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Posts Tagged ‘exercise stress testing’

In this politically and scientifically  uncertain world nothing is  in black and white. How can you  expect  EST to behave differently ?

Even as  we  are fully  aware of the  limitations  of EST  ,  it  does not make sense   to categorize  EST result into either positive or negative .

In fact , our  estimate suggests  a significant bulk of the patient would fall in the grey zone  .

It is referred  in various terms by  the reporters of EST .

  • Borderline positive
  • Mildly positive
  • Equivocal
  • Inconclusive

What does all these terms mean to the patient ?

It mans only one thing . . .

Physician  who reports  the  EST    is unable to  conclude whether  his patient has  significant  CAD  or not . It is a dignified way of  expressing  the  limitations .

Many factors may play a role. (See the illustration above )

  • Patient factors : Poor exercise stress levels and conditioning
  • Lesion factors:  Collateralised CAD, treated CAD  can result in partial or mild  changes.
  • Machine factors :Caliberation errors.
  • Interpreter : (Physician ) factors

Error in measurement of ST segment . What is borderline  for  one doctor may indeed be true positive  for the other and vice versa .

How will be the  EST in  a  revascularised  or  medically treated CAD ?

If revascularization is a complete success ,  stress test  would  revert back to normal or it can be a borderline as we have just mentioned.

To our  surprise ,  it may  remain  positive in spite of apparently successful procedure.(Residual wall motion defects , scar mediated  ?)

How to proceed  after this borderline EST/TMT ?

Few options are available for the physician/patient

Talk  with the patient again  , assess the  baseline risk  of CAD   if it is low ignore the TMT result and reassure.

  • Repeat  stress test after  a month.
  • Stress thallium
  • Doubutamine  stress
  • CT angiogram
  • Regular Cath  angiogram* (May be the best , of course it also carries a  risk of labeling  the condition as  mild  CAD / non critical CAD etc )

For the  patient  the  easiest  option  may be ,   self  referral to a different cardiologist .   (Also called second opinion )

Final message

There is indeed an entity called   borderline  EST  . Do not dare to  ignore it  or else  face the consequences .

Read  related articles in this site .

1.Can medical management convert EST positive to negative ?

2. Should every one with positive EST should undergo CAG ?

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There are innumerable  stresses  to human beings in daily life .

Heart  experiences a few  either directly or indirectly.

  1. Physical stress
  2. Pharmacological  stress
  3. Mechanical stress
  4. Hemodynamic stress
  5. Mental stress

Squatting is rarely realised as a form of physical   stress to heart .  Rather , squatting can also  be termed as a  good exercise  ( Western toilets sans it !)

Squatting  raises the afterload at the level of aorta due to  increments  in SVR (exact mechanism not clear ,neural reflex ?)  and temporary reduction in venous return.

After load raise is synonymous with increased  ventricular wall stress  . So,  it is logical to expect wall motion defect in  vulnerable hearts* when confronted with sudden increase in afterload .(*Ischemic hearts with delicate coronary blood flow ) .Hence ,  sudden squatting , a seemingly simple  maneuver   ,  can  unmask  silent CAD .It can be aptly be named as poor man’s stress echo.

Of course , it  doesn’t   mean in any way ,  it should not be used in rich ! The  purpose of science  is  to make things simpler and cheaper . If squatting can replace  dobutamine with fair degree of accuracy  atleast in a few ,  it can help  control the escalating  costs of  cardiology triaging   due to   many futile diagnostics !

http://content.onlinejacc.org/cgi/reprint/46/5/931.pdf

When squatting  is a stress in normal persons , paradoxically it gives relief to patients with cyanotic heart disease

Read the related articles in this  site .

How squatting relieves hypoxia in TOF ?

Squat Echocardiography in TOF

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