On “Patency of Radial Arteries Reconstructed after Radial Forearm Flap Harvest (J Reconstr Microsurg 2007;23:347–350)”

We read with great interest the recent article by Dr. Kiehn and coworkers[1] reporting their patency rates following reconstructed radial arteries after radial forearm flap harvesting. We would appreciate a comment on some questions raised by their research.

Over more than 5 years, all patients who underwent radial artery reconstruction following harvesting of a radial forearm flap involving the radial artery were evaluated. A total of 34 patients underwent radial artery forearm flap harvesting, 18 patients with consecutive reconstruction of the radial artery with a vein graft. Seven of these patients (38%) underwent clinical examination, with five patients (28%) undergoing ultrasonic evaluation of blood flow in the reconstructed vessel. Based on these five patients out of the 18 with reconstructed radial arteries following harvesting, the authors cite “high rates of successful reconstruction” using a reverse vein graft. We congratulate the authors on their clinical results. but only 28% of all reconstructed patients were evaluated, less than a third of all reconstructed cases. We currently do not know anything about the potential blood flow in the two thirds of the patients who were not studied. Given the reasonably small number of subjects with a valid ultrasound examination (five patients), we believe this report gives some preliminary insights. However, larger prospective trials in a randomized study design are necessary.

Kiehn et al report that the mean age was 45 years (range, 20 to 73 years). We would be appreciative if the authors could comment in more detail on some of the patients' characteristics, such as the frequency of smoking or use of acetylsalicylic acid medication. Furthermore, we would like to know whether signs of arteriosclerosis, such as coronary artery disease, vascular occlusive disease or carotid arteriosclerosis, were evident among the reported patients and if these conditions would interfere with the decision to perform radial artery reconstruction.

The authors report no complications during the vein harvesting either performed at the cephalic vein or the saphenous vein. However, we wonder whether the reconstruction of the radial artery, albeit technically feasible as reported by Dr. Kiehn, should even be performed. In other words, do we have to reconstruct the radial artery in a patient with a patent ulnar artery at all?

In 1971, Carpentier first described the use of the radial artery as a source for coronary artery bypass graft harvesting.[2] The advantages of the radial artery as a graft source are the ease of harvesting, a low propensity for wound infection, a larger diameter than other arterial grafts, and a thick muscular wall that facilitates the construction of a coronary anastomosis. Radial artery grafts provide excellent long-term patency. A randomized controlled trial in 561 patients found 1-year angiography occlusion rates of 8.2% for the radial artery and 13.6% for the saphenous vein.[3] Ten-year patency rates of 92% for the radial artery and 98% for the left internal thoracic artery have been reported in an observational study.[4] However, histological studies[5] of distal and proximal radial artery specimens taken during coronary revascularization revealed the predictive factors for intimal hyperplasia of the radial artery graft to be age > 50 years (1.052), cigarette smoking (14.073), and arterial hypertension (2.777).

Concerns about reduced palmar blood flow after radial artery harvesting have been raised previously. The methods to assess forearm and palmar blood flow include forearm plethysmography[6] or technetium-99m–albumin scans[7] and the clinical Allen's test. Pulse volume recording plethysmography as a semiquantitative measurement found an overall decrease of digital blood flow after radial artery harvesting 7 days postoperatively in 24 patients, predominantly in the first two fingers,[8] which is concordant with findings by flow index differences calculated by photoelectric plethysmography.[9]

Palmar microcirculation has been studied using a combined laser Doppler spectrophotometry system, the oxygen-to-see (O2C) system (LEA Medizintechnik, Giessen, Germany), in a small initial group of 15 patients undergoing cardiac surgery with radial artery harvesting preoperatively and at the second postoperative day, revealing no significant differences in tissue oxygen saturation, postcapillary venous filling pressures, and capillary blood flow at 2- and 8-mm tissue depths.[10] However, the small patient group and the limited postoperative observation period for the assessment of microcirculation prompted us to examine whether radial artery harvesting changes the palmar microcirculation over the long term. We studied 114 patients 25 months after radial artery harvesting for coronary revascularization using detailed spatial analysis of palmar microcirculation at 14 positions at each hand using the real-time quantitative laser Doppler spectrophotometry O2C system . Long-term objective evaluation of superficial and deep palmar microcirculation confirms that radial artery harvesting for coronary revascularization does not compromise palmar microcirculation.[11] A cutoff level of < 67 years of age was identified by microcirculatory monitoring. Beyond this, significant deterioration of palmar microcirculation is more likely to occur.[12] Given these observations among arteriosclerotic patients undergoing coronary revascularization with a mean age of 62 years, one can at least raise the question whether radial artery reconstruction in selective cases with a strong ulnar artery is necessary. Kiehn et al should consider these published reports, mainly from the cardiac surgery specialty, but with certain potential implications for the reconstructive microsurgeon as well.

REFERENCES

• 1 Kiehn M, Brooks D, Lee C, Kind G, Buntic R, Buncke G. Patency of radial arteries reconstructed after radial forearm flap harvest.  J Reconstr Microsurg. 2007;  23 347-350
• 2 Carpentier A, Guermonprez J L, Deloche A, Frechette C, DuBost C. The aorta-to-coronary radial artery bypass graft: a technique avoiding pathological changes in grafts.  Ann Thorac Surg. 1973;  16 111-121
• 3 Desai N D, Cohen E A, Naylor C D, Fremes S E. Radial Artery Patency Study Investigators . A randomized comparison of radial-artery and saphenous-vein coronary bypass grafts.  N Engl J Med. 2004;  351 2302-2309
• 4 Possati G, Gaudino M, Prati F et al.. Long-term results of the radial artery used for myocardial revascularization.  Circulation. 2003;  108(11) 1350-1354
• 5 Chowdhury U K, Airan B, Mishra P K et al.. Histopathology and morphometry of radial artery conduits: basic study and clinical application.  Ann Thorac Surg. 2004;  78 1614-1622
• 6 Chong W C, Ong P J, Hayward C S, Collins P, Moat N E. Effect of radial artery harvesting on forearm function and blood flow.  Ann Thorac Surg. 2003;  75(4) 1171-1174
• 7 Rafael Sadaba J, Conroy J L, Burniston M, Maughan J, Munsch C. Effect of radial artery harvesting on tissue perfusion and function of the hand.  Cardiovasc Surg. 2001;  9(4) 378-382
• 8 Lee H S, Chang B C, Heo Y J. Digital blood flow after radial artery harvest for coronary artery bypass grafting.  Ann Thorac Surg. 2004;  77 2071-2075
• 9 Stead S W, Stirt J A. Assessment of digital blood flow and palmar collateral circulation. Allen's test vs. photoplethysmography.  Int J Clin Monit Comput. 1985;  2 29-34
• 10 Knobloch K, Lichtenberg A, Pichlmaier M, Tomaszek S, Krug A, Haverich A. Palmar microcirculation following harvesting of the radial artery in coronary revascularisation.  Ann Thorac Surg. 2005;  79 1026-1030
• 11 Knobloch K, Tomaszek S, Busch K H, Vogt P M. Palmar microcirculation does not deteriorate 2 years after radial artery harvesting: implications for reconstructive free forearm flap transfer.  Langenbecks Arch Surg. 2007;  392 315-322
• 12 Knobloch K, Tomaszek S, Haverich A, Vogt P M. Age deteriorates palmar microcirculation following radial artery harvesting.  Asian Cardiovasc Thorac Ann. 2007;  15 486-492