- Email: [email protected]
SCVIR 1991 Annual Meeting Notes
Special Communication
SCVIR 1991 Annual Meeting Notes David W. Hunter, MD, University of Minnesota Hospital and Clinic, Minneapolis John F. Cardella, MD, Penn State University, Hershey, Pennsylvania Flavlo Castaneda, MD, St Francis Medical Center, Peoria, illinois Carol C. Coleman, MD, Veterans Affairs Medical Center, Minneapolis Andrew H. Cragg, MD, University of Iowa Hospitals and Clinics, Iowa City, Iowa Michael D. Darcy, MD, Malllnckrodt Institute of Radiology, St Louis Marcos Herrera, MD, Veterans Affairs Medical Center, Minneapolis Louis I. Juravsky, MD, FRCP, Dartmouth-Hitchcock Medical Center, Hanover, New Hampshire Thomas McNamara, MD, UCLA Center for the Health Sciences, Los Angeles Louis G. Martin, MD, Emory University, Atlanta Tony P. Smith, MD, University of Iowa Hospitals and Clinics, Iowa City, Iowa Fred Steinberg, MD, Cedar Sinai Medical Center, Los Angeles Patricia Thorpe, MD, Creighton University Medical Center, Omaha Robert L. Vogelzang, MD, Northwestern Memorial Hospital, Chicago Joseph W. Yedllcka, Jr, MD, University of Minnesota Hospital and Clinic, Minneapolis E. Kent Yucel, MD, Massachusetts General Hospital, Boston
JVIR 1991; 2:175-180
© SCVIR 1991
DURING the past several years, the Annual Meeting of the Society of Cardiovascular and Interventional Radiology (SCVIR) has grown rapidly and, as it experiences a growth spurt, has the look of a gangly adolescent who is beginning to glimpse maturity. The meeting is taking on a form that reflects the desperate need, in both our Society and our specialty in general, for accurate and careful clinical and basic science. The level of sophistication of the members has risen dramatically in the past several years, and the need for "show and tell" lab sessions is clearly diminishing while the need for open forum scientific sessions is clearly expanding. The opening 2 days of the meeting on Saturday and Sunday were dedicated entirely to scientific sessions. The need for separated concurrent sessions, as occurred on Sunday and throughout the rest of the week, was clear when one considered the amount of time dedicated to scientific sessions and the number of papers that had been submitted and were worthy of presentation. However, this format left many of us with a nagging feeling that we were missing a lot, even if we were hearing something that was important and well done. Future meetings will, hopefully, expand the amount of time given to scientific sessions so that there will be less need to run so many sessions concurrently so that more people can hear more presentations. Monday through Thursday, there was a mixture of scientific sessions and plenary sessions, in which general reviews of critical topics were presented by nationally known speakers, and refresher courses and workshops, which also ran concurrently. The refresher courses allowed the speakers to discuss topics in greater depth, and the workshops allowed hands-on experiences while permitting and, indeed, even encouraging questions in a more intimate format. In most of the "person on the street" interviews that were done to see how people were enjoying the meeting, comments were universally favorable about the meeting format and were a testimony to the superb job done by Gordon McLean. The workshops, which had been so important in the past when people were unfamiliar with the techniques of this emerging sub-
175
176 • Journal of Vascular and Interventional Radiology May 1991
Registration Figures: SCVIR 16th Annual Meeting Category 1991 1990 SCVIR member/fellow/in-training Nonmember ARNA/AVIR Total professionals Exhibitor Spouse/companion Total attendees
777 348 130
740 319 134
1,255
1,193
670 124
721 312
2,049
2,226
Note.-In 1991, international attendees representing 23 countries (including Canada) made up approximately 6% of total participants.
specialty, seemed to be losing favor and, indeed, becoming much less necessary, as the vendors give more hands-on demonstrations with new equipment and the practitioners of interventional radiology become sophisticated and experienced in their application of new techniques.
PLENARY SESSIONS Although the plenary session presentations were primarily intended to provide everyone with a "core" body of information, they were often much better than a simple review and provided state-of-the-art updates and overviews that were comprehensive and stimulating. Some of the more exceptional included overviews of the epidemiology and pathophysiology of peripheral vascular disease by Eric Martin and P. Macke Consigny, respectively; an extensive literature review of the results of renal angioplasty by Louis Martin (Results of treatment for ostial lesions are better than they have in the past, and patients with these lesions are acceptable candidates for angioplasty; renal vein renins are specific, but insensitive and not reliable indicators of success.); and an excellent review of the pathophysiology and techniques of thrombolysis by Tom McNamara and Dan Picus. (Urokinase is favored, thrombolysis is more effective if flow-limiting lesions are treated, autologous arteries work better than synthetic grafts, and bypass veins work better than synthetic bypass grafts.) An excellent overview of the surgical approach to femoropopliteal occlusive disease was given by Bruce Perler (Bypass results generally show 65% five-year survival when veins are used, a goal toward which all percutaneous therapies must aspire.), and an excellent review of the restenosis problem, which is at the basis of all current efforts to improve on the classical angioplasty data, was given by Gary Becker. (At pathologic examination 60% of restenosis studied had evidence of intimal hyperplasia, which may eventually yield to medical treatments.)
