A case of popliteal stent fracture with pseudoaneurysm formation

Successful Management of Arterial Pseudoaneurysm Caused by Stent Fracture

Pseudoaneurysm is a relatively common complication of arterial injury. Arterial pseudoaneurysms have many different etiologies, including trauma, iatrogenic injury, vascular repair, infection, and vasculitides. In this case report, we present a pseudoaneurysm created by a fracture of superficial femoral artery (SFA) stent secondary to a mechanical fall. To our knowledge, this is the first report of a symptomatic pseudoaneurysm caused by a SFA stent fracture. The large, unruptured pseudoaneurysm in this case was successfully treated with a covered stent and pseudoaneurysm exclusion.

Femoropopliteal Artery Stent Fracture with Recurrent In-Stent Reocclusion and Aneurysm Formation: Successful Treatment with Self-Expandable Viabahn Endoprosthesis

Primary stenting in femoropopliteal lesions of intermediate length has recently shown favorable outcomes. However, stent fractures are a concern after bare metal stent implantation. The incidence of stent fracture varies widely (ranging from 2% to 65%) depending on factors such as the treated lesions or stent type and may potentially lead to various complications. We reported a case of stent fracture with complete dislocation combined with recurrent in-stent reocclusion and aneurysm formation in a patient with occlusive disease of the femoropopliteal artery, which was successfully treated with self-expandable endovascular stent graft.

Quantification of popliteal artery deformation during leg flexion in subjects with peripheral artery disease: a pilot study

PURPOSE

To quantify the in vivo deformations of the popliteal artery during leg flexion in subjects with clinically relevant peripheral artery disease (PAD).

METHODS

Five patients (4 men; mean age 69 years, range 56-79) with varying calcification levels of the popliteal artery undergoing endovascular revascularization underwent 3-dimensional (3D) rotational angiography. Image acquisition was performed with the leg straight and with a flexion of 70°/20° in the knee/hip joints. The arterial centerline and the corresponding branches in both positions were segmented to create 3D reconstructions of the arterial trees. Axial deformation, twisting, and curvatures were quantified. Furthermore, the relationships between the calcification levels and the deformations were investigated.

RESULTS

An average shortening of 5.9%±2.5% and twist rate of 3.8±2.2°/cm in the popliteal artery were observed. Maximal curvatures in the straight and flexed positions were 0.12±0.04 cm(-1) and 0.24±0.09 cm(-1), respectively. As the severity of calcification increased, the maximal curvature in the straight position increased from 0.08 to 0.17 cm(-1), while an increase from 0.17 to 0.39 cm(-1) was observed for the flexed position. Axial elongations and arterial twisting were not affected by the calcification levels.

CONCLUSION

The popliteal artery of patients with symptomatic PAD is exposed to significant deformations during flexion of the knee joint. The severity of calcification directly affects curvature, but not arterial length or twisting angles. This pilot study also showed the ability of rotational angiography to quantify the 3D deformations of the popliteal artery in patients with various levels of calcification.

A symptomatic pseudoaneurysm caused by stent fracture in the external iliac artery

Pseudoaneurysms, as a result of endovascular stent fracture, are a rare yet important vascular surgery complication. A 64-year-old man presented with a painful mass in the left groin with accompanying critical ischemia of the left leg. Diagnostic angiography revealed a pseudoaneurysm caused by stent fracture in the left external iliac artery. The patient was treated with embolization of the left external iliac artery and ultimately above-the-knee amputation. Awareness of this uncommon complication is important due to its potential risk of severe disability.

Traumatic Popliteal Artery Pseudoaneurysm Developed during a Soccer Game

A 38-year-old male was admitted to our hospital due to painful swelling of his right popliteal fossa. He had been kicked in his right popliteal fossa during a soccer game about three weeks earlier. Computerized tomographic angiography of the lower extremity demonstrated a 4-cm-wide, 3-cm-long aneurysmal change of the popliteal artery. He underwent aneurysmectomy and graft interposition using a great saphenous vein graft. Pathologic findings of the resected specimen were consistent with those of a pseudoaneurysm.

Clinical relevance and treatment of carotid stent fractures

OBJECTIVE

To review all published reports and investigate the clinical relevance and need for treatment of carotid stent fractures.

METHODS

Electronic and hand-searching of the published literature and the Manufacturer and User Facility Device Experience (MAUDE) database.

RESULTS

Thirteen articles were published. There are 10 case reports and 3 clinical studies. There are 26 reports of fractured stents in the MAUDE database. Fifty-five cases of carotid stent fractures are reported in total. A total of 201 carotid stents were examined in the 3 studies, and the incidence of fractures was 8.9% (18/201). Fractured stents were 22 Xact, 20 Acculink, 6 Precise, 2 Exponent, 1 Nexstent, 1 Genesis, 1 Symbiot, and 2 nonspecified nitinol self-expandable stents. Twenty-seven of the treated carotid lesions were atherosclerotic, 3 restenoses after carotid endarterectomy, 2 postradiational, 1 pseudoaneurysm, and 22 lesions of unknown pathology. Calcification was reported in 15 of the 27 atherosclerotic lesions (55.5%). Time from implantation to fracture ranged from 0 days (fracture during implantation) to 37 months. In 55% of the cases, stent fracture was associated with restenosis. Six patients presented with symptoms. Treatment was reported for 32 patients: 14 patients underwent de novo stent placement, 2 balloon angioplasty, 2 carotid endarterectomy, 2 bypass graft (1 vein, 1 polytetrafluoroethylene), 1 anticoagulation, and 11 patients were followed up.

