Handbook of Advanced Interventional Cardiology - part 4 potx

The shaft of the balloon catheter will straighten the proximal segment and a wire indwelled inside an infl ated balloon can be advanced without much diffi culty to the distal end, provid

shear stress at the exit of the newly stented area following the straightening of the vessel.7 Different options in the treatment

of long lesion are listed in Table 9-4

TECHNICAL TIP

Long or short balloons: Long balloons can dilate long

lesions with one balloon placement rather than doing peated infl ations with a short balloon, thus avoiding plaque shifting and giving a better, smooth initial result Dilating a

re-Table 9-2

Evaluation of complexity prior to interventions 6

Factors affecting the ability to access the lesion

Left main disease

Presence of branches affecting wire passage

Factors affecting the ability to cross the lesion with a wire or

a balloon

Degree of stenosis and length of lesion

Lesion morphology: eccentricity, thrombus, presence of calcium, complexity

Lesion characteristics that affect the outcome

Characteristics associated with increased incidence of section

dis-Characteristics associated with increased incidence of thrombotic occlusion

Lesion characteristics that affect the reconstruction of a

Diffuse disease

Severe calcifi cation (stiff, non-accommodating channel)Marked tortuosity or angulation

Complex Lesions 185

long lesion with a short balloon can disrupt the plaque in multiple places and allow blood to enter the channel behind the plaque causing dissection For long lesions located on bends, there is less occurrence of dissection with the use

of a long balloon placed entirely around the bend.8 The rate

of restenosis, however, continues to be quite high in PCI of any long lesion.7

Rotational atherectomy was considered desirable for debulking long and superfi cially calcifi ed lesion but it should be used with caution because of the large amount of atheromatous debris removed and released It may cause

Table 9-3

New risk assessment schema

Risk factors

Strongest correlates Non-chronic total occlusion

Degenerated saphenous vein graft (SVG)

Moderately strong

correlates

Length >10 mmLumen irregularityLarge fi lling defectCalcium + angle >45°

EccentricSevere calcifi cationSVG age >10 years

Results

Highest risk either of the strongest correlatesHigh risk ≥3 moderate correlates without strong-

est correlatesModerate risk 1–2 moderate correlates without

strongest correlates

Table 9-4

Strategies of long lesion interventions

1 Pretreatment with antiplatelet agents

2 Ample use of intracoronary (IC) nitroglycerine to prevent distal vessel spasm

3 Avoid excessive particle embolization during rotablation

4 Avoid vessel-fl ow mismatch

5 Debulking prior to stenting

6 Drug-eluting stent

7 Brachytherapy (VBT)

excessive distal microembolization with subsequent

no-re-fl ow and ischemic events.9

The data from the New Approaches to Coronary vention (NACI) registry showed that each 1-mm increase in lesion length was associated with an increased relative risk

Inter-of 1.014 (95% CI, 1.004–1.025) for target lesion ization (TLR) at 1 year.10 With drug-eluting stent (DES), spot stenting is the technique of the past

revascular-EVIDENCE-BASED MEDICINE APPLICATIONS

Drug Eluting Stent: The SIRolImUS-Eluting Stent in

De Novo Native Coronary Lesions (SIRIUS) trial: In this

trial, for the control group, the rate of restenosis was 29.7% for 8-mm bare stents and 52.4% for bare stents measuring

40 mm By contrast, the rate of restenosis of the eluting stents of <8 mm length was only 1.7% It was 6.5%

sirolimus-in lesions treated with 40-mm stents In general, for every

10 mm of bare metal stent implanted, the rate of restenosis increased by 13% In the sirolimus group, this increase was 1.6% for every additional 10-mm stent used from a baseline

fi ed segment) and the tissue next to the calcifi ed area The mechanism of acute lumen gain after PTCA in calcifi ed lesion

is dissection while it is plaque compression and vessel sion in fi brotic lesion Higher pressure infl ation also increases

expan-Table 9-5

Restenosis versus stent length

In-segment restenosis Stent length Control (%) Sirolimus (%)

is not as commonly used as before.

TECHNICAL TIPS

**Device selection: First, predilate a lesion with POBA If

the lesion can be dilated then stenting would be feasible Most lesions with mild calcifi cations respond to this; sim-ply try If a lesion cannot be fully dilated at 18 ATM then stent placement is contraindicated since incomplete stent expansion increases the risk of subacute thrombosis and restenosis Then rotablation or cutting balloon angioplasty can be tried However, if the lesion is distal and the proximal segment is severely calcifi ed and tortuous (>60° angula-tion), then it is diffi cult to advance a cutting balloon to the lesion site In these heavily calcifi ed lesions, primary rotab-lation is suggested.13

**Advancing a stent in a tortuous artery: Even after

ro-tablation and balloon dilation, stenting of severely calcifi ed lesions is still diffi cult because hard and eccentric plaque in

a proximal tortuous segment may still prevent the ment of stent In these circumstances, it is important not

advance-to force the stent inadvance-to the lesion since this maneuver may result in stent deformation and inability to remove the stent later, if needed In order to advance the stent, the guide backup should be optimal, the “buddy wire” technique may

be used to straighten the proximal segment, to shift the stent over the edge of the plaque Complete predilation of the lesion or further debulking of the lesion with rotablation may be needed.13

