Archive for the ‘Cath lab Hardware’ Category

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


Read Full Post »

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.

Read Full Post »