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Iliofemoral versus femorofemoral bypass: a 6-year audit
ABSTRACTS James S. T. Yao, MD, Abstracts
Section Editor
Cellular biology of human intimal hyperplastic stenosis Chan P, Munro E, Pate1 M, et al. Eur J Vast Surg 1993;7: 129-35. Rackground: Graft stenosis after bypass is a significant problem. The authors of this study examined the following hypothesis: intrinsic differences exist in the growth characteristics of the smooth muscle cells (SMC) from patients in whom clinically significant bypass graft stenosis develops as compared with those patients who undergo primary bypass. Specifically, the authors sought to determine whether there were differences in the ability of heparin to inhibit growth of SMC derived from patients with graft stenosis compared with those undergoing primary bypass. The authors also characterized the growth rates of cells from artery, vein, atherosclerotic plaque, and stenotic graft lesions. Methods and Results: SMC cultures were derived from explants of tissue obtained from stenotic lesions of patients undergoing revision surgery, normal-appearing saphenous vein of patients undergoing graft revision for stenosis, artery and vein from patients undergoing primary cardiac or peripheral vascular surgery, and atherosclerotic plaque from endarterectomy specimens. The identity of the SMC was verified by alpha actin staining and morphologic appearance. The growth rate of the cells from each of the different groups did not differ with regard to the time taken for cells to migrate from the explant culture or time to achieve confluence. It proved to be more difficult to grow cells from atherosclerotic plaque than from any of the other tissues. Heparin inhibited the growth of SMC derived from the vein of patients undergoing primary operation but did not inhibit the growth of SMC derived from the normalappearing vein or the stenotic lesion of those undergoing revision for graft stenosis. Summary: There was no diff‘erence noted in the growth rate of SMC regardless of whether they were derived from artery, vein, stenotic lesion, or atherosclerotic plaque. The inhibitory effect of heparin was markedly reduced in SMC derived from vein of patients with graft stenosis. This suggests that patients undergoing revision surgery have an intrinsic difference in their SMC population that predisposes them to hyperplasia and restenosis. Comments: The authors have made an important observation that mav prove useful in identification of patients at risk for reitenosis after angioplasty and bypass. The potential clinical implications include the selection of revascularization procedures, graft surveillance protocols, and patient selection for trials of pharmacologic agents that inhibit SMC hyperplasia. A more succinct presentation of the important points of this study was published in Lancet 1993;341:341-2. II. Tim&by Baxter, MD Universiy of Nebraska Medical @naba, Neb.
<;entev
494 Journal
Surgery/September
of Vascular
Proliferation of human smooth muscle cells promoted by lipoprotein(a) Grainger DJ, Kirschenlohr HL, Metcalfe JC, Weissberg PL, Wade DP, Lawn RM. Science 1993;260:1655-8. Background: Lipoprotein(a) (Lp[a]) is a unique lipoprotein composed of a low-density lipoprotein with the glycoprotein ape(a) attached to ape(B). Ape(a) has 80% homology to plasminogen but has no plasminogen-like activity. Epidemiologic studies have identified the plasma level of Lp(a) as a major risk factor for both coronary and peripheral atherosclerosis. In this report, Grainger et al. examined the effect of Lp(a) on the proliferation of human and rat vascular smooth muscle cells (VSMC) in tissue culture. Methods and Results: Lp(a) stimulated human VSIVIC growth in a dose-dependant manner. The effect of recombinant ape(a) alone was similar, although higher molx concentrations were required. Low-density lipoprotein had no effect. None of these compounds affected the doubling time of rat VSMC. The authors examined the mechanism by which Lp(d~ and ape(a) stimulated proliferation. Ape(a) shares considerable homology with hepatocyte growth factor, suggesting that ape(a) could directly stimulate cellular proliferdtion. Another possibility