Dr.S.Venkatesan MD

It is a fashionable topic  in  cath meetings and workshops  to discuss  about thrombus loaded coronary arteries. Still  visualizing a  thrombus  in coronary angiogram is  never a  mean  task !  It needs  lots of  visual  acuity  and  imagination to recognise   intra coronary thrombus.

• A lesion which looks fresh with multiple layers of  irregularity within the lumen is  often assumed to be thrombus.
• An   intra luminal filling defect   is the  most often  used  “criteria  to suspect” a  thrombus

A long segment thombus with dye penetrating and coating the thrombus all around

Thrombus  vs plaque ?

Both are  radiolucent .  But a thrombus  or a plaque coated  with  dye  will make it radio opaque. The radio opacity of a thrombus is determined by extent of dye coating ,  the thickness of the dye layer, obliqueness to the x-ray beam . A thrombus plaque  interface can have two different  planes  of densities.

Theoretically dye can not encircle  a plaque  in its entire circumference as it will be attached to vessel wall (Unless  circumferential  dissection is present  )  Hence , dye can not coat a plaque fully ,  at best it can give  an appearance of eccentric filing defect  with over hanging edges .  While a  thrombus  can manifest with a  complete filling defect

Thrombus vs dissection

This is  still more complex   . Both can have a filling defect  .A  flap is a  line like  filling defect To complicate the issues further,  both thrombus and dissection occur together in the same spot .

How confidently  one can  identify a thrombus in coronary angiogram ?

During acute MI there is no difficulty in identifying it ,  as every acute  obstruction  must contain some thrombus* . Some interventionists  have special  ocular   sense   to   detect thrombus. Few others rely  on their intuition  rather than  solid evidence.

Sucking out a thrombus during primary angioplasty  has now become standard concept and is indeed  feasible  in most situations. It is obvious we have a task  on hand to identify thrombus correctly and quickly during primary PCI /UA .

Blind suction,  even though rewarding should be avoided.  Caution is required as blind  suction pulls a plaque with force !

A plaque debri  with a  thrombus, a dissected flap  all can combine together   to produce a complex  “masala”  of  coronary lesion especially after a difficult guidewire cross . This is refereed to as a battered coronary artery .These are the lesions which are prone for recurrent acute or sub acute thrombosis even if the lesion is  stented  properly.

During  primary PCI   thrombus coated dissected plaque  is just tucked  and  opposed behind the  gentle stent struts.The thin layers of thrombus between stent struts and the vessel wall is  missed  , 100 out of 100 times   by coronary angiogram . (IVUS very good in detecting this) .Because of this risk , Intensive anti -coagulation in complex PCI becomes mandatory

* Diagnosing thrombus in a chronic lesion is  much . . .much  difficult !

What are specific  modalities available  to  confirm thrombus

IVUS, Angioscopy, OCT are  hi tech tools to identify intra coronary  thrombus .(Which i feel  have little practical  value in real emergency situations)

Final message

Thrombus  may be a  key  finding  in acute coronary syndrome (Of course  the contribution of fissure, injured ,  plaques to the lesion can never be underestimated . ) Still , we have no simple , accurate method to identify it  ( Forget quantifying it) . Lots of assumption , guess work and gut feeling is at play in the cath lab .

We  expect better online , real time tools to improve out tentativeness inside the coronary artery  .

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