Shigeru SAITO, MD, FACC Kamakura & Sapporo, JAPAN Antegrade Guidewire Basics: Guidewire Tip Shaping, Escalation Strategies and Drilling vs. Penetration Shigeru SAITO, MD, FACC Kamakura & Sapporo, JAPAN

Shigeru Saito, MD I have no real or apparent conflicts of interest to report.

Tip Shaping

How to shape the distal tip of the guidewire in CTO lesions If the lumen diameter is big, the curve of the distal tip should be also big. If the lumen diameter is small, the curve of the distal tip should be also small. How about CTO? The lumen diameter is actually zero in CTO lesions. Thus, the tip curvature should be minimum.

How I shape the tip of guidewires? For CTO lesions For non-CTO lesions Use a small needle to shape the tip. Shaping has smooth curve. The diameter of the curve is 3 to 6 mm. We bend the tip. 2 bending points. Distal bending is only 1 to 2 mm in length.

The bending of the distal tip 0.32mm 0.53mm

Escalation Strategies

Concepts defining Guidewire Performance Tip Load (Stiffness) Shaping Memory Tip Flexibility Support Strength Torque Transmission Slip Ability Tracking Ability Trap Resistance

The Definition of Tip Stiffness Floppy guidewires: Less than 1 gram Intermediate guidewires: 1 to 3 grams Guidewires designed for CTO: Equal to or more than 3 grams

Guidewire Selection (2) Conventional Guidewires Miracle 3G Direct Step-Up Gradual Step-Up Conquest-Pro Conquest-Pro12 Miracle 12G Miracle 4.5G Miracle 6G

PCI for CTO lesions between July 2004 and January 2005 (Phase III) Total number of lesions (patients): 78 lesions (patients) Demographics: Male 62 patients (80%) RCA/LAD/LCX: 28%/39%/33% Overall success rate: 72/78 = 92%

Which guidewire finally crossed the CTO lesion? Among 72 CTO lesions successfully crossed between July 2004 and January 2005

PCI for CTO lesions between July 2004 and January 2005 Very important finding: For the majority of lesions with CTO, very stiff guidewires are not necessary. However, very stiff guidewires are also necessary in selected lesions with CTO. Thus, I recommend “Direct increments from 3 grams to 12 grams” but not “Gradual increments”

Introduction of tapered-tip guidewires

Characteristics in Phase I and II periods Phase I Phase II p Number of pts 182 80 Male gender 78% 83% NS Age (y.o.) 65 +/- 11 67 +/- 8 NS Triple vessel disease 21% 20% NS LVEF (%) 49 +/- 18 49 +/- 13 NS Culprit artery NS LAD 36% 36% LCX 24% 30% RCA 40% 34% Duration of occlusion (months) 15 +/- 10 17 +/- 24 NS Length of occlusion (mm) 17 +/- 5 18 +/- 6 NS Tapered-type occlusion 33% 35% NS Bridge collateral 14% 15% NS Prior MI 59% 55% NS

Success rates in PCI for CTO lesions was improved in ShonanKamakura G Hospital Saito S, et al. Angioplasty for chronic total occlusion by using tapered-tip guidewires. Catheter Cardiovasc Interv 2003; 59: 305-11. P=0.019

Technical characteristics in Phase I and II periods Saito S, et al. Angioplasty for chronic total occlusion by using tapered-tip guidewires. Catheter Cardiovasc Interv 2003; 59: 305-11. Phase I Phase II p Number of pts 182 80 Use of contra-lateral angiography 20% 23% NS Use of hydrophilic guidewires 8% 6% NS Use of tapered-tip guidewires 0% 60% <0.001

Pathology of CTO lesions - the presence of small vascular channels - By courtesy of Toshinobu Horie, MD

Pathology of CTO Lesions Katsuragawa M, Fujiwara H, Miyamae M, Sasayama S. Histologic Studies in Percutaneous Transluminal Coronary Angioplasty for Chronic Total Occlusion: Comparison of Tapering and Abrupt Types of Occlusion and Short and Long Occluded Segments. J Am Coll Cardiol 1993; 21: 604-11 Pathological structure of CTO lesions: CTO lesions usually have small vascular channels of 160 to 230 microns in diameter, which are connecting to the proximal free space of the occlusions. Usually these small vascular channels cannot be identified by a fluoroscopic or cine- angiographic observations. Tapered-end CTO lese lesions usually have small vascular channels connecting between the lumens before and after occlusion. When the small vascular channels are not connecting to the distal vascular lumen, they are usually connecting to small side branches or vaso vasorums. The areas of loose fibrous tissues are surrounded by the area of dense fibrous tissues.

