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'''Editors-In-Chief:''' [[C. Michael Gibson]], M.D., Alexandra Almonacid M.D., and Jeffrey J. Popma M.D.; '''Associate Editors-in-Chief:''' Ian McCormick, M.D., Duane Pinto, M.D., Brian C. Bigelow, M.D.
'''Editors-In-Chief:''' [[C. Michael Gibson]], M.D.; Alexandra Almonacid M.D.; Jeffrey J. Popma M.D.; '''Associate Editors-in-Chief:''' Duane Pinto, M.D.; Brian C. Bigelow, M.D.


==Overview==
==Overview==
Severe [[vessel]] [[tortuosity]] and the presence of eccentric angulated [[lesion]]s have long been identified as significant predictors of percutaneous coronary intervention (PCI) failure, as well as worse clinical outcomes<ref name="pmid15219518">{{cite journal| author=Gibson CM, Bigelow B, James D, Tepper MR, Murphy SA, Kirtane AJ et al.| title=Association of lesion complexity following fibrinolytic administration with mortality in ST-elevation myocardial infarction. | journal=Am J Cardiol | year= 2004 | volume= 94 | issue= 1 | pages= 108-11 | pmid=15219518 | doi=10.1016/j.amjcard.2004.03.038 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15219518  }} </ref>. Challenges in the treatment of angulated [[lesion]]s and [[lesion]]s in tortuous segments includes difficulty in delivering the interventional equipment and the increased risk of [[vessel]] [[dissection]] and [[vessel perforation]].


Severe [[tortuosity]] and moderate-to-severe [[calcification]] have long been identified as significant predictors of procedure failure, as well as worse clinical outcomes.
==Angiography==
A highly curved or [[tortuous]] [[vessel]] segment may result in substantial foreshortening of the [[artery]]. The length of the [[stenosis]] should therefore be assessed in the most unforeshortened projection so that the appropriate length of [[stent]]s and [[balloon]]s can be selected.


==Angulated Lesions==
==Selection of PCI Equipment in the Patient with an Angulated and Tortuous Vessel Segment==
===Guiding Catheter Selection===
When choosing a guiding catheter, it is important to select the appropriate guiding catheter based upon the [[vessel]] location, takeoff, and size so that coaxial alignment and support are maximized.


* [[Balloon angioplasty]] of highly angulated lesions is associated with an increased for risk coronary [[dissection]].  
"Deep seating" the guide or selective [[coronary artery|coronary]] [[intubation]] may provide improved support to deliver [[guidewire]]s, [[balloon]]s, or [[stents]] in a [[tortuous]] and angulated [[vessel]]. However, this aggressive strategy is associated with an increased risk of [[vessel]] injury. If using this technique, a guide with side holes helps to maintain [[perfusion]]. If a guide catheter with side holes is used, [[intracoronary pharmacotherapy]] may not be delivered at high concentrations.


* In the settings of coronary stenting, angulated lesions represent a challenge due to the inability of delivering the stent to the [[stenosis]] and straightening of the arterial silhouette after stent implantation that may predispose to the presence of stent fracture.
There are specific guiding [[catheters]] that may be selected so that coaxial alignment may be optimized. For instance, larger guiding catheters (7 or 8 French) offer improved support. Additionally, the material composition of the catheter is also important, as the material affects [[torque]] control, kink resistance, risk of [[vessel]] trauma, and stiffness. Different catheters can also be used depending on whether you are working with the left or right system. Extra backup (XB) guiding catheters in the [[left coronary system]], and Ampltaz left (AL) guiding catheters in the [[right coronary system]], can provide improved support. However, these catheters can increase the risk of guide trauma to the [[proximal]] [[vessel]], so extra care must be taken. If the operator is unable to pass the wire word the [[angioplasty]] equipment, then consideration should be made to switch to a guide catheter system that provides greater support. The operator should also confirm that the guiding catheter is in coaxial alignment with the [[lumen]] of the [[artery]] to improve the delivery of [[guidewire]]s and equipment. This is particularly true in the [[right coronary artery]]. Switching to the 45° RAO view can help in determining the anterior posterior angulation of the guide catheter.


