfunction
Fibrinoid necrosis of the arterioles
Deposition of platelets and fibrin
Breakdown of normal autoregulatory functionThe resulting ischemia prompts further release of vasoactive substances including prostaglandins, free radicals, and thrombotic/mitotic growth factors, completing a vicious cycle of inflammatory changes.