Archive for March, 2017

Improper or technically deficient stent deployment is a major factor for post stent events .Few terminologies are used in assessing stent deployment.

Under expanded stent (UES) 

A stent is not fully  expanded to the desired or to its specified diameter.

This is often due to inadequate balloon pressure during inflation .

Many times its technical and It requires post dilatation.

Under-deployed stent is  often  due to a struts hitting a  hard surface or calcium .

What is mal-apposed stent  ? (MPS)

It’s a fine gap between the vessel wall and the stent.

It can be observed immediate or late. Immediate is usually due undersizing of stent.

Intermediate or late malapposition  can be due to many  reasons

  1. Due to dissolution of thrombus in the  vessel stent interface
  2. Positive vessel remodelling creating new gap between vessel wall  and stent remodeling
  3. Vessel wall regaining vasomotion and  ? ( Is it the culprit with bio vascular scaffold)
  4. Stent rejection hypersensitivity and inflammatory reaction is a rare possibility.

What is the acceptable mal-apposition ?

No stent deployment is perfect . Mal-apposition can be focal confined to one or two struts or can be diffuse . (Branch vessel are naturally malapposed)Doing a routine OCT /IVUS is inviting trouble as no cardiologist can sleep in  comfort even after a reasonably good procedure.So we have created a safe  dead space with a width of 200 micron as an acceptable mal-apposition  (As if , the 7 micron RBCs and 2 micron  platelets can’t  get trapped in this dead space)

Is routine post-dilatation the  answer for all  mal-appostion?

Not really , still It is most logical step. Liberal post-dilatation  can be a problem as it may increase plaque prolapse and may re-release or dislodge  the  thrombus trapped during the initial expansion and triggering a no- reflow.

Undersizing vs underexpanded stent

Selecting a smaller stent for a given vessel diameter is another common error that result in MPS. This again can be tackled(Though not ideal)  by high pressure inflations.



Is self expanding stent best option for preventing mal-apposition ?

May be.It has more radial strength, and it is expected to take care of the current and possible  future gaps of created by positive remodeling.

Other stent related issues 

  • Plaque prolapse
  • Stent edge dissection
  • Longitudinal miss
  • Stent fatigue and fracture

Final message 

UES and MPS , though discussed separately by cardiologists , from the patient point of view , the difference is  camouflaged in technical semantics since both carry risk significant risk of recurrent ACS or restenosis .It has become fashionable to believe one needs to  be worried more about visible UES than invisible MPS.


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Bifurcation  angioplasty is a  newly conquered(Or not yet !)  target  for Interventional cardiologists.We have come a long way  in planning  interventions  for left main  with state of the art  hardware, expertise and  image assistance .However , every  classification , approach, strategy  for BFL talks about tackling the main and  side branches meticulously.

Still . . . one question  is not answered clearly is  . . .

A mini MCQ.

Answer: Open for contribution.

My inference

*It all depends upon the Indication and Individual arterial ischemic burden. In ACS, if  LAD territory is infarcted and beyond 24 hours.LAD becomes a  side kick to the vital LCX which supplies  the remaining life sustaining myocardium which includes the critical basal segments.

Final message 

Since , the risks involved in the interventions of  left main and its bifurcation is inherently linked  with , what exactly we mean (and do ! ) to the side branch .Its mandatory we spare few intellectual moments before our hands invade the coronary battle zone.

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Here is an Interaction between  a ER physician  and a cardiologist !


“I should say I am happy for this cartoon cardiologist , It at least thinks , verifies ECG . . . and resists entry for a dubious STEMI to cath lab ”


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