Other plenary sessions of note included two talks on interventional neuroradiology, which were new to the SCVIR meeting and very exciting, by Randall Higashida and Joseph Eskridge; an outstanding biliary session with an excellent overview of biliary stents by Dana Burke (Metal stents may not be particularly good for patients with benign disease, and recurrence rates for stent obstruction with metal stents do not seem to improve on data with plastic stents.); and a good review of biliary extracorporeal shock wave lithotripsy (ESWL) by Melvin Clouse, who reflected not only the general downbeat tone from the recent published experiments but also the more rational balanced view that there may be specific indications for ESWL in the future. An excellent discussion of how best to manage the pain from deep interventional procedures was provided by Bob Vogelzang. (Excellent results were obtained with celiac ganglion blocks in three studies; there is a possible role for pleural blocks, and excellent results were obtained in postprocedural pain management by allowing the patients to administer their own medications.) The plenary sessions also provided an overview of the diagnosis and treatment of vasculogenic impotence by Alan Greenfield and Joseph Bookstein; an excellent overview of contrast media by Michael Bettmann (Selective use of less expensive ionic media is still a viable option, especially when they are used in the context of hospital-wide guidelines.); a very scientific and carefully worded review of filters by Gary Dorfman (There is a clear-cut need for all studies to use careful selection of the patients that they chose as their denominators when assessing complications; only those patients who have had adequate follow-up should be included in the denominator, and when this is done the complications rates, including inferior vena cava (lVC) occlusion and recurrent pulmonary embolism, will probably be very similar for all filters.); and an equally balanced and critical but hopeful anal-
1991 SCVIR Meeting Notes • 177 Volume 2 Number 2
ysis of lasers and their place in the treatment of vascular disease by Michael Pentecost. Two other sessions attended by all participants in the meeting are of particular note. The first was a very impressive Young Investigator Award presentation by Douglas Redd, of Emory University School of Medicine, on Raman spectroscopy as a possible means for accurately detecting plaque, allowing for selective laser ablation of plaque in blood vessels. The other was an interesting and impressively clear presentation of the physician payment reform mess by Charles Booth of the Health Care Financing Administration, which obviously impressed enough members so that they were willing, on the following day, to not only approve a substantial assessment for completion of a survey to develop a resource-based relative-value scale for interventional radiology, but were even willing, at the same time, to substantially increase their dues to set aside funds for similar problems in the future. SCIENTIFIC SESSIONS The real excitement in the meeting appeared to come from the scientific sessions, where papers were presented by representatives from many different countries and many different types of medical institutions. There were clear instances where scientific con-
tent was lacking and the data had not been carefully analyzed or the study population had not been adequately controlled. However, there were many other studies in which there was a clear indication of highquality effort on the part of the investigator, including selection of a reasonable number of patients to accomplish the stated objective, careful analysis of the data, continuation of the study to a point where follow-up was adequate to prove the hypothesis, adequate use of control groups or historical controls, and careful statistical analysis with appropriate statistical tests for the size and nature of the group involved. An overall review of the abstracts from the meeting is available for people who desire more specifics. Several papers stood out, either because of their impressive scientific nature or their potential impact on the way we practice. Three of them concerned vascular stent placement, one of the most rapidly expanding areas of interventional radiology. The first of these has been published recently and was presented at the Radiological Society of North America (RSNA) scientific assembly but is, nonetheless, so important in terms of its long-term effects on the way we perform angioplasty that it deserves special mention: This is a comparison study of iliac angioplasty versus placement of a Palmaz balloon-expanded stent (A-005) that showed fewer failures and complications with stent placement and a statistically significant improvement in the clinical outcome and restenosis percentage for the stent patients that was definitely present by 2 years. Another paper (B-088) studied changes in the vasa vasorum that occur following stenting and showed neovascularity developing from the neointima, with a suggestion of increased restenosis in those vessels in which the new vasa vasorum penetrated through the internal elastic membrane. A third paper (B-147) described 82 patients with iliac artery occlusions who underwent angioplasty and stent placement as their primary treatment and in whom a 73% success rate was achieved with the Wallstent. There was a 27-month 90% patency rate in those who had undergone a technically successful procedure. In one outstanding filter paper (B-069), computed tomography (CT) was used to study patients with standard Greenfield filters. A careful analysis of patients, even though they were not randomized and therefore had a potential severe selection bias, showed 11 of 28 with thrombus in the IVC; nine of the thrombi were acute, but only three of those nine patients had symptoms. Thirteen of 28 patients studied had penetration of the struts through the wall, although in seven of those penetration was minimal. Five of the 28 patients who had IVC thrombosis developed fibrosis of the IVC over time. If all filters were carefully studied, surely similar data would be obtained with many of them. A study of atherosclerotic rabbit vessels treated with angioplasty (B-123) showed that there is
