CORONARY GUIDEWIRES

Dr. Raji Rajan&

Dr. A. George KoshyGovernment Medical College,

Trivandrum

•GRUNTZIG First performed Angioplasty in 1974•1977 – First coronary angioplasty•Polyvinyl Chloride balloon catheter with short guidewireattached to its tip

•1982 – Simpson reported First experience with over the balloon system•It had an independently movable guidewire within the balloon dilation catheter

• To track through the vessel

• To access the lesion

• To cross the lesion atraumatically

• To provide support for interventional devices

Guidewire main characteristics

Torque control Is an ability to apply rotational force at aproximalend of a guidewire and have that force transmittedefficiently to achieve proper control at the distal end

Trackability Is an ability of a wire to follow the wire tiparound curves and bends without bucking or kinking, tonavigate anatomy of vasculature

Steerability Is an ability of a guidewire tip to be delivered tothe desired position in a vessel

Flexibility Is an ability to bend with direct pressure

Prolapse tendency Tendency of the body of a wirenot to follow the tip around bends

Radiopacity/visibility Is an ability to visualise aguidewire or guidewire tip under fluoroscopy.

Tactile feedback Is tactile sensation on a proximalend of a guide wire that physician has that tells himwhat the distal end of the guidewire is doing

Crossing Is an ability of a guidewire to cross lesionwith little or no resistance

Support Is an ability of a guidewire to support apassage of another device or system over it

STRUCTURE

CORE-Material

Diameter

Core taper

TIP

COILS, COVERS & COATINGS

Core

• Inner part of the guidewire

• Extents through the shaft of the wire from the proximal to the distal part

• Distal taper

• Stiffest part of the wire that gives stability and steerability

Core Material Core material affects the flexibility, support, steering

and trackability

• Stainless steel

– superior torque characteristics, can deliver more push,provides good shapeability and excellent support

– more susceptible to kinking and is less flexible

• Nitinol

– pliable but supportive, less torquability than SS

– generally considered kink resistant & have a tendency toreturn to their original shape, making them potentiallyless susceptible to deformation during prolonged use

Core Diameter• Influences the performance of the wire

• Larger diameter improves support and allows 1:1 torque response

• Smaller diameter enhances the flexibility

Core taper• Variable length

• Continuous/segmented

• Short taper and smaller number of widely spaces gradual tapers increases support and transmission of push force

• Longer tapers and larger numbers of segmented tapering increases flexibility

Tip

• Tapers distally to a variable extent

– 2-piece core- distal part of core does not reachdistal tip of wire→ shaping ribbon, extends todistal tip

– 1-piece core- tapered core reaches distal tip weld

• 2-piece→ easy shaping & durable shapememory

• 1-piece →better force transmission to tip &greater “tactile response” for operator

Coils, Covers & Coating

Keeps the diameter at .014 inch• Coils

– Stainless steel– Outer coil Design – Coils placed over tapered core and

tip of the wire– Tip coil Design – Tip alone is covered with coils– Flexibility, support, steering, tracking, visibility &

tactile feedback– Radio opaque platinum coils– Intermediate coils placed on the working length of the

wire

Coils

• Covers– Polymer or plastic

– Lubricity

• Coating– Distal half

– Affects lubricity and tracking

– Creates tactile feel

– Reduces friction

– Facilitates movement of wire within the vessel and deliverability of intervention equipment

Hydrophobic• Applied over the entire working length except

the distal tip

• Require no activation by liquid

• ↓friction, ↑trackability

• Preserves tactile feel, allows easier anchorability / parking - esp CTO

• Silicone, Teflon

Hydrophilic• Applied over the entire working length of wire

including tip coils• Attracts water - needs lubrication• Thin, non slippery, solid when dry→ becomes a gel

when wet– ↓friction– ↑trackability– ↓Thrombogenic↓tactile feel- ↑risk of perforationTendency to stick to angioplasty cath

• Useful in negotiating tortuous lesions and in“finding microchannels” in total occlusions

Shapeability and shaping memory

• Shapeability - allows to modify its distal tip conformation

• Shaping memory - ability of tip to return back to its basal conformation after having been exposed to deformation & stress

– Both do not necessarily go in parallel

– SS core wires -easier to shape (↑memory- nitinolcore)

– 2-piece core + shaping ribbon - easier to shape & ↑memory

Classification

Based on Tip Flexibility• Floppy – Eg:- Hi torque balance middle weight, Hi

torque balance, Hi torque transvers• Intermediate – Eg:- Hi torque intermediate,

Choice intermediate• Standard – Shinobi, Boston Scientific

Based on Device support• Light – Eg:- Hi torque balance• Moderate – Eg:- Hi torque balance middle Weight• Extra support – Eg:- Hi torque whisper

Based on coating

• Hydrophilic : Eg:- CholCETM PT Floppy

• Hydrophobic : Eg:- Asahi soft

Depending on tip load

• Floppy, Balanced & Extra support

• Tip load - force needed to bend a wire when exerted on a straight guide wire tip, at 1 cm from the tip– Floppy - <0.5g