**Expanding a stent with CB after failure of high sure infl ation: Even after being advanced to the lesion

pres-area, not every stent can be fully deployed due to pected severe calcifi cation of the lesion In a case report

unex-by Colombo et al., while a stent was being deployed in the

proximal LAD, the distal part of a stent could not be opened even at 30 ATM So the balloon was exchanged with a cutting balloon (CB) that was advanced into the distal seg-ment and infl ated at 12 ATM The CB was withdrawn and

exchanged for a non-compliant balloon that fully expanded the stent at 28 ATM.14

CAVEAT: Avoid stent embolization while exchanging

a balloon in a tortuous and calcifi ed segment: While

exchanging a balloon on a half deployed stent, the stent is easier to be dislodged backward, especially if the stent has

a funnel shape (the proximal end is larger than the distal deployed end) Make an extra effort to keep the stent immo-bile while removing the old balloon and advancing the new balloon inch by inch These situations happen in the follow-ing situations: (1) angulated segment; (2) sharply tapered vessel with distal segment much smaller than proximal segment; and (3) insertion site between saphenous vein graft or internal mammary artery graft to the native vessel

un-In summary, in PCI for calcifi ed lesions, the results are usually suboptimal because only 24% of cases achieved 90% cross-sectional area of the reference lumen.15 Even with higher pressure infl ation (>18 ATM), some stents are still un-derdilated Without prior calcium removal, it may not be pos-sible to fully expand a stent, because of severe calcifi cation

or large plaque burden In order to advance the stent through calcifi ed and rigid lumen, extensive manipulation would de-nude the endothelial layer and cause more intimal hyperplasia and restenosis Cutting balloon angioplasty or plain balloon angioplasty with one or two buddy wires can help to break the plaque and allow full stent deployment Rotational atherec-tomy is the method of choice for debulking the calcifi ed lesion with adjunctive angioplasty or stenting, however, the resteno-sis rate after bare stent and rota-stent was still high There are

no new data with DES or brachytherapy on calcifi ed lesions

ANGULATED LESIONS

An angulated lesion is defi ned as a lesion on a bend of 45° or more With simple POBA, the success rate was 70% with 13% ischemic complications.16 The risk of acute closure was 2% if the bend was less than 45°, and 8% if the bend was between 45° and 90°; it was 13% if the bend was more than 90°.7

BEST METHOD

Advance a wire through angulated segments:

1 First maneuver – select a balanced wire: At fi rst a fl

op-py wire seems to navigate easily the tortuous segments

It does not cause pseudo-lesions or wire bias However, after a few excessive turns, it is impossible to advance

Complex Lesions 189

a too fl oppy wire further It behaves like a wet noodle In contrast, it may be diffi cult to make a fi rst extensive twist and turn with a very fi rm wire Furthermore, a stiff wire may cause “bias” while passing through heavily calcifi ed and angulated segment and shift interventional devices against the wall of the artery, making their passage dif-

fi cult In most cases a moderately fi rm wire is ate.17

appropri-2 Add a second wire: On many occasions, a fl oppy

wire is able to be advanced though tortuous segments; however, it is not strong enough to tract a device Then

a second, soft or stiffer wire may need to be advanced parallel to the fi rst one by wrapping around the fi rst one (the “buddy wire”)

3 Add a second device: Sometimes, a wire may be

ad-vanced at best to the proximal end of a distal segment

of an artery Then, advance a balloon as far as possible, then the wire, to the distal end

or twice so the fi rst wire can turn around the bend and be directed separately to its own branch

**Advance a stiff wire with the help of a balloon: Ideally,

in many PCIs, it is best to have a wire advanced deeply to the distal end of any instrumented artery However, in many real-life situations, a wire could easily cross the lesion at the mid-segment (e.g of the RCA or LCX) and at best, might only be advanced just to the proximal end of the distal seg-ment (e.g before the PDA or after a large OM) Advance a balloon near the tip of the wire then advance the wire If the balloon can be advanced across the lesion, then infl ate the balloon at low pressure, thus avoiding dissection While the balloon is infl ated, advance the wire to the distal end The shaft of the balloon catheter will straighten the proximal segment and a wire indwelled inside an infl ated balloon can be advanced without much diffi culty to the distal end, providing a better support for later device tracking (Figure 9-1 A–C)

BEST METHOD

Avoiding perforation while advancing a balloon around

a bend: should we add a new wire or change the balloon?

Sometimes, if the wire is too soft and the currently available high-pressure balloons may have a very stiff tip that is not

fl exible enough to make a turn around the bend, its tip keeps pointing straight to the lateral wall The reason is the tip of the balloon catheter is stiffer than the shaft of the wire So the

Figure 9-1: (A) There is diffi culty in advancing the wire (B)

The wire can be advanced only to the mid-segment of the LAD While the balloon is infl ated, the wire can be advanced

further (Continued)

A

B

Complex Lesions 191

balloon-wire complex would have to follow the direction of its stiffer component (the tip of the balloon), pointing toward the wall, rather than curving around the bend A further push may puncture the wall In this case, either insert a second stiffer wire (buddy wire) to make the curve more rounded and so less bias for the balloon, or choose a lower profi le and more

fl exible balloon.17 In any circumstance, a second, stiffer wire

is preferred because, as in this case, if a balloon cannot be advanced, how can a stent be advanced through the angu-lated segment? The stent may succeed to be advanced on the second, stiffer wire rather the fi rst, softer wire

1 First maneuver – look at the angiogram – no calcium:

Before wiring, the fi rst factor predictive of success for advancing any interventional device (wire, balloon, stent

or thrombectomy, etc.) across a tortuous segment is the lack of calcifi cation (e.g in young patients) These arter-ies can let any stiff device slide through without problem

Figure 9-1: (C) The wire is advanced to the distal LAD, thus

securing an excellent wire position and support for further movement of bulkier devices

C

2 Second maneuver – look at the angiogram – large arteries: The second factor is the size of the artery If the

artery is quite large, the wire can bypass the angles and connect all these segments on a straight line or a round curve that facilitates a lot the advancement of devices (Figure 9-2 A–C)

3 Third maneuver – look at the angiogram – the angle after wiring: After wiring, if the wire is able to stretch on

a straight-line form or round curve, then the chance for the devices to move forward is much higher

4 Fourth maneuver: The usual requirements: Finally,

one cannot overemphasize the optimal backup of a guide, the trackability by a stiffer wire and the fl exibility

of the interventional device All of these will help to vance the device to the area needed (Table 9-6)

ad-**How long a balloon should be when wrapping around

a bend: There is less occurrence of dissection with the use

of a long balloon placed entirely around the bend because the longer the balloon, the greater the force required to

Figure 9-2: Advancing a wire through tortuous arteries (A)

The tortuous LCX with 90° angle from the LM There was a severe lesion at the ostium of the large OM There was a bro-ken tip of a wire in the distal segment of the OM This was the result of the jailed wire technique when a wire was jailed at the

