- Email: [email protected]
Poster Session 1
Sunday, March 9, 1997 3:30-5:00 pm Poster Session 1 3:30 pm Stepping Intravenous Digital Subtraction Angiography (SIVDSA) for Imaging the Aorta and Run-Off In Patients with Nonpalpable Femoral Pulses R.F. Oser, MD, Birmingham, AL • K.M. Hamrick, MD • RL Ballard, MD • S. Saddekni, MD PURPOSE: To demonstrate the efficacy of IVDSA utiliz-
ing a stepped digital system in imaging the lower extremity (LE) vasculature in patients with nonpalpable femoral pulses. MA1ERlALS AND METIlODS: Four patients with nonpalpable femoral pulses referred for aortography, were imaged using SIVDSA. A single, large bolus of contrast material (90 mL Hexabrix at 15-20 mUsec) was given through a 5-F pigtail catheter in the right atrium; and stepped digital imaging of the abdomen, pelvis, and lower extremities was performed. All patients were imaged with use of the Siemens Multistar T.O.P. system. RESULTS: Diagnostic images of the aorta and LE run-off were obtained in all patients. The trifurcation vessels were well seen in three of four patients. Two of four patients had aortic occlusion; the two remaining patients had iliac occlusions. In one patient, IVDSA was used to guide arterial puncture and subsequent intervention. CONCLUSIONS: Central venous injection of a large bolus of contrast material results in prolonged opacification of the arterial tree. When combined with stepped digital imaging, the entire vasculature, from the diaphragm to the ankle, can be visualized. Because all collaterals fill with intravenous injection, SIVDSA provides visualization of the femoral arteries and LE vasculature, which is equal to or better than conventional arteriography in cases of aortic or bilateral iliac occlusion.
Take Home Points: 1. SIVDSA can provide a safe and effective means of imaging the pelvic and lower extremity vasculature in patients with aortic or bilateral iliac occlusion. 2. rvDSA can be used to guide arterial puncture and subsequent intervention in patients with nonpalpable femoral pulses.
3:40 pm Evaluation of Primary Venous Aneurysms: A Case Series and Review s.P. Murray, MD, Lajolla, CA • Aj. Meglin, MD • ML Rosado-de-Christenson, MD PURPOSE: Primary venous aneurysms are rare, with only
limited case reports in the literature. They have been thought previously to be of little clinical significance.
The purpose of this report is to define extracranial venous aneurysms and discuss their clinical presentation, natural history, and management. We will show radiologic and pathologic appearance. MA1ERIALS AND METIlODS: We reviewed 10 cases from two tertiary-care hospitals and the AFIP. Skull-based and CNS aneurysms, arteriovenous-fistula and postcatheterization aneurysms were excluded. Clinical presentation, location, size, natural history, and radiologic appearance were recorded. RESULTS: There were seven females and three males ranging in age from 17 to 77 years (mean, 45.2). Presenting symptoms included localized swelling or painful mass (5), thromboembolic disease 0), and painless mass (1). Two aneurysms were incidental findings. Locations included greater saphenous vein 0), superior vena cava (2) and one each in the common femoral, popliteal, soleal, and internal jugular veins. Aneurysms varied in size from 1.5 cm to 7 cm (mean, 3.2). Previous surgery or trauma was noted in four patients. One patient developed thrombus during hospitalization, requiring emergent resection. No patients developed complications after resection. CONCLUSIONS: Primary venous aneurysms are rare. Multiple aneurysms occur more frequently than preViously noted. Etiologies include trauma and previous surgery. Patients do well after surgical resection. Venous aneurysms should be viewed with high potential for thromboembolic disease.
Take Home Points: 1. Multiple aneurysms occur more frequently than preViously noted. 2. Patients do well after surgical resection. 3. Venous aneurysms should be viewed with high potential for thromboembolic disease.
3:50 pm Multislab-MRA of the Carotid Arteries from the Aortic Arch to the Circle of Willis I Link, MD, Kiel, Germany. Ie. Steffens, MD • S. Mueller-Huelsbeck, MD • F. Wesner, MD • M. Heller, MD PURPOSE: To determine the value of multislab MRA in
carotid artery stenoses. MA1ERIALS AND METIlODS: Fifty consecutive patients with arterial angiograms of the carotid arteries were enrolled in the study. MRA was performed with a l.5T Magnetom Vision (Siemens), using a head-neck coil. Ten slabs in transaxial orientation were performed in multiple overlapping thin slab technique (TR 35msec; TE 6msec; flip angle25°; FOV 265mm; matrix 155x256; acquisition time 26min). Reconstructions were performed with maximum intensity projection technique. The de-
249
gree of stenosis was evaluated according to NASCETcriteria. RESULTS: Imaging of the entire vessels from the aortic arch to the circle of Willis was of diagnostic quality in each patient. Agreement of MRA and DSA in normal arteries was 93% (28/30) and was 67% (l0/15) in mild 74% (14/19) in moderate, and 96% (26/27) in severe stenoses. All conclusions (9/9) were correctly diagnosed with MRA and DSA. Three tandem lesions and one fibromuscular dysplasia were depicted with MRA. Only 5/8 ulcers were diagnosed on MRA. CONCLUSION Multislab MRA is a valuable technique to assess the entire carotid circulation noninvasively with good correlation to DSA.
