Archive for the ‘Cath lab Hardware’ Category

We know, The Mysterious Alibaba cave opens  with a voice password . . . legend  tell us it had unlimited hidden treasures. It would appear , CTOs mimic the cave in several ways. What is inside ? Should we open it ?  Can we come out safely ? Do we have any magical password in cath lab to get across the complex tissue boulders ?,   every cardiologist would love to have one !

chronic total occlusion alibaba cave corsair fileder xt pronova guideliner micro catheter asahi cart reverese cart cross boss sting ray

Dear CTO,Open Sesame . . . I have come with all the wires you love !  Please let me in !


“CTOs are never an emergency  . . .but please realise  we can very easily create one  while resuscitating a dead snake  ! 

Don’t think hard on evidence , then , you may not do a single case of CTO in your life .Forget all those pessimistic trials like OAT,COAT, etc and the recent ones DECISION-CTO. Ignore all guidelines. Ask your patient, and his insurance company , if they are willing , reserve the cath lab and get ready.

Pre-procedure  planning

Spend at least a hour to analyse the CTO Imagery one day prior and create n action plan.

Keep knowledgeable staff for assisting , but never ask for fellow colleagues help because it hurts our ego !  Cardiac surgeon’s back up is a welcome addition even if it’s on paper.

If possible , try to ask the patient genuinely ,what is his symptom at least once !  before starting the procedure. 

Timing of the procedure.

Don’t post a CTO patient  either on a busy Monday morning  or lazy Friday afternoon.

Hardware Inventory

The wires ,catheters, the balloons form the essential tool box .There is more than a  handful of coronary automobile companies manufacture this .It is all about metallurgy , knowledge of wires, catheters , and tip thickness, (Bullet shaped as in Asahi ) , slipping , hydrophophic or philic,  polymer coating , trackability, pushability , memory etc etc.

Guide wire tip morphology is as Important as the  Lesion characteristics !

Analysis of the lesion (Probably most important)

Unlike conventional PCI we have no initial target.We need to poke first and find the target next ! Distal vessel status  is most important ( Careful review of retrograde filling  through collaterals could give more information than CT angiograms .Calcification, diffuse disease can be a real hurdle)

Lesion morphology

Softness of lesion has to be felt (Requires good wire which has sensor (Paccinian corpuscles and Merckle disc ideal ?) I guess the cortical tactile feel is as vital as the  intervention expertise .I know at least one diabetic colleague of mine who finds it difficult  to cross a CTO  and admits he never found it easy to feel  the lesion through the wires . Autonomic dysfunction ?)

Operator  expertise

(Note: These are like reading  swimming guidelines , you can’t learn in the shores reading books ! you have to plunge !)

Many techniques are proposed .Sequential approach (Ironically experts are licensed to use  specialized wired wires directly .Beginners  are advised to go with non specialized hardware and escalate step by step) Some centers are blessed with new age weapons like cross Boss and sting ray that confront the lesions in multiple frontiers. (Carpet bombing?)

CTO playground. : Its essentially a coronary contact sport with expert septal surfing , tunnelling, knuckling , kneeling , bending . Of course , It  can end up in a gratifying win in few , still most of us tend to play this game without a goal (post !)

They are basically about poking the head of the lesion and trying to cross an occluded vessel  millimeter  by mm towards the presumed distal vessel in an Imaginary trajectory. Proximal cap, central core ,the blind tunnel , distal capsule and exit points each must be successfully conquered.

CTO crossing is  the ultimate capacity of the operator to realise and feel the position of the wires in true lumen and their confidence levels in their conviction!

Multiple wires up to three are used some times to poke the lesion two of them are used to shut the false tracks and the other one is expected to enter the true lumen (Looks too good on theory !) . These are referred to in as many terms like parallel wire see-saw , CART ,Reverse CART etc .Retrograde techniques do help us but has no magic solutions.The lumen contrast , guide wire tip movement and its  side branch entry  would help.

Tacking complication :Always anticipate , it’s not negative mind set to look for it  !

Keep pericardiocentesis kit , covered stents , micro  snares and other retrieval devices ready in cart. Your support staff should be well versed with what is happening around them. Some of  the dye leaks and stains are safe .They imply minor perforations that form  sealed hematomas  (The plane of perforations also matters. myocardial (ab-pericardial ) leaks are well tolerated .Distal perforations are also safe as long as CTO is not opened ) Online echocardiography should be readily available to monitor  pericardial space leak.

When bleed into pericardial space is life threatening , A comical, but life saving option is to close the artery and restore the CTO  its original state and come out of the lab quietly ! 

Newer Imaging guidance : Can be useful , still may not matter much  when considering the interventional acumen .

CTO PCI : Time as therapeutic end point.

CTO is not an endless game with out time frame .In my opinion it shouldn’t cross 45 minutes each as in a  soccer  game with a brief  strategic time out and of course with liberal use of ,yellow and red cards

Future directions

Japanese are the ones who pioneered  CTO Interventions . We expect more Innovations ! Is it the forward looking IVUS ? It is akin to tunneling for underground metro train with GPS guiding .If you can mark the proximal and distal  points , rest will be be taken care by mortised self tunneling catheters from Robotic arms steered by sophisticated algorithms.