OM when a stent was deployed at the mid-LCX across the OM

(Continued)

A

Complex Lesions 193

Figure 9-2 B,C: (B) After wiring, it was clear that the wire

by-passed all the angles and formed a straight line from the tip of the guide to the OM There was no sharp angle between the left main and LCX This straight line facilitated the advance-ment of a balloon or stent (C) The ostium of the OM after stenting was wide open

B

C

straighten it.18 A long balloon covers the lesion and cent areas so the stress pressure may be spread evenly over the lesion, rather than concentrated at the edge of the lesion Short balloons may avoid the curve altogether in le-sions not directly located on the angle If the balloon does not cover the whole plaque, infl ation of the balloon could result in plaque fracture and seepage of blood behind the plaque starting a dissection Ideally, the balloon should be long enough such that there is a 10-mm margin of balloon extending beyond the bulk of the atheroma.17

adja-Even so, it is diffi cult to have excellent results in sharply angulated lesions with simple POBA Rotational atherectomy can be used if there is superfi cial calcifi cation but the success rate is lower In a more angulated bend, there is increased risk of perforation due to preferential ablation Some stents can curve along the mildly angulated contour of an arterial segment If the angle is too sharp, more than 90°, a stent cannot be suffi ciently bent; rather, it straightens the angulated segment The reste-nosis rate for these lesions straightened by a bare stent was not higher when compared with stented lesions not on a bend.19There are no new data with DES or VBT on angulated lesions

LESIONS WITH THROMBUS

Thrombus is recognized angiographically as fi lling fects, irregular surfaces, or overhanging edges surrounded

de-by contrast (Figure 9-3 A,B) With IVUS, a thrombus is seen as

a mobile, pedunculated, hypoechoic mass; a brightly led mass, or by channels or fl ow within the plaque However, the angiographically-labeled thrombotic lesions, when seen under IVUS, showed only 50% truly thrombotic One-third

speck-of these so-called thrombotic lesions were purely calcifi ed

or they were just soft plaque without calcium or thrombus.20

In patients undergoing PCI, the presence of pre-existing thrombus did not bear a poor prognosis for in-hospital (0.8%

vs 0.6%, P=NS) or 6-month mortality (2.1% vs 1.8%, P=NS) However, the major ischemic events, including death/MI,

Table 9-6

Factors that guarantee success of device advancement

in angulated segments

1 Lack of calcifi cation (accommodating vessel)

2 Large size of vessel so the wire can bypass the angles3

4

Possibility of wiring on a straight-line form or round curveExcellent guide support, wire trackability and device

fl exibility

In a report by Douglas et al., an attempt to remove the

thrombus was made by fi rst twisting a 0.014" wire and a balloon-on-a-wire to trap fi brin strands and subsequently withdrawing both wires into a deeply seated guide catheter This maneuver yielded a large amount of thrombus, and subsequent angiography showed an excellent result with

Figure 9-3: Lesion with thrombus (A) Small round lucent

ob-ject, surrounded by contrast in the mid RCA (Continued)

A

no evidence of residual thrombus.21 Rarely, large proximal thrombi have been aspirated into a soft deep-seated guide.The administration of thrombolytic agents can lead to deformity and/or fragmentation of large clots, with resultant abrupt closure or ischemia related to distal thromboemboli-zation On many occasions, it has been either ineffective or resulted in paradoxical vessel occlusion.21 When urokinase was no longer available in the US, rPA was used instead, with similar results; however, it could cause stroke In the presence

of thrombus, the use of glycoprotein 2b3a inhibitor is strongly advocated In instances of refractory or large thrombi, me-chanical thrombectomy is indicated.22

TECHNICAL TIPS

**Maneuvering the AngioJet: The AngioJet catheter

is a 5F device operated on 0.14" or 0.18" guidewire The catheter is advanced over the guidewire until it reaches the thrombotic area Then it is activated by pressing the foot switch on the drive unit It is advanced at 2–3 mm/second, sweeping towards the distal end Alternatively, the device

Figure 9-3: (B) Diffuse, large thrombi in the proximal RCA.

B

Complex Lesions 197

can be advanced towards the distal end, crossing the thrombotic area without being activated Once in the distal area, the catheter is activated and withdrawn slowly while still in action This retrograde method may cause less de-bris embolization, although there was no fi rm evidence of its effectiveness These passes can be repeated until the thrombus burden is cleared.23

Experiences with the X-SIZER device: The X-Sizer

(Endicor Medical, Valkenswaard, The Netherlands) is

a simple device combining vacuum technology with a patented helix cutter housed in the tip of a small catheter When engaged, the slow-spinning blades serve to entrain the thrombus or soft material, which is then macerated and sucked out

In the X-TRACT trial, at 30 days, the overall MACE rates were similar (17% in the X-Sizer group and 17.4% in the control group) However, large MIs, defi ned as a CPK-

MB greater than 8 times normal limits, were reduced by 46%; 8.3% in the control group compared to 4.5% in the X-Sizer group There was 1 perforation in the X-Sizer group and 4 in the control group.24

***Off-label maneuvering of the distal fi ltering device:

Extraction of large thrombus in the Fogarty maneuver In a

case report by Eggebrecht et al., a 6.0 mm fi lter Angioguard

(Cordis Sunnyvale, CA) was deployed in the distal LAD with thrombus seen in the mid-segment In an off-label ma-neuver, the expanded fi lter was withdrawn from the distal segment to the proximal segment in a Fogarty maneuver

In the fi rst attempt, a 2 × 2 mm thrombus was found The Fogarty maneuver was repeated three times After that, PCI was carried on as usual.25 In this case, the passage

of an umbrella-type device could break the culprit plaque and trigger distal embolization and dissection The authors were right when they chose the title of their article: “Abuse

of a novel device”

