Hypertensive crisis: Etiopathology and diagnosis


This article explains various causes and pathophysiology of hypertensive crisis. It also explains diagnostic procedures like history, physical examinations, lab tests, diagnostic tests like electrocardiogram, chest radio graph etc involved in diagnosing hypertensive crisis.

Introduction

Hypertensive crisis is a condition when patient experiences sudden spike in blood pressure and this can even turn into a life-threatening event. It is also known as acute hypertension. It is so severe that it can immediately result in a stroke. It involves two conditions. One is hypertensive urgency and the other one is hypertensive emergency. Hypertensive urgency is a condition in which symptoms are almost absent in most of the individuals. Even the ones who are suffering from it do not know about it and this condition is discovered in them accidentally. End-organ damage or life-threatening events have not taken place, but these conditions may develop in them at any time. In case of hypertensive emergency, patient shows various symptoms and undergoes one or more than one end-organ damage. In both the conditions, patient is kept under close monitoring and blood pressure is brought down slowly to avoid any brain damage. End-organ damage which has taken place is usually irreversible and treatment is provided as per the organ affected. Since it is a medical condition, treatment too is mainly performed in a hospital by a team of doctors. Hypertensive patients should take care to prevent worsening of symptoms by following a preventive care.

Causes of hypertensive crisis

Medicines
  • Alpha-2 adrenergic agonists which act centrally and when withdrawn all of a sudden cause sudden spike in blood pressure
  • Intoxication caused due to sympathomimetic drugs
Kidney diseases
  • Chronic pyelonephritis,
  • Kidney failure
  • Systemic sclerosis
  • Renal artery stenosis
  • Reno vascular hypertension
  • Systemic lupus erythematosus
  • Tubulointerstitial nephritis
  • Macroscopic polyarteritis nodosa etc
In pregnancy
  • Eclampsia which are convulsions during pregnancy
  • Severe per-eclampsia
Brain disorders
  • Brain injury
  • Infarction or hemorrhage caused by cerebrovascular accident
Cardiac problems
  • Heart attack
  • Heart failure
  • Stroke
Other causes
  • Not taking blood pressure regulating drugs/antihypertensive drugs
  • Autonomic hyperactivity
  • Collagen-vascular diseases etc


Pathophysiology of hypertensive crisis

During onset of hypertensive emergency, there will be failure of normal autoregulation. Systemic vascular resistance rises almost all of a sudden i.e., there is an abrupt rise and this itself is the triggering factor seen along with sudden rise in blood pressure. This will cause underlying secondary hypertension to complicate. Endothelium secretes nitric oxide and prostacylin . This modulates vascular tone. In this way, endothelium plays a major role. Another important factor is activation of rennin-angiotensin system. It gets activated when walls of blood vessels stretch on sudden spike of b.p. Endothelium will also face injury due to endothelial decompensation in case of shut down of vasodilatory response. There will be further increase in blood pressure. This cycle continues where resistance and damage of endothelium continue side by side. If the cycle is not stopped then homeostatic failure leading to brain and local autoregulation failure begin. Also leads to end-organ damage and myocardial infarction. Endothelial injury is mainly caused due to sudden spike in blood pressure followed by fibrinoid necrosis. Vascular damage can cause deposition of platelets and fibrin. There will be failure of normal autoregulatory function. Consequently, ischemia develops and there will be further release of vasoactive entities. This completes the vicious cycle.

Diagnosis of Hypertensive crisis

It is very important to differentiate between hypertensive urgency and hypertensive emergency because both the conditions require different treatment procedures. Thus, diagnosis becomes a crucial step. Diagnosis will mainly include taking history, performing physical examinations, blood tests, other tests like electrocardiogram and chest radio graph etc. These tests will help to different the two hypertensive crisis events as well as diagnose the possible end-organ damage that has taken place and the treatment required for the same.

