Posts Tagged ‘coronary stenting’

It is estimated nearly half a  million PCIs are done all over the globe every year .Evaluating diagnostic angiogram is a critical  vital step, but  often times it is given less time and left to fellows .This is done mostly offline by Image  processing software. Curiously , lesion assessment  becomes a causality to the   visual acuity .It ends up  with lot  of whims , intuition and bloated egos of senior cardiologists !

Technical issues

The fundamental flaw in the  lesion assessment is ,there is  a dissociation in choosing the  “best view”  for lesion morphology  and  length  . Size need not be well  assessed in  the same view as morphology . For example , LAD is fore shortened  in LAO caudal view  ,  length measurement would be  erroneous  ,  still morphology may be well delineated .(Vice versa in RAO caudal view )

PTCA guidewire calibratedcalibrated ptca guidewire

Other source of errors

Reference catheter may be far  away in the Aorta , and confer a  magnification error . This becomes important especially in ostial lesions and associated  major branch lesions. The computer uses the edge detection algorithm  which carries an   inherent error .

Advantage of guide wire as a scale

  • Instant online measurement
  • Always on . Repeatedly used in multiple views .
  • You can’t ask for more accuracy .The scale is within the coronary artery  hugging the lesion
  • The end on view is effectively nullified .
  • Magnification  factor do not operate.
  • Finally , and most importantly in complex  tortuous , tandem lesions few mm errors can be disastrous .These calibrated guide wires will make our life lot easier.

Final message

Measuring  a coronary lesion remains a delicate issue . If only we have radio opaque  rings every 1mm or so in the distal end of the guide wire , we can measure the lesion  instantly and most accurately.

This will  definitely make our life  not only simple but help our patients with accurate stent sizing and avoid costly geographical miss (or inappropriately  long stent  that increase  metal load .)

After thought

I do not know whether  any of the existing  guide wires have this facility .(I guess it is not   . . .then , let this idea  be patented in my name !)  After all , It is a mean  task for all those mighty coronary hardware companies to add  few radio opaque rings to all  PTCA guide wires!

Medtronic, Abbot, Boston  are you listening ?

And . . . your opinion please !


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Landing an aircraft is a high precision job. A pilot and co pilot with the help of air traffic control  must  do this job meticulously every time .They   are not  afford to make any mistake .Number of lives are at stake.

In cath lab something similar happens every day  although a single life is at stake !   We call this coronary stent landing  . If  it lands  wrongly  it is referred to as  geographical miss ,  a descriptive  terminology for a poorly deployed coronary stent !  ( In strict terms it  should be called as  failed PCI !)

But there are few vital differences   between the two . . .

If an aircraft overshoots  the  runway   it is visible to every body and it becomes a national news next day !

If you deploy a stent away from a lesion it is usually a  silent  event  . Only a few alert fellows and staffs know it ! Patient  often gets discharged  next day (of course after paying the bills )  and  the consequence is often delayed  by weeks  or months  when he comes back knocking  the  ER doors with an ACS !

Final message

The stent -plaque  dissociation is  much more common than we perceive ,  for the simple reason cardiologists have  learnt  to accept   luminal shadows  as surrogate markers for plaques . ( Coronary blindness !)

It is imperative to  apply all our senses properly  in the cath lab ,  like  our  pilots  do while they land  . Be prepared  for  turbulent weather which  is common in cath lab as well !


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