* Vessel curvature at the site of maximum stenosis should be measured in the most unforeshortened projection using a length of curvature that approximates the balloon length used for coronary [[Vasodilation|dilation]].
A long [[femoral sheath]] can straighten [[iliac]] [[tortuosity]] and improve guiding catheter support.


==Goals of Treatment==
===Guidewire Selection and Technique===
====Shaping the Wire====
In severely angulated [[artery|arteries]], sometimes both a primary bend and a secondary bend to the [[coronary artery|coronary]] [[guidewire]] are required. The primary bend should approximate the shape of the [[lesion]] while the secondary bend should approximate the shape of the [[artery]] in the [[tortuous]] segment.


In the treatment of angulated and tortuous lesions, the main goals include the:
====Initial Guidewire Selection====
 
A flexible "workhorse" wire with a floppy tip can be used to initially cross the [[lesion]]. It is important to remember that a stiff [[guidewire]] in a very [[tortuous]] [[vessel]] may frequently lead to "[[vessel]] pleating" and pseudo-[[lesion]]s.
* Successful delivery of equipment
* Avoidance of complications, including vessel [[perforation]], [[dissection]], and premature stent deployment
* Maximizing of procedural success, including the restoration of normal [[epicardial]] flow and [[myocardial perfusion]]
 
==Treatment Choices and Advantages of Each Choice==
===Guiding Catheter Selection===
There are specific guiding [[catheters]] that may be selected so that coaxial alignment may be optimized. For instance, larger guiding catheters (7 or 8 French) offer improved support.  Additionally, the material composition of the catheter is also important, as the material affects [[torque]] control, kink resistance, risk of vessel trauma, and stiffness.  Different catheters can also be used depending on whether you are working with the left or right system.  Extra backup (XB) guiding catheters in the [[left coronary system]], and Ampltaz left (AL) guiding catheters in the [[right coronary system]], can provide improved support.  However, these catheters can increase the risk of guide trauma to the proximal vessel, so extra care must be taken.


===Guidewire Selection and Technique===
Conventional 0.014-inch [[guidewire]]s are often sufficient when treating angulated and [[tortuous]] [[lesion]]s, but other options may offer distinct advantages. For instance, stiffer-tip [[guidewire]]s (wires in which the core of the wire goes all the way to the tip of the [[guidewire]]) offer a greater ability to manipulate the tip, while tapered-tip [[guidewire]]s may be useful if the wire prolapses away from the [[lesion]]. Although stiff wires are better able to track [[balloons]] to [[lesion]]s than flexible wires, they may handle poorly and be more likely to result in [[adverse events]]. Since extra-support wires have a stiffer shaft, they may help straighten [[tortuosity]] and ease movement. However, extra-support wires can also increase the likelihood of "[[vessel]] pleating" and "pseudo-[[lesion]]s".
Conventional 0.014-inch guidewires are often sufficient when treating angulated and tortuous lesions, but other options may offer distinct advantages. For instance, stiffer-tip guidewires (wires in which the core of the wire goes all the way to the tip of the guidewire) offer a greater ability to manipulate the tip, while tapered-tip guidewires may be useful if the wire [[prolapses]] away from the [[lesion]]. Although stiff wires are better able to track [[balloons]] to lesions than flexible wires, they may handle poorly and be more likely to result in [[adverse events]]. Since extra-support wires have a stiffer shaft, they may help straighten [[tortuosity]] and ease movement. However, extra-support wires can also increase the likelihood of vessel pleating.  Thus, extra care should be taken depending on the selected guidewire.  


