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With regard to “The role of air plethysmography in monitoring results of venous surgery”
JOURNAL OF VASCULAR SURGERY
Volume 18, Number 1
Sayers et al. seems to be similar in nature to ours, 1 there are important differences with respect to tissue procurement and methodology. In our study, tissue was randomly harvested from either the proximal or distal greater saphenous vein mink. Sayers et al. harvested tissue only near the saphenofemoral junction. Because the vascular reactivity can vary among proximal and distal greater saphenous vein, it is difficult to compare the results. Histologic study of superficial veins from patients with primary varicosity show a remarkable heterogeneous involvement of vein wall thinning and fibrosis, which may make evaluation of short isolated segments misleading. We chose to randomly sample along the saphenous vein and pool the results to better assess each patient's overall vascular reactivity. We evaluated 5 mm rings, maintaining the circular architecture, compared to rectangular strips used in the study by Sayers et al. Age is an additional factor to be considered. Ages in our control and varicose groups were compatible. Because senescence can mimic varicose changes, it is important to control for this variable. A younger mean age of the patient group may account for some of the differences in endothelial and smooth muscle cell fimction. Optimal tension and maximal contraction to norepinephrine were about the same for our controls compared with the values given by Sayers et al. This similarity validates comparable in vitro techniques. However, the maximal contractions to norepinephrine in the diseased segments in our study were significantly less than those observed by Sayers et al. The reasons for this are unclear. It may be a reflection of location of the harvested segments, individual severity of the disease or the presence of cocaine in the incubation media (used only by Sayers et al.). Cocaine inhibits the neuronal uptake of norepinephrine and it is not clear whether the uptake or metabolism of the norepinephrine is altered in varicose compared with control veins. Direct comparisons of relaxations cannot be made, because different agents (acetylcholine and nitroprusside) were used by Sayers et al. We chose not to use acetylcholine, because previous work by Luscheta had demonstrated weak or absent relaxation in human greater saphenous vein. We tested the effects of the calcium ionophore A23187, forskolin, and nitric oxide. Relaxations to agents (nitric oxide, forskolin) that cause endothelium-dependent relaxation by different intracellular pathways were impaired in diseased saphenous veins. In summary, although there are similarities between our study and that of Sayers et al., differences in the location of tissue samples and methods make it difficult to compare results effectively. We found differences in structure and function of the endothdium and smooth muscle when we compared pooled, random samples, taken at different levels of greater saphenous vein from patients with primary varicosity, with normal controls. Additional studies comparing responses between proximal and distal
Letters to the Editors
139
superficial veins from patients with primary varicosity are warranted. C. LoweZl,MD Peter Gloviczki, 3423 Virginia A~I. Miller, PhD
Vasoalar Surgery Mayo Clinic 200 First St. S.W. Rochester, MN 55905
REFERENCES 1. Lowell RC, Gloviczki P, Miller VM. In vitro evaluation of endothelial and smooth muscle function of primary varicose veins. J VAsc SURG1992;16:679-86. 2. Luscher TF. Endothelium-derived vasoacfive factors and regulation of vascular tone in human blood vessels. Lung 1990;l(suppl):27-34. 24/41]46559
With regard to "The role o f air plethysmography in monitoring results o f venous surgery" To the Editors:
We read with interest the article by GiUespie et al. (J VASC SURG 1992;16:674-8) in which the preoperative and postoperative venous function tests as measured by air plethysmography (APG) are compared in 25 limbs. This article endorses the use of APG, because the measurements obtained showed improvement in the various indexes measured after appropriate surgery, but no comparison with other measurements was undertaken. To date, there has been no independent study comparing the use of APG with the established "gold standard" of ambulatory venous pressure (AVP) measurement. In the methods section the authors state that "residual volume fraction (RVF) correlates directly with ambulatory venous pressure"; this statement is presumably taken from the work of Christopoulos et al.,1 because no data are presented to support this statement. In the discussion, however, the authors state that "volume changes of the leg measured by A P G . . . do not necessarily reflect changes in lower extremity venous pressure, probably because of venous compliance." These statements seem to be contradictory and are unsupported by any data in this article. We agree, however, with the latter statement that changes in venous volume do not necessarily reflect changes in venous pressure. We have studied 103 limbs with different grades of venous insufficiency by APG and AVP measurement to determine the relationship between AVP and RVF. 2 We found a Spearman correlation coefficient of only 0.03 between RVF and AVP, which suggests that the measurement of RVF should not be used as a substitute for AVP, the accepted "gold