Drawing of CTO Lesions Small vascular channels Katsuragawa M, Fujiwara H, Miyamae M, Sasayama S. Histologic Studies in Percutaneous Transluminal Coronary Angioplasty for Chronic Total Occlusion: Comparison of Tapering and Abrupt Types of Occlusion and Short and Long Occluded Segments. J Am Coll Cardiol 1993; 21: 604-11 Small vascular channels (160 to 230 microns diameter) Connect with proximal part Non visualized by angiography Islands of dense fibrous tissues

Introduction of hydrophilic tapered-tip guidewires

Plastic-Jacket Hydrophilic Tapered-Tip Guidewire Rationales for CTO Lesions: They can easily enter into non-visible microchannels because of their small diameters. They can easily enter into non-visible microchannels because of their lower friction resistance. They can rarely damage or induce intimal dissection because of their lower tip stiffness.

Fielder-XT 16cm Radio-opaque spring coil 16cm Polymer Sleeve & SLIP COAT® 0.014” PTFE Coating Stainless Steel Core 0.009” 3cm 1cm

17cm Polymer-Dipping with Hydrophilic Coating WIZARD O.D: 0.010” O.D: 0.014” 16.5cm Radiopaque 17cm Polymer-Dipping with Hydrophilic Coating Model Tip Stiffness Radiopaque Coating Length WIZARD 1 1g 16.5cm Hydrophilic 178cm WIZARD 3 3g

Modified Flow Chart for the Guidewire Selection CTO Starting from Floppy Guidewire Plastic-Jacket Hydrophilic Tapered-tip Diameter Guidewire Miracle 3 Fibrous/Calcified Miracle 12 Conquest-Pro/12

Flow Chart for the Guidewire Selection CTO Starting from Floppy Guidewire Micro channels +/- Plastic-Jacket Hydrophilic Tapered-tip Guidewire Miracle 3 Fibrous/Calcified Miracle 6/12 Conquest-Pro/12

Drilling vs. Penetration

Manipulation of Guidewires There are 2 types of techniques to manipulate the guidewires. #1: To advance the guidewire, where it is going (Drilling Technique) #2: To aim at the target, penetrate the obstruction and advance the guidewire to the target (Penetrating Technique) For the usual or tortuous lesions, #1 may be better, We can choose non tapered-tip guidewires or hydrophilic plastic guidewires for these lesions. For the very hard lesions, #2 may be better, We can choose tapered-tip guidewires with strong penetration power for these lesions. However, we have to understand that heavily calcified plaque cannot be penetrated even by using the stiffest guidewire. The current most difficult subset is the combination of the tortuosity and the presence of very hard plaque.

Reconsideration of physical properties

Penetration Power of Guidewires Penetration power of the guidewire is defined as follows: Tip stiffness divided by tip surface area (sharpness). The power can be modified by the decreased friction resistance earned by hydrophilic coating. Regular guidewires: 0.014 inches Cross-it: 0.010 inches Confienza: 0.009 inches

Calculation of Penetration Power

Measurement of Tip Stiffness according to the Length extending from a Microcatheter Height Gauge Electrical Balance Test Guidewire Φ0.8 Section of a Tube 5~20mm Pushing by 0.5 mm

Effect of Microcatheter on Guidewire Stiffness Extrapolated by using the 2nd order fitness function. 61 24 2.4 2007.02.22. CTO Summit, New York, USA

Tip Stiffness through Microcatheters For CTO guidewires, tip stiffness is dramatically changing with the length extending out of microcatheters. We have to handle those guidewires carefully while understanding this characteristics of stiff guidewires different from floppy ones.

Measurements of Torque Transmission 30mm Test guidewire PTFE tube of 0.56mm inner diameter Angle Disk Video Torque Motor 180

Torque transmission of stiff guidewires is lost in tortuous peripheral arteries

Torque Transmission of Stiff Guidewires In tortuous peripheral arteries, torque transmission is lost for stiff guidewires more than floppy ones. Thus, in patients with tortuous peripheral arteries, we have to place long (metal) stiff introducers.

Use of Microcatheters

Use of over-the-wire system is essential! Use of over-the-wire (OTW) system To provide better support to guidewires To provide more precise torque control To enable guidewire exchange 1.5-mm OTW balloon Microcatheters: The following OTW support systems without balloons are preferable to OTW balloons, since they have distal shaft softer than the latter and align a guidewire more easily with coronary arteries. Transit (Cordis) Prowler (Cordis) Excelsior (Boston Scientific) Finecross (TERUMO, Japan) Progreat (TERUMO, Japan)

Antegrade Guidewire Basics Final Messages We have to understand lesion characteristics. We have to understand physical properties of each guidewire. Fine manipulation of guidewires is important. Success rate is improving for CTO lesions.