A Bare-Metal Stents Treatment of Arterial Injuries at the Joint Levels
Peripheral arterial injuries, particularly those occurring at joint levels, present significant challenges in clinical practice. These injuries are associated with a high risk of limb loss, necessitating rapid diagnosis and intervention to achieve limb salvage and, in some cases, save lives. Traditional open repair has historically been the primary treatment option for traumatic vascular injuries. However, with the evolution of endovascular techniques and tools, minimally invasive percutaneous endovascular therapies have emerged as an attractive alternative. These therapies offer the advantage of performing diagnostic evaluation and therapeutic intervention nearly simultaneously, potentially improving outcomes in acute traumatic vascular lesions.
Covered stents are often preferred for repairing injured arterial lesions due to their ability to effectively seal the injury site. However, when injuries occur near joint levels, the use of covered stents carries a significant risk of covering crucial branch vessels, which can lead to acute ischemia. In such cases, bare-metal stents may serve as a viable alternative, offering the advantage of preserving side branches while addressing the injury. Despite this potential benefit, there is limited knowledge regarding the efficacy and safety of bare-metal stents in this context. This study aimed to assess the feasibility and long-term outcomes of bare-metal stent implantation therapy for arterial injuries at joint levels.
The study involved a retrospective chart review of 16 patients who presented with peripheral arterial injuries at joint levels between June 2005 and March 2014. The mean age of the patients was 49 years, with a range of 34 to 71 years. The injuries were primarily caused by car accidents (13 cases) and falls from height (3 cases). The locations of the injuries included the knee joint (7 cases), elbow joint (5 cases), hip joint (2 cases), and shoulder joint (2 cases). The pathologies observed included complete transection (2 cases), partial transection (3 cases), pseudoaneurysm (5 cases), arteriovenous fistula (3 cases), and intimal injury (3 cases). All patients presented with hemorrhagic shock upon arrival at the hospital, with a mean blood pressure of 103/62 mmHg and a mean heart rate of 112 ± 34 beats per minute.
Given the urgency of the situation, the researchers opted for urgent intravascular repair rather than surgical repair to stanch bleeding and minimize limb ischemia time. Successful endovascular repair was defined as the restoration of blood flow confirmed by angiography at the end of the procedure without contrast extravasation. All patients received lifelong antiplatelet therapy consisting of acetylsalicylic acid 100 mg daily postoperatively. Follow-up evaluations were conducted at 1, 3, 6, and 12 months, and yearly thereafter, or whenever symptoms arose. The evaluation criteria included graft and branch vessel patency, limb loss, the presence or absence of other complications, and death. Diagnostic angiography was performed if symptomatic stent-graft stenosis or occlusion was suspected, and angiography was recommended at the last follow-up to obtain an objective assessment of stent patency.
All endovascular procedures were successfully performed without perioperative death or amputation. A total of 21 bare-metal stents were implanted, all of which were LifeStent (Bard Peripheral Vascular, Tempe, AZ, USA). The length of the stents ranged between 4 and 15 cm, with a diameter of 6 mm. The mean duration of hospital stay was 18 days, ranging from 8 to 46 days. During hospitalization, one patient required intra-arterial thrombolysis due to stent thrombosis but had no subsequent issues during follow-up. No other operation-related complications were observed.
The average follow-up period was 73 ± 14 months, ranging from 60 to 106 months. During follow-up, two patients presented with non-incapacitating claudication at 11 and 15 months, respectively. Subsequent arteriography revealed significant (>50%) stent stenosis, which was successfully treated with angioplasty and remained patent on monitoring. Fifty percent of the patients underwent at least one arteriography during the study period. The results demonstrated satisfactory blood flow at the stents and branch vessels, with no evidence of stent migration, deformation, or fracture. Overall, all 16 patients were alive, actively using their limbs without symptoms such as collateral vessel occlusion or stent fracture.
Acute traumatic arterial injuries to the peripheral arteries near joint levels are uncommon but remain a challenging problem, particularly due to the presence of main branch vessels. The effect of the stent on branch blood flow must be carefully considered in such cases. Conventional endovascular treatment techniques often involve coated stent deployment, which is believed to help maintain blood flow. However, for injuries near joint levels, the potential for a coated stent to cover the origin of a branch artery, leading to acute ischemia, remains a significant concern. In this study, bare-metal stents were implanted instead of coated stent-grafts to avoid covering branch vessels near the joints. Bare-metal stents have been proven effective for complex aneurysms and may effectively isolate thoracic aortic aneurysms. A bare-metal stent may act as a passive barrier by reducing blood flow near the injury site, with the changed hemodynamic conditions potentially promoting the activation and aggregation of platelets.
The conventional concept suggests that repairs near joint levels are infrequent due to the potential risk of stent fracture. However, the endovascular repair strategy employed in this study appears promising for stopping bleeding without causing structural damage. This may be attributed to the improved radial strength and ability of the stents to recover from being crushed. The lower stress on the stent may serve as an essential protective factor against stent migration, deformation, or fracture. A study designed to identify the effect of biomechanical deformations on stents revealed that different bare-metal stents exhibit a variable ability to withstand chronic deformation in vitro. The most likely explanation for this variability is the considerable differences in stent patterns, as the stent pattern has a significant impact on the amount of localized strain experienced by a strut. The LifeStent used in this study is more susceptible to axial stress, but repetitive bending does not lead to any fracture. As the walls of the injured arteries were within the normal range, low axial compression was noted, which is the main reason for the favorable prognosis. Additionally, acceptable results are often achieved after the treatment of relatively short segmental lesions. In this study, the length of the injured lesion was limited, and the implanted stent was shorter than 10 cm, which may be another protective factor.
Previous studies have indicated a comparatively high rate of late clinical failure after stent implantation in the treatment of chronic limb ischemia due to thicker neointimal formation. However, in this study, the thickness and lumen of the artery wall were generally within the physiological range. The low-stress effect of the implanted stent on the arterial wall may not result in apparent neointimal hyperplasia. Rather than dilating the artery lumen, the stent was applied mainly to cover the injury site, which did not impose high stress on the artery wall. As stent forces alone are an essential risk for the vessel-wall response, low strain is related to relatively low levels of hyperplastic or hypertrophic activity. Therefore, intimal thickening did not significantly increase. Additionally, the crucial mechanical-chemical signal transduction transmission remains, and the vascular endothelium might be directly stimulated by joint motion. Moreover, the special local hemodynamics near the joint may alter the blood-flow patterns and wall shear stress frequently, possibly leading to vascular adaptation and remodeling.
This study has several limitations. The focus on arterial trauma at joint levels resulted in a limited number of cases, which may be subject to reporting bias. Furthermore, data on follow-up time were inconsistent. Despite these limitations, the study demonstrates the advantage of bare-metal stents in preserving side branches and establishes the safety, feasibility, and efficacy of bare-metal stent implantation therapy for arterial injuries at joint levels.
doi.org/10.1097/CM9.0000000000001103
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