General description of procedure, equipment, technique
Transradial angiography and intervention includes vascular procedures performed via radial arterial access. Because the radial artery is smaller in diameter compared with the femoral artery, and is more superficially located, hemostasis after transradial procedures is easily obtained.
The body of evidence suggests a significant reduction in access-site bleeding and vascular complications with radial access compared with femoral access. In most patients, the radial artery will readily accommodate 6-French systems allowing the vast majority of interventional procedures to be performed. In many catheterization laboratories worldwide, radial access is the predominant approach, with femoral access reserved for “bailout” when the radial approach fails. There is significant variation between countries; in the United States, the primary approach for percutaneous coronary procedures is still femoral access, with radial approach reserved for femoral failures.
According to available survey data, most radial operators worldwide use the same catheters that are used for the traditional femoral approach. The only differences are that radial access sheaths are often hydrophilic and require a micropuncture needle and small gauge guidewire, and some operators prefer to use catheters designed specifically for the radial approach. After arterial access is obtained and the catheters are advanced to the ascending aorta, both diagnostic and interventional procedures are performed in the usual fashion. There is no difference from the femoral approach. Postprocedure hemostasis, however, is quite different. The arterial sheath is immediately removed after the procedure and hemostasis is usually obtained with a dedicated radial hemostasis device. This leads to immediate postprocedure ambulation for patients and is one reason why most patients prefer radial access to femoral access.
Indications and patient selection
As stated above, radial approach can be used to perform the majority of percutaneous coronary interventions (PCIs). It is particularly helpful when patients are at high risk for bleeding complications or for those who have a “hostile” groin—morbid obesity, groin infections, or severe peripheral arterial disease.
Conventionally, either the Allen or Barbeau test is used to determine whether the hand to be used for the procedure has dual circulation (i.e., the radial and ulnar arteries connected in the palm via the palmar arch). Ostensibly this is to identify patients who may be at risk for hand or digital ischemia in case of radial artery occlusion (RAO). While some operators avoid radial approach in patients without evidence of dual circulation, survey data indicate that many operators, particularly outside the United States, do not routinely check for dual circulation. It should be mentioned that there is no correlation between the results of the Allen or Barbeau test and subsequent hand or digital ischemia.
To perform the Allen test, both the radial and ulnar arteries are manually occluded until the hand blanches, then the pressure on the ulnar artery is released. The test is normal (dual circulation present) if color returns to the hand. A seemingly more objective way of assessing dual circulation is to perform the Barbeau test. A pulse oximeter probe is placed on the thumb and a plethysmographic (arterial) waveform is noted on the monitoring screen. The radial artery is then manually occluded for 2 minutes. Responses are categorized as A, B, C, or D: A—no diminution of the arterial waveform; B—some diminution but the waveform is always present; C—the waveform flattens, but the arterial pattern returns within 2 minutes; D—the waveform flattens and the arterial pattern does not return within 2 minutes. Operators that use the Barbeau test will often avoid radial access in patients with a type D response as this may indicate lack of dual circulation to the hand.
Most operators prefer to use the right radial artery because this closely approximates right femoral artery procedures; however, use of the left radial artery may have advantages in patients with prior coronary artery bypass grafting, especially those with pedicle left internal mammary artery grafts. In addition, procedures using the left radial artery are shorter and use less radiation than right radial procedures. This may be particularly advantageous during primary PCI, where door-to-balloon time is an important predictor of clinical outcomes.
The only absolute contraindications to radial access are absence of bilateral radial pulses, presence of a dialysis graft in the arm to be used for access, and patient refusal. Relative contraindications are operator inexperience with radial technique, and an abnormal test for dual circulation in the hand to be used for access.
Details of how the procedure is performed
In general, the equipment needed for a radial procedure includes:
- micropuncture access kit (hydrophilic sheath, micropuncture needle or catheter-over-needle system, small gauge wire)
- 260cm 0.035″ exchange guidewire
- adhesive film (e.g., TegadermTM) to secure the sheath
- catheters: diagnostic—Judkins (JL3.5, JR5), or dedicated radial curves (e.g., Tiger, Jacky, Kimny, Barbeau); interventional guide catheters—extra-back up curves for the left coronary artery, Judkins right or Amplatz for the right coronary artery. Other options include Ikari, Amplatz, Kimny, and XB-RCA
- Two syringes of verapamil or other arterial vasodilator
- Nitroglycerin for intra-arterial injection
- Unfractionated heparin
Patients are positioned on the catheterization laboratory table in the usual fashion. As mentioned above, most operators prefer the right radial artery; as such, the patient’s arm is usually positioned at their side. Another option is to have the arm abducted for access, then move the arm medially to the patient’s side. For left radial access, the arm is positioned on cushions or pillows to be above the left groin.
Arterial access can be obtained with either a bare needle (“anterior puncture”) or catheter-over-needle system (“counterpuncture”). With either technique, the point of access should be just proximal to the radial styloid process. With the anterior puncture technique, the micropuncture needle is advanced through the skin into the radial artery until arterial flow is seen, the needle is then stabilized and the micropuncture wire is advanced into the artery.