Take Home Points: Multislab MRA allows visualization of the entire cervical arteries; good correlation with DSA. 4:00 pm Variance in Diameter and Compatibility Between Commonly used Arterial Sheaths, Angioplasty Balloons, and Catheters .f.K. St. George, MD, Lebanon, NH • Bf. McClellan, RT • .f. Georgia, MD • D. Langdon, MD • M.A. Bettmann, MD PURPOSE: Arterial sheaths are widely used in both diagnostic and interventional procedures. Unlike catheters, arterial sheaths are not designated by their OD French size, but rather by the ID. MATERIALS AND METHODS: ID and OD measurements of 5-9-F sheaths from numerous manufacturers were measured. Additionally, the sheaths were tested for compatibility with commonly sized balloons (5-12 mm), 7-8-F guide catheters and 5-6-F diagnostic catheters from both the same and competitive venders. RESULTS: This exhibit provides a comprehensive evaluation, and tabulation of !D/OD, compatibility, fit, and construction of commonly used sheaths, angioplasty balloons, and catheters. There can be significant variation among the venders. For example, the Arrow reinforced arterial 7-F sheath has an OD approaching 11 F. The use of this particular sheath in a brachial artery resulted in a large pseudoaneurysm and median nerve palsy. CONCLUSION A summary of the compatibility, fit, and size of different sheaths, balloons, and catheters will be available.
Take Home Points: 1. There can be significant variation in the fit, size, and compatibility between different vender's sheaths, balloons, and catheters.
250
2. The incidence of arterial complications increases with larger puncture size and it is important to appreciate the requirements and sizes of available intravascular products.
4:10 pm Intravascular Stents: Effects on Branching Vessels Originating from a Stent-containing Parent Artery G. Geremia, MD, Chicago, IL • T W. Kim, MD • M.P. Haklin, MD • 1. Brennecke, DVM, PhD PURPOSE: The purpose of this study is to observe the effects (patency, stenosis or occlusion) on the internal carotid artery and external carotid artery branches after the intravascular placement of a porous metallic stent across their origins within the common carotid artery. MATERIALS AND METHODS: Five mongrel dogs, each weighing 25 kg were used in this experiment. Selective catheterization of a Single carotid artery in each dog was performed after femoral artery cutdown. Angiography of the distal common carotid artery, which included external carotid artery branches and the internal carotid artery, was performed. An intravascular stent was deposited within the distal carotid artery such that it occupied a segment of the parent artery, which included the origins of smaller branching arteries (eg, internal carotid, laryngeal, lingual, occipital, and ascending pharyngeal). Angiography was performed immediately after stent placement at 1 week, 4 weeks, and 8 weeks after stent placement. The specimens were resected after this period and histopathologically studied. RESULTS: The stented parent carotid arteries, including their branches, remained radiographically patent and unchanged in all five specimens. Histopathologic study revealed neointimal proliferation in response to the stent. The neointimal proliferation extended into the origins of the branches. However, no branch was occluded or stenosed by this proliferation reaction. CONCLUSION Small branching vessels originating from a stented vascular segment remained patent after stent placement despite subsequent neointimal proliferation.
Take Home Points: Neointimal proliferation in response to an intravascular stent did not cause occlusion of small branching vessels originating from the stented segment. 4:20 pm Assessment of Biocompatibility of Stent-Grafts in an Animal Model .f. Link, MD, Kiel, Germany • B. Feyerabend, MD • U. Linstedt, MD • M. Grabeuer, MD • H. Trousen, MD • M. Heller, MD PURPOSE: To investigate the biocompatibility of Dacroncovered stent-grafts in an animal model. MATERIAL AND METHODS: A total of nine stent-grafts (Endopro-System, Min Tec, Bahamas) (length, 3 cm; diameter, 5 mm) were implanted in eight swine. Follow-up angiography was performed after 2-5 weeks. The specimen were stained for histologic examination with hematosin-eosin (HE) and Elastica-van-Gieson.
