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After navigation beyond the axillary artery, two further barriers to TRA might include a tortuous subclavian system or a distal insertion of the subclavian into aorta (arteria lusoria – retroesophageal right subclavian artery). Risk factors for subclavian tortuosity include hypertension, female gender, older age, non‐smokers, short stature, and high body mass index [30]. A deep breath held in inspiration straightens subclavian tortuosity of the passage into the ascending aorta allowing correct catheter orientation in the ascending aorta. Occasionally, a breath hold in deep expiration (forced Valsalva) can facilitate wire passage into the ascending aorta. In older patients, using hydrophilic coated guide catheters can ease passage into the ascending aorta whilst “super stiff” 0.035" wire (left inside the catheter tip) can prevent kinking and facilitate selective intubation of the coronary ostia. In very rare cases (0.29%), the right subclavian artery is aberrant and enters very distally into the aortic arch or descending aorta. Whilst it is technically feasible to negotiate the retroesophageal right subclavian artery (RORSA), early identification of this issue with conversion to alternative access should be considered to avoid unnecessarily long procedures with excessive radiation and higher risks of arterial dissection with aberrant right subclavian artery origin [31]. The use of guide extension catheters (mother daughter guides) can help to improve support for PCI where the guide catheter support alone is insufficient (Figure 3.2h).