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Fracture of an Iliac Artery Palmaz Stent
Case Report
Fracture of an Iliac Artery Palmaz Stentl Barry A. Sacks, MD Arnold Miller, MD Michael Gottlieb, MD
Index terms: Arteries, grafts and prostheses, 938,458,988,458 * Arteries, femoral, 929.458 Arteries, iliac, 988.458 Arteries, tibial, 929.458 Stents and prostheses, 988.458
JVIR 1996; 7:53-55
'From the Departments of Radiology (B.A.S.),Surgery (A.M.),and Nephrology (M.G.),MetroWest Medical Center, 67 Union St, Natick, MA 01760. Received May 3, 1995;revision requested June 13; revision received July 24; accepted July 27. Address correspondenceto B.A.S.
WE report a case in which a fracture occurred within the third of three sequential overlapping 39-mm-long Palmaz stents (Johnson & Johnson Interventional Systems, Warren, NJ) placed in the right common iliac to proximal external iliac arteries. The fracture occurred where the third stent overlapped with the distal end of the second. Substantial intimal hmerplasia occurred in the bare area between the fracture fragments, resultinn in substantial recurrent stenosis l l m o n t h s after initial la cement. Although it is impossible to conclusively prove the cause for this complication, possible mechanisms are discussed.
".
CASE REPORT A 62-year-old man with severe ischemic heart disease underwent coronary artery bypass grafting in 1988, which was complicated by renal failure that necessitated hemodialysis. During the same year, a renal transplant failed and the patient continued to undergo hemodialysis. In May 1991 he presented with painful, ischemic toes of the left foot. Ankle pressures could not be measured because of incompressibility of the tibial arteries. Arteriography demonstrated a left common iliac occlusion. A right-to-left femorofemoral bypass graft relieved all symptoms of ischemia. He did well for 18 months when left foot ischemia recurred, exacerbated during dialysis with minor decreases in blood pressure. Repeated arteriography showed new stenoses in the right common and external iliac arteries, proximal to the take-off of a patent femorofemoral bypass. Moderate stenosis of the proximal right supeficial and deep femoral arteries was noted, but the distal runoff was good. The left superficial femoral artery was occluded, with reconstitution of the popliteal artery and good
distal runoff. A percutaneous balloon angioplasty procedure performed on the right common and external iliac stenoses in October 1992 reduced the initial gradient from 80 mm Hg to 20 mm Hg. Despite the angioplasty, the left leg ischemia worsened and a left femoropopliteal saphenous vein below-knee bypass procedure was performed 3 weeks later. At surgery, the left femoral arterial systolic pressure was 70 mm Hg despite the patent femorofemoral bypass graft. Because of the concern that the new left femoropopliteal graft might occlude, repeated diagnostic arteriography was performed on postoperative day 3 to reevaluate the inflow. Persistent and possibly new stenoses of the right common and external iliac arteries were noted. Despite the apparent recent postangioplasty gradient of 20 mm Hg, repeat pressure measurements again revealed a gradient of 70 mm Hg from the aorta to the right common femoral artery. Three sequential overlapping 39-mm-long Palmaz stents were placed percutaneously (Fig 1)and dilated, first to 7 mm then 8 mm, with reduction in the iliofemoral gradient to 14 mm Hg. The markedly calcified vessels did not permit complete, smooth symmetric expansion of all the stents. The residual irregularities were thought to account for the residual gradient. A larger balloon was considered but not employed because of the risk of vessel rupture in such a calcified artery. He did extremely well until 13 months later when he developed recurrent severe claudication of the right calf and foot. Pain had actually started a few months earlier but because the patient's cardiac condition had deteriorated, any intervention was considered risky. He had required two hospital admissions for uncontrol-
54
Journal of Vascular and Interventional Radiology
January-February 1996
lable angina and a documented subendocardia1 infarction. (Coronary angiography, performed in September 1992, before the initial right iliac angioplasty, had shown occlusion of all previous bypass grafts with diffuse three-vessel coronary artery disease and extremely poor ventricular function). As a result, he was treated conservatively initially. However, when the right foot pain became unremitting with gangrenous toes, surgery was planned. Because right superficial and deep femoral artery stenoses had been demonstrated previously, in the presence of a palpable right femoral pulse, endarterectomy and patch angioplasty of the right common, superficial, and deep femoral arteries were performed after the patient was given regional anesthesia. Despite a good anatomic result, there was only slight improvement of the foot ischemia. A repeated arteriogram obtained from the right groin demonstrated