RESULTS: Eight of nine stent-grafts were occluded in follow-up angiography and only one stem-graft proved to be patent. Histologic evaluation of the treated arteries revealed fibroblasts, hemosiderin deposits, calcification, and neovascularization. An inflammatory reaction with granulocytes was seen both in the vessel lumen and in the vessel wall along the Dacron cover. In three cases inflammatory reaction was severe, in two cases inflammatory reaction was moderate, and in three cases inflammatory reaction was mild. A foreign body reaction with polynuclear giant cells lining the Dacron cover was seen in all specimens. CONCLUSION Patency rate of Dacron covered stemgrafts is poor in animals. The biocompatibility of this type of Dacron-covered stent-graft seems to be limited by an inflammatory reaction.
Take Home Points: Inflammatory reaction against Dacron-covered stent-graft-poor patency in the experimental setting. 4:30 pm Visualization of Flow Patterns Following Stent and Stent Graft Deployment in a Flow Model
Take Home Points: 1. Different stent designs reveal different flow patterns. 2. Different stem designs reveal no pressure gradients. 3. Flow patterns depend on remaining stenosis. 4:40 pm Porous Metallic Stents: Use in the Treatment of Arteriovenous Fistulas G.K. Geremia, MD, Chicago, IL • M. Haklin, MD • L. Brennecke, DVM; PhD • j. Douglas, MD • M. Bakon, MD • C Flowers, MD PURPOSE: The purpose of this study is to observe the effectiveness of porous metallic stents in treatment (closure) of experimentally created arteriovenous fistula. MATERIALS AND METHODS: Experimental arteriovenous fistulae between the carotid artery and jugular vein, 2 mm in diameter, were created in five mongrel dogs. A single porous metallic stent (Schneider, Minneapolis, MN) was deposited intravascularly imo the carotid artery so that it laid across the fistula hole. Angiography was performed before, immediately after, and 4 and 8 weeks after stem placement.
S. Mueller-Hue/sbeck, MD, Kiel, Germany •
RESULT Complete closure of the fistula was observed in
H. Schwarzenberg, MD • F. Wesner, MD • j. Link, MD
three of five animals 4 weeks after stem placement. Two dogs demonstrated significant reduction of blood flow through the fistula 8 weeks after stem placement. Histopathologic study revealed dense, mature fibrous connective tissue that formed across the fistula and occupied the spaces between the wire mesh network of the stent. The stem wires were covered by neointima and they depressed the underlying elastic lamina.
• R. Drost, MD • M. Heller, MD PURPOSE: To determine flow characteristics and pressure gradients after in-vitro application of different stents and stem grafts. lv1ATERlALS AND METHODS: Five vascular stems (Angiomed™, Cragg™, two Palmaz™ P308, Strecker™, Wa]]TM) and one stem graft (Cragg Endopro™), corresponding in length (60 mm) and diameter 00 mm), were deployed in a closed flow-model. The inner diameter of the tube measured 9 mm. Flow from 1.5 L/min to 10 L/min was simulated. Turbulent and laminary flow characteristics and pressure gradients were semiquantitatively determined in either expanded stent, 25% and 50% stenosis. The flow was visualized with the use of anionic particles shot with two helium-neon lasers. RESULTS: Visualization of flow was achieved in all stems
or stem grafts. No significant pressure gradients were measured (P< .000l). In case of physiological flow of 1.5 L/min and complete expansion the Angiomed™ stent 09.3%) permitted maximum of laminary flow, the Wall™ stent (66,2%) least (P < .000l). In 25% stenosis the Wall™ stem (57,5%) allowed maximum and the Cragg Endopro™ stem 09.8%) least laminary flow (P < .000l). Any of the stent ensured laminary flow, when contracted to 50% stenosis. CONCLUSIONS: Different flow patterns, resulting from differem stent designs, may influence neointimal hyperplasia and occurrence of restenoses.
CONCLUSION In some cases, placement of an endovascular stem across a fistula hole may be technically easier than placement of balloons or coils. In our experiment, endothelial overgrowth filled in interstices between the wires. This resulted in complete closure of the fistula hole in three cases and partial closure in two cases. These results will be demonstrated on VHS video.
Take Home Points: 1. Some arterio-venous fistulas may be closed with porous metallic stems. 2. Endothelium fills the interstices of the stem. 3. Stems may be technically easier to use versus balloons. 4:50 pm Endovasculady Assembled Aortic Graft: A Feasibility Study A. K6nya, MD, PhD, Houston, TX • K.C Wright, PhD • S. Wallace, MD PURPOSE: To create an aortic stem-graft whose assembly can be performed endovascularly.