178 • Journal of Vascular and Interventional Radiology May 1991
a definite increase in the release of smooth muscle mitogens from dilated vessels. This sets the stage for future evaluation of mechanisms of restenosis. A simple but important paper evaluating anticoagulation during vascular procedures (A-OIO) showed that activated clotting time (ACT) is a valuable tool for monitoring heparinization, and, in particular, only 33% of patients who received 5,000 U of heparin achieved an ACT of 275 seconds, which is a target value used by many investigators, particularly in the coronary circulation. Two papers in which either the Wallstent or Palmaz stent was used for creation of portosystemic shunts (B-060 and B-064) showed remarkably high success rates, with only one rebleeding episode between the two studies, and one occluded stent in either study. A final paper (B-091) was a repeat of a recently published paper presented at the RSNA scientific assembly, demonstrating the effectiveness of ultrasound (US) compression in the treatment of acute pseudoaneurysms with a 100% success rate in the aneurysms treated within the first 72 hours. There were several excellent papers on angioplasty, including one that recommended operating on distal graft stenoses because of low angioplasty success rates (A-002) and one that showed an increase in technical success rates of angioplasty to 96% with use of a hydrophilic guide wire (B-155). Two papers showed high technical and clinical success rates for brachiocephalic angioplasty (C-204 and C-2l9). One showed a high success rate, limited complications, and good clinical response with angioplasty performed to treat transplant renal artery stenosis (C-209). Basic science papers of note included one showing no effect on rabbit artery recoil by increasing balloon size or balloon inflation time (B-113), one demonstrating increased vasospasm in areas where the endothelium was absent and thrombin and serotonin were present (B-128), and one showing the possibility of detecting degranulated or activated platelets at angioplasty sites by using a technetium-labeled antibody (B-133). Four papers discussed the role of atherectomy in the treatment of failed dialysis access grafts. All failed to show a significant improvement in the success rates for atherectomy compared with standard angioplasty (B-089, B-097, B-105, and C-2oo). There were only a few papers presented on laser angioplasty and these showed results, as most other papers have shown, that are at best comparable to results with angioplasty, and no clear-cut new winning technologies appeared on the horizon. Some other notable stent papers included a rabbit model in which decreased elastic recoil was shown by temporary stent placement of up to 48 hours (B-096), a paper showing some early success with stents in the treatment of vein stenosis in patients with failing dialysis grafts (B-093), and a paper showing that treatment of iliac artery occlusion can be improved if
stenting is added to the classic angioplasty regimen (B-152). There were many very good papers in the embolization field, including two showing effectiveness of chemoembolization for hepatic tumors, although chemoembolization was not compared with other treatment modalities (A-008 and B-115). The ability of simple coil occlusion to nonoperatively treat splenic artery pulsating hematomas, which probably implies pending rupture (B-099), was described as was a new, and somewhat fascinating, treatment for pseudoaneurysms of dialysis access grafts in which a direct stick and detachable balloon occlusion are used (B085). A new permanent particulate embolization material that is easy to inject and "molds" itself to the artery to form a gluelike occlusion (B-130) was described. A method of treating puncture site pseudoaneurysms by injecting them with thrombin while occluding the neck (B-15l) was presented. One paper demonstrated remarkably good results of treatment for a variety of vascular malformations in pediatric patients, primarily with ethanol (B-156), and another described a small but highly successful series of three pediatric patients with renovascular hypertension, on the basis of small segmental artery occlusion, who were treated with subsegmental embolization (B-16l). There were a variety of excellent clinical papers dealing with thrombolysis. Two suggested decreased lysis times with aggressive high-dose intrathrombus infusions, especially with the pulsed-infusion technique (A-007 and B-127). Two showed that rapid lysis techniques can be used in dialysis access grafts without significant problems developing with leakage through dialysis puncture sites (C-205 and C-2l0). One study suggested that lysis gave better long-term patency rates for clotted dialysis access grafts than did surgery (B-lOl). One study suggested that thrombolysis patients could be monitored out of an intensive care setting (B-107), but several studies showed
1991 SCVIR Meeting Notes. 179 Volume2 Number2
