© Thieme Medical Publishers
On “Analysis of Flow Changes to the Foot after Sacrifice of One of the Major Arteries (J Reconstr Microsurg 2009;25:35–39)”
12 March 2009 (online)
We read with great interest the recent report from Dr. Sönmez and coworkers analyzing the flow changes to the foot after sacrifice of one of the major arteries. We would like to congratulate the authors on raising the important, albeit somewhat neglected question of compensatory blood flow at the lower extremity. Given the interesting findings in 11 patients (mean age 37 years) analyzed with a mean follow-up of 42 months after end-to-end anastomosis of a free flap to either the anterior or posterior tibial artery, we would like to comment on some issues.
Sacrifice of a major artery at the upper extremity does not necessarily lead to sustained malperfusion. As far as the perfusion of the hand after radial artery harvesting is concerned, the authors cited Doppler ultrasound studies that did not report any sustained impairment of the hand perfusion. Various methods to assess forearm and palmar blood flow have been proposed besides Doppler ultrasound, including forearm plethysmography, technetium-99m–albumin scans, and the clinical Allen's test with or without simultaneous Doppler ultrasound. 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, which is concordant with findings by flow index differences calculated by photoelectric plethysmography.
As far as palmar microcirculation is concerned, combined laser Doppler and spectrophotometry monitoring (oxygen-to-see system, LEA Medizintechnik, Giessen, Germany) did not reveal significant differences within 24 hours postoperatively after radial artery harvesting in a small initial group of 15 patients undergoing cardiac surgery. Subsequently, a large-scale clinical trial among 114 patients at mean 25 months after radial artery harvesting was performed to answer the question of potential long-term impairment of palmar microcirculation. However, using the aforementioned technique in 114 arteriosclerotic patients at 14 palmar positions did not reveal significant changes more than 2 years following radial artery harvesting. As far as age as a contributing factor is concerned, a cutoff value of 67 years was determined by microcirculatory assessment; beyond this age, significant deterioration of palmar microcirculation after radial artery harvesting is more likely to occur in arteriosclerotic patients. However, currently no such plantar microcirculatory mapping has been published to the best of our knowledge, which would be of distinct interest.
The authors mentioned that all examinations were performed at rest. This is an important issue in our view, as baseline perfusion of the foot does not necessarily indicate impairment at exercise as well. In further studies, it would be important to determine whether exercise-induced potential changes of plantar perfusion are encountered in a comparable patient group with only one tibial artery without concomitant vascular disease. Furthermore, the vascular reaction both at rest and after exercise might not be necessarily be the same in arteriosclerotic patients with or without concomitant vascular-active agents. These issues are to be addressed in the future.
Unfortunately, Table 2, illustrating the comparison of Doppler ultrasound values at the operated and nonoperated foot, is likely to be wrong, because all values for diameter, cross-sectional area, Vmax, Vmin, and blood flow are identical, although the Results section indicates changes. This should be addressed in the revised proof in our view.
Given the limited sample size of 11 patients with five end-to-end anastomoses to the posterior and six to the anterior tibial artery, no significant change does not necessarily indicate no impairment. A power analysis, even in a post hoc fashion, might help in this regard to estimate the number of patients needed to detect a significant change in the aforementioned Doppler parameters. However, this study warrants further prospective investigations on a large sample size. Furthermore, it would be interesting to determine which tibial artery is key for the plantar perfusion. In other words, what is the minimum perfusion (or number of anastomosed vessels) to maintain perfusion of the foot sole?
Given the recent reports on composite tissue allotransplantation (CTA) at the upper extremity as well as at the face,  one is tempted to ask when it is time for the lower extremity to be involved. Data from the second report of the International Registry of hand and composite tissue transplantation document 18 male patients receiving 24 hand/forearm/digit transplantations (11 unilateral and four bilateral hand transplantations, two bilateral forearm transplantations, one thumb transplantation) from September 1998 to February 2006.
As far as CTA of the foot is considered, the aforementioned issues are of distinct interest to gain insights in the minimum prerequisites to achieve successful CTA of the lower leg/foot. Thus, we would like to thank the authors especially in the perspective of potential future composite tissue allotransplantation of the leg/foot.
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Dr. Karsten Knobloch, M.D. , Ph.D.
Plastic, Hand and Reconstructive Surgery
Hannover Medical School, Germany