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Hydrophilic guide wire for laser-assisted angioplasty
Volumc9 Number 3 March 1989
Letters to the Editors 507
apy and suffered multiple thrombotic complications after the anticoagulation had worn off. After proper identification of the lupus anticoagulant, these patients were . placed on long-term medications but still experienced subsequent thrombotic complications. Thus in the "Discussion" section ofthe article, we point out the importance ofproper preoperative diagnosis ofthe lupus anticoagulant so that these patients can receive full anticoagulation therapy perioperatively. And, this means preoperative anticoagulation such as heparin, followed by postoperative heparin, 'and then subsequent long-term s0dium warfarin administration (Coumadin) for at least 3 months. Alternative therapy is perioperative administration of corticosteroids for 2 to 4 weeks and life-long. aspirin therapy. Simply covering these patients with anticoagulants during the intraoperative period is not adequate. Once a single thrombotic event OCCW'S, the patient is at an extremely high risk for subsequent thrombotic complications despite, any further anticoagulation therapy. We stated in the "Discussion", page 754, second column, second para.. graph, last sentence, "As shown in these three patients with thrombotic complications reported in our study, institution of these medications intraoperatively after the thrombotic complication has' already occurred may not prevent further thrombotic complications." . Thus Des. Baumgartner, White, and White describe a patient who supports the principles outlined above. 1 thank them for sharing with us their experience. Samuel S. Ahn, MD
AssiStant Professor of Swgery Section of Vascu1ar Surgery UCLACenter for the Health Sciences Los Angeles, CA 90024-1749
Does
~mpliance 'mismatch
alone cause
neoin~ hyperplasia?
To the Editors: We have objections to two important points made by Okuhn et al. in their article, "Does compliance mismatch alone cause neointimal hyperplasia?" (J VAse SURG 1989; 9:35-45.) The first concerns the authors' reference to observed neointimal hyperplasia as being limited to "a single focus (of minimal intimal thickening)" and, therefore, "inconsequential". This appears to contradict the data presented in their Table 11, wherein the R-verage intimal thickness and area at the distal band-artery interface and matching control location, respectively, are given as 38.9 ± ·57.2 versus 8.6 ± 7.9 microns (thickness) and 8.8 ± 11.8 versus 0.7 ± 1.4 mm2 • These average values would be higher if data from two dogs (28%) in which no thickening was observed at all were excluded. Nevertheless they still give 45- and 12.6-fold differences in thickness and area, respectively, between banded and unbanded sides. Considering extreme values, (which we estimate by adding two
standard deviations (95% confidence band) to the mean this difference could be as large as 17- and 46-fold. Banding must have been associated with intimal thickening in some dogs, at least! We grant that the observed variances preclude assigning statistical significance :to these differences, but to ignore the data and conclude instead, that compliance mismatch 'had no effect on intimal thickening seems inappropriate. The second point concerns their assertion that "exuberant near occlusiPe neointimal hyperplasia" in the PTFE side-arms verifies the animals' capacity to "mount a neointimal hyperplastic response". We share the authors' conceIt) over the possibility that their animals might belong to a subgroup of dogs that tends to have a more passive response to mitogenic stimuli,· and thus, might have been "incapable" of experiencing neointimal hyperplasia in the presence of an intact (nonthrombogenic) endothelialluminal surface. Nevertheless, to use histological results from occludetl PTFE side-arms that experienced no blood flow for 3 months or more as evidence of the animals' being capable of experiencing neointimal hyperplasia seems inappropriate. In~ hyperplasia, near-occlusive or otherwise, cannot occur -in .·a vessel that is already occluded! Three months is enough time for host cells to infiltrate and ~organize" thrombus to the point ofhaving the appearance of neointimal hyperplasia. Because of this, our vascular pathologist is usually unwilling to differentiate between the two, especially when grafts are known to have occluded long before explantation. It seems to us, therefore, that observations of "intimal thickness" related to the PTFE side-arms bear no relevance to the authors' conclusions regarding their animals' biochemistry or hematology or' both. Okuhn et ai. thus present data that show substantial'. effecrsof incompliant banding in at least some dogs, and raise the possibility,· which they cannot disprove, that their animals might not -have been ~apable of mounting a hyperplastic response. Yet they too readily conclude that compliance ~smatch alone is an insufficient stimulus for the development of neointimal hyperplasia. Based on our own work, we happe~ to agree with that conclusion, but we believe that the results presented herein do not support it. William M. Abbott, MD
Joseph Megeiman, PhD Depamnent of Swgery Massachusetts General Hospital Boston, MA 02114
Hydrophilic guide wire for laser-assisted angioplasty To the Editors: We read with interest the enlightened experience of Diethrich et al. (J VAse SURG 1988;8:201-2) with the Terumo guide wire (Glidewire, Medi-tech). As interventionalists and nonsurgeons, we too have had a very positive