that lysis procedures still carry major complication rates of 5%--7% (B-132 and B-1I7), which must make one somewhat cautious. Another study suggested that drip infusions may have a rate limit for the speed at which thrombolysis can occur, according to a cat model, of approximately 100,000 U/h (B-1I2). Two large clinical studies of thrombolysis showed approximately 74% overall success rates, with certain categories of patients faring better, including those with grafts (especially proximal grafts), with good runoff, and without diabetes (B-1I7 and B-122). One study disputed findings of some recent studies by showing that failure of the guide-wire test did not predict a poor success rate for thrombolysis (E-325). In one study in which low-dose recombinant tissue plasminogen activator at 0.5-mg/h was used, no increased complication rate was seen compared with urokinase (E-335). Results were presented for a variety of different filters, including the titanium Greenfield filter, with a 3% pulmonary embolism (PE) rate and 10% rate of new lower extremity edema (A-004); the Vena-Tech filter, with a 3% PE rate, 8% IVC occlusion rate, 3% caudal migration rate (A-014), and a 43% rate of nonopening from the jugular approach (B-061); the Bird's Nest filter, with a 3% PE rate, 10% wall penetration rate, and 13% IVC thrombus rate (B-065); and the
GUnther filter, with a 19% IVC occlusion rate, a 20% IVC wall penetration rate, and a 73% caudal migration rate. The GUnther filter was, therefore, not recommended for general use (E-326). Other vascular papers of interest included a paper on nonsubtracted digital lower extremity angiography that showed diagnostic accuracy similar to that of cutfilm step-table angiography (B-094), and a study showing that sedation with a combination of Versed and Fentanyl was better than sedation with Versed alone for patients undergoing angiography (B-102). A new catheter for providing perfusion to acutely occluded vessels (B-11I) was described, as was a means for providing high-dose chemotherapy to the liver by selectively removing the hepatic vein effluent with a specially designed venous catheter (B-120). A study comparing magnetic resonance angiography for evaluation of renal artery stenosis showed some early promise, with 100% specificity for healthy patients and 100% sensitivity for stenoses greater than 50% (C202). Interestingly, there were no papers demonstrating clinical utility of intravascular US, although the Miami Vascular Institute continues to work on a study randomizing patients who have undergone intravascular US into those in whom US is used to effect the treatment and those in whom it is not. People who wish to contribute their data to this study will probably help speed these results to an earlier conclusion. There were several interesting papers on biliary intervention, including three that showed good results with the Wallstent for both benign and malignant stenoses (A-003, B-143, and B-163). However, none of these papers showed any significant difference between the metallic stents and a variety of plastic stents or catheters, with reocclusion rates that ranged from 12% to 24% and were higher in the group with malignancies. One group that had very poor results were those with sclerosing cholangitis (B-163). Another paper showed that intraductal US does not, at the present time, appear to add any diagnostic information to that obtained with high-quality cholangiography (B-071). A paper on biliary drainage showed that complications were equal for benign and malignant conditions during the acute phase, but were increased for patients with malignant occlusions versus benign occlusions in the chronic phase (8% vs 4%) (B-055). Another paper showed that, even when nondilated ducts are seen at US and findings are negative at CT, cholangiography is warranted in the presence of clinical indications of biliary problems, since 42% of such patients had an abnormality discovered at cholangiography, including equal numbers of strictures and stones. These authors had a 100% success rate with standard fine-needle technique whenever they allowed themselves unlimited numbers of punctures (B059). Another paper showed that gallbladder drainage
180 • Journal of Vascular and Interventional Radiology May 1991
was a safe alternative to standard percutaneous biliary drainage in appropriate patients, with only a 4%
complication rate and a 100% technical success rate (B-124). Two papers dealing with portosystemic shunts showed that the technical process of creating the shunt could be shortened and the complication rate decreased by using US and fluoroscopy, rather than a transhepatic basket or target, to assist in the puncture from the hepatic vein to the portal vein. Another basic science paper showed that acute decompression of the portal system via an external circuit to the femoral vein was possible, both for clinical purposes and for studying portal vein dynamics (B-131). An interesting paper showed poor results with balloon dilation of ureteral strictures (36% success rate) that were even worse in devascularized lesions and in lesions after radiation therapy or extensive surgery (20%) (B-054). Two papers showed the possibility of ablating benign or malignant prostate tissue with either freezing or heat probes directly in the prostate (B-058 and B-066). An interesting paper on the management of abdominal abscesses showed that the
presence of a fistula did not change the success rate but markedly increased the time to resolution to 52 days. Patients with Crohn disease did not do nearly as well (C-208). Several papers demonstrated new techniques, including a means for performing percutaneous diskectomy with an 82% clinical success rate (A-015), the ability to use color US to find all of the relevant thrombi in patients with deep vein thrombosis who are also studied with venography (B-090), and a comparative study in the treatment of lymphoceles showing that a 58% success rate with standard drainage could be improved to 83% with the addition of betadine sclerotherapy (C-213). No particularly impressive mechanical thrombectomy or atherectomy devices were presented at the meeting, although developmental work on a variety of different devices employing a variety of different mechanisms was presented, which may have some interesting future possibilities. The membership created a fabulous and exciting meeting. Do we really need a "Fellows" category any more?
