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.
Reference
ORBITA trial : First let us do some harm . . . second , we shall . . !?
Posted in Cardiology -Interventional -PCI, Cardiology -Technology, Cardiology -Therapeutic dilemma, cardiology -Therapeutics, Cardiology -unresolved questions, cardiology journal club, cardiology wisdom, Medical education, Medical ethics, Uncategorized, tagged ABUSE OF STENTS, ACC AHA ESC ORBITA GUIDELIES, CHRONIC STABLE ANGINA GUIDELINES, drsvenkatesan, HOW ORBITA TRIAL WILL CHANGE MY PRACTICE, INAPPROPRIATE USE CRITERIA AUC STENTS, LANCET ORBITA STUDY, ORBITA COURAGE BARI2D FAME 2, ORBITA IMPERIAL COLLEGE, ORBITA study, ORBITA TRIAL LANCET, ORBITA trial review and comments, ORBITA VS COURAGE, reviewing ORBITA trial study critically, TCTMD 2017 ORBITA, WAHT WE LEARN FROM ORBITA STUDY on November 6, 2017| 2 Comments »
Cardiologists at confused cross roads !
Perils of limited Intellect & Infinite greed
When not so appropriately trained cardiologists do Inappropriate things “use becomes misuse” . . . then, it won’t take much time for science to become total abuse. That’s what happened with the murky world of coronary stents .No surprise, it’s time to firefight the healers instead of the disease !
Now ,Comes the ORBITA study . Yes , it looks like a God sent path breaking trial that spits some harsh truths not only in cardiology, but also in behavioral ethics .Let us not work over time and hunt for any non-existing loop holes in ORBITA. Even if it has few, it can be condoned for sure as we have essentially lived out of flawed science for too long Injuring many Innocent hearts !
Yes , its enforced premature funeral times for a wonderful technology !
GIF Image courtesy http://www.tenor.com
Meanwhile, let us pray for a selective resurrection of stenting in chronic coronary syndromes and stop behaving like lesser professionals !
Postample
Extremely sorry . . . to all those discerning academic folks , who are looking for a true scientific review of ORBITA , please look elsewhere !
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