Response to Letter to the Editor Regarding “Patency of Radial Arteries Reconstructed after Radial Forearm Flap Harvest (J Reconstr Microsurg 2007;23:347–350)”

We appreciate the opportunity to respond to the correspondence of Drs. Knobloch and Vogt regarding our article.[1]

Their critique of the methodology of our study appropriately demonstrates the limitations of retrospective analysis of clinical data. Our patients are drawn from a large geographic area. They are often young and tend to be mobile and difficult to track beyond the acute treatment period. This tendency restricted participation in the study. Of the patients who underwent reconstruction, 38% did participate, and all were noted to have patent reconstructions by Allen's test. A subset of patients in this group was further evaluated with duplex ultrasound to assess the diameters of the vein graft and anastomoses. These are the 28% of patients that Knobloch and Vogt incorrectly identify as the follow-up cohort. Although the number of patients in this study is small, the results do demonstrate that radial artery reconstruction in the setting of a patent ulnar artery and long vein grafting is feasible. This is contrary to previously published reports cited in our original article. Unfortunately, the size of the cohort did not allow relevant analysis of the influence of factors such as age, smoking, and atherosclerosis on the success or failure of reconstruction.

The question of the necessity of radial artery reconstruction following harvest for arterial grafting or creation of a radial forearm flap is different than the question of feasibility we posed in our article. Given the large number of studies devoted to assessing perfusion of the hand after radial artery harvest, perhaps it is inevitable that authors of such studies would focus on the former rather than the latter question. The study Knobloch and Vogt kindly brought to our attention[2] is interesting but tangential in relevance to our article.

Knobloch and Vogt also question whether there is ever a need to reconstruct radial arteries in patients that have patent ulnar arteries. They present several of their own studies in which they analyzed tissue oxygen, postcapillary venous filling pressures, and capillary blood flow of resting extremities. In their studies up to 2 years after radial artery harvest, they noted no significant difference in extremities with radial artery harvest compared with extremities without radial artery harvest up to age 67, after which they concluded significant deterioration of palmar microcirculation was more likely to occur.[2] Regrettably, their investigation may not be sufficient to answer the question they pose. Analyses designed to determine the adequacy of blood flow should consider factors that impact perfusion, such as temperature and position, and they should demonstrate the aerobic capacity of the extremity. With sustained grip, transcutaneous PO ₂ levels drop significantly in extremities following radial artery harvest.[3] On focused evaluation, 10% of patients in one study reported mild symptoms consistent with mild exercise intolerance, although these complaints were not elicited in routine clinic follow-up after surgery.[4] In addition, the increase in flow in the ulnar artery results in thickening of the vessel intima and media and may be associated with an accelerated rate of development of atheromatous plaques. In a longitudinal evaluation of patients undergoing radial artery harvest, changes in vessel wall thickness reached significance after 10 years after surgery, but not at 5 years, suggesting that such changes are progressive.[5]

As Knobloch and Vogt have shown from their own studies, older patients have a diminished capacity to perfuse the hand through the ulnar artery alone. As younger patients who underwent radial artery harvest age, perhaps there will be additional reports of difficulties due to diminished perfusion. The occasional report documenting difficulties after harvest of the radial artery whether as a flap or isolated entity does demonstrate, however, the importance of the ability to reconstructed the artery in this setting.[6] Most patients may never experience difficulties related to radial artery harvest,[7] and we do not advocate routine reconstruction for all patients undergoing radial artery harvest. The practice of primary reconstruction may be of value for some patients, such as those who are at higher risk for trauma, undertake heavy labor, and those with a disposition to the development of atherosclerosis. Because many of our patients have these characteristics and two microsurgical teams are usually available for our free-flap reconstructions, we generally opt to perform radial artery reconstruction for our patients. Our own investigations of the use of optical diffusion imaging spectroscopy for determination of digital tissue oxygen concentrations in clinical practice have not generated clear information regarding the ultimate clinical relevance of these often variable measurements.[8] As such, we have not applied this technology to answering this clinical question.

The focus of our study was not whether radial artery reconstruction is clinically important but whether or not it can be reliably performed. The former is an interesting question but beyond the scope of our retrospective analysis. As Knobloch and Vogt point out, a larger prospective randomized trial might provide additional insight into the question of the absolute necessity of radial artery reconstruction.

Sincerely,

REFERENCES

• 1 Kiehn M, Brooks D, Lee C et al.. Patency of radial arteries reconstructed after radial forearm flap harvest.  J Reconstr Microsurg. 2007;  23 347-350
• 2 Knobloch K, Vogt P M. Letter to the editor.  J Reconstr Microsurg. [Online publication date: Oct. 16, 2008]; 
• 3 Gaudino M, Anselmi A, Serricchio M et al.. Late haemodynamic and functional consequences of radial artery removal on the forearm circulation.  Int J Cardiol. 2008;  129 255-258
• 4 Manabe S, Tabuchi N, Toyama M et al.. Oxygen pressure measurement during grip exercise reveals exercise intolerance after radial harvest.  Ann Thorac Surg. 2004;  77 2066-2070
• 5 Gaudino M, Serricchio M, Tondi P et al.. Chronic compensatory increase in ulnar flow and accelerated atherosclerosis alter radial artery removal for coronary artery bypass.  J Thorac Cardiovasc Surg. 2005;  130 9-12
• 6 Higgins J P, Orlando G S, Chang P, Serletti J M. Hypothenar hammer syndrome after radial forearm flap harvest: a case report.  J Hand Surg [Am]. 2001;  26 772-775
• 7 Heller F, Wei W, Wei F C. Chronic arterial insufficiency of the hand with fingertip necrosis 1 year after harvesting a radial forearm flap.  Plast Reconstr Surg. 2004;  114 728-731
• 8 Colwell A S, Buntic R F, Brooks D, Wright L, Buncke G M, Buncke H J. Detection of perfusion disturbances in digit replantation using near-infrared spectroscopy and serial quantitative fluoroscopy.  J Hand Surg [Am]. 2006;  31(3) 456-462