Hypertension and Ischemic Stroke: Following the Guidelines Breaks the Laws of Nature by Kevin Klauer, D.O.
Tuesday, September 15, 2009 
Kevin Klauer, M.D.
If you’re not a pro tPA person, here’s one more reason. If you like tPA in stroke, you definitely need to read further.
Hypertension has always been regarded as a bad thing, in particular, with respect to ischemic stroke. Well, this is a half-truth. Chronic, untreated hypertension is a bad thing and is a critical factor and precipitating cause of ischemic stroke. However, you cannot apply that logic to the physiology of acute ischemic stroke. Although the current recommendation of the American Heart Association and American Stroke Association is to reduce blood pressures at or above 185 mm Hg systolic or 110 mm Hg diastolic to facilitate the “safe” delivery of tPA in ischemic stroke.
This is where the departure from rational thinking occurs. In order to deliver a controversial drug, the AHA and ASA advocate something that is likely to worsen ischemic stroke.
In the zone of infarction and ischemic penumbra, the brain has lost its autoregulation of blood flow, and thus, is strictly dependant upon cerebral perfusion pressure (CPP) to perfuse the injured, ischemic brain. CPP is directly dependent upon systolic blood pressure (CPP = SBP-ICP). If you drop the SBP, you stand a fairly good chance of reducing CPP and worsening ischemia, extending the infarct.
What many tPA proponents haven’t considered is that acute hypertension is completely different from chronic hypertension. Hypertension in the setting of acute ischemic stroke is likely to be transient and cerebroprotective. It generally will go away in hours to days and is a physiologic attempt to better perfuse the ischemic brain.
There is only one thing worse than hypertension in ischemic stroke: Someone treating it!
Varon J, et al. The Diagnosis and Management of Hypertensive Crises. Chest 2000;118:214-227.
Blumenfeld JD, et al. Management of Hypertensive Crises: The Scientific Basis for Treatment Decisions. The American Journal of Hypertension 2001;14:1154-1167.
Guidelines, Hypertension, Ischemic Stroke, Klauer in Procedures
Reader Comments (3)
Yes, and in every single ED setting it has been an uphill battle to reverse the automatic knee jerk treatment of elevated blood pressure. Sometimes, many times actually, I wonder if we are doing more harm than good with this vital sign. If it's OK we do nothing, but let it be the least bit elevated at discharge and the push is on to order clonidine or some generally accepted remedy!
Of course, a similar argument holds for temperature.
Just an aside, cerebral perfusion pressure is Mean Arterial Pressure minus intracranial pressure. I fully agree with you on the acute treatment. It is beginning to be a scary world out there when we activate the stroke team and the decision is made to lyse a patient who seems to be a poor candidate for lytic use. Why? "Because we get sued for not giving it!"
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