Interventional Cardiology. Группа авторов

grafts with a transverse origin can often be cannulated with a JR4 guide catheter; however, guide support can be suboptimal. If the vein graft points downwards (inferior or vertical such as often for right coronary artery (RCA) grafts), coaxial engagement may be difficult with a JR guide. A multipurpose or RCB guide is usually coaxially aligned when the take off is inferior and would also offer good support if required. Left‐sided vein grafts lesions can also often be attempted with a JR guide or, if more support is needed, with an Amplatz or Hockeystick guide catheter. If the ascending aorta is large or dilated, a guide with a more pronounced secondary curve is frequently required such as the left coronary bypass (LCB) or a large Amplatz left shape may be selected.

      Left and right internal mammary arteries

      Although the LIMA can often be reached with a JR guide, the more acute primary angle and longer tip of an internal mammary artery (IMA) guide is preferable. Short‐tip hook‐shaped IMA catheters can occasionally be required to intubate a very steep take off angle. Sometimes, because of subclavian stenosis or extreme tortuosity, the IMA can only be selectively cannulated via the left radial approach.

      Gastroepiploic artery grafts

In an attempt to simulate the longevity of IMA grafts and overcome the problem of reaching the distal RCA, the gastroepiploic artery (GEA) is sometimes used as an in situ graft to the posterior or inferior surface of the heart (RCA, posterior descending artery, posterior left ventricular) [3]. The GEA can be cannulated using catheters designed for abdominal vascular intervention such as Cobra or Simmons catheters [4]. The celiac trunk is accessed from the abdominal aorta in the direction of the common hepatic artery (the other branch being the splenic artery) (Figure 5.4). The gastroduodenal artery arises in an inferior direction and gives off the pancreatico‐duodenal branch beyond which it becomes the GEA, which passes through the diaphragm to reach the inferior wall of the heart (Figure 5.4). Anastomotic stenoses are not rare and may require percutaneous treatment [5].

Figure 5.4 Vascular anatomy of a pedicle graft of the right gastroepiploic artery to right coronary artery.

Support

      Complex anatomic situations including tortuosity, calcification, or diffuse atherosclerosis frequently require escalating degrees of backup support. The components of the “backup” support intrinsic to an angioplasty system includes the guide catheter, guidewire(s), and balloon(s) in the target artery. The components can be changed individually or in combination as demanded by the difficulties that are encountered. Hybrid strategies using more complex wire and/or balloon‐based techniques are sometimes required to overcome more challenging anatomies.

      Guide catheter support

      The role of shape selection has been discussed. Guide catheter support is either passive or active. Passive support is provided by a large diameter catheter positioned optimally in the coronary ostium whereas active support is provided by judiciously advancing a small diameter catheter to deeply intubate an epicardial artery.

      Passive support

Although 6 Fr guide catheters are successfully used for most cases of angioplasty, larger catheters are required when complex lesions are encountered such as complex bifurcations, very tortuous or calcified arteries or CTOs [6] (Figure 5.5).

Figure 5.5 Approaches to increase guide catheter support for treating complex lesions. Guidewires.

      Active support

      Guide catheters smaller than 6 Fr can be advanced over the guidewire and balloon catheter shaft to sub‐selectively engage the proximal or mid segment of an artery (Figure 5.5). This technique is also referred to as active engagement or “deep seating” of the guide catheter. The risk of damage to the artery can be minimized by ensuring that the catheter is advanced coaxially over a balloon already inside the vessel. Stabilization of the system while advancing the guide catheter is sometimes required and can be achieved by inflating a balloon within the artery. When considering the use of active support, it is important to bear in mind that deep engagement of large arteries can cause profound ischemia. The use of side holes may not prevent and may even delay detection of catheter‐induced ischemia. A further risk is that of air embolism following aspiration through the Y‐connector while the back pressure in the guide catheter is reduced as a result of damping inside the artery. Despite these risks, for a skilled operator capable of rapidly advancing and withdrawing catheters, active support offers an efficient solution in most cases.

      Hybrid support

Several additional strategies have been described based upon the concept of inserting an additional device, wire, balloon, or other catheter specifically to augment support when active and/or passive support of the guide catheter proves insufficient (Figure 5.6).

Figure 5.6 “Intraluminal” hybrid support techniques that can be used to substantially augment guide catheter support when treating complex lesions.

      Wire support

The buddy wire technique refers to the passage of a second or third guidewire distal to a target lesion to provide additional support for delivery of angioplasty equipment. This is a commonly used strategy for crossing difficult lesions with a balloon or a stent [7]. The additional wire provides a rail that facilitates advancement across calcification, tortuosity, or recently deployed stents. The wire facilitates active engagement of the guide catheter and can straighten tortuosity when a supportive wire is used. This technique is also the first essential step for the distal anchor balloon technique. Although it can at first appear to be counterintuitive, advancing an additional wire into a branch that lies proximal to the target lesion, this may increase support enough to allow passage of a balloon, stent, or additional wire along the first wire into the tortuous distal vessel (Figure 5.6) and is anyway the first step for a side branch anchoring technique [8]. Using a buddy wire is a simple strategy that can be facilitated using a dual lumen microcatheter in case of excessive tortuosity or presence of dissections post initial balloon dilatation. This avoids the risks of deep engagement or the delays and potential difficulties of upgrading the guide catheter. A floppy, steerable wire can advance easily and be exchanged using an OTW catheter for a wire with a more supportive shaft but soft flexible tip. The use of stiff hydrophilic wires as a “buddy wire” is discouraged because of the risk of perforation. Occasionally, if support from the guide and an additional wire still proves insufficient, additional techniques are needed and are delineated subsequently.