CONCLUSION

Carotid stent fractures are mainly reported in self-expandable nitinol stents. Plaque calcification may be a risk factor for stent fractures. No difference was observed between open and closed-cell design. Stent fractures were often associated with restenosis and usually were asymptomatic. The actual incidence, clinical relevance, and optimal treatment remain to be clarified from larger prospective studies designed to investigate the issue.

The role of vessel geometry and material properties on the mechanics of stenting in the coronary and peripheral arteries

There have been notably higher rates of restenosis with stents used to restore blood flow to many stenosed peripheral arteries compared with their coronary counterparts. The mechanical environment of arteries such as the femoral and popliteal (and the stent fracture that this can cause) has previously been identified as a contributing factor to the relatively low success rates for this procedure. The aim of this study was to investigate how other factors, namely the differences in geometries and mechanical properties of the arteries and the stents used in them, might influence the outcome in these different arteries. Finite element models of the stents and arteries were created, and the results compared in terms of stresses induced in the arteries, the lumen gain, and the deformation of the stent due to pulsatile loading. It was found that deploying a Nitinol stent in a peripheral artery induced lower stresses in the vessel wall than expanding a stainless steel stent in a coronary artery, although the lumen gain was also lower. The predicted strain amplitude induced in Nitinol stents by the cardiac cycle was below the value required to cause fatigue failure. This study does not provide any evidence to suggest that differences in the geometry and material properties between peripheral and coronary arteries, or the types of stent used to restore vessel patency, are the dominate factors responsible for the higher rates of restenosis observed in peripheral arteries.

Intravascular foreign bodies: danger of unretrieved fragmented medical devices

A warning on the danger of unretrieved device fragments and recommendations to mitigate the danger were issued by the Food and Drug Administration in January 2008. The causes of intravascular foreign bodies are classified into three main categories: improper manipulation and usage, device defects, and others, such as patient and anatomical factors. Device failure after long-term use is rarely predicted at the time of approval, since device abnormality is rarely experienced in animal studies and clinical trials conducted during development of the device. Stent fracture due to metal fatigue is one example. Complex complications could occur from simultaneous use of two or more devices with diverse characteristics. The success rate of percutaneous retrieval of intravascular foreign bodies has improved with the advances in commercially available devices. However, the procedure is not always successful and sometimes surgical removal becomes necessary. Appropriate device selection and acquisition of experience in using the device are important. When an intravascular foreign body cannot be retrieved, the risk of complication could be high. Magnetic resonance imaging examination sometimes causes adverse events, including burns due to the heat generated by metal movement. Such information should be correctly recorded. Furthermore, it is necessary to provide patients with adequate information about the characteristics of implanted devices and unretrieved fragments. We reviewed the literature on unretrieved medical device fragments and include articles that describe the Japanese experience.

In situ fracture of stents implanted for relief of pulmonary arterial stenosis in patients with congenitally malformed hearts

BACKGROUND

One of the most common uses of stents in patients with congenitally malformed hearts is treatment of pulmonary arterial stenosis. Although there are reports of fractured pulmonary arterial stents, little is known about the risk factors for, and implications of, such fractures.

METHODS

We reviewed angiograms to identify fractures in stents previously inserted to relieve stenoses in pulmonary arteries from 1990 through 2001 in patients who also underwent follow-up catheterization at least 3 years after placement of the stent. We undertook matched cohort analysis, matching a ratio of 2 fractured to 1 unfractured stent.

RESULTS

Overall, 166 stents meeting the criterions of our study had been placed in 120 patients. We identified fractures in 35 stents (21%) in 29 patients. All fractured stents were in the central pulmonary arteries, 24 (69%) in the central part of the right pulmonary artery, and all were complete axial fractures, or complex fractures along at least 2 planes. Stent-related factors associated with increased risk of fracture identified by multivariable logistic regression included placement in close apposition to the ascending aorta (p = 0.001), and a larger expanded diameter (p = 0.002). There was obstruction across 28 of 35 fractured stents, which was severe in 11. We re-stented 21 of the fractured stents, and recurrent fracture was later diagnosed in 3 of these. A fragment of the fractured stent embolized distally in 2 patients, without clinically important effects.

CONCLUSIONS

In situ fracture of pulmonary arterial stents is relatively common, and in most cases is related to compression by the aorta. There is usually recurrent obstruction across the fractured stent, but fractured stents rarely embolize, and are not associated with other significant complications.

Stent fracture following stenting of a myocardial bridge: report of two cases

Myocardial bridge is the most common congenital coronary anomaly. Patients with this anomaly are usually asymptomatic, but it may cause myocardial ischemia that may lead to myocardial infarction. Treatment for myocardial bridge remains controversial. Current recommendations include medical therapy, surgical treatment (unroofing myotomy), coronary artery bypass, and percutaneous coronary stenting. We report two cases of stent fracture following stenting of a myocardial bridge. The risk of stent fracture leading to restenosis and/or stent thrombosis should be considered when assessing the risks and benefits of coronary revascularization of a myocardial bridge.