SCVIR 1991 Annual Meeting Notes David W. Hunter, MD, University of Minnesota Hospital and Clinic, Minneapolis John F. Cardella, MD, Penn State University, Hershey, Pennsylvania Flavlo Castaneda, MD, St Francis Medical Center, Peoria, illinois Carol C. Coleman, MD, Veterans Affairs Medical Center, Minneapolis Andrew H. Cragg, MD, University of Iowa Hospitals and Clinics, Iowa City, Iowa Michael D. Darcy, MD, Malllnckrodt Institute of Radiology, St Louis Marcos Herrera, MD, Veterans Affairs Medical Center, Minneapolis Louis I. Juravsky, MD, FRCP, Dartmouth-Hitchcock Medical Center, Hanover, New Hampshire Thomas McNamara, MD, UCLA Center for the Health Sciences, Los Angeles Louis G. Martin, MD, Emory University, Atlanta Tony P. Smith, MD, University of Iowa Hospitals and Clinics, Iowa City, Iowa Fred Steinberg, MD, Cedar Sinai Medical Center, Los Angeles Patricia Thorpe, MD, Creighton University Medical Center, Omaha Robert L. Vogelzang, MD, Northwestern Memorial Hospital, Chicago Joseph W. Yedllcka, Jr, MD, University of Minnesota Hospital and Clinic, Minneapolis E. Kent Yucel, MD, Massachusetts General Hospital, Boston
JVIR 1991; 2:175-180
© SCVIR 1991
DURING the past several years, the Annual Meeting of the Society of Cardiovascular and Interventional Radiology (SCVIR) has grown rapidly and, as it experiences a growth spurt, has the look of a gangly adolescent who is beginning to glimpse maturity. The meeting is taking on a form that reflects the desperate need, in both our Society and our specialty in general, for accurate and careful clinical and basic science. The level of sophistication of the members has risen dramatically in the past several years, and the need for "show and tell" lab sessions is clearly diminishing while the need for open forum scientific sessions is clearly expanding. The opening 2 days of the meeting on Saturday and Sunday were dedicated entirely to scientific sessions. The need for separated concurrent sessions, as occurred on Sunday and throughout the rest of the week, was clear when one considered the amount of time dedicated to scientific sessions and the number of papers that had been submitted and were worthy of presentation. However, this format left many of us with a nagging feeling that we were missing a lot, even if we were hearing something that was important and well done. Future meetings will, hopefully, expand the amount of time given to scientific sessions so that there will be less need to run so many sessions concurrently so that more people can hear more presentations. Monday through Thursday, there was a mixture of scientific sessions and plenary sessions, in which general reviews of critical topics were presented by nationally known speakers, and refresher courses and workshops, which also ran concurrently. The refresher courses allowed the speakers to discuss topics in greater depth, and the workshops allowed hands-on experiences while permitting and, indeed, even encouraging questions in a more intimate format. In most of the "person on the street" interviews that were done to see how people were enjoying the meeting, comments were universally favorable about the meeting format and were a testimony to the superb job done by Gordon McLean. The workshops, which had been so important in the past when people were unfamiliar with the techniques of this emerging sub-
175
176 • Journal of Vascular and Interventional Radiology May 1991
Registration Figures: SCVIR 16th Annual Meeting Category 1991 1990 SCVIR member/fellow/in-training Nonmember ARNA/AVIR Total professionals Exhibitor Spouse/companion Total attendees
777 348 130
740 319 134
1,255
1,193
670 124
721 312
2,049
2,226
Note.-In 1991, international attendees representing 23 countries (including Canada) made up approximately 6% of total participants.
specialty, seemed to be losing favor and, indeed, becoming much less necessary, as the vendors give more hands-on demonstrations with new equipment and the practitioners of interventional radiology become sophisticated and experienced in their application of new techniques.
PLENARY SESSIONS Although the plenary session presentations were primarily intended to provide everyone with a "core" body of information, they were often much better than a simple review and provided state-of-the-art updates and overviews that were comprehensive and stimulating. Some of the more exceptional included overviews of the epidemiology and pathophysiology of peripheral vascular disease by Eric Martin and P. Macke Consigny, respectively; an extensive literature review of the results of renal angioplasty by Louis Martin (Results of treatment for ostial lesions are better than they have in the past, and patients with these lesions are acceptable candidates for angioplasty; renal vein renins are specific, but insensitive and not reliable indicators of success.); and an excellent review of the pathophysiology and techniques of thrombolysis by Tom McNamara and Dan Picus. (Urokinase is favored, thrombolysis is more effective if flow-limiting lesions are treated, autologous arteries work better than synthetic grafts, and bypass veins work better than synthetic bypass grafts.) An excellent overview of the surgical approach to femoropopliteal occlusive disease was given by Bruce Perler (Bypass results generally show 65% five-year survival when veins are used, a goal toward which all percutaneous therapies must aspire.), and an excellent review of the restenosis problem, which is at the basis of all current efforts to improve on the classical angioplasty data, was given by Gary Becker. (At pathologic examination 60% of restenosis studied had evidence of intimal hyperplasia, which may eventually yield to medical treatments.)