It is possible to first cross the lesion with a less rigid wire and then exchange it for a heavy-duty wire through a balloon [[lumen]]. This can be accomplished in an over-the-wire (OTW) system or an [[intracoronary]] catheter such as an Ultrafuse or Transit catheter. OTW balloon systems push and track more easily than monorail systems<ref name="pmid2964142">{{cite journal |author=Bonzel T, Wollschläger H, Kasper W, Meinertz T, Just H |title=The sliding rail system (monorail): description of a new technique for intravascular instrumentation and its application to coronary angioplasty |journal=Z Kardiol |volume=76 Suppl 6 |issue= |pages=119–22 |year=1987 |pmid=2964142 |doi= |url=}}</ref> and enable guidewires to be exchanged.
====Switching to a Stiffer Wire after Crossing with the Flexible Wire====
It is possible to first cross the [[lesion]] with a flexible workhorse wire and then exchange it for a heavy-duty wire through a [[balloon]] [[lumen]]. This can be accomplished in an over-the-wire (OTW) system or an [[intracoronary]] catheter such as an Ultrafuse or Transit catheter. OTW [[balloon]] systems push and track more easily than monorail systems<ref name="pmid2964142">{{cite journal |author=Bonzel T, Wollschläger H, Kasper W, Meinertz T, Just H |title=The sliding rail system (monorail): description of a new technique for intravascular instrumentation and its application to coronary angioplasty |journal=Z Kardiol |volume=76 Suppl 6 |issue= |pages=119–22 |year=1987 |pmid=2964142 |doi= |url=}}</ref> and enable [[guidewire]]s to be exchanged.


In severely angulated arteries, sometimes both a primary bend and a secondary bend to the cornary guidewire are required. The primary bend should approximate the shape of the lesion while the secondary bend should approximate the shape of the artery in the tortuous segment.
====Utilization of Balloons to Improve Wire Passage====
Placement of a blocking [[balloon]] inflated at low pressures can help deflect a [[guidewire]] into the appropriate segment or branch. Long [[balloon]]s (30-40 mm) help straighten angulation [[proximal]] to the [[lesion]] to facilitate passage of the [[guidewire]].


Placement of a blocking balloon inflated at low pressures can help deflect a guidewire into the appropriate segment or branch.
====Directable Tip Guidewires====
There are new directable-tip [[guidewire]]s and catheters that are of assistance in angulated [[lesion]]s in [[tortuous]] [[vessel]] segments. The Seer-It device manufactured by [[Cordis]] Corporation and a catheter that allows for the tip to be flexed named The Venture Catheter manufactured by St.Jude Medical Incorporated are new technologies that may be of use.


There are new directable-tip guidewires and catheters that are of assistance in angulated lesions in tortuous vessel segments. The Seer-It device manufactured by Cordis Corporation and a catheter that allows for the tip to be flexed named The Venture Catheter manufactured by St. Jude Medical Incorporated are new technologies that may be of use.
====Use of the "Buddy Wire" Technique====
In some circumstances, the addition of a second [[guidewire]] across the [[stenosis]], commonly referred to as a “buddy wire,” will aid in the delivery of the device. The second wire often straightens the [[vessel]] allows for easier delivery of the device or [[stent]]. If a buddy wire is used, a wire of different stiffness and [[lubricity]] from the original wire is usually chosen. Care should be taken to remove the body wire before deploying the [[stent]] or activating an [[atherectomy]] device. Furthermore, concerns regarding wire entrapment and [[microembolization]] of wire coating should be considered. These topics are actively being researched, but to date, they have not proven to be significant clinical problems.