was that Lp(a) could comperitively inhibit the activation of transforming growth factor beta (TGF-P) by plasminogen. TGF-P is secreted by human VSMC and reduces VSMC proliferation whell activated. In a series of experiments, the authors demonstrated that, indeed, ape(a) is a competitive inhibitor of the plasminogen activation of TGF-P. Rat VSMC do not produce TGF-P in culture, and Lp(a) did not stimulate proliferation in these cells. Summary and Comments: Lp(a) is an intriguing particle. There is strong evidence for its involvement in both coronary artery and peripheral vascular atherosclerosis. The data presented by Granger et al. suggest that Lp(a) promotes VSMC proliferation, which would promote both atherosclerosis and intimal hyperplasia. Because an increasing number of lipid laboratories now can measure Lp(a) levels, we may soon have clinical data to confirm whether Lp(a) is an important factor in intimal hyperplasia, as suggested by these convincing in vitro data. Unfortunately, unlike the other lipid abnormalities that are associated with an increased risk of primary atherosclerosis and hyperplasia, at present there is limited ability to alter plasma levels of Lp(a). Joseph H. Rae, MD University of California, San Francisco, Calif:
San Francisco
Iliofemoral versus femorofemoral bypass: a 6-year audit Ng RLH, Gillies TE, Davies AH, Baird RN, Horrocks M. Br J Surg 1992;79:1011-3. 1994
JOURNAL OF VASCULAR Volume 20, Number 3
Bukground:
SURGERY
Abstracts
To compare
the patency, morbidity, and versus femorofemoral bypass for unilateral iliac artery occlusive disease, the results of a 6-year experience at one center were retrospectively reviewed. Methods and Results: From 1984 to 1990, 226 patients underwent 231 operations. The study group consisted of 183 men and 43 women with a mean age of 67 (range 43 to 94) years. Seventy-two patients had 75 iliofemoral grafts, and 154 patients had 156 femorofemoral grafts. Synthetic graft material, usually Dacron, was routinely used, although 1% of the iliofemoral group and 1.9% of the femorofemoral group had reversed vein grafts. Initial data were obtained from a computer database supplemented from the patient records. Late follow-up was obtained by outpatient visits in mid 1991 or by direct telephone contact or indirectly via their general practitioners. Cumulative survival and primary patency rates were calculated. Patients who died or were lost to follow-up were excluded from each interval in the patency calculations. Indications for operation and the incidence of preoperative risk factors were similar for both groups. The numbers of iliofemoral bypass performed each year of the study remained relatively constant, whereas the annual number of femorofemoral bypass procedures steadily increased. The early postoperative mortality rate was 6% (4 of 72) in the ihofemoral group and 1.3% (2 of 154) in the femorofemoral group. Early reoperation rates were 11% (8 of 75) for iliofemoral bypass and 5.1% (8 of 156) for the femorofemoral procedure. Combined early and late reoperation rates were 31% for the iliofemoral group and 16% for the femorofemoral group. The contralateral reoperation rate in the iliofemoral group (8%) was not significantly increased over that (4.5%) of the femorofemoral group. Themean length of hospital stay for the iliofemoral bypass (10.7 days) was significantly longer than that for the femorofemoral bypass (8.6 days) (p < 0.05). The femorofemoral procedure resulted in significantly higher 6-year cumulative patency (92% vs 75%) and survival rates (74% vs 55%) than did the iliofemoral operation (p < 0.01). Summary: The authors concluded that femorofemoral bypass may be a more favorable option than iliofemoral bypass, with a significantly shorter hospital stay and lower complication and reoperation rates. Comments: The number of grafts lost to follow-up or lost because of patient death in each interval were not specified in the patency analysis, and there were less than 10 grafts in each group at 6-year follow-up. The p values for comparisons of the reoperation and early mortality rates were not specified. All of the conclusions of the authors of this retrospective review may not be fully justified by the data.