a moderate recurrent stenosis in the proximal common iliac artery, just above the most proximal stent, and a very tight stenosis in the external iliac artery (Fig 2). Close inspection showed the distal stenosis to be a t the site of a fracture within the Palmaz stent. Intimal thickening between the fracture fragments appeared to be a major component of the stenosis. The proximal stenosis responded well to repeat percutaneous transluminal angioplasty, but the distal stenosis was extremely resistant. Four different angioplasty balloon catheters (two Ultrathin, one PEMT, and one Blue Max; Medi-tech/Boston Scientific, Watertown, Mass) were used in a n attempt to dilate the stenosis a t the site of the stent fracture. On inflation, each balloon was punctured by sharp metal fragments a t the stent fracture site. Deployment of another overlapping stent within the stenosis was considered but abandoned because of concern that the balloon of the deployment catheter would be punctured with the stent only partially expanded, creating additional problems. A self-expandable Wallstent was not considered a t the time. This, however, probably also would have failed. The rigid vessel would certainly not allow self expansion to the predetermined diameter, and attempted balloon dilation probably would have
Figure 1. (a)Three overlapping 39-mm-long Palmaz stents are shown (arrows). Note the diffuse irregularity in the stent contours that is almost certainly related to the very diseased, calcified artery. (b) Arteriogram obtained after stent placement shows a good result, despite diffuse irregularity due to substantial calcification. been equally unsuccessful. As a consequence, surgery was undertaken and a polytetrafluoroethylene graft from the left axillary artery (the patient had a vascular access in the right arm) was inserted into the femorofemoral graft, with complete relief of the patient's ischemia and healing of a right transmetatarsal amputation. His vascular status remained stable until his sudden cardiac arrest and death 22 months later.
DISCUSSION Complications associated with Palmaz stents may be technical, related to deployment, or biological, a consequence of the stent within the arterial lumen (1-5). These complications generally manifest either acutely-with sudden vessel thrombosis, distal embolization with clot or plaque contents, or vessel rupture or dissection--or more chronically-as restenosis or delayed thrombosis. There are two interesting aspects of this case: the occurrence of fracture of a Palmaz stent and the degree of intimal proliferation in association with distortion of the stent filaments causing recurrent luminal stenosis.
Other than the segments of incomplete expansion, due to the rigid vessel, no problems with the stent could be demonstrated either during placement or on the immediate follow-up arteriogram. Although a localized indentation could be seen in retrospect above the site where the fracture subsequently occurred, the stent segments overlapped as they should and no other abnormalities were noted. The stent fracture was only appreciated 14 months later when repeat arteriography was performed for recurrent symptoms of ischemia. Unfortunately, no intervening abdominal or pelvic radiographs had been obtained. One can only speculate on the cause of the fracture and its site. Because the stent was not placed in a segment of artery subjected to flexion or external compression, neither direct stent injury nor metal fatigue could be implicated. The segment of iliac artery in which the stent was placed was not only straight but was also rigid and densely calcified. Deployment of the stent against a substantially rigid, irregular stenotic vessel wall may have contributed abnormal stresses (6,7). The fracture also occurred in a region where the stent went from double
Sacks et a1
55
Volume 7 Number 1
ping double to a single layer, may have added additional stress. With time, and complicated by the intimal hyperplasia (81, the overt stent fracture developed.
Figure 2. Arteriogram obtained at the time of recurrent symptoms demonstrates two areas of restenosis (arrows). One was in the proximal right common iliac artery, and the other was a severe stenosis in the right external iliac artery.
(overlapping) proximally to single distally, and this may have contributed additional abnormal stress. It has been shown that the Palmaz device is the most rigid stent and offers the most resistance to expansion (6,7); this was undoubtedly significant in these calcified vessels. Additionally, intimal hyperplasia has been shown to occur a t sites of persistent deformity, a t the ends of the stent as well as in the gap left between non-overlapping stents. It is extremely unlikely that intimal hyperplasia, possibly developing in a n area
Figure 3. Magnification plain radiograph obtained at the same time as the angiogram in Figure 2 shows a fracture (arrows) within the third stent at the inferior end of the second. Note the deformity and distortion of the stent ends at the fracture site.
