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Posts Tagged ‘bifurcation lesion’

If human coronary artery is comparable to live wire , attempting  bifurcation (BFL) stenting is akin to tame a live snake .True BFL  (with Medina 1, 1, 1)  being the most complex of all .The fact is ,we have atleast a dozen strategies for BFL with varying loads of metal abutting the ostia ,side branch and carina.This  would essentially Imply we are still struggling with these lesions .

While current science tends to vouch PCI* for most  BFLs . . . wisdom  might whisper CABG !

Who should do complex PCI ?

Obviously,  not every interventional cardiologist can. Confidence is one thing , but , falling short of minimum standard of care is rampant in India. Newer Imaging tools, techniques are promising , unfortunately  still the gap between, knowledge , science and  reality continue to widen.

* Its true ,some expert Interventionists do a good job !

What is the simplest approach for Bifurcation lesions ?

Final message 

We have come a  long way in BFL. Still , some of the lesions can sting  like a snake ! I am sure, everyone of us would have lost sleep after a complex BFL PCI !( Praying the humble  heparin and DAPT to do the rescue act ! )

bifurcation lesions medina stenting srategies 002

How to escape this double headed threat ?

A meticulous assessment of  patient  &  lesion , mindfulness in choosing the hardware & Imaging , diligent usage of anticoagulants & DAPT and  . . . finally  willingness to listen to your own conscience ,  will ensure a gratifying result that includes abandoning the procedure !

Reference 

For everything in Bifurcation Intervention

The ultimate source : Visit the in this link  European Bifurcation  Club

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bifurcation angle

  • At any branch point three angles are possible .True bifurcation angle is formed between LAD and LCX .
  • The angle between LM and LAD or LM and LCX can also be important in specific situations ,especially when we encounter short left mains and Medina 1,1,0 lesions .
  • Major bifurcation angle can  occur in mid  segments  as well ,  between LAD / major Diagonal  , LCX and OM.
  • Logic would tell us the  left main  bifurcation  angle is relatively fixed by the anatomical AV and IV grooves. Still early course of LAD and LCX can be out of grooves.
  • Further ,the bifurcation angle is imparted some amount of dynamism by cardiac cycle . It can vary between 80 -120 degrees (LAD/LCX).
  • Most importantly various  angiographic views can alter the true angle (by illusion ) in dramatic fashion . RAO caudal view appear ideal to measure it. (LAO caudal make every bifurcation angle obtuse !)
  • Acute angled bifurcations are prone for stent related mechanical issues both during deployment and in the long term outcome . (When two stent technique is used) This is because ,  acute  angled bifurcations has a tendency to drift the carina , and  encroach  the lumen  which can create new  turbulence . Of course final kissing balloon is expected to reduce this hemodynamic side effect at least on paper !

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Kissing balloon is the standard technique used to tackle   branch vessel stenosis . When a vessel branches out and both branches has a lesion,  single balloon can not dilate a lesion optimally . This  is  because , the side branch  not only shares a common ostial tissue but also  shares  plaque material within the walls of main and side  vessel . Dilating one vessel alone could result in unpredictable plaque shift.

Carina is the most important anatomic structure in a bifurcation zone . It acts like a grade separator. Diverting and deflecting blood flow .The  length and angle of this grade separator determine the ostial  shape as well . A right angled side branch will have  a circular ostium .An acute-angled branch  will have oval orifice .  The plaque burden and distributions at this point becomes vital for many reasons.

When we do PCI this carinal area should be  optimally pressed and plastied  and of course covered well with the metal struts.The  simultaneous kissing with two balloons ,  one in main vessel another in side branch will reduce many of the issues . This area is a weak link for interventional cardiologists. It needs lots of efforts to protect the side vessel.

When do we do kissing balloon ?

Two broad categories.

  • Pre-dilatation and preparing a lesion ( Not routine  )
  • Post dilatation is more often done .

Look closely the layers of contention in the carinal zone. Lesion not depicted .

Kissing interface : When the balloons kiss  what lies  in between ?

  1. Simple  Balloon to Balloon Kissing with nothing intervening(Proximal to branch point )
  2. Balloon- Single layer of Stent-balloon kissing
  3. Carinal  Kissing -Balloon -Two layers of Carinal tissue -one layer of Stent -Balloon Kissing ( See above image )
  4. Twin stent kissing

When do  balloons refuse to Kiss ?

When there is a hard interface between the vessels like a severely  calcified intima /Adventia .

Eccentric /overhanging  lesions intervening.

Incomplete kiss

It need to be emphasized balloons come  into contact easily in  acute-angled lesions.

