1
334 CORRESPONDENCE Ann Thorac Surg 1990;50:33&7 had previously marked the IMA with this technique. I found it to be a substantial aid in avoiding damage to the patent IMA graft. E. Ross Kyger 111, MD, PA Thoracic 6 Cardiovascular Associates of East Texas-Lupin 6 Nacogdoches 609 S ]oh Redditt Dr Lupin, TX 75901 Vein Graft Permeability To the Editor: The interesting article by Finck and co-workers [l] in the Novem- ber 1989 issue of The Annuls describes measurement of whole- tissue radioactivity (counts/g/5 min) of autologous internal jugu- lar vein used as a carotid artery bypass graft in 9 dogs, compared with the ipsilateral internal jugular vein in animals killed 24 hours after injection of label at 1, 2, and 3 months. Further evidence of changes in the arterialized vein are provided by scanning electron microscopy (Fig 28 shows what seem to be three activated platelets, not mentioned in the caption or text) and by staining with Evans blue dye. Not mentioned in the Materials and Methods section is whether tissue counts were corrected for labeled plasma in the specimens by serial sampling of the blood after injection of label. Finck and co-workers have commented on the wide range of values within each group, and the inability to conclude whether radioiodinated albumin uptake was truly in- creasing with time. Using the published values for plasma volume in the dog [2], the range of plasma volume in the animals in this study would be 950 to 1,500 mL, an unknown fraction of which was in the tissue vascular space, which may explain the wide range of values. It would be helpful to know whether tissue radioactivity was corrected by estimates of unbound 1251,and how the time interval of 24 hours for equilibration of exchange- able albumin pools was selected; in humans, this has been reported to be 4 to 5 days [3]. We have had a similar interest, and have found increased '251-labeled albumin flux into human saphenous veins distended at operation in comparison with the same vein before distention [4, 51, and will follow the future work of Finck and co-workers with interest. There is a typographical error in Table 1; the mean difference between graft and control in animals 7 through 9 should be 3.67, not 3.77. John H. Kennedy, M D Department of Molecular Physiology AFRC Institute of Animal Physiology and Genetics Research Babraham, Cambridge, England CB2 4AT Alain Tedgui, PhD INSERM U141 41 Bld de la Chapelle 75475 Paris, France Armand Piwnica, M D Cardiovascular Surgery H6pital Luriboisiere 2, rue Ambroise-Pare 75010 Paris, France References 1. Finck SJ, Mashburn JP, Kottke BA, Orszulak TA. Evaluation of arterialized vein graft permeability with Evans blue dye and iodine 125-labeled albumin. Ann Thorac Surg 1989;48:646-50. Altman PL, Dittmer DS, eds. Biological handbooks, respira- tion and circulation, 147, Blood volumes. Washington, DC: American Physiological Society, 1974:391. Rothschild MA, Bauman A, Yalow RS, Berson SA. Tissue distribution of II3' labeled human serum albumin following intravenous administration. J Clin Invest 1955;34:1354-8. Kennedy JH, Tedgui A, Juan L, Lavergne A, Piwnica A. Effect of preoperative hypertension on 1251 albumin uptake by vein graft media. J Cardiovasc Surg 1989;30:985-8. Kennedy JH, Lever MJ, Addis BJ, Paneth M. Changes in vein interstitium following distension for aortocoronary bypass. J Cardiovasc Surg 1989;30:992-5. Reply To the Editor: We thank Drs Kennedy, Tedgui, and Piwnica for their interest in our recent article. Tissue counts were not corrected for labeled plasma in the specimens. Serial sampling of the blood after the injection of the label would have allowed calculation of the influx rate of albumin into the vein wall (tissue radioactivity divided by specific activity of serum albumin) [l]. Expressing the results in this manner might have narrowed the range of results within each group of dogs. However, because of the small number of dogs in each group, we doubt whether any conclusions could have been drawn about increases in endothelial permeability with time. We chose to harvest our vein grafts 24 hours after administra- tion of Evans blue dye and '251-labeled albumin. This was done, in part, because of our previous experience and work by others with Evans blue dye uptake by arterial endothelium [l, 21. We also chose the 24-hour interval because of reported stable serum iodinated albumin activity at this time [2]. Sanford 1. Finck, M D Mayo Clinic lacksonville Jacksonville, FL 32224 Jay P. Mashburn, M D Bruce A. Kottke, M D Thomas A. Orszulak, M D Mayo Clinic and Mayo Foundation Rochester, M N 55905 References 1. Bell FP, Adamson IL, Schwartz CJ. Aortic endothelial perme- ability to albumin: focal and regional patterns of uptake and transmural distribution of '311-albumin in the young pig. Exp Mol Pathol 1974;20:57-68. 2. Finck S, Walker J, Vaccaro PS, Kakos GS, Howanitz EP, Cornhill JF. The effect of ischemia on canine carotid endothe- lial permeability. J Surg Res 1986;41:419-24. Is Systemic Cooling Essential for Open Heart Surgery? To the Editor: Doctor Bigelow had a dream: "cool the whole body, reduce oxygen requirements, and interrupt the circulation and open the heart" [l]. His dream led to open heart surgery. Today, however, with refined anesthesiology techniques and pump oxygenator systems, cooling the whole body appears superfluous. It would suffice to cool the heart for myocardial protection by infusion of cold cardioplegic solutions. We do not use the cooler of the heat
