LAUSR

In a previous issue of Angiology, Vukovic et al report on the preoperative ultrasonic assessment of the radial artery for use as a conduit for coronary artery bypass graft (CABG). The radial artery is increasingly used as the access route for diagnostic and interventional cardiac catheterization. Historically, the brachial artery was surgically exposed at the elbow and used as the access site for cardiac catheterization, later followed by the femoral artery. Large-diameter sheath and catheters initially caused frequent local vascular complications. However, the continued improvement of catheter technology and intervention techniques led to the development of ever smaller catheters. This finally led to the idea of catheter access via the radial artery as bleeding complications were less likely given the superficial location and good accessibility. Surprisingly, vascular access via the radial artery did not only reduce bleeding complications but also improved overall survival for patients. This is especially evident for the treatment of acute myocardial infarction (AMI) and consequently resulted in the recommendation of using the radial artery as the preferred access route for AMI. However, there are 2 sides to the coin. The caliber of the radial artery is considerably smaller compared to the femoral artery, and in some cases, the procedure cannot be completed because of vascular spasm or obstruction of the radial artery; a switch over to the femoral artery then becomes necessary. Additionally, it is unavoidable to irritate and potentially damage the arterial wall during the catheterization procedure. This can lead to vascular occlusions, and it was shown that the structure and function of the radial artery were impaired after catheterization. The long-term consequences of these changes are not yet understood. However, there are indications that the radial artery quality, when used as a bypass graft, is worse if it was previously used to perform a cardiac catheterization procedure. Comparable results are published for radial arteries utilized for radiocephalic arteriovenous fistula (AVF) in hemodialysis patients after transradial catheterization procedures. The most apparent change in the artery wall is a thickening of the intima-media complex, with subsequently rising probability of graft failure directly dependent on the vessel wall thickness. Strategies for artery selection are sometimes applied to reduce the failure rates of AVF but did not really penetrate the daily clinical routine. For CABG, veins and arteries (eg, left internal mammary artery) are both used. Arterial grafts offer a longer patency rate compared to veins. Harvesting arterial grafts, however, is much more time consuming; the preparational techniques are more difficult, and arterial grafts can only be applied for specific coronaries. The no-touch vein harvesting technique has dramatically changed the long-term patency results for venous grafts. Veins harvested using this technique demonstrate nearly comparable long-term patency results as arteries. However, physiologically, using an artery for CABG makes much more sense than using a vein, as the venous wall is not designed to cope with arterial pressures. Unfortunately, the quality of arterial grafts continues to decline. This observed impairment in arterial graft vessel quality can either be explained by the increasingly older and even more morbid population receiving a CABG or alternatively it may have been caused by previously performed medical interventions. Especially, the increasing use of coronary interventions via the radial artery may be relevant in this context. Irrespective of the underlying cause, it is necessary to assess radial artery quality, before deciding to harvest it for CABG use. Ultrasound is a noninvasive method, is free of side effects, and thus appears to be the method of choice to assess the quality of the radial artery. Because of the superficial location of the radial artery and its good accessibility, structural or functional changes of the radial artery can be assessed using ultrasound visualization techniques. Besides being able to quantify the free lumen of the radial artery, detailed information about the structure and morphology of the arterial wall can be obtained. The concept applied in the study of Vukovic et al is logical. A sonographically guided preselection of radial arteries for coronary grafts using clear ultrasonic criteria is an excellent idea. However, well-designed and more extensive prospective studies need to be performed before making any definitive statements.