==Delivery of Interventional Equipment in Angulated Lesions and Tortuous Vessels==
===Over the Wire Versus Monorail Balloons===
===Over the Wire Versus Monorail Balloons===
Monorail catheters, also known as rapid-exchange catheters, were designed to allow an easier exchange of catheters by a single operator. They consist of a short catheter shaft that contains two lumens; one is used for balloon inflation and extends through the whole length of the catheter, and the second houses the guidewire and only runs through a portion of the shaft. While monorail catheters have advantages, including enhanced visualization and low-profile balloons, their major limitation include poor performance in tight and angulated lesions<ref>Kern, Morton J. and Deligonul, Ubeydullah.  Interventional Cardiac Catherization Handbook. St. Louis: Mosby, Inc., 1996. 24-26</ref>. Therefore, over the wire system balloons may offer an advantage in tortuous and angulated vessel segments.
Monorail catheters, also known as rapid-exchange catheters, were designed to allow an easier exchange of catheters by a single operator. They consist of a short catheter shaft that contains two [[lumen]]s; one is used for [[balloon]] inflation and extends through the whole length of the catheter, and the second houses the [[guidewire]] and only runs through a portion of the shaft. While monorail catheters have advantages, including enhanced visualization and low-profile [[balloon]]s, one of their major limitations includes poor performance in severely [[stenosis|stenotic]] and angulated [[lesion]]s<ref>Kern, Morton J. and Deligonul, Ubeydullah.  Interventional Cardiac Catherization Handbook. St. Louis: Mosby, Inc., 1996. 24-26</ref>. Therefore, over the wire system (OTW) [[balloon]]s may offer an advantage in [[tortuous]] and angulated [[vessel]] segments.


===Fixed Wire Balloon Catheters===
===Fixed Wire Balloon Catheters===
Fixed balloon catheters, which have distal flexible steering tips with the balloon mounted on a central hollow wire, may deliver more easily across tortuous vessels or [[stenosis]], but also cannot recross the [[lesion]] without first removing the system<ref>Kern, Morton J. and Deligonul, Ubeydullah.  Interventional Cardiac Catherization Handbook. St. Louis: Mosby, Inc., 1996. 24-26</ref>. Furthermore, steerable catheters, such as the Venture catheter, may allow for improved direction of the wire into extremely angulated side branches.
Fixed [[balloon]] catheters, which have [[distal]] flexible steering tips with the [[balloon]] mounted on a central hollow wire, may deliver more easily across [[tortuous]] [[vessel]]s or [[stenosis]], but also cannot recross the [[lesion]] without first removing the system<ref>Kern, Morton J. and Deligonul, Ubeydullah.  Interventional Cardiac Catherization Handbook. St. Louis: Mosby, Inc., 1996. 24-26</ref>. Furthermore, steerable catheters, such as the Venture catheter, may allow for improved direction of the wire into extremely angulated side branches.
 
===Use of the "Buddy Wire" Technique===
In some circumstances, the addition of a second guidewire across the [[stenosis]], commonly referred to as a “buddy wire,” will aid in the delivery of the device.  The second wire often straightens the vessel allows for easier delivery of the device or stent.  If a buddy wire is used, a wire of different stiffness and [[lubricity]] from the original wire is usually chosen.  Care should be taken to remove the body wire before deploying the stent or activating an atherectomy device. Furthermore, concerns regarding wire entrapment and [[microembolization]] of wire coating should be considered.  These topics are actively being researched, but to date, they have not proven to be significant clinical problems.
 
==Making a Selection==
 
When choosing a guiding catheter, it is important to base your decision on the vessel location, takeoff, and size so that coaxial alignment and support are maximized.
 
"Deep seating" the guide or selective coronary intubation may provide improved support to deliver guidewires, balloons, or [[stents]].  However, it also comes with the price of increasing the risk of vessel injury.  If using this technique, a guide with side holes helps to maintain [[perfusion]]. If a guide catheter with side holes is used, [[intracoronary]] [[pharmacotherapy]] may not be delivered at high concentrations.  Generally, the trade off for using a more aggressive guide is an increased likelihood for guide trauma to the proximal vessel.  Furthermore, a long [[femoral sheath]] can straighten iliac [[tortuosity]] and improve guiding catheter support.
 
The choice of [[balloon]], guidewire, and [[stent]] is ultimately based on the operator preference and [[vessel]] [[anatomy]].  There are some guidelines that can be followed, though.  For initial attempts at crossing the [[lesion]], start with a "workhorse" wire.  It is important to remember that a stiff guidewire in a very tortuous vessel will frequently lead to vessel pleating and deformation of the vessel.  If unable to direct a wire into an angulated vessel, consider using a steerable catheter, such as a Venture catheter, to assist in guiding the wire in the right direction.
 
