12.1.1.1.1

Donor Vessel Injury During Retrograde Chronic Total Occlusion Percutaneous Coronary Intervention

See Online Cases 22 , 50 , 66 , 69 , and 97 .

Although, by definition, CTO signifies that the target vessel is occluded for greater than 3 months, CTO PCI can be complicated by occlusion of a collateral-donor vessel instrumented for contralateral angiography or for the retrograde approach ( Fig. 12.2 ). This is one of the most serious complications of CTO PCI and requires prompt identification and management, since it is frequently followed by extensive ischemia and hemodynamic decompensation. Unless this complication is rapidly and diligently treated with PCI or coronary artery bypass graft surgery (CABG), it may result in death, particularly when the donor vessel is the last remaining vessel (a common situation in patients with prior CABG).

Example of donor vessel dissection during retrograde chronic total occlusion (CTO) percutaneous coronary intervention (PCI).

PCI of a right coronary artery (RCA) CTO (A). After a failed antegrade crossing attempt, retrograde crossing was performed (B) and the retrograde guidewire was externalized (C). During RCA stenting over the externalized guidewire (D), the patient developed severe chest pain and hypotension due to proximal left anterior descending artery (LAD) dissection (D). The LAD was immediately stented (E) with restoration of antegrade flow and stabilization of the patient (F, G). After removal of the entrapped retrograde guidewire and stenting of the right coronary artery an excellent final angiographic result was achieved (H) (see Online Case 22 ).

Similar to planning of any PCI, a pretreatment plan should be in place in case donor vessel occlusion occurs. For example, when performing retrograde recanalization of the right coronary artery in a patient with left main disease, pre-PCI intravascular ultrasound (IVUS) of the left main coronary artery is important. Similarly, prophylactic hemodynamic support may increase procedural safety in patients with multivessel disease and low ejection fraction or those undergoing the retrograde approach through the last remaining vessel ( Section 12.1.2.1 ) (see Online Case 51 ). In contrast to conventional PCI, management of donor vessel occlusion may be complicated by the presence of hardware in the acutely occluded segment (microcatheters, externalized wires, etc.) that can hinder stenting as an emergency bailout solution .

Example of left internal mammary artery (LIMA) graft dissection.

Percutaneous coronary intervention of a right coronary artery chronic total occlusion (A) was attempted with dual injection via a catheter inserted in the LIMA graft (B). Engagement of the LIMA graft was challenging due to an acute take-off angle. A GuideLiner catheter was used to engage the LIMA, causing ostial LIMA dissection with decreased antegrade flow (C). LIMA flow was restored after stenting (D), enabling continuation of the procedure (E), with a final successful outcome (F) (see Online Case 50 ).

Causes

• 1.
  

  Catheter-induced vessel injury. This may occur with either diagnostic or guide catheters, especially during equipment withdrawal, which may cause the guide to deeply engage the vessel, or with forceful pulling of the snared retrograde guidewire.

  
  
• 2.
  

  Donor-vessel thrombosis can occur during long procedures requiring coronary artery intubation by microcatheters or guidewires, especially when the level of anticoagulation is suboptimal ( Section 3.5 ).

Prevention

• 1.
  

  Pay close attention to the position of diagnostic and guiding catheters (especially during equipment manipulations) and to the pressure waveform (dampening of the pressure waveform should be avoided and promptly corrected if it occurs). When dual injection is performed, the donor vessel catheter should be disengaged or removed as soon as it is not needed.

  
  
• 2.
  

  Never use a catheter with side holes to engage the CTO donor vessel, as it may mask suboptimal catheter position and flow compromise.

  
  
• 3.
  

  Maintain high activated clotting time (ACT) (the authors suggest >350 s during retrograde CTO PCI and >300 s during antegrade CTO PCI) to prevent donor vessel thrombosis ( Section 3.5 ). The ACT should be checked every 20–30 min, which is more easily accomplished by inserting a small venous sheath and delegating this task to a nurse, with a clear message that any drop in ACT below the prespecified safety level should be communicated and corrected with additional boluses of unfractionated heparin.

  
  
• 4.
  

  Avoid the retrograde approach through diffusely diseased donor vessels. Consider intracoronary imaging to investigate the anatomy of the donor vessel in advance. If the donor artery requires PCI, it should be performed before CTO PCI.