– Balanced – 0.5-0.9g

– Extra support - >0.9g

Guidewire Manipulations

• Two step process

• Shaping the wire tip

– It minimizes the amount of force applied to the wire

– For steering into the vessel

– For visualization of torquing effort

Shaping the Wire Tip

Steering of the wire

• Small alternating rotations to left and right

• Excessive rotations should be avoided to prevent wire tip fracture

Optimum guide wire positioning

• Should be placed as distally as possible in the target vessel

• Allows extra support when crossing with balloon/stent catheters

• ↓ chance of the wire becoming displaced backwards across the lesion and necessitating re-crossing

Avoid vessel perforation when positioning wires with hydrophilic coatings very distally

Strategies if Guidewire fails to cross

• Make the guide more coaxial with the lumen of the artery

• Use a balloon to direct the wire

• Modify the bend at the tip of the wire

• Change the wire

Complications

• Vessel perforations– Uncommon <1%

– Risk factors• Hydrophilic wires, core to tip

• Chronic total occlusions

– Diagnosis• Angiographic diagnosis

• Small extraluminal extravasation of blush in the distribution of target vessel

• Emergency echo to r/o pericardial effusion and tamponade

– Prognosis• Extend of extravasation into pericardium

–Classification• Type I – Extraluminal crater without extravasation

• Type II – Containing pericardial or myocardial blushing

• Type III - having≥ 1 mm diameter with contrast streaming: and cavity spilling

–Management• Reversal of anticoagulations

• Prolonged balloon inflation

• PTFE covered stent

• Coil embolization

• Use of gel foams

Pseudolesions/Concertina effect• Stenosis that appears in any artery after the coronary

guidewire is placed in the artery

• Appears in tortuous vessels that have been straightened out by the guidewire

Diagnosis

• Will disappear if the wire is withdrawn

• Replacement of a stiff wire with a flexible floppy wire eliminates pseudolesion

• Microcatheter or a balloon catheter can be placed distal to the lesion

Complications

• In some cases cause hemodynamic compromise and ischemia

Guidewire Entrapment

Factors

• Presence of calcified vessels (Eg:- RCA)

• Repeated use of wire for multiple interventions

• Repeated attempts at crossing the same lesion multiple times with the same wire

• Two wires my become entrapped when the “Buddy wire” technique is used

• Crossing fresh stent struts

Management

• Advance a small profile balloon or a small calibercatheter (transit catheter) to the attachment siteand pull back gently

• When a second or “buddy wire” gets trappedbetween a stent and the vessel wall gentletraction can be used

• Surgery

Guidewire fracture and Embolization

• Risk factors are calcified lesion, bifurcation stenting and prolonged procedures

• Management– Surgery

– Snaring the Embolized wire fragment

• The Amplatz Gooseneck Microsnare

• The EnSnare Triple Loop Device

• The X Pro Micro Elite Snare

• The Alligator Retrieval Device

– Push and paste

Balance Middleweight Universal wire(Abbott Vascular/Guidant, Santa Clara, CA)

• Quite steerable - tip is suitable for bending in a “J” configuration for distal advancement into the distal vessel bed with minimal trauma while still maintaining some torque

• shape retention relatively poor -any J configuration tends to become magnified over time → consequent loss in steerability

• moderately torquable- progression - minimal friction (light hydrophilic coating) - Dye injection may also be helpful to propagate distal advancement

• suitable for rapid, uncomplicated interventions• low risk to cause dissections/distal perforations• support - low to moderate

Fielder™ / Fielder FC™ (Asahi Intec Co.)

• Special guidewire - distal coil coated with polymer sleeve & further coated with a hydrophilic coating

• Provides advanced slip performance & trackability for highly stenosed lesion & tortuous vessels

• Very good torque performance • Combines both slide and torque performance • Primary wire used in the retrograde technique of

recanalization of CTO

Whisper

• Durasteel™ Core-to-tip designed to improve steering, durable shape retention and tactile feedback

• Full Polymer cover with Hydrophilic coating intended for deliverability and smooth lesion access

• Responsease™ “transitionless” core grind designed to provide improved tracking and better torque response

• Tip coils designed to provide softer, shapeable tip and also improve tactile feedback

Galeo guide wire

Guidewire Strategies for Approaching CTO

• A) Guidewires for Approaching Micro-channels– Crosswire NT– Whisper / Pilot– Rinato– Shinobe / Shinobe Plus– ChoICE PT / ChoICE PT ES– PT Graphix– PT2

• B) Guidewires for Drilling Strategy– Persuader– Miracle Bros– Cross-It

• C) Guidewires for Penetrating Strategy– Cross IT– Conquest Pro– Liber 8

• D) Guidewires for Retrograde Technique

– Fielder/FielderFC– X -treme– Whisper– ChoICE PT2– Runthrough / Runthrough

Hypercoat

Selection of a Guidewire

• Vessel anatomy

• Lesion morphology

• Devices to be used

Conclusion

It is suggested that the operator may use a limited number of wires from the several types available for purchase