In right  angled lesions the balloons come to contact only in the proximal part.

Definite indications  for  kissing ?

Kissing is not without complications . While two guide wires are placed in all  bifurcation lesions  , kissing is  not necessary in many  lesions  .Of course it is a must in all true bifurcation lesions (Medina 111 , 011, 101, )  It may not be required in  1,0,0 if carina is away from lesion.

*Kissing can rarely aggravate the same issue which is supposed to prevent  ie plaque shift .This is due to differential pressure transmission by two balloons.

Is there a role for  twin balloon POBA  without any stenting ?

Most cardiologists would not believe  in POBA anyore (For wrong reasons though ! )

A distal RCA with a PDA ostial branch lesion could be tackled with twin balloon POBA.

Which  balloon is to be used?

It depends on whether we use the technique  as POBA, single stent or double stent technique. Non compliant balloons are  ideal  as it exerts   more pressure on the vessel wall .

Kissing   at  what  pressure ?

The pressure used is often between 8-14 ATM.

Experts may use differential pressure inflation depending on the lesion characters.

Which  is the Most complex form of kissing ?  

Two stents, two balloons . Here the interface contains two metal layers . At carnia the two metals engulf   two layers of  tissue as well .

Final message

Bifurcation lesions  are being  conquered with more success in recent years.

The techniques have refined. Stent designs and drug eluting stents  are  helping us in many ways.

We have learnt  from our  mistakes and accepted the limitations.

Wisdom  prevails now , there is a universal consensus  for less  metal in the notorious  carinal  area.

Still, ignorance  remains*  as  a major  guiding force   . . . when  we  navigate  the difficult atheromatous terrains  in  live human  coronary arteries !

*With due respects to IVUS, OCT and FFR .

**Forward looking IVUS, and camera tipped guidewires may change the scenerio.

 

Further reading

What-is-the-simple-approach-to-bifurcation-pci ?


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Bifurcation lesions and ostial lesions  continue to  challenge the expertise of   interventional cardiologists.

Variety of techniques have been described. Geo positioning of a ostial lesions ,  exactly on the rim of ostium  is required  . This is very difficult in  many patients  , as stent migration either into side branch or protrusion into the main branch is common. Both reduce  optimal  PCI outcome  .

Here is a innovative  technique   described  first by  Szab0 in 2005 TCT conference .

Highlights of the technique

  • It is a twin guide  wire technique.
  • The Circumflex guide  wire  is threaded over the most proximal strut  of  balloon mounted  LAD stent .
  • The guidewire makes sure the LAD stent move beyond the LAD ostium .
  • Of course some technical limitation is  there, this seems to be a good option at least in some deserving  LAD ostial or LCX ostial lesions

Technical hitch

The balloon and stent is to be manhandled prior to deployment.  We are little awry to do it

The review article in the journal  Eurointervention

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Coronary stents have revolutionised the management of CAD. Stents are metallic scaffolding devices that help keep the atherosclerotic plaque  plastered within the coronary arterial wall.Thus it gained the name angioplasty. Stents have aradial strength that  exerts a constant force on  the plaque . Since metals are unfriendly partners for coronary artery , we need to have minimum metal within the coronary artery.The stent struts weave around the lumen generally the stento/ artery area ratio should be as less as possible (15%).

But this has a trade off .The uncovered area of plaque tend to project into the lumen .This is many times not significant.But can be a problem if the plaque is very soft and bulk of the lipid core may reenter the lumen.this event is called plaque prolapse.

plaque-prolapse

What is the time taken for plaque to prolapse ?

Generally it is late event.But it can happen immediately after the procedure also.

Which type of lesions are more likely to have plaque prolapse ?

Eccentric and complex lesions especially with overhanging edges are prone for prolapse

What is the sequale ?

It can be benign.If there is a erosion due to stent struts can precipitate an ACS.It progresses into instent restnosis in many.

What is the angiographic appearnce ?

Angiographically it often appears as luminal  irregularity withi stented segment .

Many times , it may appear as a filling defect also.

Is there any specific issues in plaque prolapse in drug eluting stents ?

Coornary artery is not drugged uniformly by the drug eluting stents.In fact contact  lines of metalic struts  , through it’s micropore oozes the drug with polymer.Pathological studies have revelaed non homogenous drug penetration and resultant irregularity on the plaque surface.This could amplify the plaque penetration preferentially in few areas.

How to manage plaque prolapse ?

It should be managed as any other instent restenosis.Plaque resection with atherectomy devices has not solved the problem to the desired levels.A second stent is the most common approach advocated by the cardiologists.(Whic is not ideal though !)

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