  
  
• 5.
  

  Keep the retrograde guidewire encased by a microcatheter or over-the-wire balloon during all manipulations.

  
  
• 6.
  

  Consider inserting a workhorse “safety“ guidewire into the donor vessel, both to stabilize the guide catheter, but also to allow rapid treatment of the donor vessel in case of acute donor vessel occlusion.

  
  
• 7.
  

  Guidewire externalization leads to the creation of a wire loop with outstanding support for PCI devices, at the expense of communicating to the contralateral guiding catheter any traction during PCI, causing deep guide engagement and possibly vessel damage. During externalization meticulous attention should be paid to the contralateral catheter at all times.

  
  
• 8.
  

  Flush regularly all guiding and diagnostic catheters to prevent in-catheter thrombosis. Back-bleed the guide catheter after performing balloon trapping to minimize the risk of air embolization.

  
  
• 9.
  

  Avoid use of the left internal mammary artery (LIMA) graft for retrograde CTO PCI because LIMA dissection can occur ( Fig. 12.3 ; see Online Case 50 ) and/or LIMA wiring may cause acute closure or severe ischemia if the LIMA tortuosity is straightened by the guidewire.

  
  
• 10.
  

  Convert the retrograde system to a fully antegrade system either by using the kissing microcatheter technique, or by using the tip-in technique; that is, advancing an antegrade microcatheter over the retrograde wire into the distal vessel and then exchanging the retrograde wire for an antegrade workhorse guidewire (Step 8 in Chapter 6 ).

Treatment

• 1.
  

  Successful treatment of abrupt occlusion of the collateral donor artery becomes the highest priority of PCI. Treatment of the CTO, in most cases, should be aborted.

  
  
• 2.
  

  In anticipation of hemodynamic collapse, notify medical staff to prepare a hemodynamic support device, such as intraaortic balloon pump or an Impella, ensure femoral artery access (in radial procedures), and prepare drugs, while you concentrate in solving the abrupt occlusion.

  
  
• 3.
  

  Stenting is usually required to treat donor vessel dissections, as it is the fastest way to prevent its extension. If this complication occurs in the context of retrograde CTO PCI, the operator faces the problem of hardware in the donor vessel. Treatment options include:

  
  
  
  
  • A.
    

    Withdrawing the retrograde wire, leaving the retrograde microcatheter beyond the acute occlusion, and exchanging for a regular PCI wire for stenting, avoiding the advancement of a new wire through a dissected segment.

    
    
  • B.
    

    Using the externalized retrograde wire as a platform for stenting the acutely occluded donor vessel (provided it is anatomically feasible, for example in a short, limited dissection).

    
    
  • C.
    

    Performing PCI with a second wire, potentially jailing the externalized retrograde wire with the stent ( Fig. 12.2 ).

  
  
  
  

  Options B and C are more likely to be followed if CTO PCI is virtually completed (pending only CTO stenting, for example), while option A is probably the best choice if the CTO has not yet been crossed. Option C requires great caution during withdrawal of the jailed retrograde wire through the collateral channels (it may require protection with an antegrade microcatheter). An overall assessment of the patient’s safety is mandatory at the time of deciding the best possible choice (e.g., contralateral femoral artery access may be required for intraaortic balloon pump insertion, making option A the preferred option).

  
  
• 4.
  

  Aspiration of thrombus and administration of glycoprotein IIb/IIIa inhibitors may be needed for donor vessel thrombosis. The ACT should be checked, as thrombosis may occur in other locations of the instrumented collateral donor vessel or the CTO target vessel.

12.1.1.1.2

Aortocoronary Dissection

See Online Case 10 .

Aortocoronary dissection is a rare complication that can occur with any PCI, but is more common with CTO PCI (especially retrograde procedures) (frequency was 0.8%–1.8% in two contemporary series ), and most commonly occurs in the right coronary artery ( Figs. 12.4 and 12.5 ). Dissection may be limited to the coronary sinus, but may extend to the proximal ascending aorta or even beyond the ascending aorta .

Illustration of an aortocoronary dissection during retrograde chronic total occlusion (CTO) intervention.