251
MATERIALS AND METHODS: The first portion of the
graft to be deployed consisted of two anchoring Z stents connected by struts over which a small-pore polyester tube was placed and attached. A triple-body inner Z stent was then placed within the graft lumen between the anchoring stents. A coaxial delivery system was designed for the two-stage deployment, which was evaluated in eight dogs. RESULTS: Graft delivery was completely successful in
four cases. In the second and third dogs, the lumen of the graft material had to be recatheterized for deployment of the inner stent because of technical problems with the delivery system. These problems were solved by improving the method for joining the sections of the delivery system. In two animals, premature deployment of the inner stent resulted in a wide gap between this stent and the caudal anchoring stent. The gap was easily bridged with a single body Z-stent in both animals. CONCLUSION: Endovascular assembly of an aortic stent
graft is feasible. This approach to graft deployment reduces the size of the delivery system, which may obviate the need for a cutdown. Take Home Points: Endovascular assembly of an aortic stent graft is feasible and reduces the size of the required delivery system.
Monday, March 10, 1997 3:30-5:00 pm Poster Session 2
cally significantly higher (P < .05) in those patients with high systolic blood pressure (;;" 160 mm Hg), anticoagulant therapy during UGCR procedure, and wide pseudoaneurysmal neck (;;" 2 mm), in comparison with the control patients. CONCLUSION: Hypertension and anticoagulant usage as well as the wide neck of pseudoaneurysm are three significant factors that contribute to failure of UGCR of postcatheterization femoral artery pseudoaneurysms.
Take Home Points: Hypertension should be managed for a successful UGCR procedure. 3:40 pm Changes in the Aortic Bifurcation Angle in the Presence of Abdominal Aortic Aneurysms T. Fathy Massoud, MD, Los Angeles, CA • G j. Hademenos, PhD • j. W Sayre, PhD •
E. W.l. Fletcher, MD PURPOSE: To compare values of the aortic bifurcation
angle (ABA) in the presence of abdominal aortic aneurysms (AAAs) with those from normal subjects. MATERIALS AND METHODS: The ABA was measured on frontal angiograms of 71 patients (37 males and 34 females; mean age, 66 years) with nondiseased aortas and common iliac arteries, and 27 patients (17 males and 10 females; mean age, 69 years) with angiographically documented AAAs. Statistical analysis was performed
with multivariable (age, sex, and AAA presence) linear regression analysis and a two sample KolomogorovSmirnov test for equality of distributions.
3:30 pm Factors Contributing to Unsuccessful US-guided COD1pression Repair of PostcatheteriZation pseudoaneurysms X. Yang, MD, PhD, Kuopio, Finland • H. Manninen, MD, PhD· E. Kaukanen, MD • S. Soimakallio, MD, PhD PURPOSE: To clarify the factors contributing to failure of
US-guided congression repair (UGCR) of postcatheterization femoral arterial pseudoaneurysms. MATERIALS AND METHODS: We reviewed the clinical courses of 5,632 patients who underwent different car-
diovascular catheterizations through a femoral approach during the period of 2 years. Femoral arterial pseudoaneurysm was found in 45 (0.8%) patients. Altogether, 17 factors including patient's clinical features, anticoagulant therapy, catheterization procedures, UGCR procedures, and pseudoaneurysmal characteristics, were analyzed by using the statistics of multiple logistic regression. RESULTS: The pseudoaneurysms were successfully treated with UGCR in 37 (82.2%) patients. Another eight (17.8%) patients with unsuccessful UGCR required sur-
252
gical repair. The frequency of UGCR failure was statisti-
RESULTS: The range of ABAs for normal subjects was 15°-80° (mean, 39.0°) and that in the presence of AAAs was 15°-120° (mean, 57.4°). The Kolomogorov-Smirnov test yielded a statistical result D = 0.4674, which was highly significant (P < .00001). A strong bimodal distribution (with a peak at acute angles [mode 20°] and another peak at obtuse angles [mode 90°]) was observed
for values of ABAs in the presence of AAAs. The ABAs of normal subjects showed a unimodal distribution (mode 40°). There was no statistical correlation between ABA and patient age or sex. CONCLUSIONS: When compared to normal, the ABA changes significantly in the presence of an AAA to assume either a markedly acute configuration or an obtuse splaying. Knowledge of these induced alterations in ABA is useful in understanding the morphogenesis of AAAs and as reference values for endovascular procedures centered on the aorto-iliac junction, including stent graft placement.