of residual irregularity, caused the stent fracture. In this case, the intima1 hyperplasia not only caused significant luminal restenosis a t the fracture site, but may somehow have contributed to the added separation and deformity of the broken struts (Fig 3). As no percutaneous or surgical intervention had taken place since the original stent placement procedure, it is difficult to explain the occurrence of the findings. The most plausible explanation is that a n occult fracture occurred a t the time of deployment, due to markedly abnormal stresses from balloon deployment within a very rigid vessel. The site of overlap between the second and third stents where the metal struts changed from overlap-
References 1. Eeckhout E, Goy JJ, Vogt P, Stauffer JC, Sigwart U, Kappenenberger L. Complications and follow-up after intracoronary stenting: critical analysis of a single-center experience. Am Heart J 1994; 127:262-272. 2. Haude M, Erbel R, Issa H, Straub U, Rupprecht HJ, Treese N, Meyer J. Subacute thrombotic complications after intracoronary implantation of Palmaz-Schatz stents. Am Heart J 1993; 126:15-22. 3. Gray RJ, Dolmatch BL, Horton KM, Romolo JL, Zarate AR. Migration of Palmaz stents following deployment for venous stenoses related to hemodialysis access. JVIR 1994; 5:117-120. 4. Hadjimiltiades S, Gourassas J , Louridas G, Tsifodimos D. Use of half of the Palmaz-Schatz stent in a stent-related dissection. Cathet Cardiovasc Diagn 1993; 29:35-39. 5. Carrozza JP, Kuntz RE, Fishman RF, Baim DS. Restenosis after arterial injury caused by coronary stenting in patients with diabetes mellitus. Ann Intern Med 1993; 118:344-349. 6. Lossef SV, Lutz RJ, Mundorf J , Barth KH. Comparison of mechanical deformation properties of metallic stents with use of stress-strain analysis. JVIR 1994; 5:341-349. 7. Flueckiger F, Sternthal H, Klein GE, Aschauer M, Szolar D, Kleinhappl G. Strength, elasticity, and plasticity of expandable metal stents: in vitro studies with three types of stress. JVIR 1994; 5:745-750. 8. Palmaz JC. Intravascular stents: tissue-stent interactions and design considerations. AJR 1993; 160:613-618.
Fracture of an Iliac Artery Palmaz Stentl Barry A. Sacks, MD Arnold Miller, MD Michael Gottlieb, MD
Index terms: Arteries, grafts and prostheses, 938,458,988,458 * Arteries, femoral, 929.458 Arteries, iliac, 988.458 Arteries, tibial, 929.458 Stents and prostheses, 988.458
JVIR 1996; 7:53-55
'From the Departments of Radiology (B.A.S.),Surgery (A.M.),and Nephrology (M.G.),MetroWest Medical Center, 67 Union St, Natick, MA 01760. Received May 3, 1995;revision requested June 13; revision received July 24; accepted July 27. Address correspondenceto B.A.S.
WE report a case in which a fracture occurred within the third of three sequential overlapping 39-mm-long Palmaz stents (Johnson & Johnson Interventional Systems, Warren, NJ) placed in the right common iliac to proximal external iliac arteries. The fracture occurred where the third stent overlapped with the distal end of the second. Substantial intimal hmerplasia occurred in the bare area between the fracture fragments, resultinn in substantial recurrent stenosis l l m o n t h s after initial la cement. Although it is impossible to conclusively prove the cause for this complication, possible mechanisms are discussed.
".