Long balloons (30-40 mm) help straighten angulation and are highly conformable.  If additional guidewire support is necessary, then Over-the-Wire (OTW) balloon systems may be superior.  In such systems, the balloon can be advanced to a position proximal to the lesion, thereby providing additional support.  If OTW systems fail, then lower profile monorail and fixed wire systems, such as the SVELTE stent in some countries.  Also, shorter stents are easier to deliver than longer stents, and newer bare metal stents, such as those made of a [[chromium]] [[cobalt]] [[alloy]], may be easier to deliver than older generation stents.  Furthermore, newer [[drug eluting stents|drug eluting stents (DES)]], such as Xience/Promus or Endeavor, have smaller strut profiles and may also be easier to deliver, in comparison to first generation DES.
 
==Anticipated Outcomes==
 
In general, high procedural success (>85%) and low complication rates (<3%) have been reported.  However, these assessments of outcomes are limited by variable definitions of angulation and [[tortuosity]].  More specifically, angulation >60 degrees is associated with an increased risk of failure.  Also, rotational [[atherectomy]] of lesions >45 degrees should be avoided, as they are have lower success rates and an increased risk of [[dissection]] and [[mortality]].
 
Stenting of highly angulated lesions may be associated with higher [[restenosis]] rates at the points of angulation.


==Real-time Technical Assessment==
===Delivery of Stents in Angulated in Tortuous Lesions===
If OTW systems fail, then lower profile monorail and fixed wire systems, such as the SVELTE [[stent]] in some countries. Also, shorter [[stent]]s are easier to deliver than longer [[stent]]s, and newer [[bare metal stent]]s, such as those made of a [[chromium]] [[cobalt]] [[alloy]], may be easier to deliver than older generation [[stent]]s. Furthermore, newer [[drug eluting stents|drug eluting stents (DES)]], such as Xience/Promus or Endeavor, have smaller strut profiles and may also be easier to deliver, in comparison to first generation [[DES]]. A [[Guidewire wiggle wire|Wiggle wire]] can be used to facilitate the passage of a [[balloon]] or [[stent]] in [[tortuous]] segment by optimizing the coaxial push.


Easy [[torque]] response, advancement, and absence of distal wire kinking suggest an [[intraluminal]] position. Optimal intraluminal position of the guidewire, [[angioplasty]] [[balloons]], and [[stents]] can be confirmed [[angiographically]] by using standard proximal injections through the guiding catheter, or by using distal injections through the central [[lumen]] of the angioplasty balloon or transit [[catheter]].
===Additional Techniques to Improve the Passage of Wires and Balloons across Angulated Segments===
Having the patient take a deep breath in and hold it can straighten a [[vessel]] segment and can improve both wire and device passage. In some rare instances having the patient completely exhale and hold it can also improve wire and device passage.


==Considerations for Alternative Approach==
==Complications==
In general, high procedural success (>85%) and low [[complication]] rates (<3%) have been reported. However, these assessments of outcomes are limited by variable definitions of angulation and [[tortuous|tortuosity]]. More specifically, angulation >60 degrees is associated with an increased risk of failure. Also, [[rotational atherectomy]] of [[lesion]]s >45 degrees should be avoided, as they are have lower success rates and an increased risk of [[dissection]] and [[mortality]]. [[Stent]]ing of highly angulated [[lesion]]s may be associated with higher [[restenosis]] rates at the points of angulation. There may also be an increased risk of [[stent]] fracture in these [[lesion]]s.


The initial strategy can be modified based on the [[angiographic]] success of the delivery and deployment of equipment. When the [[guidewire]], [[balloons]], or [[stents]] cannot navigate the vessel tortuosity or angulation, improved guiding catheter support may improve success. Also, having the patient breathe deeply can help straighten the vessel.
There is an increased risk of sub[[intima]]l passage of the [[guidewire]] in highly angulated [[vessel]] segments. A 1:1 [[torque]] response, easy advancement of equipment, and the absence of [[distal]] wire kinking suggest a safe [[intraluminal]] position. The position of the wire can be confirmed by advancing a small [[balloon]] [[distal]]ly in performing a [[distal]] [[injection]].


