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Hypertensive response to exercise stress test and risk of future stroke !

Posted Apr 16 2011 11:05am

 Hypertension  ranks  number one  in the risk for future  stroke . Surprisingly this is true  for ischemic  as well as  hemorrhagic strokes.

 What  causes  thrombosis or  rupture of small cerebral arterioles ?

 It is somewhat similar to coronary events . ( With one major exception,  coronary vesels  are   not prone for rupture ) .It is  believed   sudden spikes of   blood pressure  and the resultant endothelial injury are responsible. Atherosclerotic plaque fissure and inflammation  also  contribute. 

Is embolic stroke related to hypertension ?

The vast majority of embolic stroke are believed to  arise from heart .This belief is getting gradually eroded , as we now know aortic arch and carotid arteries vie for this honour . .(This was indirectly proved in AFFIRM trial  when rhythm control failed  to reduce the incidence of  stroke inpateints with AF ,   implying much of the strokes arise  in the upstream rather than within the cardiac chambers )  

Meanwhile , there is no controversy  in  SHT  promoting  both cardiac  and non cardiac embolus to brain

Systolic ,  Diastolic or Mean pressure   which is  important  in the genesis of stroke  ?

All parameters  are  important , but the   systolic blood pressure  is vested with more  vigour  to damage the  cerebral arterioles. The reason  systolic pressure is more important lies  in the  fact ,  it  can  attain  high pressure peaks instantly ,  unlike diastolic or pulse pressure which  slowly builds up. Further , systolic BP  carries  leading edge of the pressure  curve with high Dp/Dt and hits  the target  first !

At what pressure the cerebral artery becomes  uncomfortable ?

We do not know  the answer as yet , but any systolic pressure above 180 mmhg is a huge stress for the cerebral arterioles.The rapidity with which the BP  raises  (Dp/Dt) also becomes  important  . High blood pressure increases the shearing stress .It  interferes with nitric oxide synthesis and promotes endothelin release which precipitates  cerebro vascular event.

How do you identify people who are at risk for stroke ?

While  cardiac physicians are obsessed with exercise stress test to predict CAD  very  few  are worried about  stroke . In fact the same exercise stress test can be used to stratify stroke risk. The exercise induced systolic blood pressure  raise  is a useful risk stratifying  tool. This concept is there for more than a decade without reaching the clinical domain.

The following paper was  published in stroke journal (2001)  from the picturesque university of  Kupio Finland.(See below )  It is a wonderfully done study and throws great insight into the  new  emerging  science of  Intra cerebral hypertension .

 

The following can be summed up as risk factors for stroke during EST  (Derived from   various sources  and  . . .  with   liberal dose of personal  logic !)

  • Raise of 20 mmhg  SBP  at  2  minutes .
  • Increment of >  20mmhg in SBP any subsequent minute.   
  • Any  SBP  above 200mmhg during  EST
  • Failure to  reach baseline SBP  at 6 minutes recovery .
  • SBP  or DBP remaining high  even  after  the heart rate reaches baseline.

 

 Final message

For the kind attention  of all  cardiac physicians . . .  whenever you do an  EST for a cardiac indication ,  please spend the first  few  minutes  carefully ,and   look at the  blood pressure response . It is encouraged ,  to  specifically mention about the  behavior of  SBP  and write a remark about the propensity for  stroke in  every EST/TMT report .   Let us grow our brain  sense as well   . . .  for   the sake of our patients !

Thanks again  to Dr S.Kurl et all from Finland  for their  nice article which  stimulated  me to write  this post .

Reference

Further queries

How common is stroke following a EST procedure ?  Can high blood pressure dislodge a carotid plaque during a stress test ?

The answers will be posted soon once I  get it . ( Of course you can do it if you know !)


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