CASE REPORT A 62-year-old man with severe ischemic heart disease underwent coronary artery bypass grafting in 1988, which was complicated by renal failure that necessitated hemodialysis. During the same year, a renal transplant failed and the patient continued to undergo hemodialysis. In May 1991 he presented with painful, ischemic toes of the left foot. Ankle pressures could not be measured because of incompressibility of the tibial arteries. Arteriography demonstrated a left common iliac occlusion. A right-to-left femorofemoral bypass graft relieved all symptoms of ischemia. He did well for 18 months when left foot ischemia recurred, exacerbated during dialysis with minor decreases in blood pressure. Repeated arteriography showed new stenoses in the right common and external iliac arteries, proximal to the take-off of a patent femorofemoral bypass. Moderate stenosis of the proximal right supeficial and deep femoral arteries was noted, but the distal runoff was good. The left superficial femoral artery was occluded, with reconstitution of the popliteal artery and good
distal runoff. A percutaneous balloon angioplasty procedure performed on the right common and external iliac stenoses in October 1992 reduced the initial gradient from 80 mm Hg to 20 mm Hg. Despite the angioplasty, the left leg ischemia worsened and a left femoropopliteal saphenous vein below-knee bypass procedure was performed 3 weeks later. At surgery, the left femoral arterial systolic pressure was 70 mm Hg despite the patent femorofemoral bypass graft. Because of the concern that the new left femoropopliteal graft might occlude, repeated diagnostic arteriography was performed on postoperative day 3 to reevaluate the inflow. Persistent and possibly new stenoses of the right common and external iliac arteries were noted. Despite the apparent recent postangioplasty gradient of 20 mm Hg, repeat pressure measurements again revealed a gradient of 70 mm Hg from the aorta to the right common femoral artery. Three sequential overlapping 39-mm-long Palmaz stents were placed percutaneously (Fig 1)and dilated, first to 7 mm then 8 mm, with reduction in the iliofemoral gradient to 14 mm Hg. The markedly calcified vessels did not permit complete, smooth symmetric expansion of all the stents. The residual irregularities were thought to account for the residual gradient. A larger balloon was considered but not employed because of the risk of vessel rupture in such a calcified artery. He did extremely well until 13 months later when he developed recurrent severe claudication of the right calf and foot. Pain had actually started a few months earlier but because the patient's cardiac condition had deteriorated, any intervention was considered risky. He had required two hospital admissions for uncontrol-
54
Journal of Vascular and Interventional Radiology
January-February 1996
lable angina and a documented subendocardia1 infarction. (Coronary angiography, performed in September 1992, before the initial right iliac angioplasty, had shown occlusion of all previous bypass grafts with diffuse three-vessel coronary artery disease and extremely poor ventricular function). As a result, he was treated conservatively initially. However, when the right foot pain became unremitting with gangrenous toes, surgery was planned. Because right superficial and deep femoral artery stenoses had been demonstrated previously, in the presence of a palpable right femoral pulse, endarterectomy and patch angioplasty of the right common, superficial, and deep femoral arteries were performed after the patient was given regional anesthesia. Despite a good anatomic result, there was only slight improvement of the foot ischemia. A repeated arteriogram obtained from the right groin demonstrated a moderate recurrent stenosis in the proximal common iliac artery, just above the most proximal stent, and a very tight stenosis in the external iliac artery (Fig 2). Close inspection showed the distal stenosis to be a t the site of a fracture within the Palmaz stent. Intimal thickening between the fracture fragments appeared to be a major component of the stenosis. The proximal stenosis responded well to repeat percutaneous transluminal angioplasty, but the distal stenosis was extremely resistant. Four different angioplasty balloon catheters (two Ultrathin, one PEMT, and one Blue Max; Medi-tech/Boston Scientific, Watertown, Mass) were used in a n attempt to dilate the stenosis a t the site of the stent fracture. On inflation, each balloon was punctured by sharp metal fragments a t the stent fracture site. Deployment of another overlapping stent within the stenosis was considered but abandoned because of concern that the balloon of the deployment catheter would be punctured with the stent only partially expanded, creating additional problems. A self-expandable Wallstent was not considered a t the time. This, however, probably also would have failed. The rigid vessel would certainly not allow self expansion to the predetermined diameter, and attempted balloon dilation probably would have
Figure 1. (a)Three overlapping 39-mm-long Palmaz stents are shown (arrows). Note the diffuse irregularity in the stent contours that is almost certainly related to the very diseased, calcified artery. (b) Arteriogram obtained after stent placement shows a good result, despite diffuse irregularity due to substantial calcification. been equally unsuccessful. As a consequence, surgery was undertaken and a polytetrafluoroethylene graft from the left axillary artery (the patient had a vascular access in the right arm) was inserted into the femorofemoral graft, with complete relief of the patient's ischemia and healing of a right transmetatarsal amputation. His vascular status remained stable until his sudden cardiac arrest and death 22 months later.
DISCUSSION Complications associated with Palmaz stents may be technical, related to deployment, or biological, a consequence of the stent within the arterial lumen (1-5). These complications generally manifest either acutely-with sudden vessel thrombosis, distal embolization with clot or plaque contents, or vessel rupture or dissection--or more chronically-as restenosis or delayed thrombosis. There are two interesting aspects of this case: the occurrence of fracture of a Palmaz stent and the degree of intimal proliferation in association with distortion of the stent filaments causing recurrent luminal stenosis.