With sufficient experience, the operator will be able to determine whether continued attempts will eventually be successful or whether additional maneuvers and/or equipment change(s) will be more successful.  Patients with severely angulated or tortuous lesions that supply large areas of the [[myocardium]] should be considered for [[CABG|coronary artery bypass graft (CABG) surgery]], especially if multivessel disease is present and percutaneous revascularization is deemed high risk or unsuccessful.
==Coronary Artery Bypass Grafting==
Patients with severely angulated or [[tortuous]] [[lesion]]s that supply large areas of the [[myocardium]] should be considered for [[CABG|coronary artery bypass graft (CABG) surgery]], especially if multivessel disease is present and percutaneous [[revascularization]] is deemed high risk or unsuccessful.


==Future Considerations==
==Future Considerations==
The degree of angulation at bifurcation [[lesion]]s, which is a possible independent predictor of percutaneous coronary intervention (PCI) outcome, can be assessed with three-dimensional [[quantitative]] [[coronary angiography]]. The feasibility of this analysis is currently being investigated.


The degree of angulation at bifurcation lesions, which is a possible independent predictor of [[PCI|percutaneous coronary intervention (PCI)]] outcome, can be assessed with three-dimensional quantitative coronary angiography.  The feasibility of this analysis is currently being investigated.
Furthermore, it is suggested that PCI affects the distal [[bifurcation]] angle (between the [[LAD]] and [[LCx]]). Both the proximal (between the [[Left coronary artery|left main]] and [[LCx|circumflex branch of left coronary artery]]) and [[distal]] bifurcation angles are affected by motion during the [[cardiac cycle]].
 
Furthermore, it is suggested that [[PCI]] affects the distal [[bifurcation]] angle (between the [[LAD]] and [[LCx]]). Both the proximal (between the [[Left coronary artery|left main (LM)]] and [[LCx|circumflex branch of left coronary artery (LCx)]]) and distal bifurcation angles are affected by motion during the [[cardiac cycle]].


==References==
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Latest revision as of 16:28, 22 January 2013

Percutaneous coronary intervention Microchapters

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Overview

Risk Stratification and Benefits of PCI

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Factors Associated with Complications
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PCI in Specific Lesion Types

Classification of the Lesion
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Editors-In-Chief: C. Michael Gibson, M.D.; Alexandra Almonacid M.D.; Jeffrey J. Popma M.D.; Associate Editors-in-Chief: Duane Pinto, M.D.; Brian C. Bigelow, M.D.

Overview

Severe vessel tortuosity and the presence of eccentric angulated lesions have long been identified as significant predictors of percutaneous coronary intervention (PCI) failure, as well as worse clinical outcomes[1]. Challenges in the treatment of angulated lesions and lesions in tortuous segments includes difficulty in delivering the interventional equipment and the increased risk of vessel dissection and vessel perforation.

Angiography

A highly curved or tortuous vessel segment may result in substantial foreshortening of the artery. The length of the stenosis should therefore be assessed in the most unforeshortened projection so that the appropriate length of stents and balloons can be selected.

Selection of PCI Equipment in the Patient with an Angulated and Tortuous Vessel Segment

Guiding Catheter Selection

When choosing a guiding catheter, it is important to select the appropriate guiding catheter based upon the vessel location, takeoff, and size so that coaxial alignment and support are maximized.

"Deep seating" the guide or selective coronary intubation may provide improved support to deliver guidewires, balloons, or stents in a tortuous and angulated vessel. However, this aggressive strategy is associated with an increased risk of vessel injury. If using this technique, a guide with side holes helps to maintain perfusion. If a guide catheter with side holes is used, intracoronary pharmacotherapy may not be delivered at high concentrations.

