Ostial lesions

15.1.1

Planning

Aorto-ostial lesions can be challenging to engage and severe ischemia can occur upon engagement. It is best to have a guidewire preloaded within the guide catheter before attempting to engage, so that the wire can be immediately advanced into the coronary artery upon engagement, allowing subsequent guide disengagement to prevent ischemia (“hit and run”). Alternatively, the wire can be advanced into the vessel with non-selective guide engagement, minimizing the risk of ischemia and ostial trauma.

Aorto-ostial lesions can be fibrotic, calcified, rigid, and prone to recoil. As a result, they can be challenging to dilate, sometimes requiring atherectomy.

15.1.2

Monitoring

Pressure dampening is common when treating aorto-ostial lesions, requiring constant attention to the guide pressure waveform ( Section 5.6 ).

15.1.3

Medications

Medications are administered as described in Chapter 3 , Medications. No special medications are required for treatment of aorto-ostial lesions.

15.1.4

Access

• Arterial access is obtained as described in Chapter 4 , Access.

• Radial or femoral access are both acceptable for aorto-ostial lesion stenting. In highly complex cases femoral access and large (i.e., 7 or 8 French) guide catheters may provide better support, but are more likely to cause pressure dampening upon engagement.

15.1.5

Engagement

A common challenge associated with aorto-ostial lesion PCI is pressure dampening upon engagement ( Fig. 15.2 ), that may lead to ischemia and hemodynamic compromise .

Other causes of pressure dampening (such as intracatheter thrombus or debris, catheter kinking, non-coaxial alignment, or transducer malfunction) should be considered and excluded as discussed in Chapter 5 , Coronary and Graft Engagement, Section 5.6 , Step 6.

Prevention of pressure dampening:

• Use small (such as 6 French) guide catheters.

• Avoid deep guide engagement.

• Use guide catheters with side holes ( Section 30.2.5 ). However, side-hole guides may provide a false sense of security, as pressure dampening and ischemia may not be appreciated. They should not be used in an unprotected left main coronary artery, given the large area at risk of ischemia, but can be used in the right coronary artery, bypass grafts, and a protected left main coronary artery. Similarly, they should not be used in the right coronary artery if it is the donor vessel to a totally occluded vessel in the left system. Disadvantages of side-hole guide catheters include contrast exit though the side holes that may hinder visualization of the lesion, and lead to use of larger contrast volume for completing the PCI.

• Use of the Ostial Pro device ( Section 30.13.1 ) for keeping the guide catheter outside the ostium.

• Place a second guidewire through the guide catheter into the aortic root (“floating wire”) to keep the guide catheter off the coronary ostium ( Fig. 15.3 ).

  

• Use a small guide catheter extension to engage the coronary artery and “back out” the guide catheter.

Solutions:

• A guidewire should be inserted and advanced to the tip of the guide catheter prior to engagement, to facilitate immediate wiring upon engagement, as described under “Planning”. Use of extra support guidewires (such as Grand Slam, Iron Man, Wiggle, etc.) can facilitate guide engagement and disengagement as well as coaxial alignment.

• Use smaller (such as 6 French) guide catheters as larger guide catheters are more likely to cause pressure dampening upon engagement.

• Less aggressive guide catheters, such as a JR4 (and sometimes IM catheters for shepherd’s crook RCA) are preferred for isolated aorto-ostial disease, as they are easier to intermittently engage and disengage. These catheters, however, may not provide enough support for more diffusely diseased or tortuous vessels compared with more aggressive guide catheters, such as AL shapes.

• Avoid contrast injections while pressure is dampened to minimize the risk of coronary ostial dissection that can propagate down the coronary artery or in the ascending aorta.

• Intermittently disengage the guide catheter to alleviate ischemia. Disengagement is best done by torquing the guide to a noncoaxial position as opposed to pulling it back, as the latter may lead to loss of distal wire position.

• Place a second guidewire through the guide catheter into the aortic root (“floating wire”) to keep the guide catheter off the coronary ostium.

  Contrast injection while pressure is dampened can lead to aorto-coronary dissection.

  Aorto-coronary dissection :

  Prevention:

  • Use small guide catheters.

  • Avoid deep guide engagement.

  • Use gentle manual injection—avoid automated injectors or use a gentle injection preset.

  • Avoid injection while pressure is dampened.

  • If possible, wire the vessel prior to contrast injection.

  • Use a small guide catheter extension to engage the coronary artery, keeping the guide catheter outside the ostium.

    Solutions:

  • Maintain guidewire position within the target vessel.

  • STOP INJECTING contrast.

  • If vessel needs wiring, confirm intraluminal position with IVUS (without contrast injections).

  • Stent vessel ostium to seal entry into the dissection flap.

Guide engagement in patients with protruding stents in the aorta .

Engaging vessels with prior aorto-ostial stenting can be difficult due to protruding stent struts, and may result in stent deformation. Sometimes, it can also be challenging to engage the guide catheter in a coaxial manner. In such cases, the vessel can often be wired with the guide catheter disengaged (and ideally knuckling the wire to avoid wire advancement through stent struts), followed by guide engagement over the wire. In the RCA, wiring through previously deployed aorto-ostial stents is easier with a JR4 guide catheter. If a more supportive guide shape is needed, guide exchange can be performed using a microcatheter and a 300 cm supportive guidewire ( Chapter 5 : Coronary and Graft Engagement, Section 5.7 , Step 7).

15.1.6

Angiography

Performing coronary angiography is described in detail in Chapter 6 , Coronary Angiography.

• Nitroglycerin should be administered before angiography to exclude coronary spasm.

• For aorto-ostial lesions with severe dampening upon engagement, nonselective angiography can reduce the risk of dissection, but may provide suboptimal quality images.

• The “independent-hand” technique for holding the guide catheter ( Fig. 15.4 ) can significantly facilitate all steps of aorto-ostial lesion stenting.

  

• Multiple angiographic acquisitions should be avoided to minimize the risk of aorto-ostial lesion dissection; intravascular imaging can help determine the presence and severity of aorto-ostial lesions and response to treatment.

• If the contrast is not allowed to clear the coronary artery after injection, ventricular fibrillation or ventricular tachycardia may occur. Failure of the contrast to clear is likely due to occlusion of the ostium from the catheter. The catheter should be disengaged, to allow contrast clearance.

• Determining the optimal view to define the true ostium is essential to avoid geographic miss during stenting. If a patient has a prior coronary CT angiography, the optimal angle can be noted prior to the procedure. In general, the following projections offer the least foreshortening of the ostium:

  • RCA: steep LAO +/− caudal.

  • Left main: LAO caudal and LAO cranial.

  • Right-sided SVGs: LAO.

  • Left-sided SVGs: RAO.

  • LIMA and RIMA: AP with shallow cranial.

15.1.7