SMALL VESSEL INTERVENTIONS

A small vessel is defi ned as a vessel with a minimum men diameter of less than 2.5 mm by quantitative coronary angiography The procedural problems encountered during PCI of small vessels are listed in Table 9-7 There was no dif-ference in restenosis rate between PTCA or stenting in the Benestent trial.26 The reason is that in small vessels, although there is no difference in intimal hyperplasia, the loss index is still higher, relatively speaking, in the smaller lumen of a ves-sel with diameter <2.5 mm

lu-TECHNICAL TIP

**Wire selection and manipulation: In a small vessel,

when manipulated, the wire’s tip is straightened more by the confi ned diameter of the small vessel, so steering is more diffi cult The tip curve should be short and is curved as dictated by the diameter of the vessel The distal tip is soft rather than stiff because this is a poor area for manipulation and it is easier to exit the true lumen, causing perforation.27

TAKE-HOME MESSAGE

Stenting in a small vessel:27

1 Do not attempt stenting without excellent coaxial ment and good backup support of the guide

align-2 Do not attempt stenting if the lesion is not fully dilated after high pressure infl ation (>15 ATM)

3 Use moderate push to advance the stent Avoid forceful

or prolonged manipulation of stent catheter to cross the lesion

4 If the lesion cannot be easily crossed, try deeper tion of the guide without aggressive manipulation

intuba-5 Carefully assess the stent position in several projections before infl ating the balloon

6 Once deploying the stent, angiogram in multiple views

to assess the result and to be sure that the distal part of the lesion is covered by the stent, without residual distal dissection

7 In a small vessel, do not leave the stent with incomplete dilation, and/or residual distal narrowing or dissection

8 In case of residual narrowing distal to the stent, repeated long infl ation at low pressure with a balloon catheter matched to the vessel size is advised

**Selection of balloons: Non-compliant balloons are

sug-gested because small vessels usually have hard lesions,

Table 9-7

Procedural problems with PCI of small vessels

1 Occlusion of the blood fl ow by still defl ated balloon

2 Diffi culty in advancing devices (wire, balloon, stent, etc.)

3 Infl ation of compliant balloon can cause perforation

4 Dissection more likely occlusive

5 More signifi cant residual stenosis

6 Higher rate of restenosis

7 More diffi cult to stent

8 Suboptimal results after stenting

9 Small area of myocardium in jeopardy

Complex Lesions 199

thus high pressure may be needed, making the proper size balloon critical If the balloon is expanding its size with increasing pressure, then it is oversized and can change greatly the balloon:artery ratio In lesions located in tapered vessels, balloon selection based upon proximal reference diameter may result in increased risk of dissection, where-

as balloon sizing based on distal reference segment may yield suboptimal results but seems to be recommended as the fi rst choice in small vessels Additional infl ation of only the proximal part with a short balloon will be the second step of the process.27

EVIDENCE-BASED MEDICINE APPLICATIONS

The RAVEL and SIRIUS trials: small vessels analysis:

The randomized study with the sirolimus-eluting Bx ity-Expandable stent (RAVEL) trial compared DES with bare stent in all vessel sizes (<2.36 mm, 2.36–2.84 mm and

Veloc->2.84 mm) At 6 months follow-up, there was 0% restenosis

in all vessels with DES, while it was much higher in the bare stent group (Table 9-8) In the SIRolImUS-Eluting Stent

in De Novo Native Coronary Lesions (SIRIUS) trial, there was a sizable rate of restenosis of 8% in small vessels with diameter <2.3 mm, while it was acceptable in larger size vessels (Table 9-9).28

The contradictory results among the DES trials (Table 9-10) can be explained by different lesion and patient characteristics as well as different procedural parameters Stenting of short focal lesions in truly small vessels is su-

Table 9-8

Vessel size and restenosis rate in the RAVEL trial 28

Mean radial diameter DES Bare stent

The SIRIUS trial : vessel size sub-analysis

In-stent restenosis TLR (up to 270 days )

Vessel size Sirolimus Control Sirolimus

perior to balloon angioplasty and cost-effective Stenting

of long lesions and small vessels in pseudo-small vessels with diffuse disease can have very good results with the DES

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Nguyen T, Hu DY, eds Advances and Challenges in Today’s

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2 Williams D, Vlachos H, Kelsey S et al Procedural

strate-gies and outcomes of PCI in 1999: Results of the dynamic

registry J Am Coll Cardiol 2000; 35 (Suppl A): 30A.

3 Nguyen T, Tresukosol D, Pham HM et al Percutaneous

coronary interventions for complex lesions and high-risk

pa-tients In: Nguyen T, Hu DY, Saito S et al., eds Management

of Complex Cardiovascular Problems Futura Publishing Co,

2000

4 Ryan TJ, Faxon DP, Gunnar RM et al Guidelines for

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diovascular procedures (subcommittee on PTCA) J Am Coll

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5 Ellis S, Guetta V, Miller D et al Relation between lesion

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Circulation 1999; 100 : 1971–6.

6 Holmes D, Berger P Complex and multivessel treatment

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7 Tan KH, Sulke N, Taub N et al Lesion morphological

determinants of coronary balloon angioplasty success and

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8 King III SB Complications of angioplasty In: King III SB,

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9 Reisman M, Cohen B, Warth D et al Outcome of long sions with high speed rotational atherectomy J Am Coll Car-

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10 Saucedo JF, Kennard ED, Popma JJ et al Importance of

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11 The SIRIUS Trial: Presented by M Leon at the eter Therapeutics meeting, Washington DC, 2002

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14 Colombo A, Stankovic G Cutting balloon angioplasty:

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Co-lombo’s Tips and Tricks in Interventional Cardiology Martin

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15 Vavuranakis M et al Stent deployment in calcifi ed

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16 Ellis S, Topol E Results of percutaneous transluminal

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18 Douglas JS Jr Percutaneous interventional approaches

to specifi c coronary lesions In: King III SB, Douglas JS, eds

Atlas of Heart Disease Mosby, 1997: 11.10.

19 Hadjimiltiades S, Gourassas J et al Effect of stent tion, relative to a coronary bend, on restenosis (abstract) Eur

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20 Kotani J, Mintz G, Pregowski J et al Does a thrombotic

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21 Singh M, Reeder G, Ohman M et al Does the presence of

thrombus seen on a coronary angiogram affect the outcome

after PCI ? An angiographic trial pool data experience J Am

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22 Douglas JS Jr Management of coronary lesion with

as-sociated thrombus In: Ellis S, Holmes Jr D, eds Strategic

Approaches in Coronary Interventions, 2nd edn Lippincott

24 Ischinger T Thrombectomy with the X-SIZER catheter system in the coronary circulation: Initial results from a multi-

center study J Invasive Cardiol 2001; 12 : 81–8.