The needle is withdrawn and the sheath is advanced over the wire, through the skin, into the artery. The counterpuncture technique differs in that the needle or catheter-over-needle system is advanced through the skin until a “flash” of blood is seen. Then it is advanced further through the posterior wall of the artery. The needle is then slowly withdrawn until arterial flow is seen. If the catheter-over-needle system is used, the needle is removed once the system is pushed through the posterior wall of the artery. The catheter is then slowly withdrawn until arterial flow is seen coming through the catheter. One randomized study comparing the two techniques suggested that success rates are higher with the counterpuncture technique.
Once the sheath is in place, vasodilators are administered through the sidearm. A commonly used vasodilator is verapamil at doses ranging from 3 to 5mg. Importantly, verapamil induces a burning sensation so patients should be warned. “Washing” the verapamil back and forth with blood from the sheath sidearm may also mitigate some of the burning.
Unfractionated heparin at a dose of 70u/kg (maximum 5,000 units) should be administered to reduce the risk of radial artery occlusion. The timing of the administration is controversial, but it is reasonable to give the dose when the catheter is in the ascending aorta. There is no difference in the therapeutic effect of heparin whether it is given intra-arterially (i.e., through the radial artery sheath) or intravenously. If given intra-arterially, the patient should be warned that it also induces a burning sensation.
Advancing catheters through the arm and chest vasculature
Catheters should be backloaded with the 260cm 0.035″ guidewire and the guidewire should lead through the arm and chest vessels. Fluoroscopic guidance of the catheter-wire system is usually not necessary; however, any resistance should prompt fluoroscopic evaluation and angiography to identify the source of resistance. Once the catheter-wire system is in the subclavian artery, the patient should be prompted to take a deep breath in order to elongate the mediastinum and direct the catheter and wire into the ascending aorta. All catheter exchanges should take place over the 260cm guidewire so that access to the ascending aorta is not lost.
Tips and tricks
- Use of the 0.035″ guidewire inside the diagnostic catheter (but not protruding through the distal end) can often facilitate engagement of the coronary artery. This is especially useful when the Judkins left catheter is used for the left coronary artery. It is also useful to facilitate engagement of the extra back up curve guide catheters for the left coronary artery.
- Tortuosity or loops of the arm vasculature can be overcome using a floppy tipped wire (e.g., Wholey) for mild cases, and 0.014″ wires for more severe cases.
- Inadequate backup during PCI can often be remedied by using buddy wires, or adjunctive devices such as the GuidelinerTM mother-in-child catheter.
The arterial sheath is removed at the end of the procedure regardless of the activated clotting time. The technique used to achieve hemostasis has a significant influence on short- and long-term radial artery patency. The use of “patent” or “nonocclusive” hemostasis is associated with marked reductions in radial artery occlusion.
The patent hemostasis procedure is done by applying enough pressure after sheath removal to achieve hemostasis, but not enough to occlude antegrade flow in the radial artery. The general approach is to withdraw the arterial sheath 3cm, apply the hemostatic wrist band over the access site and tighten it, and then remove.
A pulse oximeter is placed on the thumb of the hand that has been accessed and the plethysmographic signal is noted. Pressure is then applied to the ulnar artery just medial to the pisiform bone of the hand. At this point, the plethysmographic signal should be flat—the radial artery being occluded by the hemostatic band and the ulnar artery occluded at the pisiform bone. The hemostatic band is loosened while pressure is held on the ulnar artery until the plethysmographic signal returns, which indicates antegrade radial artery flow.
This must be balanced against bleeding that can occur at the radial artery access site during the process of loosening the band. Priority is given to achieving hemostasis, not antegrade radial flow. Patent hemostasis cannot be achieved in approximately 25 to 30% patients due to bleeding from the radial access site during the process of loosening the band.
Interpretation of results
Performance characteristics of the procedure (applies only to diagnostic procedures)
Outcomes (applies only to therapeutic procedures)
Observational as well as randomized trials have shown that radial approach is associated with a near 60% reduction in access site bleeding and vascular complications compared with the femoral approach. Some studies also suggest an association between radial approach and reduced mortality among patients with ST-segment elevation myocardial infarction, ostensibly through a reduction in major bleeding complications. Studies also indicate that patients prefer the radial approach, and that the reduction in vascular complications is associated with a reduction in healthcare resources.
Alternative and/or additional procedures to consider
The most common alternative to radial access is femoral arterial access, which is the traditional route for performing coronary angiography and intervention. As mentioned above, radial access has significant advantages, but cannot be performed in all patients. In these patients, or when radial access fails, bailout to the femoral approach is reasonable.
Brachial access is mostly of historical interest, and is usually reserved for patients who have no other vascular access. In a randomized trial comparing radial, brachial, and femoral access, brachial access was associated with the most vascular complications. This is likely because it is an “end” artery, and its compromise places the patient at significant risk for arm ischemia.
Complications and their management
Complications of the radial approach are rare, and can be classified into complications of radial access, arterial transit, or hemostasis.
