anatomy using “balloon assisted tracking”: 91‐year‐old with acute coronary syndrome undergoes coronary angiography via the right distal radial artery. Figure illustrates steps of balloon assisted tracking (BAT) up a tortuous “high take off” radial artery originating in the axillary artery. The BAT technique is also used to deliver a guide catheter extension into the LAD (h). (a) High takeoff radial (origin above antecubital fossa) with short loop. (b and c) Wiring the loop with an 0.014" coronary guidewire, in this case the first step of wiring and placing the wire as proximally as possible whilst applying gentle traction and clockwise/counterclockwise catheter torque did not straighten the loop. (d and e) PTCA balloon (2.5x15mm) is placed with half protruding out the distal end of catheter and deployed at around 10–12 ATM. (f) entire assembly is advanced over coronary wire tracking the loop. (g) Clockwise or counter‐clockwise torque is applied with gentle traction to straighten loop. (h) The balloon assisted tracking (BAT) technique can be used in the coronary artery to help deliver the guide extension (e.g. Guideliner®) into the distal LAD for stent delivery without dissecting the vessel proximally.
Other Barriers
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).
Complications and management
Major vascular complications occur in 0.2% of radial procedures and major bleeding in 1.0% [32]. As with all procedures, complications can often be prevented with careful technique and experience (Table 3.2).
Table 3.2 Complications of transradial access.
| Intra‐procedural | Post‐procedural |
|---|---|
| Radial artery perforation | Radial artery occlusion (typically clinically silent) |
| Radial artery spasm | Hematoma +/‐ compartment syndrome |
| Catheter entrapment | Pseudoaneurysm |
| Arterial dissection | Atheroembolism/thromboembolism |
Spasm
The radial artery is a muscular vessel with abundant α‐adreno‐receptors located in the adventitia. The mean size of the proximal radial artery is 2.55mm ± 0.39 and is marginally bigger than the distal radial artery in the anatomical snuffbox (2.34mm ± 0.36, difference 0.2 ± 0.16mm; p < 0.001) (33). With limited vessel clearance, catheter advancement can induce local trauma with resultant vasospasm and arm pain. Any further catheter manipulation without remedial action will exacerbate the problem and lead to access‐site crossover. Radial artery spasm (Figure 3.1d) occurs in roughly 15% of procedures with several predictive risk factors including female sex, higher radial artery takeoff, smaller artery diameter, larger cathetersize, increased number of punctures and pain response during cannulation [34].
With increased operator experience and the development of hydrophilic catheters, the incidence of vasospasm has reduced [35]. Preventative measures that vasodilate the artery and limit arm pain can be employed to lower the risk of spasm. Intra‐arterial lignocaine injection can induce vasospasm and should be avoided [36]. Administration of a “radial cocktail” of anti‐spasmodic drugs via the arterial sheath should be routinely administered [37]. Both glyceryl trinitrate (0.1–0.4 mg) and verapamil (2.5–5 mg) have a strong evidence base in preventing spasm without significant hemodynamic consequences [38]. We prefer heparin (2000–5000 IU) administration into the aorta rather than via the radial sheath given that it is painful and potentially mediates spasm while simplifying a TFA approach should this be necessary. Adequate sedation/analgesia also play an important role in reducing failure of TRA [39].
Hematoma
Hematomas occur in <5% of TRA cases and rarely require imaging or blood transfusions (unlike those associated with femoral access). Typically, they are caused by guidewire‐ or catheter‐induced damage to small arterial branches proximal to the puncture site (Figure 3.3d and e). Bertrand’s Early Discharge After Transradial Stenting of Coronary Arteries (EASY) hematoma scale (<link href="urn:x-wiley:9781119697343:xml-component:w9781119697343c3:c3-fig-0004">Figure 3.4</link>) is helpful for sizing hematoma associated with traditional proximal radial access (<link href="urn:x-wiley:9781119697343:xml-component:w9781119697343c3:c3-fig-0004">Figure 3.4</link>). Grade I, ≤5 cm (local hematoma, superficial); grade II, ≤10 cm (hematoma with moderate muscular infiltration); grade III, >10 cm below the elbow (forearm hematoma and muscular infiltration); grade IV, hematoma extending above the elbow and grade V, compartment syndrome [40,41]. Early detection is key to preventing progression to a major complication such as compartment syndrome [42]. Pressure bandaging, withholding anti‐coagulating medications and inflation of a blood pressure cuff immediately proximal to the hematoma to 20 mmHg below systolic blood pressure for 15 minutes is usually sufficient to manage larger hematomas (Figure 3.3d).
Figure 3.3 Complications of Transradial Access. (a) Radial perforation caused by a hydrophilic 0.035" (Benson) wire. (b) Subclavian artery spiral dissection caused by 0.035 in J‐wire in a patient with marked subclavian tortuousity. (c) Catheter kinking and entrapment (retrieved via the same access site in this case after unwinding and wiring with 0.035" wire). (d) Illustration of forearm hematoma compression. Note the forearm hematoma is proximal and distinct from puncture site at the distal radial artery. This likely resulted from wire or catheter induced damaged to small arterial branches proximal to the puncture site. The manual sphygmomanometer is inflated 15–20 mmHg above systolic blood pressure for 5–10 minutes before a repeat clinical examination of the site. (e) Grade IV hematoma complicating proximal TRA PCI for myocardial infarction in a 94‐year‐old
