Historical Aspects

Catheterisation of the human heart via upper limb access sites has a long history, and has played a pivotal role in the development of interventional cardiology. The first catheterisation of a human heart was performed in 1929 when Werner Forssman cut down on to his own left anti-cubical vein and inserted a ureteric catheter which he then advanced in to his right atrium. Similarly, the first study of the left side of the human heart was performed in 1950 when Zimmerman cut down on to the ulnar artery of a patient with aortic regurgitation and retrogradely inserted a catheter in to the left ventricle. In the late 1950’s Sones performed the first selective coronary angiograms utilising a surgical technique to expose and cannulate the brachial artery.

These techniques require considerable surgical expertise to identify, dissect out, cannulate and repair the upper limb vessels. This limited the wide spread application of cardiac catheterisation. In 1962, however, Ricketts and Abrams employed a percutaneous transfemoral approach to considerably simplify the technique of coronary angiography. In 1967 Judkins developed a series of pre-shaped catheters to further simplify the procedure. With these two developments upper limb access sites were largely superseded by the simpler percutaneous transfemoral approach. By the late 1980’s the majority of invasive cardiologists performed their diagnostic and interventional cardiac procedures by percutaneous access to the femoral artery. Undoubtedly, these technical advances facilitated an explosive growth in diagnostic and therapeutic cardiology that would not have been possible if cardiologists had remained reliant on technically demanding surgical techniques for upper limb vascular access. It seemed clear at this time that upper limb vascular access would be reserved for a very small number of patients with contra-indications to the use of the femoral artery.

Femoral and Brachial Access Site Complications

The introduction of coronary artery stents in the early 1990’s led to a sudden re-appraisal of the dominant position occupied by the femoral access site. The intensive anti-thrombotic regime employed in the pre-thienopyridene era led to an explosion of femoral access problems, with 15 – 20% of patients suffering from debilitating complications of a procedure that was meant to improve their quality of life. This prompted cardiologists to re-examine the utility of upper limb arterial access sites. The radial artery has been employed for many years for haemodynamic monitoring. It is an attractive access site because of its favourable neuro-anatomy. The radial artery has a superficial course at the wrist which facilitates percutaneous puncture. The artery overlies the forearm bones, and compression haemostasis is therefore simplified. No major veins or nerves lie close to the radial artery limiting the risk of neurological damage or arterio-vennous fistula formation. The hand and forearm have a dual blood supply, with the ulnar artery limiting the risk of ischaemic complications if radial artery occlusion occurs as a consequence of the procedure. The application of compression to a radial artery puncture site facilitates immediate ambulation after a cardiac procedure improving quality of life. Cardiac catheterisation via the radial artery was first described by Campeau in 1989. Ferdenand Kiemeneij and his colleagues at the OLVG Hospital in Amsterdam adapted this technique to perform coronary angioplasty and stenting and reported the first series in 1993. The early studies demonstrated acceptable results for angiography and intervention with a large reduction in access site complications. This greatly reduced procedure related costs. In the early studies there was an increase in procedure failure rate due to puncture or guiding catheter issues.

With no specifically designed transradial equipment available and limited knowledge about optimal catheter selection and manipulation, there is no doubt that many femoral operators found radial procedures to be a considerable challenge at this time. With the introduction of Ticlopidine and Clopidogrel and the development of vascular access closure devices many cardiologists were happy to return to the femoral artery as their primary access site. It is apparent, however, from studies of contemporary populations that femoral vascular access problems remain important. Major femoral complications occur in up to 1% of diagnostic studies, and 2% of angioplasty procedures. Because of the unfavourable neuro-anatomy of the femoral triangle, these complications are often life or limb threatening. In addition to this, as many as 25% of patients have bruising and discomfort that impairs their quality of life. Vascular access closure devices come in many guises. Studies in highly selective populations demonstrate a high rate of successful deployment with minimal complications. In real world clinical scenarios however, these devices have a long learning curve, often fail, or can not be deployed because of contra-indications. A recent meta-analysis of randomised trials comparing vascular closure devices to pressure haemostasis in 4000 patients also confirms that these devices increase the rate of femoral vascular access complications.

Because of concerns about the continuing high rate of femoral complications in contemporary practice, and the failure of vascular closure devices to solve this, interest in transradial access continues, and there are now many UK operators who use the radial artery as their access site of choice. The growth in radial access has been facilitated by the development of specific transradial introducers and sheaths, catheters and compression haemostasis systems. These developments, along with increasing operator experience, has simplified and optimised the technique. In recent randomised trials, radial access has a clear advantage over femoral access in relation to reduced access site complications, with no difference in procedures success rates.

Technical Issues

For a cardiologist seeking to develop skills in transradial access, it is wise to exercise some caution. The skills required to perform a transfemoral procedure are identical to those required to perform a transradial procedure. A cardiologist will, however, need to modify his technique to operate safely from the radial artery. There is a mandatory learning curve during which success rates will be reduced, procedure duration extended and operators will inevitably be frustrated with their inability to perform what should be straight forward procedures. For experienced cardiologists, this learning curve will be shorter. The skill of successfully and reliably puncturing the radial artery can be acquired in as little as 20 – 30 cases. There is then a longer curve required to become accustomed to operating from a distal upper limb puncture site. After the first 1 – 200 cases, the learning curve flattens, but is still present as the operator learns to deal with unusual or difficult anatomy or challenging interventional cases requiring advanced guiding catheter techniques.

For an experienced radial operator there are very few limitations. Current 6F guiding catheters are suitable for almost all PCI cases. Procedural failure is extremely rare. In reality, there are no absolute contra-indications to radial access, and complications are infrequent and usually easily managed.

When starting out as a radial operator it is wise to get some training and hands on experience with an experienced operator. There are well established courses that provide an overview for beginners and technical updates for experienced operators. An initial diagnostic programme in selected patients helps to increase confidence and smoothes the transition through the learning curve. Initial angioplasty cases should be selected in less challenging anatomical situations. Starting your radial programme with a list of cases in whom femoral access has failed or is contra-indicated because of severe peripheral vascular disease will not be a happy experience.

Transradial Procedures in the UK: Where are we going?

Since the late 1990’s there has been a rapid growth in the use of the radial access site by UK cardiologists. Based on sales of radial access compression systems, there are currently around 2500 transradial procedures performed each month, with a continuing rapid month on month rise as more cardiologists are trained and take up this approach. In 2004 the Cardiothoracic Centre in Liverpool performed more than 1,100 transradial angioplasty procedures. The advantages of patient preference and comfort, prevention of vascular complications and cost reduction will continue to provide a powerful stimulus for this growth. Two oversubscribed international transradial fellowship programmes are steadily increasing the number of UK based expert radial operators. If current trends continue, it is quite likely that the radial approach will become the dominant access site for UK cardiac procedures sometime in the next 10 – 15 years.

Jim Nolan