Take Home Points: 1. AAAs induce changes in the aortic bifurcation angle (ABA), which becomes either very acute (- 20°) or obtuse (- 90°) compared to normal (- 40°).
ing a stepped digital system in imaging the lower extremity (LE) vasculature in patients with nonpalpable femoral pulses. MA1ERlALS AND METIlODS: Four patients with nonpalpable femoral pulses referred for aortography, were imaged using SIVDSA. A single, large bolus of contrast material (90 mL Hexabrix at 15-20 mUsec) was given through a 5-F pigtail catheter in the right atrium; and stepped digital imaging of the abdomen, pelvis, and lower extremities was performed. All patients were imaged with use of the Siemens Multistar T.O.P. system. RESULTS: Diagnostic images of the aorta and LE run-off were obtained in all patients. The trifurcation vessels were well seen in three of four patients. Two of four patients had aortic occlusion; the two remaining patients had iliac occlusions. In one patient, IVDSA was used to guide arterial puncture and subsequent intervention. CONCLUSIONS: Central venous injection of a large bolus of contrast material results in prolonged opacification of the arterial tree. When combined with stepped digital imaging, the entire vasculature, from the diaphragm to the ankle, can be visualized. Because all collaterals fill with intravenous injection, SIVDSA provides visualization of the femoral arteries and LE vasculature, which is equal to or better than conventional arteriography in cases of aortic or bilateral iliac occlusion.
Take Home Points: 1. SIVDSA can provide a safe and effective means of imaging the pelvic and lower extremity vasculature in patients with aortic or bilateral iliac occlusion. 2. rvDSA can be used to guide arterial puncture and subsequent intervention in patients with nonpalpable femoral pulses.
3:40 pm Evaluation of Primary Venous Aneurysms: A Case Series and Review s.P. Murray, MD, Lajolla, CA • Aj. Meglin, MD • ML Rosado-de-Christenson, MD PURPOSE: Primary venous aneurysms are rare, with only
limited case reports in the literature. They have been thought previously to be of little clinical significance.
The purpose of this report is to define extracranial venous aneurysms and discuss their clinical presentation, natural history, and management. We will show radiologic and pathologic appearance. MA1ERIALS AND METIlODS: We reviewed 10 cases from two tertiary-care hospitals and the AFIP. Skull-based and CNS aneurysms, arteriovenous-fistula and postcatheterization aneurysms were excluded. Clinical presentation, location, size, natural history, and radiologic appearance were recorded. RESULTS: There were seven females and three males ranging in age from 17 to 77 years (mean, 45.2). Presenting symptoms included localized swelling or painful mass (5), thromboembolic disease 0), and painless mass (1). Two aneurysms were incidental findings. Locations included greater saphenous vein 0), superior vena cava (2) and one each in the common femoral, popliteal, soleal, and internal jugular veins. Aneurysms varied in size from 1.5 cm to 7 cm (mean, 3.2). Previous surgery or trauma was noted in four patients. One patient developed thrombus during hospitalization, requiring emergent resection. No patients developed complications after resection. CONCLUSIONS: Primary venous aneurysms are rare. Multiple aneurysms occur more frequently than preViously noted. Etiologies include trauma and previous surgery. Patients do well after surgical resection. Venous aneurysms should be viewed with high potential for thromboembolic disease.
Take Home Points: 1. Multiple aneurysms occur more frequently than preViously noted. 2. Patients do well after surgical resection. 3. Venous aneurysms should be viewed with high potential for thromboembolic disease.
3:50 pm Multislab-MRA of the Carotid Arteries from the Aortic Arch to the Circle of Willis I Link, MD, Kiel, Germany. Ie. Steffens, MD • S. Mueller-Huelsbeck, MD • F. Wesner, MD • M. Heller, MD PURPOSE: To determine the value of multislab MRA in
carotid artery stenoses. MA1ERIALS AND METIlODS: Fifty consecutive patients with arterial angiograms of the carotid arteries were enrolled in the study. MRA was performed with a l.5T Magnetom Vision (Siemens), using a head-neck coil. Ten slabs in transaxial orientation were performed in multiple overlapping thin slab technique (TR 35msec; TE 6msec; flip angle25°; FOV 265mm; matrix 155x256; acquisition time 26min). Reconstructions were performed with maximum intensity projection technique. The de-
249
gree of stenosis was evaluated according to NASCETcriteria. RESULTS: Imaging of the entire vessels from the aortic arch to the circle of Willis was of diagnostic quality in each patient. Agreement of MRA and DSA in normal arteries was 93% (28/30) and was 67% (l0/15) in mild 74% (14/19) in moderate, and 96% (26/27) in severe stenoses. All conclusions (9/9) were correctly diagnosed with MRA and DSA. Three tandem lesions and one fibromuscular dysplasia were depicted with MRA. Only 5/8 ulcers were diagnosed on MRA. CONCLUSION Multislab MRA is a valuable technique to assess the entire carotid circulation noninvasively with good correlation to DSA.