25 Eggebrecht H, Baumgart D, Naber C et al Extraction

of Large Intracoronary Thrombus in AMI by percutaneous Fogarty Maneuver Intentional abuse of a novel interventional

device Cathet Cardiovasc Interv 2002; 55: 228–32.

26 Sawada Y, Nasaka H, Kimura T et al Initial and six-month

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28 Regar E, Serruys P, Bode C et al for the RAVEL Study

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*Basic; **Advanced; ***Rare, exotic, or investigational

From: Nguyen T, Hu D, Saito S, Grines C, Palacios I (eds), Practical

Handbook of Advanced Interventional Cardiology, 2nd edn © 2003

Futura, an imprint of Blackwell Publishing

Chapter 10

Chronic Total Occlusion

Kazuaki Mitsudo, Thach Nguyen,

Jui Sung Hung

**Selection of wire: (1) A blunt tip to grind

**Selection of wire: (2) A sharper tip to penetrate

**Selection of wire: (3) A strong shaft to increase ability

**Selection of wire: (4) Going through tight spaces by wearing a slippery coat

Trouble-shooting tips

**Shaping the tip

**Delicate handling of the wire

CAVEAT: How to navigate a wire

**Parallel wire method (seesaw wiring)

**Support catheters

**Options for crossing the CTO lesion

**Subintimal channel stenting

presence of bridging collaterals.1 A chronically occluded artery with good collateral supply has the functional signifi cance of 90% stenosis.2 Percutaneous interventions (PCI) of the CTO lesion present great challenges including low success rate, prolonged procedure time, large amount of contrast use, high re-occlusion rate, and costs In the past, the results of revascu-larization of CTO were disappointing.3 However, with improved wire design, advanced imaging techniques, and increased op-erator skills, the primary success has been as high as 90%.4The goal of intervention in CTO is to penetrate the total occlusion and place the wire in the true lumen of the distal vessel without causing intimal dissection Crossing a CTO segment consists of penetrating a proximal fi brous cap, then a long segment of heterogenous (atheromatous or old thrombotic) material, and fi nally a distal fi brous cap If the CTO evolves from acute occlusion, it contains large quantity

of thrombotic material, with the old fracture plaque forming the distal cap If it progresses from occlusion of a severe stenotic lesion, then a large amount of atheromatous plaque would

be present Shortly after PCI, silent reocclusion occurred in

a small percentage of patients due to suffi cient recruitment

of collaterals The use of glycoprotein 2b3a inhibitors did not improve the outcome The factors predicting procedural suc-cess are shown in Table 10-1.5

TECHNICAL TIPS

*Selection of guides: The choice of the guide is very

im-portant because, without adequate support, it is impossible

to push a wire or balloon through a CTO lesion Usually,

a left Judkins (short-tip, for easier deep intubation), left Amplatz, left extra-backup (left Voda, Boston Scientifi c, USA; EB, eXtra Back-up, Cordis USA; EBU, Extra Back-

Up, Metronic, USA; or GL, Geometric Left, Guidant USA) guides are chosen for cannulation of the LCX or LAD, and

a right Judkins, left Amplatz, Multipurpose or extra-backup guide for the RCA according to the size of the ostium and the orientation of the proximal segment of the vessel In

Table 10-1

Factors infl uencing the success of CTO interventions

1 Duration of occlusion (75% if <3 months, 37% if >3 months), worst if the duration is unknown

2 Presence of antegrade fl ow (76%), absence of antegrade

Chronic Total Occlusion 205

general, guides with side holes are not recommended cause of poor vessel opacifi cation and wastage of contrast However, if persistent wedging of the vessel cannot be avoided, a guide with side holes can provide limited ante-grade fl ow with ischemic relief

be-**Optimal angiograms: Adequate visualization of the

distal vessel beyond the CTO lesion is essential in mapping the direction where the wire should be pointed and also for confi rming its position in the distal true lumen If there is no visible distal fl ow from bridging collaterals or due to insuf-

fi cient ipsilateral collaterals, a contralateral angiogram can

be done to opacify the distal lumen through retrograde collaterals These proximal and distal angiograms will help

to direct a wire across the fi brous caps or a long occluded segment The wire position should be always confi rmed

by two projection angles When single-plane fl uoroscopy

is used, mistakes are often made regarding the wire route Therefore, biplane cine-angiography is more accurate than bi-directional angiography in single-plane because the wire position and direction can be better recognized and confi rmed at any time with use of less contrast

**Optimal projection angles: The best projection angles

differ according to the region of interest (ROI) The operator should explore the angles in which the stump can be seen most clearly, especially at the entry point In general, it is desirable for the two projection angles to be perpendicular

to the vessel axis of the ROI (Figure 10-1), and also dicular to each other (orthogonal projection) Because the summation of the blind area is smallest in the orthogonal projection (Figure 10-2), it will be easier to lead the wire tip

perpen-to the distal true lumen

**Entry point: If there is an angiographically tapered

oc-clusion, the tapering stump is the starting place to probe the occlusion It frequently contains small recanalized channels or neochannels (160–230 microns in diameter),6which are potential routes for wire crossing However, if the stump is eccentrically oriented, the chance of crossing the CTO is lower, while the risk of subintimal wire passage is higher When the stump cutoff is abrupt and fl at, and the entry point is not identifi ed by an angiogram, the center of the stump should be tried as entry point In this situation, the invisible dimple of the probable entry point is explored by using the tip of a conventional wire, not a sleek hydrophilic-coated tip If the artery is large enough and the entry point

is at a side rather at the end of a stump, intravascular sound (IVUS) can be used to identify the entry point (Figure 10-3) When there are extensive bridging collaterals (caput medusae), the chance of wire crossing is also lower The

ultra-Figure 10-1: Required projection angles Projections with

perpendicular angles to the occlusion site of the vessel or guidewire tip site of the occluded part are recommended Each ROI (region of interest) has its suitable projection angle ( ) The angle optimal for the central ROI is not always suit-able for the other ROI (X) For example, for viewing a proximal RCA site, the LAO/caudal or RAO/cranial is best For the mid-RCA site, it is the straight LAO or RAO view For the distal RCA site, the LAO/cranial or RAO/caudal projections are the most suitable