mortalityrates associated with iliofemoral
J. O’Hava, MD ClevelandClinic Foundation Cleveland,Ohio
Patrick
Combined carotid and coronary revascularization: preferred approach to the severe vasculopath
the
495
Rizzo RJ, Whittemore AD, Couper GS, et al. Ann Thorac Surg 1992;54: 1099- 109. Backpound: The optimal management plan to minmize both perioperative stroke after coronary artery bypass grafting (CABG) and perioperative myocardial infarction (MI) after carotid endarterectomy (CEA) remains elusive. Addressing this issue, investigators from the divisions of cardiac and vascular surgery of Brigham and Women’s Hospital, Boston, surveyed retrospectively the outcome after two-team combined CEA and coronary artery revascularization performed for 127 patients over a 13-year interval (1978 to 1991). The authors considered this cohort of patients to represent a particularly high-risk group because of the multiple system extent of their clinically apparent atherosclerotic disease. Methods and Results: When possible, these investigators choose not to perform CEA or CABG in isolation for patients with clinically significant atherosclerotic involvement in both arterial segments. In this study, 75% had New York Heart Association functional class III or IV, 38% had left main coronary artery disease, 28% had a left ventricular ejection fraction less than 0.5, whereas six (5%) required a preoperative intraaortic balloon pump. One third of all patients had asymptomatic carotid artery disease, whereas 70% of those with symptoms had a history of transient ischemic attacks, and the remaining 26 patients had had a previous stroke. Fifty-nine percent had bilateral carotid artery disease, and 16% had contralateral carotid artery occlusion. The authors acknowledge that a strict protocol for patient selection for carotid artery screening, carotid angiography, and choice of carotid artery to select for endarterectomy in the event of bilateral asymptomatic disease was lacking in this retrospective survey. Overall there were eight (6.3%) perioperative strokes, seven (5.5%) of which were permanent. Six of these eight events were ipsilateral to the CEA. Additionally, there were two (1.6%) perioperative transient ischemic attacks, one ipsilateral to the carotid artery operation and seven (5.5%) heart-related deaths. Three of these deaths followed a perioperative MI, whereas three other perioperative MIS were not fatal. Importantly, there were no strokes in the asymptomatic carotid artery group. Stroke was 15% in patients with contralateral carotid artery occlusion and 19% in those with prior stroke. The mean carotid artery clamp time in the patients not needing a shunt was 31 minutes. Mean aortic clamp time for CABG was 41 minutes, whereas mean cardiopulmonary bypass time was 77 minutes. Although there was no control group available for comparison, during a concurrent 8-year subsegment of the study period, the same vascular surgery team posted 482 isolated CEA operations, with perioperative death and permanent stroke rates of 0.6% and 1.5%, respectively. Likewise, during a concurrent 4-year subsegment of the study period the same cardiac surgical team posted 3012 isolated CABG operations, with perioperative death and permanent stroke rates of 4.0% and l.O%, respectively. Additional late mortality and morbidity events were reported to confirm the “vasculopathic” characteristics of this 127-patient cohort.
Section Editor
Cellular biology of human intimal hyperplastic stenosis Chan P, Munro E, Pate1 M, et al. Eur J Vast Surg 1993;7: 129-35. Rackground: Graft stenosis after bypass is a significant problem. The authors of this study examined the following hypothesis: intrinsic differences exist in the growth characteristics of the smooth muscle cells (SMC) from patients in whom clinically significant bypass graft stenosis develops as compared with those patients who undergo primary bypass. Specifically, the authors sought to determine whether there were differences in the ability of heparin to inhibit growth of SMC derived from patients with graft stenosis compared with those undergoing primary bypass. The authors also characterized the growth rates of cells from artery, vein, atherosclerotic plaque, and stenotic graft lesions. Methods and Results: SMC cultures were derived from explants of tissue obtained from stenotic lesions of patients undergoing revision surgery, normal-appearing saphenous vein of patients undergoing graft revision for stenosis, artery and vein from patients undergoing primary cardiac or peripheral vascular surgery, and atherosclerotic plaque from endarterectomy specimens. The identity of the SMC was verified by alpha actin staining and morphologic appearance. The growth rate of the cells from each of the different groups did not differ with regard to the time taken for cells to migrate from the explant culture or time to achieve confluence. It proved to be more difficult to grow cells from atherosclerotic plaque than from any of the other tissues. Heparin inhibited the growth of SMC derived from the vein of patients undergoing primary operation but did not inhibit the growth of SMC derived from the normalappearing vein or the stenotic lesion of those undergoing revision for graft stenosis. Summary: There was no diff‘erence noted in the growth rate of SMC regardless of whether they were derived from artery, vein, stenotic lesion, or atherosclerotic plaque. The inhibitory effect of heparin was markedly reduced in SMC derived from vein of patients with graft stenosis. This suggests that patients undergoing revision surgery have an intrinsic difference in their SMC population that predisposes them to hyperplasia and restenosis. Comments: The authors have made an important observation that mav prove useful in identification of patients at risk for reitenosis after angioplasty and bypass. The potential clinical implications include the selection of revascularization procedures, graft surveillance protocols, and patient selection for trials of pharmacologic agents that inhibit SMC hyperplasia. A more succinct presentation of the important points of this study was published in Lancet 1993;341:341-2. II. Tim&by Baxter, MD Universiy of Nebraska Medical @naba, Neb.