Take Home Points: Multislab MRA allows visualization of the entire cervical arteries; good correlation with DSA. 4:00 pm Variance in Diameter and Compatibility Between Commonly used Arterial Sheaths, Angioplasty Balloons, and Catheters .f.K. St. George, MD, Lebanon, NH • Bf. McClellan, RT • .f. Georgia, MD • D. Langdon, MD • M.A. Bettmann, MD PURPOSE: Arterial sheaths are widely used in both diagnostic and interventional procedures. Unlike catheters, arterial sheaths are not designated by their OD French size, but rather by the ID. MATERIALS AND METHODS: ID and OD measurements of 5-9-F sheaths from numerous manufacturers were measured. Additionally, the sheaths were tested for compatibility with commonly sized balloons (5-12 mm), 7-8-F guide catheters and 5-6-F diagnostic catheters from both the same and competitive venders. RESULTS: This exhibit provides a comprehensive evaluation, and tabulation of !D/OD, compatibility, fit, and construction of commonly used sheaths, angioplasty balloons, and catheters. There can be significant variation among the venders. For example, the Arrow reinforced arterial 7-F sheath has an OD approaching 11 F. The use of this particular sheath in a brachial artery resulted in a large pseudoaneurysm and median nerve palsy. CONCLUSION A summary of the compatibility, fit, and size of different sheaths, balloons, and catheters will be available.
Take Home Points: 1. There can be significant variation in the fit, size, and compatibility between different vender's sheaths, balloons, and catheters.
250
2. The incidence of arterial complications increases with larger puncture size and it is important to appreciate the requirements and sizes of available intravascular products.
4:10 pm Intravascular Stents: Effects on Branching Vessels Originating from a Stent-containing Parent Artery G. Geremia, MD, Chicago, IL • T W. Kim, MD • M.P. Haklin, MD • 1. Brennecke, DVM, PhD PURPOSE: The purpose of this study is to observe the effects (patency, stenosis or occlusion) on the internal carotid artery and external carotid artery branches after the intravascular placement of a porous metallic stent across their origins within the common carotid artery. MATERIALS AND METHODS: Five mongrel dogs, each weighing 25 kg were used in this experiment. Selective catheterization of a Single carotid artery in each dog was performed after femoral artery cutdown. Angiography of the distal common carotid artery, which included external carotid artery branches and the internal carotid artery, was performed. An intravascular stent was deposited within the distal carotid artery such that it occupied a segment of the parent artery, which included the origins of smaller branching arteries (eg, internal carotid, laryngeal, lingual, occipital, and ascending pharyngeal). Angiography was performed immediately after stent placement at 1 week, 4 weeks, and 8 weeks after stent placement. The specimens were resected after this period and histopathologically studied. RESULTS: The stented parent carotid arteries, including their branches, remained radiographically patent and unchanged in all five specimens. Histopathologic study revealed neointimal proliferation in response to the stent. The neointimal proliferation extended into the origins of the branches. However, no branch was occluded or stenosed by this proliferation reaction. CONCLUSION Small branching vessels originating from a stented vascular segment remained patent after stent placement despite subsequent neointimal proliferation.
Take Home Points: Neointimal proliferation in response to an intravascular stent did not cause occlusion of small branching vessels originating from the stented segment. 4:20 pm Assessment of Biocompatibility of Stent-Grafts in an Animal Model .f. Link, MD, Kiel, Germany • B. Feyerabend, MD • U. Linstedt, MD • M. Grabeuer, MD • H. Trousen, MD • M. Heller, MD PURPOSE: To investigate the biocompatibility of Dacroncovered stent-grafts in an animal model. MATERIAL AND METHODS: A total of nine stent-grafts (Endopro-System, Min Tec, Bahamas) (length, 3 cm; diameter, 5 mm) were implanted in eight swine. Follow-up angiography was performed after 2-5 weeks. The specimen were stained for histologic examination with hematosin-eosin (HE) and Elastica-van-Gieson.