140
JOURNALOF VASCULARSURGERY July 1993
Letters to the Editors
standard" measurement of venous fimction. We agree that the lack of correlation is probably due to differences in venous compliance (which does not have a linear relationship with pressure even when measured on just one vein). S. P. IC Payne, MBChB, FRCS A. J. Thrush, MSc N. J. M. London, MD, FRCS, MRCP P. R. F. Bell, M,D, FRCS W. W. Barrie, MD, FRCS
Department of Surgery University of Leicester PO Box 65 Leicester LE2 7LX United Kingdom REFERENCES 1. Chrisropoulos D, Nicolaides AN, Galloway JM, Wilkinson A. Objective noninvasive evaluation of venous surgical results. J VASCSURG 1988;8:683-7. 2. Payne SPK, Thrush AJ, London NJM, Bell PRF, Barrie WW. Venous assessment using air-plethysmography; a comparison with clinical examination, ambulatory venous pressure and duplex assessment. Br J Surg (in press). 24/41/47127
Reply To the Editors:
Payne et al. are correct; our reference stating that "residual volume fraction (RVF) correlates directly with ambulatory venous pressure" was described by Christopoulos et al.1 The lack of reference was an oversight. We did not attempt to validate previous work correlating RVF with ambulatory venous pressure. In our studies we have not found the measurement of RVF to be a reliable parameter with which to monitor the results of corrective venous surgery. In addition, work at our institution has been unable to show a correlation between RVF and pattern of disease (i.e., varicose veins or chronic venous insufficiency). 2 Our data tend to agree with the findings ofPayne et al. that there is no correlation between ambulatory venous pressure and RVF. David L. Gillespie,M D
Section of Vascular Surgery Division of Surgery Boston University Medical Center 88 E. Newton St. Boston, MA 02118 REFERENCES 1. Christopoulos D, Nicolaides AN, Cook A, Galloway JMD, Wilkinson A. Pathogenesis of venous ulceration in relation to the calf muscle pump fimction. Surgery 1989;106:829-35. 2. Cordts PR, Hartono C, LaMorte WW, Menzoian JO. Physiologic similarities between extremities with varicose veins and with chronic venous insufficiency utilizing air plethysmography. Am J Surg 1992;164:260-4. 24/41/47128
Regarding "Treatment of iatrogenic femoral artery injuries with ultrasound-guided compression" To the Editors:
The recent article by Feld et al.1 seems to provide further evidence that ultrasound-guided compression repair (UGCR) may have a role to play in the treatment of pseudoaneurysms caused by transfemoral arterial catheterization. In light of the conclusions drawn, we want to raise certain points that we believe are relevant to the current debate surrounding the optimal management of these iatrogenic problems. The authors did not state the total numbers of each type of transfemoral procedure performed at their institution during the study period. They also did not mention whether any patients subjected to these invasive procedures required surgical intervention without previous color Doppler ultrasonography. Such information must be regarded as essential to the assessment o f this new mode of treatment. When color duplex scans were obtained routinely in patients who had undergone cardiac catheterization, up to 6.25% of patients were found to have pseudoaneurysms. 2 Most of these thrombose spontaneously. In a report on UGCR, 2780 cardiac catheterizations were complicated by 24 symptomatic pseudoaneurysms (0.86%), 10 of which were successfully treated by compression, but the remaining 14 required surgical repair (0.5%). 3 Before the advent of duplex ultrasound investigation, the reported incidence of pseudoaneurysms requiring surgery after cardiac catheterization was 0.2% to 0.42%. 4 Although it is accepted that direct comparisons of figures from different institutions may not be possible, it is clear, nevertheless, that there is little evidence to show that U G C R has decreased the need for operative repair of these iatrogenic injuries. It might be argued that the increased application of color Doppler ultrasonography has simply resulted in increased numbers of pseudoaneurysms being diagnosed, most of which would have thrombosed without recourse to UGCR. Rupture of a pseudoaneurysm remains a potentially fatal condition, an unfortunate outcome that became a reality when one pseudoaneurysm, identified by color Doppler scanning, did not undergo surgery. 5 Although Feld et al. recommend operation in cases of "imminent rupture," in our experience most pseudoaneurysms that go on to rupture do so without any warning signs.* In our review of the surgical management of 50 such pseudoaneurysms, 12 had ruptured, all within 6 days of catheterization, causing shock in six cases, distal ischemia in three, and stroke in one case.* Rupture was significantly more common in patients over 65 years of age, in those receiving anticoagulants when catheterized, and in those with hepatic congestion resulting from congestive heart failure. We recommend that pseudoaneurysms in patients such as these are at increased risk of rupture and should be repaired without delay. Whereas a nonoperative method of treatment such as U G C R represents an attractive and promising option in managing iatrogenic femoral artery pseudoaneurysms, we