History

Doctor will ask certain questions to the patient or to the attender accompanying patient to record a detailed case history. It will determine nature and severity of hypertensive crisis. Some of the questions asked will be as follows -

  • Whether patient was diagnosed with high blood pressure and if yes then since how long is he taking medication for the same?
  • Whether patient is suffering from diabetes or any underlying heart disease?
  • Whether patient has undergone surgery of any kind?
  • Is he taking over the counter drugs like non-steroidal, anti-inflammatory, any other herbal medicine, illegal drugs etc?
  • Did he abruptly stop taking beta-blockers or central sympatholytic drugs?
  • Did patient previously suffer from an end-organ damage? Kidney or cerebrovascular damage particularly are important ones.


Patient will be asked about symptoms he is suffering from because symptoms are suggestive of end-organ damage patient is going through.
  • Chest pain suggests myocardial infarction/ischemia or aortic dissection.
  • Back pain too suggests aortic dissection.
  • All the neurologic symptoms like visual disturbance, mental confusion suggest that patient is going through intracerebral or subarachnoid hemorrhage or hypertensive encephalopathy.
  • Difficulty in breathing indicates acute pulmonary edema.


Physical examination

Blood pressure is measured in both arms of the patient. This is because in case if patient is suffering from aortic dissection; there will be discrepancy of almost 20mm systolic b.p. in between arms. Blood pressure should also be measured in both standing as well as in supine position. This will determine volume status. Patients who are suffering from hypertensive emergency may present themselves with depletion of intravascular volume. This condition is also known as pressure natriuresis. Head and neck examinations should be done thoroughly. Papilledema, hemorrhages, exudates, retinopathy etc are all indications that patient is suffering from hypertensive emergency. Auscultation is determined for murmurs. If patient is suffering from aortic dissection then he will show diastolic murmur along with aortic insufficiency. If patient is suffering from ischemia then he will show mitral regurgitation. Systolic or diastolic abdominal bruit means renovascular disease and presence of rales indicate vascular congestion, pulmonary edema etc. Atherosclerotic disease in smokers means patient is undergoing renal artery stenosis. Focal neurologic indications are signs of hemorrhagic stroke. Tremor indicates hypertensive encephalopathy.

Lab tests

  • Complete blood count,
  • Peripheral smear test is done to determine schistocytes. It is done to determine whether patient is suffering from microangiopathic hemolytic anemia.
  • To know whether patient is suffering from renal impairment, BUN, serum electrolytes and serum creatinine concentrations are measured. Comparison of measured serum creatinine value with baseline values should be done. This will help to diagnose whether kidney disease is acute or chronic.
  • Dipstick urine analysis will determine hematuria or proteinuria.
  • Microscopic urine analysis is performed to detect RBC or RBC casts.

Diagnostic tests

  • Electrocardiogram- Done to monitor heart. Helpful to determine whether patient is suffering from myocardial ischemia or infarction, left ventricular hypertrophy,
  • Chest X-ray- Helpful in diagnosis of heart failure or accumulated fluid around heart and lungs. It evaluates pulmonary vascular congestion. If mediastenum is widened in chest X-ray then it suggests aortic dissection.
  • CT scan of head- Determines stroke. It diagnoses intracranial bleeding, infarction, swelling etc.


Conclusion

Hypertensive crisis or acute hypertension is a medical emergency and require immediate medical treatment. Otherwise it may result in an end-organ damage of one or more organs and life-threatening events may take place in the body of the patient. It involves both hypertensive urgency as well as hypertensive emergency and most of the times it is used as a umbrella term for both these conditions. Proper diagnosis is essential which helps to determine whether patient is suffering from hypertensive urgency or hypertensive emergency which is also known as malignant hypertension. Both crisis require different treatments. History, physical examinations, lab tests and other diagnostic tests will essentially determine the cause as well as the crisis. Proper treatment given at right time can save life as well as prevent further organ damage. Know more about What to do in hypertensive crisis: Hypertensive urgency and hypertensive emergency to learn about various medical procedures involved in the emergency treatment as well as preventive measures to keep hypertensive crisis at bay.


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