Retrograde CTO intervention was performed to recanalize a proximal right coronary artery CTO ( arrow , A), using the reverse controlled antegrade and retrograde tracking and dissection technique (B). Staining of the aortocoronary junction was observed with test injections during stent placement (C), which expanded when cine angiography was performed (D). Stenting of the right coronary artery ostium was performed ( arrow , E) without further antegrade contrast injections. The patient had an uneventful recovery. This case illustrates the importance of stopping antegrade contrast injections and stenting the vessel ostium if aortocoronary dissection occurs, to seal the dissection flap at the entry point of the dissection.

Courtesy of Dr. Parag Doshi.

Examples of aortocoronary dissection.

(A) Anteroposterior cranial view showing class 2 aortocoronary dissection caused by a retrograde approach of proximal chronic total occlusion (CTO) lesion of the right coronary artery (RCA). Guide catheter: left Amplatz 1 (Cordis, Miami, FL). Presumed mechanism: contrast injection with a wedged catheter. (B) Left anterior oblique view showing class 1 (limited to right sinus of Valsalva) aortocoronary dissection caused by an antegrade approach of the ostial CTO lesion of the RCA. Guide catheter: Judkins right 4 (Cordis). Presumed mechanism: catheter trauma. (C) Anteroposterior view showing class 2 aortocoronary dissection with a parietal hematoma ( arrow ) caused by a retrograde approach of the proximal CTO lesion of the RCA. Guide catheter: right Amplatz 1. Presumed mechanism: catheter trauma.

Reproduced with permission from Boukhris M, Tomasello SD, Marza F, Azzarelli S, Galassi AR. Iatrogenic aortic dissection complicating percutaneous coronary intervention for chronic total occlusion. Can J Cardiol 2015; 31 :320–7, Elsevier.

Prevention

• 1.
  

  Consider using anchor techniques ( Section 3.6.5 ) as an alternative to aggressive guiding catheter intubation to enhance guide catheter support.

  
  
• 2.
  

  Use of guide catheters with side holes ( Chapter 2, Section 2.3.3 ) in occluded right coronary arteries significantly decreases the risk of barotrauma. However, side-hole guide catheters may provide a false sense of security, as the pressure waveform may appear normal but aortocoronary dissection can still occur.

  
  
• 3.
  

  Power injectors should also be avoided or used with caution after the proximal segment of the CTO vessel has been dilated; manual injections are preferred.

Causes ( Fig. 12.5 )

• 1.
  

  Deep coronary engagement and utilization of aggressive guide catheters, such as 8 Fr Amplatz catheters.

  
  
• 2.
  

  Guide pressure dampening.

  
  
• 3.
  

  Forceful contrast injection, especially through wedged guide catheters with dampened pressure waveform.

  
  
• 4.
  

  Predilation of the coronary ostium.

  
  
• 5.
  

  Balloon rupture.

  
  
• 6.
  

  Retrograde wire advancement into the subintimal and subaortic space during retrograde crossing attempts.

Treatment

• 1.
  

  Stop injecting contrast into the coronary artery (as injections can expand the dissection plane).

  
  
• 2.
  

  Stent the ostium of the dissected coronary artery with a stent that can expand to a diameter that will seal the dissection. The stent should be protruding 1 mm into the aorta) to cover the ostium of the dissected vessel.

  
  
• 3.
  

  Use intravascular ultrasonography to guide stent placement and ensure complete ostial coverage.

  
  
• 4.
  

  If contrast injection is considered absolutely essential to check the status of the distal vessel, it is best performed through an aspiration catheter advanced to the distal part of the vessel ( Fig. 12.6 ).

  
  
• 5.
  

  If the aortocoronary dissection is large, perform serial noninvasive imaging (with computed tomography or transesophageal echocardiography) to ensure that the dissection has stabilized and resolved ( Fig. 12.7 ). This is of particular importance if the dissection involves the ascending aorta.

  
  
• 6.
  

  Emergency surgery is rarely needed except in patients who develop aortic regurgitation, tamponade due to rupture into the pericardium, or extension of the dissection ( Fig. 12.8 ).

12.1.1.1.3

Side-Branch Occlusion

Side-branch occlusion can occur during CTO PCI, especially when subintimal dissection/reentry strategies are used, and is associated with higher frequency of post-PCI myocardial infarction ( Fig. 12.9 ; Online Cases 100 and 102 ).