Volume 18, Number 1
Sayers et al. seems to be similar in nature to ours, 1 there are important differences with respect to tissue procurement and methodology. In our study, tissue was randomly harvested from either the proximal or distal greater saphenous vein mink. Sayers et al. harvested tissue only near the saphenofemoral junction. Because the vascular reactivity can vary among proximal and distal greater saphenous vein, it is difficult to compare the results. Histologic study of superficial veins from patients with primary varicosity show a remarkable heterogeneous involvement of vein wall thinning and fibrosis, which may make evaluation of short isolated segments misleading. We chose to randomly sample along the saphenous vein and pool the results to better assess each patient's overall vascular reactivity. We evaluated 5 mm rings, maintaining the circular architecture, compared to rectangular strips used in the study by Sayers et al. Age is an additional factor to be considered. Ages in our control and varicose groups were compatible. Because senescence can mimic varicose changes, it is important to control for this variable. A younger mean age of the patient group may account for some of the differences in endothelial and smooth muscle cell fimction. Optimal tension and maximal contraction to norepinephrine were about the same for our controls compared with the values given by Sayers et al. This similarity validates comparable in vitro techniques. However, the maximal contractions to norepinephrine in the diseased segments in our study were significantly less than those observed by Sayers et al. The reasons for this are unclear. It may be a reflection of location of the harvested segments, individual severity of the disease or the presence of cocaine in the incubation media (used only by Sayers et al.). Cocaine inhibits the neuronal uptake of norepinephrine and it is not clear whether the uptake or metabolism of the norepinephrine is altered in varicose compared with control veins. Direct comparisons of relaxations cannot be made, because different agents (acetylcholine and nitroprusside) were used by Sayers et al. We chose not to use acetylcholine, because previous work by Luscheta had demonstrated weak or absent relaxation in human greater saphenous vein. We tested the effects of the calcium ionophore A23187, forskolin, and nitric oxide. Relaxations to agents (nitric oxide, forskolin) that cause endothelium-dependent relaxation by different intracellular pathways were impaired in diseased saphenous veins. In summary, although there are similarities between our study and that of Sayers et al., differences in the location of tissue samples and methods make it difficult to compare results effectively. We found differences in structure and function of the endothdium and smooth muscle when we compared pooled, random samples, taken at different levels of greater saphenous vein from patients with primary varicosity, with normal controls. Additional studies comparing responses between proximal and distal
Letters to the Editors
139
superficial veins from patients with primary varicosity are warranted. C. LoweZl,MD Peter Gloviczki, 3423 Virginia A~I. Miller, PhD
Vasoalar Surgery Mayo Clinic 200 First St. S.W. Rochester, MN 55905
REFERENCES 1. Lowell RC, Gloviczki P, Miller VM. In vitro evaluation of endothelial and smooth muscle function of primary varicose veins. J VAsc SURG1992;16:679-86. 2. Luscher TF. Endothelium-derived vasoacfive factors and regulation of vascular tone in human blood vessels. Lung 1990;l(suppl):27-34. 24/41]46559
With regard to "The role o f air plethysmography in monitoring results o f venous surgery" To the Editors:
We read with interest the article by GiUespie et al. (J VASC SURG 1992;16:674-8) in which the preoperative and postoperative venous function tests as measured by air plethysmography (APG) are compared in 25 limbs. This article endorses the use of APG, because the measurements obtained showed improvement in the various indexes measured after appropriate surgery, but no comparison with other measurements was undertaken. To date, there has been no independent study comparing the use of APG with the established "gold standard" of ambulatory venous pressure (AVP) measurement. In the methods section the authors state that "residual volume fraction (RVF) correlates directly with ambulatory venous pressure"; this statement is presumably taken from the work of Christopoulos et al.,1 because no data are presented to support this statement. In the discussion, however, the authors state that "volume changes of the leg measured by A P G . . . do not necessarily reflect changes in lower extremity venous pressure, probably because of venous compliance." These statements seem to be contradictory and are unsupported by any data in this article. We agree, however, with the latter statement that changes in venous volume do not necessarily reflect changes in venous pressure. We have studied 103 limbs with different grades of venous insufficiency by APG and AVP measurement to determine the relationship between AVP and RVF. 2 We found a Spearman correlation coefficient of only 0.03 between RVF and AVP, which suggests that the measurement of RVF should not be used as a substitute for AVP, the accepted "gold
