A 73-year-old woman presents with new-onset left-sided hemiplegia. A CT head scan is undertaken, which confirms the diagnosis of an ischaemic stroke. She is currently in resus, and the nurse in charge informs you that her BP is very high, with the most recent measurement being 196/124 mmHg. She asks you to prescribe something to help bring her BP down while you are waiting for the stroke team to review her.
This patient has presented with a stroke that has been complicated by a hypertensive emergency.
A hypertensive emergency (sometimes also referred to as ‘accelerated hypertension’ or ‘malignant hypertension) is characterised by severe a systolic BP >180 mmHg and/or diastolic BP >120 mmHg, accompanied by end-organ damage (e.g. encephalopathy, intracranial haemorrhage, acute myocardial infarction or ischaemia, dissection, pulmonary oedema, nephropathy, eclampsia, papilloedema and/or angiopathic haemolytic anaemia). It is a life-threatening condition that requires aggressive lowering of the blood pressure to limit end-organ damage and prevent an adverse outcome.
Hypertensive emergencies in the setting of a stroke syndrome (i.e. in the presence of focal neurological deficits) usually require a slower and more controlled reduction of blood pressure than in other settings. In the presence of an ischaemic stroke, rapid reduction of MAP can compromise blood flow, causing further ischaemia and worsening of the neurological deficit. Intravenous labetalol is the drug agent of choice for reduction of BP in this setting.
Significantly elevated BP (>185/110 mmHg) is a contra-indication to thrombolysis, but in exceptional circumstances, when the BP is only slightly above this threshold, there is some evidence for controlling BP before thrombolysis.