There are specific guiding catheters that may be selected so that coaxial alignment may be optimized. For instance, larger guiding catheters (7 or 8 French) offer improved support. Additionally, the material composition of the catheter is also important, as the material affects torque control, kink resistance, risk of vessel trauma, and stiffness. Different catheters can also be used depending on whether you are working with the left or right system. Extra backup (XB) guiding catheters in the left coronary system, and Ampltaz left (AL) guiding catheters in the right coronary system, can provide improved support. However, these catheters can increase the risk of guide trauma to the proximal vessel, so extra care must be taken. If the operator is unable to pass the wire word the angioplasty equipment, then consideration should be made to switch to a guide catheter system that provides greater support. The operator should also confirm that the guiding catheter is in coaxial alignment with the lumen of the artery to improve the delivery of guidewires and equipment. This is particularly true in the right coronary artery. Switching to the 45° RAO view can help in determining the anterior posterior angulation of the guide catheter.

A long femoral sheath can straighten iliac tortuosity and improve guiding catheter support.

Guidewire Selection and Technique

Shaping the Wire

In severely angulated arteries, sometimes both a primary bend and a secondary bend to the coronary guidewire are required. The primary bend should approximate the shape of the lesion while the secondary bend should approximate the shape of the artery in the tortuous segment.

Initial Guidewire Selection

A flexible "workhorse" wire with a floppy tip can be used to initially cross the lesion. It is important to remember that a stiff guidewire in a very tortuous vessel may frequently lead to "vessel pleating" and pseudo-lesions.

Conventional 0.014-inch guidewires are often sufficient when treating angulated and tortuous lesions, but other options may offer distinct advantages. For instance, stiffer-tip guidewires (wires in which the core of the wire goes all the way to the tip of the guidewire) offer a greater ability to manipulate the tip, while tapered-tip guidewires may be useful if the wire prolapses away from the lesion. Although stiff wires are better able to track balloons to lesions than flexible wires, they may handle poorly and be more likely to result in adverse events. Since extra-support wires have a stiffer shaft, they may help straighten tortuosity and ease movement. However, extra-support wires can also increase the likelihood of "vessel pleating" and "pseudo-lesions".

Switching to a Stiffer Wire after Crossing with the Flexible Wire

It is possible to first cross the lesion with a flexible workhorse wire and then exchange it for a heavy-duty wire through a balloon lumen. This can be accomplished in an over-the-wire (OTW) system or an intracoronary catheter such as an Ultrafuse or Transit catheter. OTW balloon systems push and track more easily than monorail systems[2] and enable guidewires to be exchanged.

Utilization of Balloons to Improve Wire Passage

Placement of a blocking balloon inflated at low pressures can help deflect a guidewire into the appropriate segment or branch. Long balloons (30-40 mm) help straighten angulation proximal to the lesion to facilitate passage of the guidewire.

Directable Tip Guidewires

There are new directable-tip guidewires and catheters that are of assistance in angulated lesions in tortuous vessel segments. The Seer-It device manufactured by Cordis Corporation and a catheter that allows for the tip to be flexed named The Venture Catheter manufactured by St.Jude Medical Incorporated are new technologies that may be of use.

Use of the "Buddy Wire" Technique

In some circumstances, the addition of a second guidewire across the stenosis, commonly referred to as a “buddy wire,” will aid in the delivery of the device. The second wire often straightens the vessel allows for easier delivery of the device or stent. If a buddy wire is used, a wire of different stiffness and lubricity from the original wire is usually chosen. Care should be taken to remove the body wire before deploying the stent or activating an atherectomy device. Furthermore, concerns regarding wire entrapment and microembolization of wire coating should be considered. These topics are actively being researched, but to date, they have not proven to be significant clinical problems.

Delivery of Interventional Equipment in Angulated Lesions and Tortuous Vessels

Over the Wire Versus Monorail Balloons

Monorail catheters, also known as rapid-exchange catheters, were designed to allow an easier exchange of catheters by a single operator. They consist of a short catheter shaft that contains two lumens; one is used for balloon inflation and extends through the whole length of the catheter, and the second houses the guidewire and only runs through a portion of the shaft. While monorail catheters have advantages, including enhanced visualization and low-profile balloons, one of their major limitations includes poor performance in severely stenotic and angulated lesions[3]. Therefore, over the wire system (OTW) balloons may offer an advantage in tortuous and angulated vessel segments.