140
JOURNALOF VASCULARSURGERY July 1993
Letters to the Editors
standard" measurement of venous fimction. We agree that the lack of correlation is probably due to differences in venous compliance (which does not have a linear relationship with pressure even when measured on just one vein). S. P. IC Payne, MBChB, FRCS A. J. Thrush, MSc N. J. M. London, MD, FRCS, MRCP P. R. F. Bell, M,D, FRCS W. W. Barrie, MD, FRCS
Department of Surgery University of Leicester PO Box 65 Leicester LE2 7LX United Kingdom REFERENCES 1. Chrisropoulos D, Nicolaides AN, Galloway JM, Wilkinson A. Objective noninvasive evaluation of venous surgical results. J VASCSURG 1988;8:683-7. 2. Payne SPK, Thrush AJ, London NJM, Bell PRF, Barrie WW. Venous assessment using air-plethysmography; a comparison with clinical examination, ambulatory venous pressure and duplex assessment. Br J Surg (in press). 24/41/47127
Reply To the Editors:
Payne et al. are correct; our reference stating that "residual volume fraction (RVF) correlates directly with ambulatory venous pressure" was described by Christopoulos et al.1 The lack of reference was an oversight. We did not attempt to validate previous work correlating RVF with ambulatory venous pressure. In our studies we have not found the measurement of RVF to be a reliable parameter with which to monitor the results of corrective venous surgery. In addition, work at our institution has been unable to show a correlation between RVF and pattern of disease (i.e., varicose veins or chronic venous insufficiency). 2 Our data tend to agree with the findings ofPayne et al. that there is no correlation between ambulatory venous pressure and RVF. David L. Gillespie,M D
Section of Vascular Surgery Division of Surgery Boston University Medical Center 88 E. Newton St. Boston, MA 02118 REFERENCES 1. Christopoulos D, Nicolaides AN, Cook A, Galloway JMD, Wilkinson A. Pathogenesis of venous ulceration in relation to the calf muscle pump fimction. Surgery 1989;106:829-35. 2. Cordts PR, Hartono C, LaMorte WW, Menzoian JO. Physiologic similarities between extremities with varicose veins and with chronic venous insufficiency utilizing air plethysmography. Am J Surg 1992;164:260-4. 24/41/47128
Regarding "Treatment of iatrogenic femoral artery injuries with ultrasound-guided compression" To the Editors:
The recent article by Feld et al.1 seems to provide further evidence that ultrasound-guided compression repair (UGCR) may have a role to play in the treatment of pseudoaneurysms caused by transfemoral arterial catheterization. In light of the conclusions drawn, we want to raise certain points that we believe are relevant to the current debate surrounding the optimal management of these iatrogenic problems. The authors did not state the total numbers of each type of transfemoral procedure performed at their institution during the study period. They also did not mention whether any patients subjected to these invasive procedures required surgical intervention without previous color Doppler ultrasonography. Such information must be regarded as essential to the assessment o f this new mode of treatment. When color duplex scans were obtained routinely in patients who had undergone cardiac catheterization, up to 6.25% of patients were found to have pseudoaneurysms. 2 Most of these thrombose spontaneously. In a report on UGCR, 2780 cardiac catheterizations were complicated by 24 symptomatic pseudoaneurysms (0.86%), 10 of which were successfully treated by compression, but the remaining 14 required surgical repair (0.5%). 3 Before the advent of duplex ultrasound investigation, the reported incidence of pseudoaneurysms requiring surgery after cardiac catheterization was 0.2% to 0.42%. 4 Although it is accepted that direct comparisons of figures from different institutions may not be possible, it is clear, nevertheless, that there is little evidence to show that U G C R has decreased the need for operative repair of these iatrogenic injuries. It might be argued that the increased application of color Doppler ultrasonography has simply resulted in increased numbers of pseudoaneurysms being diagnosed, most of which would have thrombosed without recourse to UGCR. Rupture of a pseudoaneurysm remains a potentially fatal condition, an unfortunate outcome that became a reality when one pseudoaneurysm, identified by color Doppler scanning, did not undergo surgery. 5 Although Feld et al. recommend operation in cases of "imminent rupture," in our experience most pseudoaneurysms that go on to rupture do so without any warning signs.* In our review of the surgical management of 50 such pseudoaneurysms, 12 had ruptured, all within 6 days of catheterization, causing shock in six cases, distal ischemia in three, and stroke in one case.* Rupture was significantly more common in patients over 65 years of age, in those receiving anticoagulants when catheterized, and in those with hepatic congestion resulting from congestive heart failure. We recommend that pseudoaneurysms in patients such as these are at increased risk of rupture and should be repaired without delay. Whereas a nonoperative method of treatment such as U G C R represents an attractive and promising option in managing iatrogenic femoral artery pseudoaneurysms, we