Use of an aspiration catheter for imaging a vessel distal to an aortocoronary dissection.

Coronary angiography demonstrating a proximal right coronary artery (RCA) chronic total occlusion (A), with the distal vessel filling via septal collaterals (B, C). Retrograde guidewire crossing was successful via a septal collateral (D) followed by use of the reverse controlled antegrade and retrograde tracking and dissection technique (E) and wire externalization (F). After stenting, aortocoronary dissection became evident (G). A 7 Fr thrombectomy catheter was inserted into the distal RCA and contrast injection confirmed adequate distal angiographic result without propagating the aortocoronary dissection (H).

Reproduced with permission from Al Salti Al Krad H, Kaminsky B, Brilakis ES. Use of a thrombectomy catheter for contrast injection: a novel technique for preventing extension of an aortocoronary dissection during the retrograde approach to a chronic total occlusion. J Invasive Cardiol 2014; 26 :E54–5.

Computed tomography (CT) follow-up of the aortocoronary dissection shown in (A) of Fig. 12.5 .

(A) Twenty-four hours after the procedure, CT angiogram examination showing dislocation of intimal calcification with an eccentric double lumen. (B) One-month CT control examination demonstrating almost total resolution of the dissected thrombosed lumen. (C) Six-month CT control examination demonstrating total resolution of the dissection.

Reproduced with permission from Boukhris M, Tomasello SD, Marza F, Azzarelli S, Galassi AR. Iatrogenic aortic dissection complicating percutaneous coronary intervention for chronic total occlusion. Can J Cardiol 2015; 31 :320–7, Elsevier.

Example of aortocoronary dissection extending into the descending aorta after chronic total occlusion intervention.

Angiography demonstrating proximal long segment dissection of the right coronary artery, extending to the sinus of Valsalva (A, B). After stenting with a 3.5 × 24 mm bare metal stent, the final angiogram revealed limited dissection to the sinus of Valsalva (B). Computed tomography imaging demonstrated a type A aortic dissection extending from the ascending aorta to the suprarenal abdominal level (C, D) with involvement of the aortic arch and celiac trunk (E).

Reproduced with permission from Liao MT, Liu SC, Lee JK, Chiang FT, Wu CK. Aortocoronary dissection with extension to the suprarenal abdominal aorta: a rare complication after percutaneous coronary intervention. JACC Cardiovasc Interv 2012; 5 :1292–3.

Acute side branch occlusion during a retrograde chronic total occlusion (CTO) intervention.

CTO of the mid-right coronary artery that filled by a diffusely diseased saphenous vein graft (A). A large acute marginal branch originated at the distal CTO cap ( arrow , A; arrows , B). Successful retrograde recanalization was achieved using a retrograde true lumen puncture technique (C). Stent placement restored antegrade flow to the distal right coronary artery but the acute marginal branch became occluded leading to inferolateral ST-segment elevation and postprocedural acute myocardial infarction.

Reproduced with permission from Michael TT, Papayannis AC, Banerjee S, Brilakis ES. Subintimal dissection/reentry strategies in coronary chronic total occlusion interventions. Circ Cardiovasc Interv 2012; 5 :729–38.

Causes

• 1.
  

  Use of dissection/reentry strategies in vessels with side branches at the proximal or distal CTO cap.

Prevention

• 1.
  

  When treating CTOs that involve a bifurcation (e.g., those involving the right coronary artery crux) ( Chapter 9, Section 9.5 and 9.6 ), a careful analysis of collateral support should be performed before the procedure to determine whether both branches have independent collateral support.

  
  
• 2.
  

  Avoid use of (antegrade or retrograde) dissection/reentry strategies when a bifurcation is present at the proximal or distal CTO cap.

  
  
• 3.
  

  Whenever possible, perform side-branch protection with a second guidewire.

Treatment

• 1.
  

  Antegrade wiring of the occluded branch (which may be challenging if dissection/reentry strategies were used for crossing).

  
  
• 2.
  

  Retrograde recanalization of the occluded branch (if collaterals to that branch exist).

  
  
• 3.
  

  Use of IVUS may facilitate the identification of the cause of side branch occlusion (for example, the presence of a subintimal track at the level of the side branch ostium) and rewiring ( Fig. 12.10 ).