Figure 10-2: Orthogonal projections Because the

summa-tion of the blind area, not projected by each view, is smallest

in the orthogonal projections, it is very useful for leading the wire into the true lumen and to confi rm successful wire entry

in the true lumen

Chronic Total Occlusion 207

reason is that these intracoronary collaterals consist of dilated vasa vasorum, which are very fragile and easily perforated When there is a side branch near the stump, the natural tendency of any wire is to seek an easy escape that is a side branch and this would lower the chance of penetrating the long occluded lumen.5 However, in expe-rienced hands, when a super-stiff wire (e.g Conquest Pro wire, Asahi Intec Co, Seto, Japan) is used, the presence of

a side branch near the stump or of bridging collaterals may not be too relevant, and the success rate of crossing the CTO could reach 90%.3

to the stiff or hydrophilic-coated wires

**Drilling strategy: Initially, a 0.014" intermediate wire

is used to cross the lesion If it cannot cross the lesion, then

Figure 10-3: Identifying entry point using IVUS (A) Obscured

entry site of occluded LAD (B) IVUS use in fi nding LAD cluded site Upon identifying entry point, transducer (dot mark indicated by arrow) is left in place as a landmark This technique can be applied when the artery is large enough for

oc-an IVUS catheter oc-and the entry site is at a side (rather thoc-an

at the end stump) (C) Use of Conquest guidewire to explore the small dimple at the transducer area results in successful crossing of CTO lesion

a stiffer wire, i.e a High Torque Standard wire (ACS Santa Clara CA, USA) or a Jowire, Miracle 3.0, 4.5, 6.0 or 12.0 g wire (Asahi Intec Co, Seto, Japan), with the small tip curved to form an abrading tool can be used (Figure 10-4, upper panel)

A 180° back and forth rotation often causes the tip to grind through the lesion If the wire buckles, it should be retracted, reoriented, and then rotated rather than forced through the lesion Constant forward pressure on the wire is more suc-cessful than aggressive tapping against the occlusion (“jack-hammering”), which does not transmit additional force.7 Once the wire enters the distal lumen, its tip should show easy free movement and smooth retraction or advancement If there is

Figure 10-4: Typical tip shapes of the tapered-tip wire

(Conquest Pro™ or Cross It™) For penetrating entry point, its 1.5–2.0 mm tip is bent at a curve of about 15–30° (upper panel) For re-entering the true lumen from the subintima, an almost 90° angle bend is required (lower panel)

Chronic Total Occlusion 209

no free rotation and no smooth advancement or retraction, the wire may lie subintimally or in a small branch along the main vessel If the stiffer wires fail to cross the lesion, the next step

is to try steeper and stiffer wire, i.e a Conquest Pro wire (Asahi Intec Co, Seto, Japan) or a Cross It 400 wire (ACS Santa Clara

CA, USA)

**Penetrating strategy: The fi rst step is similar to the

drilling strategy by using an intermediate wire If it fails to cross the lesion, a stiffer wire such as the Conquest Pro wire (Asahi Intec, Seto Japan) or a Cross It 400 wire (ACS Santa Clara CA) with its 1.5–2.0 mm tip bent at a curve of about 15–30°

is used to penetrate rather than drill the lesion (Figure 10-4, lower panel) The rotating motion should be minimized (<90° back and forth) to maintain directional control At the outset,

if the lesion is not hard, a gentle pushing force with a light touch should be applied If the lesion is hard, the pushing force should be gradually increased If the direction is incor-rect, the wire tends to go into the subintimal space or perforate the vessel because of the strong penetrating force On the other hand, if the direction is correct, the chance of successful penetration of the fi brous cap is very high.8

feather-WIRES

As a wire attempts to go through a CTO lesion, the fi rst goal is to penetrate the hard proximal fi brous cap, so the wire has to be sharp and stiff Once it enters the long atheromatous

or thrombotic segment, then it should be sleek and fl exible to

be steered inside the occlusion with little friction resistance and without creating or seeking a subintimal pathway Once it

is near the distal lumen, the wire again needs to be sharp and stiff in order to cross the distal fi brous cap and re-enter the distal patent lumen

Engineering evaluation of wires: When evaluating a

wire for CTO lesion, there are two parts to look at: (1) a central shaft of stainless steel or Nitinol, and (2) a distal fl exible tip shaped as a spring coil made of platinum or tungsten Most wires have a strong shaft to push farther and a fl exible tip

to steer the wire to different directions upon subtle proximal torque movement by the operator The wires made of Nitinol are more kink-resistant while those of stainless steel are more susceptible to kinking The similarities and differences be-tween wires are highlighted in Table 10-2

TECHNICAL TIPS

**Selection of wire: (1) A blunt tip to grind: At the

be-ginning of a PCI for CTO lesion, the most commonly used wire is the BMW (balanced middle weight) wire (Guidant,

St Paul MN) It has a soft distal tip, a thin kink-resistant

distal core and a strong stainless steel proximal shaft This wire is good for the operator just to gain an initial feel of the CTO lesion If the BMW wire fails to cross the lesion, some operators suggest the Intermediate or the Standard wire (Guidant, St Paul MN) to be tried next All these three wires have almost the same long distal spring coil (i.e good for steering), except the distal core becomes thicker (i.e stron-ger) and not sharper (the core is untapered) In general, to

be successful in drilling, these standard wires need to have

a tip stiffer than 3 g This 3 g or x g number means that 3 or x

grams are necessary to bend the tip of the wire

**Selection of wire: (2) A sharper tip to penetrate: Once

the operator realizes that the three conventional wires are not able to cross the lesion, then he or she can choose a stiffer and sharper wire or a sleeker wire A wire can be made stiffer by having a longer and bigger central core (i.e stronger with shorter fl exible tip), almost to the end of the tip Then a wire with tapering distal segment (like an arrow, with

a very short fl exible tip) would become sharper These two physical factors (i.e increased stiffness and sharpness) would help the wire to penetrate any hard surface A good example can be found in the design of the four wires of the Cross-IT XT family, (Guidant, Minneapolis, MN) The core

of the shaft is extended to the distal tip, expanded longer, thicker, and becomes longest and thickest with the Cross-