RESULTS: Eight of nine stent-grafts were occluded in follow-up angiography and only one stem-graft proved to be patent. Histologic evaluation of the treated arteries revealed fibroblasts, hemosiderin deposits, calcification, and neovascularization. An inflammatory reaction with granulocytes was seen both in the vessel lumen and in the vessel wall along the Dacron cover. In three cases inflammatory reaction was severe, in two cases inflammatory reaction was moderate, and in three cases inflammatory reaction was mild. A foreign body reaction with polynuclear giant cells lining the Dacron cover was seen in all specimens. CONCLUSION Patency rate of Dacron covered stemgrafts is poor in animals. The biocompatibility of this type of Dacron-covered stent-graft seems to be limited by an inflammatory reaction.
Take Home Points: Inflammatory reaction against Dacron-covered stent-graft-poor patency in the experimental setting. 4:30 pm Visualization of Flow Patterns Following Stent and Stent Graft Deployment in a Flow Model
Take Home Points: 1. Different stent designs reveal different flow patterns. 2. Different stem designs reveal no pressure gradients. 3. Flow patterns depend on remaining stenosis. 4:40 pm Porous Metallic Stents: Use in the Treatment of Arteriovenous Fistulas G.K. Geremia, MD, Chicago, IL • M. Haklin, MD • L. Brennecke, DVM; PhD • j. Douglas, MD • M. Bakon, MD • C Flowers, MD PURPOSE: The purpose of this study is to observe the effectiveness of porous metallic stents in treatment (closure) of experimentally created arteriovenous fistula. MATERIALS AND METHODS: Experimental arteriovenous fistulae between the carotid artery and jugular vein, 2 mm in diameter, were created in five mongrel dogs. A single porous metallic stent (Schneider, Minneapolis, MN) was deposited intravascularly imo the carotid artery so that it laid across the fistula hole. Angiography was performed before, immediately after, and 4 and 8 weeks after stem placement.
S. Mueller-Hue/sbeck, MD, Kiel, Germany •
RESULT Complete closure of the fistula was observed in
H. Schwarzenberg, MD • F. Wesner, MD • j. Link, MD
three of five animals 4 weeks after stem placement. Two dogs demonstrated significant reduction of blood flow through the fistula 8 weeks after stem placement. Histopathologic study revealed dense, mature fibrous connective tissue that formed across the fistula and occupied the spaces between the wire mesh network of the stent. The stem wires were covered by neointima and they depressed the underlying elastic lamina.
• R. Drost, MD • M. Heller, MD PURPOSE: To determine flow characteristics and pressure gradients after in-vitro application of different stents and stem grafts. lv1ATERlALS AND METHODS: Five vascular stems (Angiomed™, Cragg™, two Palmaz™ P308, Strecker™, Wa]]TM) and one stem graft (Cragg Endopro™), corresponding in length (60 mm) and diameter 00 mm), were deployed in a closed flow-model. The inner diameter of the tube measured 9 mm. Flow from 1.5 L/min to 10 L/min was simulated. Turbulent and laminary flow characteristics and pressure gradients were semiquantitatively determined in either expanded stent, 25% and 50% stenosis. The flow was visualized with the use of anionic particles shot with two helium-neon lasers. RESULTS: Visualization of flow was achieved in all stems
or stem grafts. No significant pressure gradients were measured (P< .000l). In case of physiological flow of 1.5 L/min and complete expansion the Angiomed™ stent 09.3%) permitted maximum of laminary flow, the Wall™ stent (66,2%) least (P < .000l). In 25% stenosis the Wall™ stem (57,5%) allowed maximum and the Cragg Endopro™ stem 09.8%) least laminary flow (P < .000l). Any of the stent ensured laminary flow, when contracted to 50% stenosis. CONCLUSIONS: Different flow patterns, resulting from differem stent designs, may influence neointimal hyperplasia and occurrence of restenoses.
CONCLUSION In some cases, placement of an endovascular stem across a fistula hole may be technically easier than placement of balloons or coils. In our experiment, endothelial overgrowth filled in interstices between the wires. This resulted in complete closure of the fistula hole in three cases and partial closure in two cases. These results will be demonstrated on VHS video.
Take Home Points: 1. Some arterio-venous fistulas may be closed with porous metallic stems. 2. Endothelium fills the interstices of the stem. 3. Stems may be technically easier to use versus balloons. 4:50 pm Endovasculady Assembled Aortic Graft: A Feasibility Study A. K6nya, MD, PhD, Houston, TX • K.C Wright, PhD • S. Wallace, MD PURPOSE: To create an aortic stem-graft whose assembly can be performed endovascularly.