If a dissection/reentry strategy is used it is important to minimize the extent of the subintimal dissection by reentering into the true lumen at the most proximal location possible, usually using the Stingray system, as described in Chapter 5 . Moreover, using the CrossBoss catheter may minimize the extent of subintimal dissection and facilitate reentry attempts. The presence of a coronary bifurcation at the distal CTO cap may favor use of a primary retrograde approach to minimize the risk for side-branch occlusion during antegrade crossing attempts.

Use of intravascular ultrasonography to facilitate side branch occlusion assessment and treatment.

Antegrade percutaneous coronary intervention was planned in a first attempt to recanalize a long chronic total occlusion (CTO) located in the mid-segment of the right coronary artery (RCA) ( asterisks , A). Adequate progress was made using a parallel wire technique with a polymer-jacketed guidewire and a blunt-tip coil wire down to the posterolateral branch (B). However, antegrade injections after predilation with a 1.5 mm balloon revealed occlusion of the posterior descending artery ( asterisks , C). Intravascular ultrasound (IVUS) of the mid-RCA and crux (E, F) revealed subadventitial course of the wire located in the posterolateral artery with compression of the vessel structures at the level of the RCA crux ( stars in IVUS shown in E).

IVUS-guided reentry to the posterior descending artery (PDA) with a new wire (W2) was performed (IVUS shadows of both guidewires are shown in G). This allowed successful advancement of W2 into the PDA (H) with a good result using a provisional stenting technique.

Courtesy of Dr. Javier Escaned.

12.1.1.1.4

Collateral Occlusion

Occlusion of a single large collateral (usually epicardial) vessel may cause severe ischemia and hemodynamic instability; therefore, there should be a high threshold for performing retrograde CTO PCI through such collaterals. Moreover, successful CTO recanalization causes rapid derecruitment of the collateral circulation, that may cause severe ischemia, if the vessel reoccludes.

12.1.1.1.5

Subintimal Stenting

See Online Case 73 .

Occasionally, subintimal distal position of the guidewire may not be appreciated and stents may be inadvertently deployed within the subintimal space, obstructing the outflow of the vessel ( Fig. 12.11 ). After this occurs, the patient may remain asymptomatic or may develop ST-segment elevation due to side-branch loss.

Example of distal vessel dissection due to subintimal stenting.

Coronary angiography demonstrating a chronic total occlusion of the mid-right coronary artery (RCA) ( arrows , A). The distal RCA and the right posterior descending artery ( arrowheads , A) were filling via collaterals from the left anterior descending artery. The RCA was crossed antegradely with a Pilot 200 wire, however no other catheter, such as the Tornus catheter ( arrow , B) could cross the occlusion. The RCA occlusion was crossed with a second Pilot 200 wire ( arrows , C). Although contralateral injection suggested intraluminal distal wire position ( arrow , D), after stenting antegrade flow in the acute marginal branch, right posterior descending artery and right posterolateral branch ( arrows , E) ceased. After rewiring and balloon angioplasty of the acute marginal branch, right posterior descending artery and right posterolateral branch ( arrows , F), antegrade coronary flow was restored in all three vessels (see Online Case 73 ).

Reproduced from Patel VG, Banerjee S, Brilakis ES. Treatment of inadvertent subintimal stenting during intervention of a coronary chronic total occlusion. Interv Cardiol 2013; 5 (2):165–9 with permission of Future Medicine Ltd.

Causes

• 1.
  

  Misjudgment of the guidewire position before stent implantation (i.e., impression that the wire is located in the distal true lumen) when in reality it is located in the subintimal space.

Prevention

The first step in preventing this complication is to have a high threshold of suspicion. For example, apparent intraluminal position distal to the CTO when using a wire knuckle or very aggressive guidewires (≥12 gr tapered-tip wires, for example) should always raise the concern that the wire might actually be in the subintimal space close to the lumen, and be followed by an adequate check before proceeding to balloon dilation and stenting.

To confirm that the wire has entered the distal true lumen before balloon dilation and stenting the following methods can be used (see also Chapter 4 , Step 6) :

• 1.
  

  Contralateral injection. This is the most commonly used method and is crucial for nearly all CTO procedures, even when most collaterals are ipsilateral, because ipsilateral collaterals may become compromised during crossing attempts. After CTO crossing it is recommended to check intraluminal position of the guidewire in two orthogonal angiographic projections.