IT XT 400 Then the fl exible tip has to become smaller (the shaft diameter is 0.014" while the tip is 0.010") and shorter

as it cannot be the weak end of a sharp and stiff dagger-like wire The shortest spring coil fl exible segment is for steer-ing A wire with tapering tip is effective in the penetrating strategies as well as drilling strategies The Conquest Pro (Asahi Intec, Seto, Japan) with a tip tapered from 0.014"

to 0.009" has an effective hydrophilic coating in the shaft, sparing the tip ball This design improves the wire move-

Table 10-2

Characteristics of wires

Wires Regular Aggressive

Long spring coil (increased

steerability)

Chronic Total Occlusion 211

ment without losing its effi cacy in catching a small dimple at the entry point of the occlusion with no stumps

**Selection of wire: (3) A strong shaft to increase pushability: In order to push a wire through a hard bar-

rier, the central core of the body could be extended as far

as possible next to the tip The best example is the Miracle wire (Asahi Intec, Seto, Japan), which has a high torque transmission because the body shaft and the spring coil

is a continuous core This core can therefore transmit the pushing force generated at the proximal end to increase its pushability to 3, 4.5, 6, or 12 grams This type of strong core

is effective in penetrating any hard surface (i.e increased pushability) and allows wire movement even it is operating

in a very tight space (i.e increased torqueability)

**Selection of wire: (4) Going through tight spaces by wearing a slippery coat: In order to navigate tight spaces,

many wires are coated with slippery material such as the Crosswire (Terumo, Japan),5 PT Graphics (Boston Scien-tifi c, USA), and Whisper (Guidant, USA) The main char-acteristic of these wires is that they have the lowest friction resistance against the vessel wall or lesions Its main role

is to help crossing the tiny 160–230 micron neo-channels

It does not help to drill or penetrate, because these wires have neither strong penetrating force nor drilling ability The matter can become worse because these wires do not have

a fl exible spring coil, so they are not steerable, particularly

in a tight long CTO segment Without the ability to change direction, when facing a hard surface, the slippery tip of these wires just seeks an easy escape, creating subintimal false lumen This is why these hydrophilic-coated wires should cross any lesion smoothly by themselves without being actively pushed against resistance Once crossing the distal fi brous cap into the distal true lumen, these wires should be exchanged for a regular angioplasty wire, to pre-vent inadvertent distal exit and perforation

TROUBLE-SHOOTING TIPS

**Shaping the tip: When trying to cross a hard surface or

navigating the tight space inside the totally occluded ment, the tip of any wire should have a secondary bend just 1

seg-or 2 mm from the tip (Figure 10-4, upper panel) The reason

is that the typical 4–5 mm primary commercial J tip will be straightened when a balloon is advanced near the tip for added support When the wire enters a long and totally oc-cluded segment, its primary long tip will be straightened and entrapped in the tight confi nement Without a tiny second-ary bend at the tip, the steerability of the wire will be lost

**Delicate handling of the wire: When advancing a wire

across a CTO lesion, buckling of the wire means that the wire tip is either in the wrong microchannel, or the tip is forced in a direction at an angle with the channel lumen Applying additional force, or using a balloon for additional support to prevent the wire from buckling, would then only increase the risk of subintimal tracking Handling of the wire

is based on steering, rather than pushing the tip through the occlusion This is a “trial and error” approach of carefully steering and redirecting the wire until a channel that con-nects the stump with the distal patent lumen is found While the alignment of the wire with the target lumen is continu-ously monitored, the risk of subintimal tracking and dissec-tion is signifi cantly reduced If the tip stiffness of the wire is not suffi cient to pierce the distal fi brotic cap, the wire tip will

be defl ected and again forced into a subintimal layer tinued maneuvering of the wire could then cause the wire to perforate the adventitia, resulting in a wire exit The current wire has to be changed to a wire with a stiffer tip

Con-CAVEAT: How to navigate a wire: Without adequate

visu-alization of the distal lumen, the operator will not be able to actively prevent the wire from choosing a subintimal path-way The often very resistant nature of the distal part of an occlusion sometimes requires an exchange of the wire for, again, a wire with increased tip stiffness However, it should

be stressed that as long as the wire has not yet crossed into the distal lumen, an exchange of wire should never be facilitated by using a balloon or probing catheter The rea-son is that a balloon catheter tip can damage the entry point (made with 160–230 micron diameter channels), thereby precluding additional attempts with different stiffer wires.9Also, if the wire has not yet crossed the occlusion because

of subintimal position, an exchange catheter will suffi ciently dissect the occluded segment as to preclude any additional guidewire attempts at recanalization In case of an unde-tected wire perforation, the introduction of an exchange catheter could alter a benign wire exit into a potentially life-threatening perforation of the coronary arterial wall, requiring pericardiocentesis Therefore, prior to advancing any device, either an antegrade or retrograde injection of contrast medium should angiographically confi rm the dis-tal, intraluminal position of the wire.9

**Parallel wire method (seesaw wiring): (Figure 10-5

A–H) When the wire tip goes into the subintimal space at the small branch or outside of the vessel, the second wire

is advanced leaving the fi rst wire in place (the parallel wire method) The fi rst wire has two roles One is to obstruct the incorrect pathway, and the other is to mark the route to the true lumen during wire manipulation With the existence

Chronic Total Occlusion 213

of this landmark, the operator can lead the wire tip more easily to the direction of the true lumen In the parallel wire technique, if the operator intends to use only one support catheter, the support catheter should be pulled back and re-inserted into the target vessel again with the second wire