<;entev
494 Journal
Surgery/September
of Vascular
Proliferation of human smooth muscle cells promoted by lipoprotein(a) Grainger DJ, Kirschenlohr HL, Metcalfe JC, Weissberg PL, Wade DP, Lawn RM. Science 1993;260:1655-8. Background: Lipoprotein(a) (Lp[a]) is a unique lipoprotein composed of a low-density lipoprotein with the glycoprotein ape(a) attached to ape(B). Ape(a) has 80% homology to plasminogen but has no plasminogen-like activity. Epidemiologic studies have identified the plasma level of Lp(a) as a major risk factor for both coronary and peripheral atherosclerosis. In this report, Grainger et al. examined the effect of Lp(a) on the proliferation of human and rat vascular smooth muscle cells (VSMC) in tissue culture. Methods and Results: Lp(a) stimulated human VSIVIC growth in a dose-dependant manner. The effect of recombinant ape(a) alone was similar, although higher molx concentrations were required. Low-density lipoprotein had no effect. None of these compounds affected the doubling time of rat VSMC. The authors examined the mechanism by which Lp(d~ and ape(a) stimulated proliferation. Ape(a) shares considerable homology with hepatocyte growth factor, suggesting that ape(a) could directly stimulate cellular proliferdtion. Another possibility was that Lp(a) could comperitively inhibit the activation of transforming growth factor beta (TGF-P) by plasminogen. TGF-P is secreted by human VSMC and reduces VSMC proliferation whell activated. In a series of experiments, the authors demonstrated that, indeed, ape(a) is a competitive inhibitor of the plasminogen activation of TGF-P. Rat VSMC do not produce TGF-P in culture, and Lp(a) did not stimulate proliferation in these cells. Summary and Comments: Lp(a) is an intriguing particle. There is strong evidence for its involvement in both coronary artery and peripheral vascular atherosclerosis. The data presented by Granger et al. suggest that Lp(a) promotes VSMC proliferation, which would promote both atherosclerosis and intimal hyperplasia. Because an increasing number of lipid laboratories now can measure Lp(a) levels, we may soon have clinical data to confirm whether Lp(a) is an important factor in intimal hyperplasia, as suggested by these convincing in vitro data. Unfortunately, unlike the other lipid abnormalities that are associated with an increased risk of primary atherosclerosis and hyperplasia, at present there is limited ability to alter plasma levels of Lp(a). Joseph H. Rae, MD University of California, San Francisco, Calif:
San Francisco
Iliofemoral versus femorofemoral bypass: a 6-year audit Ng RLH, Gillies TE, Davies AH, Baird RN, Horrocks M. Br J Surg 1992;79:1011-3. 1994
JOURNAL OF VASCULAR Volume 20, Number 3
Bukground:
SURGERY
Abstracts
To compare
the patency, morbidity, and versus femorofemoral bypass for unilateral iliac artery occlusive disease, the results of a 6-year experience at one center were retrospectively reviewed. Methods and Results: From 1984 to 1990, 226 patients underwent 231 operations. The study group consisted of 183 men and 43 women with a mean age of 67 (range 43 to 94) years. Seventy-two patients had 75 iliofemoral grafts, and 154 patients had 156 femorofemoral grafts. Synthetic graft material, usually Dacron, was routinely used, although 1% of the iliofemoral group and 1.9% of the femorofemoral group had reversed vein grafts. Initial data were obtained from a computer database supplemented from the patient records. Late follow-up was obtained by outpatient visits in mid 1991 or by direct telephone contact or indirectly via their general practitioners. Cumulative survival and primary patency rates were calculated. Patients who died or were lost to follow-up were excluded from each interval in the patency calculations. Indications for operation and the incidence of preoperative risk factors were similar for both groups. The numbers of iliofemoral bypass performed each year of the study remained relatively constant, whereas the annual number of femorofemoral bypass procedures steadily increased. The early postoperative mortality rate was 6% (4 of 72) in the ihofemoral group and 1.3% (2 of 154) in the femorofemoral group. Early reoperation rates were 11% (8 of 75) for iliofemoral bypass and 5.1% (8 of 156) for the femorofemoral procedure. Combined early and late reoperation rates were 31% for the iliofemoral group and 16% for the femorofemoral group. The contralateral reoperation rate in the iliofemoral group (8%) was not significantly increased over that (4.5%) of the femorofemoral group. Themean length of hospital stay for the iliofemoral bypass (10.7 days) was significantly longer than that for the femorofemoral bypass (8.6 days) (p < 0.05). The femorofemoral procedure resulted in significantly higher 6-year cumulative patency (92% vs 75%) and survival rates (74% vs 55%) than did the iliofemoral operation (p < 0.01). Summary: The authors concluded that femorofemoral bypass may be a more favorable option than iliofemoral bypass, with a significantly shorter hospital stay and lower complication and reoperation rates. Comments: The number of grafts lost to follow-up or lost because of patient death in each interval were not specified in the patency analysis, and there were less than 10 grafts in each group at 6-year follow-up. The p values for comparisons of the reoperation and early mortality rates were not specified. All of the conclusions of the authors of this retrospective review may not be fully justified by the data.