Fixed Wire Balloon Catheters

Fixed balloon catheters, which have distal flexible steering tips with the balloon mounted on a central hollow wire, may deliver more easily across tortuous vessels or stenosis, but also cannot recross the lesion without first removing the system[4]. Furthermore, steerable catheters, such as the Venture catheter, may allow for improved direction of the wire into extremely angulated side branches.

Delivery of Stents in Angulated in Tortuous Lesions

If OTW systems fail, then lower profile monorail and fixed wire systems, such as the SVELTE stent in some countries. Also, shorter stents are easier to deliver than longer stents, and newer bare metal stents, such as those made of a chromium cobalt alloy, may be easier to deliver than older generation stents. Furthermore, newer drug eluting stents (DES), such as Xience/Promus or Endeavor, have smaller strut profiles and may also be easier to deliver, in comparison to first generation DES. A Wiggle wire can be used to facilitate the passage of a balloon or stent in tortuous segment by optimizing the coaxial push.

Additional Techniques to Improve the Passage of Wires and Balloons across Angulated Segments

Having the patient take a deep breath in and hold it can straighten a vessel segment and can improve both wire and device passage. In some rare instances having the patient completely exhale and hold it can also improve wire and device passage.

Complications

In general, high procedural success (>85%) and low complication rates (<3%) have been reported. However, these assessments of outcomes are limited by variable definitions of angulation and tortuosity. More specifically, angulation >60 degrees is associated with an increased risk of failure. Also, rotational atherectomy of lesions >45 degrees should be avoided, as they are have lower success rates and an increased risk of dissection and mortality. Stenting of highly angulated lesions may be associated with higher restenosis rates at the points of angulation. There may also be an increased risk of stent fracture in these lesions.

There is an increased risk of subintimal passage of the guidewire in highly angulated vessel segments. A 1:1 torque response, easy advancement of equipment, and the absence of distal wire kinking suggest a safe intraluminal position. The position of the wire can be confirmed by advancing a small balloon distally in performing a distal injection.

Coronary Artery Bypass Grafting

Patients with severely angulated or tortuous lesions that supply large areas of the myocardium should be considered for coronary artery bypass graft (CABG) surgery, especially if multivessel disease is present and percutaneous revascularization is deemed high risk or unsuccessful.

Future Considerations

The degree of angulation at bifurcation lesions, which is a possible independent predictor of percutaneous coronary intervention (PCI) outcome, can be assessed with three-dimensional quantitative coronary angiography. The feasibility of this analysis is currently being investigated.

Furthermore, it is suggested that PCI affects the distal bifurcation angle (between the LAD and LCx). Both the proximal (between the left main and circumflex branch of left coronary artery) and distal bifurcation angles are affected by motion during the cardiac cycle.

References

  1. ↑ Gibson CM, Bigelow B, James D, Tepper MR, Murphy SA, Kirtane AJ; et al. (2004). "Association of lesion complexity following fibrinolytic administration with mortality in ST-elevation myocardial infarction". Am J Cardiol. 94 (1): 108–11. doi:10.1016/j.amjcard.2004.03.038. PMID 15219518.
  2. ↑ Bonzel T, Wollschläger H, Kasper W, Meinertz T, Just H (1987). "The sliding rail system (monorail): description of a new technique for intravascular instrumentation and its application to coronary angioplasty". Z Kardiol. 76 Suppl 6: 119–22. PMID 2964142.
  3. ↑ Kern, Morton J. and Deligonul, Ubeydullah. Interventional Cardiac Catherization Handbook. St. Louis: Mosby, Inc., 1996. 24-26
  4. ↑ Kern, Morton J. and Deligonul, Ubeydullah. Interventional Cardiac Catherization Handbook. St. Louis: Mosby, Inc., 1996. 24-26

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