Other plenary sessions of note included two talks on interventional neuroradiology, which were new to the SCVIR meeting and very exciting, by Randall Higashida and Joseph Eskridge; an outstanding biliary session with an excellent overview of biliary stents by Dana Burke (Metal stents may not be particularly good for patients with benign disease, and recurrence rates for stent obstruction with metal stents do not seem to improve on data with plastic stents.); and a good review of biliary extracorporeal shock wave lithotripsy (ESWL) by Melvin Clouse, who reflected not only the general downbeat tone from the recent published experiments but also the more rational balanced view that there may be specific indications for ESWL in the future. An excellent discussion of how best to manage the pain from deep interventional procedures was provided by Bob Vogelzang. (Excellent results were obtained with celiac ganglion blocks in three studies; there is a possible role for pleural blocks, and excellent results were obtained in postprocedural pain management by allowing the patients to administer their own medications.) The plenary sessions also provided an overview of the diagnosis and treatment of vasculogenic impotence by Alan Greenfield and Joseph Bookstein; an excellent overview of contrast media by Michael Bettmann (Selective use of less expensive ionic media is still a viable option, especially when they are used in the context of hospital-wide guidelines.); a very scientific and carefully worded review of filters by Gary Dorfman (There is a clear-cut need for all studies to use careful selection of the patients that they chose as their denominators when assessing complications; only those patients who have had adequate follow-up should be included in the denominator, and when this is done the complications rates, including inferior vena cava (lVC) occlusion and recurrent pulmonary embolism, will probably be very similar for all filters.); and an equally balanced and critical but hopeful anal-
1991 SCVIR Meeting Notes • 177 Volume 2 Number 2
ysis of lasers and their place in the treatment of vascular disease by Michael Pentecost. Two other sessions attended by all participants in the meeting are of particular note. The first was a very impressive Young Investigator Award presentation by Douglas Redd, of Emory University School of Medicine, on Raman spectroscopy as a possible means for accurately detecting plaque, allowing for selective laser ablation of plaque in blood vessels. The other was an interesting and impressively clear presentation of the physician payment reform mess by Charles Booth of the Health Care Financing Administration, which obviously impressed enough members so that they were willing, on the following day, to not only approve a substantial assessment for completion of a survey to develop a resource-based relative-value scale for interventional radiology, but were even willing, at the same time, to substantially increase their dues to set aside funds for similar problems in the future. SCIENTIFIC SESSIONS The real excitement in the meeting appeared to come from the scientific sessions, where papers were presented by representatives from many different countries and many different types of medical institutions. There were clear instances where scientific con-
tent was lacking and the data had not been carefully analyzed or the study population had not been adequately controlled. However, there were many other studies in which there was a clear indication of highquality effort on the part of the investigator, including selection of a reasonable number of patients to accomplish the stated objective, careful analysis of the data, continuation of the study to a point where follow-up was adequate to prove the hypothesis, adequate use of control groups or historical controls, and careful statistical analysis with appropriate statistical tests for the size and nature of the group involved. An overall review of the abstracts from the meeting is available for people who desire more specifics. Several papers stood out, either because of their impressive scientific nature or their potential impact on the way we practice. Three of them concerned vascular stent placement, one of the most rapidly expanding areas of interventional radiology. The first of these has been published recently and was presented at the Radiological Society of North America (RSNA) scientific assembly but is, nonetheless, so important in terms of its long-term effects on the way we perform angioplasty that it deserves special mention: This is a comparison study of iliac angioplasty versus placement of a Palmaz balloon-expanded stent (A-005) that showed fewer failures and complications with stent placement and a statistically significant improvement in the clinical outcome and restenosis percentage for the stent patients that was definitely present by 2 years. Another paper (B-088) studied changes in the vasa vasorum that occur following stenting and showed neovascularity developing from the neointima, with a suggestion of increased restenosis in those vessels in which the new vasa vasorum penetrated through the internal elastic membrane. A third paper (B-147) described 82 patients with iliac artery occlusions who underwent angioplasty and stent placement as their primary treatment and in whom a 73% success rate was achieved with the Wallstent. There was a 27-month 90% patency rate in those who had undergone a technically successful procedure. In one outstanding filter paper (B-069), computed tomography (CT) was used to study patients with standard Greenfield filters. A careful analysis of patients, even though they were not randomized and therefore had a potential severe selection bias, showed 11 of 28 with thrombus in the IVC; nine of the thrombi were acute, but only three of those nine patients had symptoms. Thirteen of 28 patients studied had penetration of the struts through the wall, although in seven of those penetration was minimal. Five of the 28 patients who had IVC thrombosis developed fibrosis of the IVC over time. If all filters were carefully studied, surely similar data would be obtained with many of them. A study of atherosclerotic rabbit vessels treated with angioplasty (B-123) showed that there is