Other than the segments of incomplete expansion, due to the rigid vessel, no problems with the stent could be demonstrated either during placement or on the immediate follow-up arteriogram. Although a localized indentation could be seen in retrospect above the site where the fracture subsequently occurred, the stent segments overlapped as they should and no other abnormalities were noted. The stent fracture was only appreciated 14 months later when repeat arteriography was performed for recurrent symptoms of ischemia. Unfortunately, no intervening abdominal or pelvic radiographs had been obtained. One can only speculate on the cause of the fracture and its site. Because the stent was not placed in a segment of artery subjected to flexion or external compression, neither direct stent injury nor metal fatigue could be implicated. The segment of iliac artery in which the stent was placed was not only straight but was also rigid and densely calcified. Deployment of the stent against a substantially rigid, irregular stenotic vessel wall may have contributed abnormal stresses (6,7). The fracture also occurred in a region where the stent went from double
Sacks et a1
55
Volume 7 Number 1
ping double to a single layer, may have added additional stress. With time, and complicated by the intimal hyperplasia (81, the overt stent fracture developed.
Figure 2. Arteriogram obtained at the time of recurrent symptoms demonstrates two areas of restenosis (arrows). One was in the proximal right common iliac artery, and the other was a severe stenosis in the right external iliac artery.
(overlapping) proximally to single distally, and this may have contributed additional abnormal stress. It has been shown that the Palmaz device is the most rigid stent and offers the most resistance to expansion (6,7); this was undoubtedly significant in these calcified vessels. Additionally, intimal hyperplasia has been shown to occur a t sites of persistent deformity, a t the ends of the stent as well as in the gap left between non-overlapping stents. It is extremely unlikely that intimal hyperplasia, possibly developing in a n area
Figure 3. Magnification plain radiograph obtained at the same time as the angiogram in Figure 2 shows a fracture (arrows) within the third stent at the inferior end of the second. Note the deformity and distortion of the stent ends at the fracture site.
of residual irregularity, caused the stent fracture. In this case, the intima1 hyperplasia not only caused significant luminal restenosis a t the fracture site, but may somehow have contributed to the added separation and deformity of the broken struts (Fig 3). As no percutaneous or surgical intervention had taken place since the original stent placement procedure, it is difficult to explain the occurrence of the findings. The most plausible explanation is that a n occult fracture occurred a t the time of deployment, due to markedly abnormal stresses from balloon deployment within a very rigid vessel. The site of overlap between the second and third stents where the metal struts changed from overlap-
References 1. Eeckhout E, Goy JJ, Vogt P, Stauffer JC, Sigwart U, Kappenenberger L. Complications and follow-up after intracoronary stenting: critical analysis of a single-center experience. Am Heart J 1994; 127:262-272. 2. Haude M, Erbel R, Issa H, Straub U, Rupprecht HJ, Treese N, Meyer J. Subacute thrombotic complications after intracoronary implantation of Palmaz-Schatz stents. Am Heart J 1993; 126:15-22. 3. Gray RJ, Dolmatch BL, Horton KM, Romolo JL, Zarate AR. Migration of Palmaz stents following deployment for venous stenoses related to hemodialysis access. JVIR 1994; 5:117-120. 4. Hadjimiltiades S, Gourassas J , Louridas G, Tsifodimos D. Use of half of the Palmaz-Schatz stent in a stent-related dissection. Cathet Cardiovasc Diagn 1993; 29:35-39. 5. Carrozza JP, Kuntz RE, Fishman RF, Baim DS. Restenosis after arterial injury caused by coronary stenting in patients with diabetes mellitus. Ann Intern Med 1993; 118:344-349. 6. Lossef SV, Lutz RJ, Mundorf J , Barth KH. Comparison of mechanical deformation properties of metallic stents with use of stress-strain analysis. JVIR 1994; 5:341-349. 7. Flueckiger F, Sternthal H, Klein GE, Aschauer M, Szolar D, Kleinhappl G. Strength, elasticity, and plasticity of expandable metal stents: in vitro studies with three types of stress. JVIR 1994; 5:745-750. 8. Palmaz JC. Intravascular stents: tissue-stent interactions and design considerations. AJR 1993; 160:613-618.