Posts Tagged ‘thrombus aspiration’


The resting coronary blood flow (CBF) is about 5 % of cardiac output. It amounts to 250 ml /min (0.8 ml /mt/gram of myocardium ) It is estimated, blood flow across LAD is 50% . LCX and RCA share 25% each, depending upon the dominance. No need to say , the net return to coronary sinus  should match the CBF at rest or exertion.(Minus a small fraction contributed by  thebesain and vene cardia minimi flow, into the right heart chambers)

Great cardiac vein (GCV) is the venous cousin of LAD. It must receive and empty 125ml of deoxygenated blood every minute into the coronary sinus, if LAD flow is normal. When LAD microcirculation is obstructed as in severe obstruction , GCV will fill and empty  sluggishly. 

Let us move on from physiology to bedside.

Primary PCI & No -reflow in LAD 

We have painfully realized, no-reflow is almost a hemodynamic death sentence to the concerned coronary artery during  primary PCI. For practical purposes, no-reflow is common in left coronary circulation, that too in LAD.  Decades of research and experience haven’t really helped us to either overcome or treat this complication effectively. 

So, it’s worth considering experimental mechanical options.

  1.  The first option is, to forcibly open the closed microvasculature by pushing the debris across arterioles, venous capillaries and subsequently to the coronary sinus. This appears tricky as the high-pressure injection can be hazardous. This can be done either hand or even controlled pressure Injection. (It is believed few centers do this unofficially and found some success. I am not sure)


  2. The second option is again mechanical but uses negative pressure to suck from the far end of microcirculation. We can pull the debris into the coronary venous circuit by using vacuum suction deep inside the main stem of the coronary sinus or even the great cardiac vein, the venous counterpart of LAD. This appears to be more comforting to the coronaries at least theoretically. (Never under-estimate the power of vacuum as a biological Intervention.I recall tender newborns pulled out with massive vacuum pressure without any issues during my O&G days)



We have proposed this idea to scientific committee. It was rejected promptly as expected even prior to applying for ethical clearance. In fact, we were eager to try our hands on this, as a life saving modality in desperate situations. Now, It is an appeal to all those scientificaly  liberal centers to try this concept that can be made legal as a part of an official trial.

Antegrade vs retrograde aspiration

It is wiser to introspect, why most antegrade thrombus aspiration strategies in epicardial coronaries failed in STEMI .Still, what is the possiblity  it might work retrogradely? Let us hope this concept becomes a success and doesn’t add on to the long list of failed attempts to this ubiquitous hemodynamic entity.

Potential risk

Since the mechanism of MVO and no=reflo  is multifactorial, mechanical suction might help only in the clearance of thrombotic debris. Further risk of microvascular endothelial injury is real.

Final message

Many fellows write to me,  asking for some research ideas. Please acknowledge if anyone proceeds with this one (If you really believe no one has thought about this Intervention before)

Reference  for Interventions within Coronary sinus 

  1. EP guys do it , in a regular fashion with CRT.They also specifically enter the Anterior cardiac and great vein during ablation in VTs originating from LV summit .
  2. Coronary sinus aspiration done for contrast removal after angiogram to prevent AKI in renal compromised patients.(Ref Osama Ali Diab Circulation: Cardiovascular Interventions. 2017)
  3. Stem cell delivery has been done through coronary sinus (Wouter A. Gathier J Cardiovasc Transl Res. 2018)
  4. Coronary  sinus retrograde perfusion  has been tried for refractory angina (David P. Faxon Circ Cardiovasc Interv. 2015)



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The key word for  successful  primary PCI  is

  •  Suction &  Aspiration of thrombus  with   micro catheters like  export catheters
  • One can do away with a stent during primary PCI but can never do away aspiration
  • Distal protection as concept is rapidly dying out as we aim to remove all the thrombus .

Tips for effective thrombus aspiration

  • Apply continuous negative pressure once catheter reaches the thrombus do not release  it till you enter back into the guide.
  • Make sure  you are sucking only  blood  products  not the  endothelium
  • Watch out for  side branch spill over.
  • 7F sheath 7F catheter ideal for aspirating  with a  micro catheter
  • Please be informed some thrombus require more negative pressure especially  in the late  presenters of STEMI

* During dire emergency when you do not have a specialized suction catheter do not hesitate to push  even a diagnostic catheter into the coronary .We have  saved few lives !

Crazy   questions  in primary PCI  ( or Is  it futuristic )

Can we connect the suction apparatus into LAD micro catheter ?

Do we have camera guided suction catheter ?

Can you flush the thrombus if you are not succeeding in aspiration ?

Is ultrasonic desiccation  of thrombus possible ?


Some of the tips were  gathered from the recently concluded  India Live  2012  conference   in New Delhi .

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No reflow is the terminology used primarily in cath labs where, even  after a successful opening and stenting  of a coronary artery the coronary blood flow is not  restored to myocardium . The point to be emphazised here is blood do cross  successfully the site of  the obstruction but fails to enter the muscle segment  to which the coronary artery is supplying. So the paradoxical situation of artery  being open but the  myocardium is closed to receive  blood flow  happens . This is termed as no -reflow.  Actually it is a  misnomer , and  ideally it should be called “no flow” because  normal distal flow  does not  occur (After PCI)  in the first instance  to get interrupted  later on  and be labeled as  no re-flow.  .The only positive effect of PCI in these situation is blood flow would have improved by few centimeters ie till it reaches  but falls short of myocardium . In fact no reflow , can be termed as  glorified and concealed  terminology  for  PCI failure . It needs urgent action . No reflow is also called as myocardial epicardial dissociation.

Mechanism of no reflow.

Curious case of open coronary artery and closed myocardium !

Coronary  microvascular plugging  is mainly  due to thrombus and atheromatous debri , myocardial  edema , microvascular spasm may also contribute.

Where can it occur ?

  • First described in cath lab, especially following primary angioplasty.
  • It can very  well happen following thrombolysis in STEMI.
  • Can occur in venous grafts.

How do you recognise no reflow?

In cath lab it will be self evident from the check angiogram. Some times it is less obvious and may  require, myocardial  blush score, TIMI frame  count, contrast echocardiography, PET scan etc. In post MI a very simple method to recognise this entity could be the observation of persistent ST elevation in ECG .


Extremely difficult. Almost every coronary vasodilator has been tried.(Nitrates, nicorandil, calcium blockers, etc).Success is less than 30%.  High pressure flushing with saline inside the coronary artery is advocated by some.Others believe it’s dangerous to do it. So prevention is the key. Avoid doing PCI in complex, thrombotic lesions. Use thrombus suction device like export catheter(Medtronic). Distal protective devices are double edged devices , useful only in experienced hands.

Unanswered question

What is the size of the particle (thrombotic and atheromatous  debri)  the   coronary microcirculation safely handle and push it into the coronary venous circulation and the coronary sinus for disposal ?

If we can lyse the thrombus into micro particles by some mechanism and make it traverse the coronary circulation this complication of microvascular  plugging can be treated and prevented .

What is the final message ?

  • No reflow is relatively common condition during emergency PCI done for ACS patients
  • More common in complex thrombotic lesions.
  • Can also  occur in STEMI
  • Treatment is often vexing . In fact the treatment of this condition is so difficult , it can be termed  almost synonymously with “Failed PCI” if flow is not restored.
  • Successful treatment of no- reflow  means not momentry restoration of  myocardial flow  by mechanical and pharmacological modalities ,but to maintain sustained myocardial   perfusion. This we realise, as patients who have had a no reflow during  a PCI, do not perform as well in the follow up  .
  • So prevention is the key.

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