178 • Journal of Vascular and Interventional Radiology May 1991
a definite increase in the release of smooth muscle mitogens from dilated vessels. This sets the stage for future evaluation of mechanisms of restenosis. A simple but important paper evaluating anticoagulation during vascular procedures (A-OIO) showed that activated clotting time (ACT) is a valuable tool for monitoring heparinization, and, in particular, only 33% of patients who received 5,000 U of heparin achieved an ACT of 275 seconds, which is a target value used by many investigators, particularly in the coronary circulation. Two papers in which either the Wallstent or Palmaz stent was used for creation of portosystemic shunts (B-060 and B-064) showed remarkably high success rates, with only one rebleeding episode between the two studies, and one occluded stent in either study. A final paper (B-091) was a repeat of a recently published paper presented at the RSNA scientific assembly, demonstrating the effectiveness of ultrasound (US) compression in the treatment of acute pseudoaneurysms with a 100% success rate in the aneurysms treated within the first 72 hours. There were several excellent papers on angioplasty, including one that recommended operating on distal graft stenoses because of low angioplasty success rates (A-002) and one that showed an increase in technical success rates of angioplasty to 96% with use of a hydrophilic guide wire (B-155). Two papers showed high technical and clinical success rates for brachiocephalic angioplasty (C-204 and C-2l9). One showed a high success rate, limited complications, and good clinical response with angioplasty performed to treat transplant renal artery stenosis (C-209). Basic science papers of note included one showing no effect on rabbit artery recoil by increasing balloon size or balloon inflation time (B-113), one demonstrating increased vasospasm in areas where the endothelium was absent and thrombin and serotonin were present (B-128), and one showing the possibility of detecting degranulated or activated platelets at angioplasty sites by using a technetium-labeled antibody (B-133). Four papers discussed the role of atherectomy in the treatment of failed dialysis access grafts. All failed to show a significant improvement in the success rates for atherectomy compared with standard angioplasty (B-089, B-097, B-105, and C-2oo). There were only a few papers presented on laser angioplasty and these showed results, as most other papers have shown, that are at best comparable to results with angioplasty, and no clear-cut new winning technologies appeared on the horizon. Some other notable stent papers included a rabbit model in which decreased elastic recoil was shown by temporary stent placement of up to 48 hours (B-096), a paper showing some early success with stents in the treatment of vein stenosis in patients with failing dialysis grafts (B-093), and a paper showing that treatment of iliac artery occlusion can be improved if
stenting is added to the classic angioplasty regimen (B-152). There were many very good papers in the embolization field, including two showing effectiveness of chemoembolization for hepatic tumors, although chemoembolization was not compared with other treatment modalities (A-008 and B-115). The ability of simple coil occlusion to nonoperatively treat splenic artery pulsating hematomas, which probably implies pending rupture (B-099), was described as was a new, and somewhat fascinating, treatment for pseudoaneurysms of dialysis access grafts in which a direct stick and detachable balloon occlusion are used (B085). A new permanent particulate embolization material that is easy to inject and "molds" itself to the artery to form a gluelike occlusion (B-130) was described. A method of treating puncture site pseudoaneurysms by injecting them with thrombin while occluding the neck (B-15l) was presented. One paper demonstrated remarkably good results of treatment for a variety of vascular malformations in pediatric patients, primarily with ethanol (B-156), and another described a small but highly successful series of three pediatric patients with renovascular hypertension, on the basis of small segmental artery occlusion, who were treated with subsegmental embolization (B-16l). There were a variety of excellent clinical papers dealing with thrombolysis. Two suggested decreased lysis times with aggressive high-dose intrathrombus infusions, especially with the pulsed-infusion technique (A-007 and B-127). Two showed that rapid lysis techniques can be used in dialysis access grafts without significant problems developing with leakage through dialysis puncture sites (C-205 and C-2l0). One study suggested that lysis gave better long-term patency rates for clotted dialysis access grafts than did surgery (B-lOl). One study suggested that thrombolysis patients could be monitored out of an intensive care setting (B-107), but several studies showed
1991 SCVIR Meeting Notes. 179 Volume2 Number2