mortalityrates associated with iliofemoral
J. O’Hava, MD ClevelandClinic Foundation Cleveland,Ohio
Patrick
Combined carotid and coronary revascularization: preferred approach to the severe vasculopath
the
495
Rizzo RJ, Whittemore AD, Couper GS, et al. Ann Thorac Surg 1992;54: 1099- 109. Backpound: The optimal management plan to minmize both perioperative stroke after coronary artery bypass grafting (CABG) and perioperative myocardial infarction (MI) after carotid endarterectomy (CEA) remains elusive. Addressing this issue, investigators from the divisions of cardiac and vascular surgery of Brigham and Women’s Hospital, Boston, surveyed retrospectively the outcome after two-team combined CEA and coronary artery revascularization performed for 127 patients over a 13-year interval (1978 to 1991). The authors considered this cohort of patients to represent a particularly high-risk group because of the multiple system extent of their clinically apparent atherosclerotic disease. Methods and Results: When possible, these investigators choose not to perform CEA or CABG in isolation for patients with clinically significant atherosclerotic involvement in both arterial segments. In this study, 75% had New York Heart Association functional class III or IV, 38% had left main coronary artery disease, 28% had a left ventricular ejection fraction less than 0.5, whereas six (5%) required a preoperative intraaortic balloon pump. One third of all patients had asymptomatic carotid artery disease, whereas 70% of those with symptoms had a history of transient ischemic attacks, and the remaining 26 patients had had a previous stroke. Fifty-nine percent had bilateral carotid artery disease, and 16% had contralateral carotid artery occlusion. The authors acknowledge that a strict protocol for patient selection for carotid artery screening, carotid angiography, and choice of carotid artery to select for endarterectomy in the event of bilateral asymptomatic disease was lacking in this retrospective survey. Overall there were eight (6.3%) perioperative strokes, seven (5.5%) of which were permanent. Six of these eight events were ipsilateral to the CEA. Additionally, there were two (1.6%) perioperative transient ischemic attacks, one ipsilateral to the carotid artery operation and seven (5.5%) heart-related deaths. Three of these deaths followed a perioperative MI, whereas three other perioperative MIS were not fatal. Importantly, there were no strokes in the asymptomatic carotid artery group. Stroke was 15% in patients with contralateral carotid artery occlusion and 19% in those with prior stroke. The mean carotid artery clamp time in the patients not needing a shunt was 31 minutes. Mean aortic clamp time for CABG was 41 minutes, whereas mean cardiopulmonary bypass time was 77 minutes. Although there was no control group available for comparison, during a concurrent 8-year subsegment of the study period, the same vascular surgery team posted 482 isolated CEA operations, with perioperative death and permanent stroke rates of 0.6% and 1.5%, respectively. Likewise, during a concurrent 4-year subsegment of the study period the same cardiac surgical team posted 3012 isolated CABG operations, with perioperative death and permanent stroke rates of 4.0% and l.O%, respectively. Additional late mortality and morbidity events were reported to confirm the “vasculopathic” characteristics of this 127-patient cohort.