Coronary perforations represent one of the most dreaded complications of any interventional operator. Because of the potential sub-intimal position of wires and equipment with CTOs, routine use of stiff and polymer-jacketed guidewires, and frequent uncertainty regarding the vessel course there is an increased risk of perforation compared with non-CTO PCI where the incidence is approximately 0.2 % [9]. The estimated incidence of coronary perforation for CTO PCI is 2.9 % (95 % confidence interval [CI] 2.3–3.6 %), however observed rates are as high as 11.9 % in the literature [2]. The most feared complication of perforation is tamponade requiring emergent pericardiocentesis or cardiac surgery. In a large meta-analysis of over 18,000 patients who had undergone CTO PCI, approximately 10 % of patient with coronary perforations developed tamponade (pooled incidence rate = 0.3 %, 95 % CI 0.2–0.5 %) [2]. Therefore, while the incidence of perforation is higher than in non-CTO PCI, the majority of perforations are self-limited and can be managed without progression to tamponade.

Not surprisingly, the rate of coronary perforation and tamponade is higher in unsuccessful PCI attempts compared with successful recanalization (perforation = 10.7 % vs. 2.1 %, p < 0.0001; tamponade = 1.7 % vs. 0 %, p < 0.0001) [2]. Further, the risk of coronary perforation is higher using a retrograde approach compared with antegrade (4.7 % vs. 2.1 %, p = 0.04) however the rates of tamponade are similar [7].

Perforations are classified according to the Ellis Criteria (Table 15.2). While this is a simplistic view of perforations in general, it helps to stratify patients according to risk for development of complications such as tamponade and provides a rough framework in order to guide further intervention. Further, perforations can be classified according to vessel location. This is important as the mechanisms and subsequent management greatly differs and range from conservative therapy for septal perforations to percutaneous intervention with coils or covered stents and even emergent surgery for epicardial or main vessel perforations. In general, the three main coronary vessel locations for perforations are: (1) main target vessel (i.e. at or near the CTO); (2) distal target vessel; and (3) donor collateral vessel, either epicardial or septal.

Main target vessel coronary perforation can occur with either antegrade or retrograde percutaneous approaches. Guidewire perforations alone via wire escalation or dissection and reentry techniques are typically self-limited and rarely lead to a hemorrhagic pericardial effusion and/or cardiac tamponade. However, if a balloon or device (e.g. stent or microcatheter) is advanced outside of the coronary architecture after guidewire perforation then the risk for hemorrhagic pericardial effusion and cardiac tamponade increases due to manual expansion of the coronary perforation. Inadvertent antegrade injection can also lead to hydraulic expansion of the guidewire perforation, leading to an uncontrolled perforation. It is also important to recognize that over-sized balloons or stents can also lead to main target vessel coronary perforation. As many target vessels undergo negative remodeling due to chronic under-filling it can be difficult to adequately size balloons/stents appropriately, in which case use of intravascular ultrasound can be helpful.

Following identification of a main target vessel perforation of any type, the initial step in management is to position an appropriately sized balloon proximal to the area of contrast extravasation in order to occlude the perforation with balloon inflation. This can also be performed with the stent delivery balloon in the case of a post stent perforation. Prolonged balloon inflations may be required to achieve hemostasis. If bleeding persists despite balloon occlusion, then a covered stent (e.g. JOSTENT Graftmaster, Abbott Vascular, Santa Clara, CA; Symbiort stent, Boston Scientific Corp., Natick, MA; Over and Under stent, IGTI Medical, Or Akiva, Israel) should be placed [10]. Type III (Table 15.2) coronary perforations usually result in cardiac tamponade and a covered stent should be implanted for this type of perforation [11]. The most efficient method to minimize bleeding in patients requiring a covered stent is to use a dual-catheter, or “ping pong” guide technique [12]. With this technique, a second guide catheter is advanced near the coronary ostium next to the first guide catheter that is currently engaged with the balloon occluding the perforation. While maintaining balloon occlusion the first guide catheter is pulled back into the aorta while the second guide catheter is engaged. The vessel is then wired from the second guide with the balloon rapidly deflated and re-inflated in order to allow wire passage distally. The covered stent is positioned proximal to the occluding balloon which is then rapidly deflated and withdrawn proximally while the covered stent is advanced and deployed to fully cover the perforated site [12]. In the case of covered stent delivery failure, a balloon can be inflated more proximally while maintaining hemostasis from the first guide catheter with the balloon inflated at the perforation site. Reattempt to deliver the covered stent will usually be successful. Prior to removing any equipment, adequate sealing of the coronary perforation should be verified.