that lysis procedures still carry major complication rates of 5%--7% (B-132 and B-1I7), which must make one somewhat cautious. Another study suggested that drip infusions may have a rate limit for the speed at which thrombolysis can occur, according to a cat model, of approximately 100,000 U/h (B-1I2). Two large clinical studies of thrombolysis showed approximately 74% overall success rates, with certain categories of patients faring better, including those with grafts (especially proximal grafts), with good runoff, and without diabetes (B-1I7 and B-122). One study disputed findings of some recent studies by showing that failure of the guide-wire test did not predict a poor success rate for thrombolysis (E-325). In one study in which low-dose recombinant tissue plasminogen activator at 0.5-mg/h was used, no increased complication rate was seen compared with urokinase (E-335). Results were presented for a variety of different filters, including the titanium Greenfield filter, with a 3% pulmonary embolism (PE) rate and 10% rate of new lower extremity edema (A-004); the Vena-Tech filter, with a 3% PE rate, 8% IVC occlusion rate, 3% caudal migration rate (A-014), and a 43% rate of nonopening from the jugular approach (B-061); the Bird's Nest filter, with a 3% PE rate, 10% wall penetration rate, and 13% IVC thrombus rate (B-065); and the
GUnther filter, with a 19% IVC occlusion rate, a 20% IVC wall penetration rate, and a 73% caudal migration rate. The GUnther filter was, therefore, not recommended for general use (E-326). Other vascular papers of interest included a paper on nonsubtracted digital lower extremity angiography that showed diagnostic accuracy similar to that of cutfilm step-table angiography (B-094), and a study showing that sedation with a combination of Versed and Fentanyl was better than sedation with Versed alone for patients undergoing angiography (B-102). A new catheter for providing perfusion to acutely occluded vessels (B-11I) was described, as was a means for providing high-dose chemotherapy to the liver by selectively removing the hepatic vein effluent with a specially designed venous catheter (B-120). A study comparing magnetic resonance angiography for evaluation of renal artery stenosis showed some early promise, with 100% specificity for healthy patients and 100% sensitivity for stenoses greater than 50% (C202). Interestingly, there were no papers demonstrating clinical utility of intravascular US, although the Miami Vascular Institute continues to work on a study randomizing patients who have undergone intravascular US into those in whom US is used to effect the treatment and those in whom it is not. People who wish to contribute their data to this study will probably help speed these results to an earlier conclusion. There were several interesting papers on biliary intervention, including three that showed good results with the Wallstent for both benign and malignant stenoses (A-003, B-143, and B-163). However, none of these papers showed any significant difference between the metallic stents and a variety of plastic stents or catheters, with reocclusion rates that ranged from 12% to 24% and were higher in the group with malignancies. One group that had very poor results were those with sclerosing cholangitis (B-163). Another paper showed that intraductal US does not, at the present time, appear to add any diagnostic information to that obtained with high-quality cholangiography (B-071). A paper on biliary drainage showed that complications were equal for benign and malignant conditions during the acute phase, but were increased for patients with malignant occlusions versus benign occlusions in the chronic phase (8% vs 4%) (B-055). Another paper showed that, even when nondilated ducts are seen at US and findings are negative at CT, cholangiography is warranted in the presence of clinical indications of biliary problems, since 42% of such patients had an abnormality discovered at cholangiography, including equal numbers of strictures and stones. These authors had a 100% success rate with standard fine-needle technique whenever they allowed themselves unlimited numbers of punctures (B059). Another paper showed that gallbladder drainage
180 • Journal of Vascular and Interventional Radiology May 1991
was a safe alternative to standard percutaneous biliary drainage in appropriate patients, with only a 4%
complication rate and a 100% technical success rate (B-124). Two papers dealing with portosystemic shunts showed that the technical process of creating the shunt could be shortened and the complication rate decreased by using US and fluoroscopy, rather than a transhepatic basket or target, to assist in the puncture from the hepatic vein to the portal vein. Another basic science paper showed that acute decompression of the portal system via an external circuit to the femoral vein was possible, both for clinical purposes and for studying portal vein dynamics (B-131). An interesting paper showed poor results with balloon dilation of ureteral strictures (36% success rate) that were even worse in devascularized lesions and in lesions after radiation therapy or extensive surgery (20%) (B-054). Two papers showed the possibility of ablating benign or malignant prostate tissue with either freezing or heat probes directly in the prostate (B-058 and B-066). An interesting paper on the management of abdominal abscesses showed that the
presence of a fistula did not change the success rate but markedly increased the time to resolution to 52 days. Patients with Crohn disease did not do nearly as well (C-208). Several papers demonstrated new techniques, including a means for performing percutaneous diskectomy with an 82% clinical success rate (A-015), the ability to use color US to find all of the relevant thrombi in patients with deep vein thrombosis who are also studied with venography (B-090), and a comparative study in the treatment of lymphoceles showing that a 58% success rate with standard drainage could be improved to 83% with the addition of betadine sclerotherapy (C-213). No particularly impressive mechanical thrombectomy or atherectomy devices were presented at the meeting, although developmental work on a variety of different devices employing a variety of different mechanisms was presented, which may have some interesting future possibilities. The membership created a fabulous and exciting meeting. Do we really need a "Fellows" category any more?