Letters to the Editors 507
apy and suffered multiple thrombotic complications after the anticoagulation had worn off. After proper identification of the lupus anticoagulant, these patients were . placed on long-term medications but still experienced subsequent thrombotic complications. Thus in the "Discussion" section ofthe article, we point out the importance ofproper preoperative diagnosis ofthe lupus anticoagulant so that these patients can receive full anticoagulation therapy perioperatively. And, this means preoperative anticoagulation such as heparin, followed by postoperative heparin, 'and then subsequent long-term s0dium warfarin administration (Coumadin) for at least 3 months. Alternative therapy is perioperative administration of corticosteroids for 2 to 4 weeks and life-long. aspirin therapy. Simply covering these patients with anticoagulants during the intraoperative period is not adequate. Once a single thrombotic event OCCW'S, the patient is at an extremely high risk for subsequent thrombotic complications despite, any further anticoagulation therapy. We stated in the "Discussion", page 754, second column, second para.. graph, last sentence, "As shown in these three patients with thrombotic complications reported in our study, institution of these medications intraoperatively after the thrombotic complication has' already occurred may not prevent further thrombotic complications." . Thus Des. Baumgartner, White, and White describe a patient who supports the principles outlined above. 1 thank them for sharing with us their experience. Samuel S. Ahn, MD
AssiStant Professor of Swgery Section of Vascu1ar Surgery UCLACenter for the Health Sciences Los Angeles, CA 90024-1749
Does
~mpliance 'mismatch
alone cause
neoin~ hyperplasia?
To the Editors: We have objections to two important points made by Okuhn et al. in their article, "Does compliance mismatch alone cause neointimal hyperplasia?" (J VAse SURG 1989; 9:35-45.) The first concerns the authors' reference to observed neointimal hyperplasia as being limited to "a single focus (of minimal intimal thickening)" and, therefore, "inconsequential". This appears to contradict the data presented in their Table 11, wherein the R-verage intimal thickness and area at the distal band-artery interface and matching control location, respectively, are given as 38.9 ± ·57.2 versus 8.6 ± 7.9 microns (thickness) and 8.8 ± 11.8 versus 0.7 ± 1.4 mm2 • These average values would be higher if data from two dogs (28%) in which no thickening was observed at all were excluded. Nevertheless they still give 45- and 12.6-fold differences in thickness and area, respectively, between banded and unbanded sides. Considering extreme values, (which we estimate by adding two
standard deviations (95% confidence band) to the mean this difference could be as large as 17- and 46-fold. Banding must have been associated with intimal thickening in some dogs, at least! We grant that the observed variances preclude assigning statistical significance :to these differences, but to ignore the data and conclude instead, that compliance mismatch 'had no effect on intimal thickening seems inappropriate. The second point concerns their assertion that "exuberant near occlusiPe neointimal hyperplasia" in the PTFE side-arms verifies the animals' capacity to "mount a neointimal hyperplastic response". We share the authors' conceIt) over the possibility that their animals might belong to a subgroup of dogs that tends to have a more passive response to mitogenic stimuli,· and thus, might have been "incapable" of experiencing neointimal hyperplasia in the presence of an intact (nonthrombogenic) endothelialluminal surface. Nevertheless, to use histological results from occludetl PTFE side-arms that experienced no blood flow for 3 months or more as evidence of the animals' being capable of experiencing neointimal hyperplasia seems inappropriate. In~ hyperplasia, near-occlusive or otherwise, cannot occur -in .·a vessel that is already occluded! Three months is enough time for host cells to infiltrate and ~organize" thrombus to the point ofhaving the appearance of neointimal hyperplasia. Because of this, our vascular pathologist is usually unwilling to differentiate between the two, especially when grafts are known to have occluded long before explantation. It seems to us, therefore, that observations of "intimal thickness" related to the PTFE side-arms bear no relevance to the authors' conclusions regarding their animals' biochemistry or hematology or' both. Okuhn et ai. thus present data that show substantial'. effecrsof incompliant banding in at least some dogs, and raise the possibility,· which they cannot disprove, that their animals might not -have been ~apable of mounting a hyperplastic response. Yet they too readily conclude that compliance ~smatch alone is an insufficient stimulus for the development of neointimal hyperplasia. Based on our own work, we happe~ to agree with that conclusion, but we believe that the results presented herein do not support it. William M. Abbott, MD
Joseph Megeiman, PhD Depamnent of Swgery Massachusetts General Hospital Boston, MA 02114
Hydrophilic guide wire for laser-assisted angioplasty To the Editors: We read with interest the enlightened experience of Diethrich et al. (J VAse SURG 1988;8:201-2) with the Terumo guide wire (Glidewire, Medi-tech). As interventionalists and nonsurgeons, we too have had a very positive