Distal target vessel perforation typically occurs after crossing the CTO using an antegrade approach. After crossing a CTO either through wire escalation or dissection and reentry, advancement of the guidewire distally can lead to coronary vessel perforation. This scenario occurs more often when the guidewire is advanced into a smaller branch of the distal target vessel, particularly when using stiff or polymer jacketed wires. One reason dual injection is essential for CTO PCI is the ability to delineate the natural course of the target vessel and identify branches beyond the distal cap of the CTO [1]. Importantly, exchanging the stiffer crossing guidewire for workhorse wires immediately after crossing the CTO lesion and reentering the true lumen can minimize the risk for distal target vessel perforation, ideally using a trapping technique (see Chap. 4). Distal target vessel perforation can be less angiographically apparent than main target vessel perforation, thus it is critical that operators pay careful attention to the distal guidewire position during CTO PCI.

As with main vessel perforation, the initial step with distal target perforation is to use balloon occlusion proximal to the perforation which may itself lead to hemostasis. Other options include advancing a microcatheter into the distal target vessel, typically a small side branch, and aspirating using a 30–60 ml lure lock syringe to collapse the vessel [13]. If bleeding persists despite these techniques then embolization is typically required using coils, vascular plugs, thrombin, subcutaneous fat, or fibrin glue [14–16].

Unique to retrograde CTO PCI is the risk for donor collateral vessel perforation. However, progression to cardiac tamponade following a donor collateral vessel perforation depends on the location of the collateral vessel (i.e. septal versus epicardial). Collateral vessel perforation normally occurs due to advancing the guidewire and/or devices when attempting to reach the distal cap of the CTO. To facilitate passage to the target vessel, some operators may dilate the septal collateral vessels, which can also lead to coronary vessel perforation.

Septal collateral vessel perforation carries a unique set of downstream consequences however cardiac tamponade rarely occurs [17]. Guidewire perforation of a septal collateral results in bleeding into the interventricular septum (i.e. septal wall hematoma) and not the pericardial space. It is also possible to perforate a septal collateral coronary vessel into any cardiac chamber, including the coronary sinus, yet this rarely leads to any adverse clinical consequence [18]. Rarely, septal hematomas can result in chest discomfort and also heart block depending on its size and location [19, 20]. (Fig. 15.2) Exceptionally, a septal wall hematoma can progress to a septal wall rupture requiring percutaneous or surgical treatment [21].

Epicardial coronary vessel perforation carries a higher risk of hemorrhagic pericardial effusion and cardiac tamponade compared with septal collaterals. Bleeding from an epicardial vessel perforation can be difficult to control due to the limited options available for management. Thus, only experienced retrograde CTO operators, able and ready to treat a perforation, should attempt recanalization through an epicardial collateral vessel. If an epicardial vessel perforation is noticed, one initial measure is to balloon occlude either the perforated epicardial collateral or its donor vessel. Then, the perforation should be approached both antegrade (if the CTO has been successfully reanalyzed, which is not always the case) and retrograde, with an attempt to achieve hemostasis using microcatheters with suction to collapse the perforated vessel and/or embolization (e.g. coils) (Fig. 15.3). Unfortunately, this approach presupposes that the CTO has been recanalized and the perforated vessel can be approached from both sides. If bleeding continues despite these measures, cardiac surgery may be required.