If the operator uses two support catheters at a time, the procedure becomes simpler If it is diffi cult for the second wire to enter the true lumen, one can exchange the roles of two wires (Figure 10-6 A–D) Using the parallel wire method with two support catheters is called “Seesaw Wiring” The operator is able to move any of the two wires at any time This method introduces fl uid (blood) into the waterless oc-clusion site, triggering the hydrophilic mechanism (slippery when wet) and thus preventing the hydrophilic wires from sticking to each other

**Support catheters: When there is a need to increase

the stiffness of the tip of the wire, an over-the-wire balloon catheter (1.5-mm with surface coating) or a transport cath-eter (Excelsior, Boston Scientifi c, Boston or Transit, Cordis, USA) can be used The catheter tip is advanced just near the entry point to enhance wire support and its torque con-trol This type of catheter facilitates wire exchange, which

is frequently needed While a softer and smaller diameter tipped catheter is preferred, kink resistance is mandatory

to avoid diffi culty in wire exchange The balloon catheter can be advanced near the tip to increase the stiffness of the wire Sometimes, the balloon and the wire can be advanced

as a unit to increase the chance of crossing a hard surface.10Then, after removal of the wire, injection of contrast could

be performed after blood has been aspirated through the

Figure 10-5: CTO lesion with bridging collateral in proximal

RCA, shown in LAO (A) and LAO (B) views before intervention

with seesaw wiring technique (Figure 10-6) (Continued)

Figure 10-5: Parallel wire method or seesaw wiring (C) (LAO

view) and (D) (RAO view) show that the wire is deviated from the true lumen, a little rightwards in (C) and leftwards in (D) Leaving the fi rst wire in place as a landmark, a second wire is advanced and directed into the true lumen The second wire is viewed at the left and right of the fi rst wire, respectively in (E) (LAO view) and (F) (RAO view)

Chronic Total Occlusion 215

Figure 10-5: Parallel wire method or seesaw wiring

(contin-ued) (G) (LAO view) and (H) (RAO view) show post-stenting angiograms

Figure 10-6: Seesaw wiring (parallel wire method with two

support catheters) (A) When the fi rst wire fails to cross into the distal true lumen, the fi rst wire is left as a landmark, and the second wire is advanced into the occlusion site using the second support catheter (B) The second wire is successfully manipulated into the true lumen (C) Alternatively, the second wire fails to enter the true lumen (D) Use of two support cath-eters facilitates role-exchange of the two wires The fi rst wire now is successfully engaged into the true lumen

catheter to prevent bolus injection of air Contrast should be diluted 50% with saline to decrease its viscosity After the contrast injection, if there is non-opacifi cation of the distal vessel, presence of a dissection, or visualization of a side branch, it is useful to continue the contrast injection while carefully pulling back the support catheter This allows the operator to determine at which level of the occlusion the catheter entered a dissection or at which level the catheter deviated into a side branch.10

**Options for crossing the CTO lesion: Once there is

dif-fi culty in crossing a CTO (which happens frequently) there are different tactics to be used They are listed in Table 10-

3 One of the most aggressive (and dangerous) tactics is

to infl ate the balloon at the most distal position achievable, followed by powerful advancement of the wire while the bal-loon is infl ated.9 This maneuver does two things As the bal-loon is infl ated, the balloon catheter stays put so the guide can be held still by the operator without being pushed out by advancing the wire through the hard surface The balloon also centers the wire so the wire can be advanced harder with lesser (and not without) chance of wire exit Another variant of this aggressive maneuver is to advance a small balloon in a side branch proximal to the CTO lesion Infl ate the balloon to anchor (immobilize) the guide and advance the wire across the CTO lesion without backing out the guide.11

**Subintimal channel stenting: Passage of the wire before

re-entry into the distal lumen is frequently observed during wiring of the CTO lesion and may result in procedural failure when antegrade fl ow cannot be established Without the use

of scaffolding stents, a subintimal passage has little chance

of remaining patent, especially if the pathway is long If entry of the wire into the distal true lumen can be achieved,

re-it is possible to create a subintimal condure-it using coronary

Table 10-3

Technical options when there is diffi culty crossing a CTO

1 Deep-seating the guide

2 Advancing the balloon or transport catheter near the entry point

3 Using a stiffer wire

4 Using a steeper and stiffer wire

5 Using double wires and support catheters

6 Using larger guide for stronger backup

7 Infl ating a balloon at the most distal location achieved or

at a side branch proximal to the stump

Chronic Total Occlusion 217

stents that yield long-term vessel patency To achieve cess in a CTO lesion, the trick is to get the wire to recross from this dissection plane back into the true distal lumen.10

suc-COMPLICATIONS

Ischemic complications occur due to dissection, tion at the occlusion site, or distal thrombotic embolizations Closure of a small side branch is often clinically insignifi cant However, distal thrombotic embolization can cause acute ST-elevation MI by blocking the retrograde collateral fl ow from the opposite coronary system The attempt to cross a CTO lesion

perfora-or a re-entry from a subintimal space can require time and patience The procedure may have to be abandoned when the

fl uoroscopic time has lapsed too long (>30 minutes) or when too much contrast media has been used (>300 mL in a patient with normal renal function) A further attempt a few days to a few months later can be tried

**Perforation: Perforation in an occluded segment may

not cause any clinical problem unless it is unrecognized and enlarged by advancement or dilation of a balloon cath-eter In order to prevent any bleeding, the support catheter should not be advanced distal to the entry point prior to con-

fi rming wire entry into the distal true lumen Bleeding can be controlled by neutralizing heparin with protamine, with in-

fl ation of a balloon at low pressure in the proximal segment

to obstruct the antegrade fl ow After pericardial drainage and control of the vessel extravasation, the patient can be given heparin again and the procedure may be continued

coherent refl ectometry (OCR) to guide the wire through the occlusion This new technology is based on the variable ab-sorption and scattering of near-infrared light by substances such as plaque, blood, tissue, and thrombus Algorithms have

Table 10-4

Investigational devices for CTO

1 The IntraLuminal Safe-Cross™ Guidewire with optical herent refl ectometry (OCR) and radiofrequency ablation

co-2 The Frontrunner™ (LuMend)