Final  message

CTO PCI remains a real Interventional challenge. We are often double blinded  in both directions (antegrade as well as retrograde ). Needs much effort ,time, hardware and most importantly a non fatigued mind and body. The benefits we get may vary  between  gratifying to outright mediocre .Of course , it surely satisfies operator ego and express pride and courage !

Is crossing and stenting  a CTO  synonymous with true success ?

Yes it is , for the cardiologist and  the hospital  . . . I’m not sure about it for the patient !

In this  sense , CTOs  mimic the mysterious Alibaba cave that tempts us with Imaginary treasures but can trap us with a wrong password !


* Who should CTO PCI  ?

I have seen  young , enthusiastic cardiologists with Immature support staff attempting CTO in remote sub- urban settings ! Though patience and expertise are essential ingredients, some amount of organised training and hardwares make CTO PCI safe and effective. Enthusiasm and affordability alone can’t be an Indication for this complex set of coronary lesions.



I still wonder why  this vital paper was never published , it was just presented in the Annual ACC conference March 2017



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Coronary artery lumen has unique character . Its well-known  LAD diameter is not constant , it tapers in its distal course.(Unlike RCA which is more tubular ) It is estimated LAD looses 15 % of its diameter for every 30mm length.Fortunately LCX has no such long course to make tapering a visible threat. (Though it may still be an Issue !)

Is there a hemodyanmic purpose for this tapering in LAD ?

Should be, God never designs anatomy without a physiological purpose.We have to find it  out.(Can it be meant for  flow acceleration as the flow is entriely diastolic in LAD while in RCA its both in systole and diastole ?_

What is the relationship between tapering angle and final distal diameter?

Schematic of an artery with a tapered angle of 0:16 .Ref XIANG SHEN Journal of Mechanics in Medicine and Biology Vol. 16, No. 8 (2016)

So, if you have a long lesion in proximal LAD and planning to stent with a 40 mm or long  stent the distal end is hyperinflated by atleast 1.5mm, if we use a non tapered stent. Though , gain of extra  diameter  in distal segments might appear attractive, this may not work to our advantage , since it defies and distorts  the natural hemodynamic flow pattern. Further , when you have tapering vessel, proximal optimisation becomes more important.

How about a tapering coronary stent ?

It should be a welcome addition to our already overflowing coronary hardware in fixing long lesions . Its still a surprise why only very few are making this type of stent.

Meril has developed a  tapered stent up to 60 mm long  (Biomime morph).It should be useful in specific lesions sub types.Its worthwhile to note  tapering stents are used more often in carotid artery .

Advantages of long tapering stent over two stents of different sizes.

  • It avoid the vulnerable overlapping zone with double metallic load.
  • Possibly cause less restenosis
  • Low risk for stent fracture
  • It reduces procedure time and of course the cost of stent by 50 %

Why the concept of Tapered stent is not that popular ?

I can only guess, probably lack of free availability and  to a certian extent ignorance as well !  However ,current status about tapering stents is expected to evolve, though many cardiologist still  feel it’s not clinicaly important issue to use a tubular stent in tapering vessel.

Alternative  interventions in tapered vessel.

  • Wall stent and other self expendable stents
  • Tapered balloon Angioplasty (Laird Am Journal of card 1996)

Experts  in this modality are  welcome to share their experience.


1.Zubaid MC, Buller C, Mancini GB. “Normal angiographic tapering of the coronary arteries”. Can J Cardiol 2002; 18: 973-980

2.Timmins LH, Meyer CA, Moreno MR, Moore JE Jr. “Mechanical modeling of stents deployed in tapered arteries”. Ann Biomed Eng 2008; 36: 2042-2050

3.Javier SP, Mintz GS, Popma JJ, Pichard AD, Kent KM, Satler LF, Leon MB. “Intravascular ultrasound assessment of the magnitude and mechanism of coronary artery and lumen tapering”. Am J Cardiol 1995; 75: 177-180

4.Laird JR, Popma JJ, Knopf WD, Yakubov S, Satler L, White H, Bergelson B, Hennecken J, Lewis S, Parks JM, Holmes DR. “Angiographic and procedural outcome after coronary angioplasty in high-risk subsets using a decremental diameter (tapered) balloon catheter. Tapered Balloon Registry Investigators”. Am J Cardiol 1996; 77: 561-568


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Interventional cardiologists in one way be labelled as intra-cardiac and intra-vascular civil engineers.Their primary  job is to create ,or close vascular tunnels and holes in various locations within the heart.How to deliver the  working hardware  to the  site of action ?. Temporary bridges ? .The vascular access is through long sheaths though which , wires, catheters, and devices , valves  are transported. It’s the key supply line to the ultimate battle field of life , right inside the beating heart.  .

So far,the sheaths  and catheters were rigid tubes with a fixed diameter.Innovative sparks come from  strange thoughts.As we struggled to take the per-cutaneous valve for  TAVR  through small caliber sheaths , some one thought why should the sheath be fixed and static .Why can’t it accommodate  liberal sized devices just by expanding its shaft like a python ,come back to its original state once the device passes by ?

Expandable sheath 164 solo path tavi tavr cathlab hardware

Thus came the expandable sheaths. Soon this concept is going to come in a big way and most complex and large device interventions will be benefited by this.

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