  
  
• 2.
  

  Contrast injection through a microcatheter. Routine use of this maneuver is discouraged, since antegrade contrast injection through a microcatheter always entails the risk of subintimal space staining and dissection propagation if the wire is not in the distal true lumen, which can then hinder subsequent reentry attempts. In selected cases, controlled microcatheter tip injections can be performed with care to verify intraluminal location, always checking for the back-bleeding sign (blood coming out of the microcatheter after waiting for at least 30 s from withdrawal of the guidewire).

  
  
• 3.
  

  Intravascular imaging. IVUS, particularly with a short-tip IVUS probe ( Section 2.9 ) that is less likely to extend the suspected dissection, can be of great help in detecting subintimal guidewire position ( Fig. 12.12 ). Optical coherence tomography (OCT) has been reported as an alternative, but is hampered by the limited penetration of OCT imaging, the distance of the OCT lens from the catheter tip, and the need to perform contrast or dextran injections that may propagate a subintimal dissection.

  
  
• 4.
  

  Observing the wire movement into distal branches. This is suggestive of true lumen position, but may also be misleading as the wire can also advance subintimally into side branches. Exchanging for a workhorse guidewire can facilitate the process, as the latter is less likely to advance into side branches.

Use of intravascular ultrasound (IVUS) to achieve and confirm successful reentry into the distal true lumen.

(A) Right coronary artery chronic total occlusion. (B) An antegrade knuckled guidewire is advanced past the distal cap. (C) Using the Stingray balloon a guidewire is advanced into the distal right coronary artery ( arrow ), however it is not 100% clear that it is located within the distal true lumen. (D, E) IVUS demonstrates that the guidewire is into the false lumen, not the distal true lumen. (F) Reentry is attempted again using the Stingray system. (G) A second guidewire is advanced distally and appears to be in a different location than the first guidewire. (H) IVUS confirms that the second guidewire is within the distal true lumen, whereas the first guidewire remains within the false lumen. (I) Final result after stenting (see Online Case 35 ).

Treatment

If subintimal guidewire position is confirmed, reentering the distal true lumen can be achieved using several strategies :

• 1.
  

  Stingray system.

  
  
• 2.
  

  Retrograde crossing of the target vessel.

  
  
• 3.
  

  Wire-based techniques, such as wire redirection, the subintimal tracking and reentry (STAR) technique or the limited antegrade subintimal tracking (LAST) and mini-STAR techniques, in which the area of subintimal dissection is limited by reentering the true lumen as close as possible to the distal cap without propagating the dissection into the distal part of the vessel, as described in Chapter 5 . However, wire-based reentry is discouraged due to unpredictability and potential for enlarging the dissection: use of the Stingray system or the retrograde approach are preferred instead.

  
  
• 4.
  

  IVUS guided reentry, following a similar technique as shown in Fig. 12.10 .

These same techniques can also be employed to reenter the true lumen in cases of acute vessel closure due to dissection during non-CTO PCI ( Figs. 12.13 and 12.14 ; Online Case 92 ).

Use of the retrograde approach to treat acute vessel closure.

(A) Severe lesion of the second obtuse marginal branch ( arrow ). (B) Subintimal guidewire crossing ( arrow ). (C) Acute vessel closure ( arrow ). (D) Successful retrograde crossing into the second obtuse marginal branch via an epicardial collateral from the distal left anterior descending artery ( arrows ). (E) After reverse controlled antegrade and retrograde tracking and dissection was performed the retrograde guidewire and the Corsair catheter was inserted into a second guide catheter ( arrow ), using the ping-pong guide catheter technique. (F) Successful recanalization of the second obtuse marginal branch after stenting (see Online Case 38 ).

Use of antegrade dissection/reentry to treat acute vessel closure.

Coronary angiography demonstrating a tortuous right coronary artery with a proximal ( arrow , A) and a mid-lesion ( multiple arrows , A). Mid-right coronary artery dissection after balloon predilation ( arrow , B). Guidewire position and antegrade flow were lost after an unsuccessful attempt for stent delivery. After failure to advance a guidewire through the dissected segment, a knuckle was formed with a Pilot 200 guidewire (Abbott Vascular) ( arrow , C) and advanced around the dissected segment. Using a Stingray balloon ( arrows , D) and guidewire distal true lumen reentry was achieved (D). Using a GuideLiner catheter ( arrow , F) two stents were successfully delivered with an excellent final angiographic result (G).

