Slender PCI

A review of 'slender' techniques for percutaneous coronary intervention.

The ‘slender’ philosophy on PCI starts with the notion ‘Less is More‘.


As Ferdinand Kiemeneij, MD, PhD, the ‘father of TRI’ and a strong proponent of slender techniques has noted, the ‘maximal miniaturaization’ of materials used in PCI benefits patients, doctors and hospitals. Changing the approach to PCI to emphasize slender and efficient techniques utilizes less materials, contrast, time, vessel trauma and cost while generating more efficiency, patient and doctor satisfaction, lab turnover and ultimately, profit.

Interest in the utilization of smaller catheters (i.e., 5F or smaller) for cardiac catheterisation and percutaneous coronary intervention has recently increased, particularly as  the popularity of TRI has grown.

Saito RadialArtery Chart

TRI is most frequently performed with 6F (2.0 mm) catheters requiring introducer sheaths with an outer diameter of 2.7 mm. Radial artery diameters, however, vary widely, and in females and the elderly can approach 1.5 mm in diameter. In patients with small radial arteries, TRI can be painful and potentially unsafe due to vessel trauma or radial artery occlusion (RAO). Clinical trials have shown lower arterial puncture-related morbidity rates when catheter diameter is reduced from 8 to 4 F.

To address the mismatch between radial lumen and sheath size in certain patients, the development of slender equipment and techniques began in Japan more than ten years ago. The Slender Club Japan (SCJ), initiated by Dr Fuminobu Yoshimachi, spearheaded the effort to develop miniature interventional products and techniques. Sheathless guides and small caliber catheters initially developed were difficult to manipulate, largely due to lack of back-up support. To overcome these challenges, techniques such as deep intubation, creating loops, use of extra wires and anchoring techniques were developed. Regularly scheduled workshops now take place to share slender experiences and learnings.

The smallest available catheters currently in are 3 F angiography catheters, though the smallest used catheters for TRI are 4 F. Smaller guides require smaller balloons, stents and wires, which are in the nascent stages of development and primarily available in Japan. Developing and manufacturing slender products requires higher quality materials and specifications than conventional equipment, making the development of such equipment challenging in today’s healthcare environment. Europe is now beginning to see introduction of more slender interventional products, and the Slender Club Europe (SCE) recently held its first meeting with the aim to incorporate learnings from the Japanese experience.

  • 4 F diagnostic catheters (Terumo Corp. and Cordis, a Cardinal Health Company)
  • 5 F guiding catheters (several manufacturers)
  • 6.5 F and 7.5 F sheathless guiding catheters (ASAHI-Intecc)
  • 6 F Glidesheath Slender introducer (Terumo Corp.)
  • 5 F sheathless guiding catheters (Medikit)
  • Contrast power injectors (several manufacturers)
  • 0.010″ wire compatible PTCA balloons (several manufacturers)
  • SLENDER IDS Integrated Delivery System (IDS) drug-eluting stent-on-a-wire

Looking forward,  the availability of 5 F-compatible manual aspiration catheters (in development) will allow for the treatment of bifurcations and primary angioplasty routinely through 5 F guiding catheters.

The advantages of downsizing to 5 F are well established, including  reductions in bleeding complications, radial occlusion, contrast use, fluoroscopy time and haemostasis time, enhancing patient comfort and facilitating same-day discharge. Many physicians value the ‘slender’ approach to PCI due to the well-documented benefits of reduced size of vascular access:

5-Fr Sheath
(n = 152)
6-Fr Sheath
(n = 303)
P Value
Total Access Site Complications 14.5% 34.3% < 0.001
Radial Artery Occlusion 13.7% 30.5% < 0.001
Pseudoaneurysm 0 1.0% 0.56
Arteriovenous Fistula 0.7% 1.0% 1.00
Moderate/Severe Bleeding 0 0
Mild Bleeding 0 2.0% 0.19

* The Leipzig Prospective Vascular Ultrasound Registry in Radial Artery Catheterization: Impact of Sheath Size on Vascular Complications Uhlemann, Madlen, MD et al (J Am Coll Cardiol Intv, 2012; 5:36-43,doi:10.1016/j.jcin.2011.08.011

Further reductions in catheter size can potentially make the TRI successful in 100% of patients.

Whether transradial or transfemoral, however, there are considerable data to support the premise that the use of smaller guide catheters, result in enhanced clinical outcomes in patients undergoing PCI. Benefits include improved patient safety and comfort, as well as financial savings. Reduced time to patient ambulation means greater same-day discharge and higher patient turnover.

To be sure, slender techniques must still be validated in larger, randomized studies. Smaller and thin-walled catheters, for example, are typically less robust and more difficult to visulaize, manipulate and position, especially early on in the learning curve. Poor back-up support can result in procedural difficulties. And several important interventional devices, such as rotablator, aspiration catheters and bioresorbable scaffolds, are not 5 F catheter compatible.  But it is also important to keep in mind that 10 years ago the use of 6 F catheters was considered ‘downsizing’ and now is the accepted standard. Necessity is the mother of invention, and slender products for PCI will be forthcoming.

Miniaturisation of materials dedicated to transradial coronary access may result in increased patient value by improving outcome and by reducing costs.