251
MATERIALS AND METHODS: The first portion of the
graft to be deployed consisted of two anchoring Z stents connected by struts over which a small-pore polyester tube was placed and attached. A triple-body inner Z stent was then placed within the graft lumen between the anchoring stents. A coaxial delivery system was designed for the two-stage deployment, which was evaluated in eight dogs. RESULTS: Graft delivery was completely successful in
four cases. In the second and third dogs, the lumen of the graft material had to be recatheterized for deployment of the inner stent because of technical problems with the delivery system. These problems were solved by improving the method for joining the sections of the delivery system. In two animals, premature deployment of the inner stent resulted in a wide gap between this stent and the caudal anchoring stent. The gap was easily bridged with a single body Z-stent in both animals. CONCLUSION: Endovascular assembly of an aortic stent
graft is feasible. This approach to graft deployment reduces the size of the delivery system, which may obviate the need for a cutdown. Take Home Points: Endovascular assembly of an aortic stent graft is feasible and reduces the size of the required delivery system.
Monday, March 10, 1997 3:30-5:00 pm Poster Session 2
cally significantly higher (P < .05) in those patients with high systolic blood pressure (;;" 160 mm Hg), anticoagulant therapy during UGCR procedure, and wide pseudoaneurysmal neck (;;" 2 mm), in comparison with the control patients. CONCLUSION: Hypertension and anticoagulant usage as well as the wide neck of pseudoaneurysm are three significant factors that contribute to failure of UGCR of postcatheterization femoral artery pseudoaneurysms.
Take Home Points: Hypertension should be managed for a successful UGCR procedure. 3:40 pm Changes in the Aortic Bifurcation Angle in the Presence of Abdominal Aortic Aneurysms T. Fathy Massoud, MD, Los Angeles, CA • G j. Hademenos, PhD • j. W Sayre, PhD •
E. W.l. Fletcher, MD PURPOSE: To compare values of the aortic bifurcation
angle (ABA) in the presence of abdominal aortic aneurysms (AAAs) with those from normal subjects. MATERIALS AND METHODS: The ABA was measured on frontal angiograms of 71 patients (37 males and 34 females; mean age, 66 years) with nondiseased aortas and common iliac arteries, and 27 patients (17 males and 10 females; mean age, 69 years) with angiographically documented AAAs. Statistical analysis was performed
with multivariable (age, sex, and AAA presence) linear regression analysis and a two sample KolomogorovSmirnov test for equality of distributions.
3:30 pm Factors Contributing to Unsuccessful US-guided COD1pression Repair of PostcatheteriZation pseudoaneurysms X. Yang, MD, PhD, Kuopio, Finland • H. Manninen, MD, PhD· E. Kaukanen, MD • S. Soimakallio, MD, PhD PURPOSE: To clarify the factors contributing to failure of
US-guided congression repair (UGCR) of postcatheterization femoral arterial pseudoaneurysms. MATERIALS AND METHODS: We reviewed the clinical courses of 5,632 patients who underwent different car-
diovascular catheterizations through a femoral approach during the period of 2 years. Femoral arterial pseudoaneurysm was found in 45 (0.8%) patients. Altogether, 17 factors including patient's clinical features, anticoagulant therapy, catheterization procedures, UGCR procedures, and pseudoaneurysmal characteristics, were analyzed by using the statistics of multiple logistic regression. RESULTS: The pseudoaneurysms were successfully treated with UGCR in 37 (82.2%) patients. Another eight (17.8%) patients with unsuccessful UGCR required sur-
252
gical repair. The frequency of UGCR failure was statisti-
RESULTS: The range of ABAs for normal subjects was 15°-80° (mean, 39.0°) and that in the presence of AAAs was 15°-120° (mean, 57.4°). The Kolomogorov-Smirnov test yielded a statistical result D = 0.4674, which was highly significant (P < .00001). A strong bimodal distribution (with a peak at acute angles [mode 20°] and another peak at obtuse angles [mode 90°]) was observed
for values of ABAs in the presence of AAAs. The ABAs of normal subjects showed a unimodal distribution (mode 40°). There was no statistical correlation between ABA and patient age or sex. CONCLUSIONS: When compared to normal, the ABA changes significantly in the presence of an AAA to assume either a markedly acute configuration or an obtuse splaying. Knowledge of these induced alterations in ABA is useful in understanding the morphogenesis of AAAs and as reference values for endovascular procedures centered on the aorto-iliac junction, including stent graft placement.
Take Home Points: 1. AAAs induce changes in the aortic bifurcation angle (ABA), which becomes either very acute (- 20°) or obtuse (- 90°) compared to normal (- 40°).