Reproduced with permission from Martinez-Rumayor AA, Banerjee S, Brilakis ES. Knuckle wire and stingray balloon for recrossing a coronary dissection after loss of guidewire position. JACC Cardiovasc Interv 2012; 5 :e31–2.

12.1.1.1.6

Distal Vessel Dissection

Similar to inadvertent subintimal stenting described earlier, occasionally distal vessel dissection may occur, hindering further attempts to reenter into the distal true lumen.

Causes

• 1.
  

  Subintimal wire crossing with failed reentry attempts, often causing subintimal hematoma that compresses the distal true lumen.

  
  
• 2.
  

  Use of stiff and/or tapered-tip guidewires that may dissect the distal vessel.

Prevention

• 1.
  

  Avoid use of large loops during subintimal dissection techniques. It is best to perform the distal part of dissection with the CrossBoss catheter to minimize the extent of subintimal dissection.

  
  
• 2.
  

  Avoid antegrade contrast injections if the wire enters the subintimal space.

  
  
• 3.
  

  Prevent excessive movement of stiff and/or tapered-tip guidewires, for example by using the trapping technique for equipment exchanges.

Treatment

• 1.
  

  Use the subintimal transcatheter withdrawal (STRAW) technique (as described in Chapter 5, Figs. 5.38 and 5.39 ) to aspirate the subintimal hematoma and reexpand the distal true lumen.

  
  
• 2.
  

  Use retrograde crossing into the distal true lumen.

  
  
• 3.
  

  Perform balloon angioplasty in the subintimal space and stop the procedure (investment procedure). Coronary angiography can be repeated after 2–3 months to allow for healing of the dissection. Occasionally, flow into the distal true lumen is restored at follow-up angiography, especially when good antegrade flow is achieved during the index procedure.

12.1.1.1.7

Embolization

Embolization, if severe, can cause profound hemodynamic compromise and requires prompt treatment.

Causes

• 1.
  

  Air. Air embolization is more likely to occur when the trapping technique is used without back-bleeding the guide catheter afterwards.

  
  
• 2.
  

  Aortic or iliac plaque, when the guide catheter is not thoroughly cleared after advancing through the aorta.

  
  
• 3.
  

  Thrombus, especially during prolonged cases if the ACT becomes low.

  
  
• 4.
  

  Coronary plaque, although this is more common when treating lesions causing acute coronary syndromes rather than CTOs.

Prevention

• 1.
  

  Always back-bleed the guide catheter after performing the trapping technique.

  
  
• 2.
  

  Always back-bleed the guide catheter after insertion, before injecting the coronary arteries.

  
  
• 3.
  

  Maintain high enough ACT throughout the case (>300 s for antegrade cases and >350 s for retrograde cases— Section 3.5 ).

Treatment

• 1.
  

  Air embolization. Administer 100% oxygen (helps with resorption of the air), aspirate (if large amount has been given); may require intracoronary epinephrine if the patient develops cardiac arrest. Hemodynamic deterioration can be very rapid, requiring rapid intervention.

  
  
• 2.
  

  Thrombus or plaque embolization. Aspiration either through an aspiration catheter (such as the Export; see Online Case 19 ), through deep guide catheter engagement, or through a guide catheter extension. If unable to aspirate, laser or rheolytic thrombectomy may be useful.

12.1.1.2.1

Perforation Classification

Coronary perforations are best classified according to location, as location has important implications regarding management. There are three main perforation locations: (1) main vessel perforation, (2) distal artery perforation, and (3) collateral vessel perforation, in either a septal or an epicardial collateral ( Figs. 12.15 and 12.16 ).

Types of coronary perforation.

Examples of the different types of coronary perforation.

The severity of coronary perforations has traditionally been graded using the Ellis classification :

• •
  

  Class 1: A crater extending outside the lumen only in the absence of linear staining angiographically suggestive of dissection.

  
  
• •
  

  Class 2: Pericardial or myocardial blush without a ≥1 mm exit hole.

  
  
• •
  

  Class 3: Frank streaming of contrast through a ≥1 mm exit hole.