Complications of radial access
- Spasm leading to catheter entrapment—as mentioned above, all patients should receive intra-arterial vasodilators when the arterial sheath is placed and as needed during the radial procedure. Rarely, spasm can be so severe that the angiographic catheter may become entrapped in the vasculature. To facilitate catheter removal, the patient should be sedated and either intra-arterial or intravenous vasodilators should be administered. After 10 to 15 minutes, the catheter should be gradually withdrawn in one smooth motion. In extremely rare cases, general anesthesia may be required.
Complications of arterial transit
- Arterial perforation—the radial artery can be perforated with either a guidewire or a catheter. The patient will usually complain of arm pain and there may be severe arterial spasm. Angiography will usually confirm the diagnosis by showing extravasation of contrast dye into the forearm. Although this complication appears dramatic, it is important to avoid panic and removing the catheter and wire from the artery. If a guidewire is across the perforation, then the catheter should be advanced slowly across it. If a guidewire is not present, then a coronary 0.014″ guidewire should be used to cross the perforated area and then a catheter should be advanced across the perforation. The presence of the catheter and attendant arterial spasm will seal close to 100% of perforations. External compression using an “ACE” type bandage wrapped around the arm can also be helpful.
Complications of hemostasis
- Radial artery occlusion—as mentioned above, the three things that are associated with a reduced risk for radial artery occlusion are 1) using smaller diameter sheaths; 2) adequate anticoagulation (70u/kg of unfractionated heparin up to 5,000 units); and 3) patent hemostasis. Approximately 40 to 50% of radial arteries that occlude within 24 hours of a transradial procedure will recanalize within 30 days.
- Forearm hematoma—this can be caused by either perforation of small branches of the radial artery or from oozing of blood from the radial arteriotomy proximally into the forearm during the patent hemostasis procedure. If left unchecked, a forearm hematoma can lead to vascular compromise and compartment syndrome of the forearm. The key to preventing compartment syndrome is early recognition and treatment of forearm hematoma. Recognition is straightforward in the postprocedure area because there will be a fullness of the soft tissue proximal to the hemostasis band or in the forearm. This may rapidly expand, so once it is recognized, it should be compressed immediately with a tightly wrapped “ACE” type bandage. Care should be taken not to wrap the bandage so tightly that capillary refill of the fingers is compromised. The bandage should be left in place for 30 to 60 minutes until the hematoma stops expanding. Often, it will be completely reduced. Any compromise of the radial pulse accompanied by extreme forearm pain in the presence of a hematoma should prompt immediate evaluation by vascular surgery.
What’s the evidence?
Rao, SV, Cohen, MG, Kandzari, DH, Bertrand, OF, Gilchrist, IC. “The transradial approach to percutaneous coronary intervention: historical perspective, current concepts, and future directions”. J Am Coll Cardiol. vol. 55. 2010. pp. 2187-95. (This narrative review summarizes the historical development of transradial PCI, its current uses, and potential future applications. The designs of ongoing clinical trials are summarized as well.)
Bertrand, OF, Rao, SV, Pancholy, S. “Transradial approach for coronary angiography and interventions: results of the first international transradial practice survey”. JACC Cardiovasc Interv. vol. 3. 2010. pp. 1022-31. (This paper reports the results of a survey of interventional cardiologists around the world who are using the radial approach. Questions about specific preprocedure patient evaluation, techniques, and equipment used are reported.)
Jolly, SS, Yusuf, S, Cairns, J. “Radial versus femoral access for coronary angiography and intervention in patients with acute coronary syndromes (RIVAL): a randomised, parallel group, multicentre trial”. Lancet. vol. 377. 2011. pp. 1409-20. (This is the largest multicenter international trial comparing radial and femoral approaches to PCI in 7,000 patients with acute coronary syndrome. The primary endpoint is a composite of 30-day death, MI, stroke, and major bleeding. There was no difference between the two arms with respect to the primary endpoint; however, major vascular complications were significantly lower with the radial approach. Moreover, the majority of patients preferred radial access if they were to need a subsequent procedure. A prespecified subgroup analysis of the trial demonstrated lower mortality with radial access among patients with STEMI.)
Rao, SV. “Observations from a transradial registry: our remedies oft in ourselves do lie”. JACC Cardiovasc Interv. vol. 1. 2012. pp. 44-46. (This article summarizes strategies to reduce the risk for radial artery occlusion.)
Pancholy, S, Coppola, J, Patel, T, Roke-Thomas, M. “Prevention of Radial Artery Occlusion—Patent Hemostasis Evaluation Trial (PROPHET Study): a randomized comparison of traditional versus patency documented hemostasis after transradial catheterization”. Catheter Cardiovasc Interv. vol. 72. 2008. pp. 335-40. (This randomized trial compared a strategy of nonocclusive hemostasis with usual care among patients undergoing transradial angiography or PCI. It demonstrated that the rate of early and late radial artery occlusion was significantly lower when the nonocclusive method was used.)
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- General description of procedure, equipment, technique
- Indications and patient selection
- Details of how the procedure is performed
- Interpretation of results
- Performance characteristics of the procedure (applies only to diagnostic procedures)
- Outcomes (applies only to therapeutic procedures)
- Alternative and/or additional procedures to consider
- Complications and their management
- What’s the evidence?