  
  
• •
  

  Class 3–cavity spilling: Perforation into an anatomic cavity chamber, such as the coronary sinus, or the right ventricle.

This classification has to be adapted to various scenarios discussed next, which were not contemplated at the time the Ellis classification was developed (i.e., perforation of epicardial and septal collateral channels).

Prevention

• 1.
  

  Balloon advancement or dilation and microcatheter advancement should not be performed when the guidewire is not confirmed to be within the vessel architecture.

  
  
• 2.
  

  In some CTOs negative vessel remodeling may occur, potentially leading to vessel rupture during dilation if the balloon is sized according to proximal vessel dimensions (i.e., oversized for the CTO segment). IVUS imaging can be of great help in clarifying the vessel size distal to the CTO.

  
  
• 3.
  

  Whenever a large balloon is required in CART and reverse CART procedures to facilitate guidewire passage, use of IVUS can facilitate safe balloon size selection (75% of media to media vessel diameter).

  
  
• 4.
  

  During over-the-wire device exchanges, uncontrolled advancement of a hydrophilic or polymer-jacketed wire to a distal small branch may cause distal vessel perforation. Use of balloon trapping (first choice) or wire extensions (second choice) are preferred whereas Nanto’s maneuver (saline injection through the microcatheter—hydraulic exchange; Section 3.7.2 ) should be avoided.

  
  
• 5.
  

  Outlining the anatomy of a collateral channel before and during its crossing, either with bilateral angiography or selective tip injections with the microcatheter, can help prevent guidewire exit and channel perforation.

  
  
• 6.
  

  Double-coil tip wires ( Section 2.5.4 and 2.5.5 ) have excellent torque control and a blunt tip that, compared with polymer-jacketed guidewires, is less likely to cause collateral channel perforation. Hence double-coil tip wires should be considered the first choice for collateral crossing.

  
  
• 7.
  

  In general, perforation of an epicardial collateral channel is more difficult to control than a septal one, and this fact should be taken into consideration when choosing the most adequate interventional collateral channel.

  
  
• 8.
  

  Unfractionated heparin is preferred for anticoagulation, as it can be reversed in case of perforation, in contrast to bivalirudin.

  
  
• 9.
  

  A glycoprotein IIb/IIIa inhibitor should not be administered during CTO PCI, even after successful crossing and stenting, as it may cause an unrecognized perforation to bleed.

12.1.1.2.2

General Treatment of Perforations ( Fig. 12.17 )

Treatments specific to the perforation are described in the following section. General measures that can decrease the risk of continued bleeding into the pericardium include the following :

• 1.
  

  Balloon inflation proximal to the perforation to stop the bleeding. This should be performed immediately to prevent accelerated accumulation of blood in the pericardial space and tamponade. Since a second arterial access is usually available in CTO PCI for contralateral injections, in many cases this can be used to introduce a second guide catheter with specific hardware to treat the perforation if needed although a single large guide catheter may suffice in many cases as shown in Fig. 12.18 ). The balloon should be the same size as the vessel and must be semicompliant and inflated to no more than 8–10 atm to ensure occlusion of antegrade flow, while avoiding stretching of the vessel. Hemostasis at the site of perforation can be maintained with an inflated balloon through the first guide catheter.

  
  
• 2.
  

  Administration of intravenous fluids and pressors , and possibly atropine, if the patient develops bradycardia due to a vagal reaction.

  
  
• 3.
  

  Appropriate timing for performing pericardiocentesis . Hemodynamic instability requires immediate pericardiocentesis, yet smaller size pericardial effusions may be best managed conservatively, as the elevated pericardial pressure due to the entrance of blood into the pericardial space may help tamponade the perforation site and decrease the risk for further bleeding. Pericardiocentesis can frequently be performed using X-ray guidance due to contrast exit into the pericardial space. Echocardiography remains important for assessing the size of pericardial effusion and the result of pericardiocentesis, and for determining whether pericardial bleeding continues. Use of an echocardiographic contrast agent can be useful for detecting ongoing bleeding into the pericardial space.

  
  
• 4.
  

  Cardiac surgery notification . Notifying cardiac surgery early may facilitate subsequent treatment, if pericardial bleeding continues in spite of percutaneous management attempts.

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