Management of Asymptomatic Popliteal Artery Aneurysms

Degrees of macrophage-facilitated healing in aneurysm occlusion devices

Insufficient healing of aneurysms following treatment with vascular occlusion devices put patients at severe risk of fatal rupture. Therefore, promoting healing and not just occlusion is vital to enhance aneurysm healing. Following occlusion device implantation, healing is primarily orchestrated by macrophage immune cells, ending with fibroblasts depositing collagen to stabilize the aneurysm neck and dome, preventing rupture. Several modified occlusion devices are available currently on-market. Previous in vivo work demonstrated that modifications of occlusion devices with a shape memory polymer foam had enhanced aneurysm healing outcomes. To better understand cellular response to occlusion devices and improve aneurysm occlusion device design variables, we developed an in vitro assay to isolate prominent interactions between devices and key healing players: macrophages and fibroblasts. We used THP-1 monocyte derived macrophages and human dermal fibroblasts in our cell culture models. Macrophages were allowed device contact with on-market competitor aneurysm occlusion devices for up to 96 h, to allow for any spontaneous device-driven macrophage activation. Macrophage secreted factors were captured in the culture media, in response to device-specific activation. Fibroblasts were then exposed to device-conditioned macrophage media (with secreted factors alone), to determine if there were any device-induced changes in collagen secretion. Our in vitro studies were designed to test the direct effect of devices on macrophage activation, and the indirect effect of devices on collagen secretion by fibroblasts to promote aneurysm healing and stabilization. Over 96 h, macrophages displayed significant migration toward and interaction with all tested devices. As compared to other devices, shape memory polymer foams (SMM, Shape Memory Medical) induced significant changes in gene expression indicating a shift toward an anti-inflammatory pro-healing M2-like phenotype. Similarly, macrophages in contact with SMM devices secreted more vascular endothelial growth factor (VEGF) compared with other devices. Macrophage conditioned media from SMM-contacted macrophages actively promoted fibroblast secretion of collagen, comparable to amounts observed with exogenous stimulation via VEGF supplementation. Our data indicate that SMM devices may promote good aneurysm healing outcomes, because collagen production is an essential step to ultimately stabilize an aneurysm.

Expanded Polytetrafluoroethylene Membranes for Vascular Stent Coating: Manufacturing, Biomedical and Surgical Applications, Innovations and Case Reports

Coated stents are defined as innovative stents surrounded by a thin polymer membrane based on polytetrafluoroethylene (PTFE)useful in the treatment of numerous vascular pathologies. Endovascular methodology involves the use of such devices to restore blood flow in small-, medium- and large-calibre arteries, both centrally and peripherally. These membranes cross the stent struts and act as a physical barrier to block the growth of intimal tissue in the lumen, preventing so-called intimal hyperplasia and late stent thrombosis. PTFE for vascular applications is known as expanded polytetrafluoroethylene (e-PTFE) and it can be rolled up to form a thin multilayer membrane expandable by 4 to 5 times its original diameter. This membrane plays an important role in initiating the restenotic process because wrapped graft stent could be used as the treatment option for trauma devices during emergency situations and to treat a number of pathological vascular disease. In this review, we will investigate the multidisciplinary techniques used for the production of e-PTFE membranes, the advantages and disadvantages of their use, the innovations and the results in biomedical and surgery field when used to cover graft stents.

Supera stent implantation for the treatment of isolated popliteal artery disease systematic review and evaluation of current endovascular strategies

<b>Introduction:</b> The anatomical location of the popliteal artery is one of the greatest challenges for percutaneous interventions. The biomechanical attributes of the vessel lead to higher rates of restenosis, stent fracture, and occlusion. Some surgeons consider the popliteal artery as a no stenting zone. Many specialists favor percutaneous transluminal angioplasty to be the first line of endovascular treatment in the popliteal artery with bail-out stent implantation if the results are suboptimal. The Supera peripheral stent system is a novel stent that has been manufactured with a high degree of flexibility and supposedly might be appropriate for implantation in the popliteal artery. </br></br> <b>Aim:</b> Evaluation of the performance of Supera stent in isolated popliteal artery disease in comparison to other methods of treatment. </br></br> <b>Methods:</b> As many as 92 articles were found in the databases and after full-text review, 4 studies matched the inclusion criteria and were evaluated. </br></br> <b>Results:</b> Primary patency rates of Supera implantation in an isolated popliteal artery at 12 months ranged from 68% to 90%. In all four studies, no stent fractures were observed. Only one study provided longer follow-up than 12 months and evaluated the performance of the Supera stent 36 months after implantation. </br></br> <b>Conclusion:</b> In conclusion, mentioned studies show promising and superior to other stent patency rates of the Supera stent regarding popliteal artery lesions. What is more, no stent fracture is promising regarding longer follow-up. However, more studies with longer follow-ups and direct comparison to other methods are required to fully evaluate Supera's performance in the popliteal artery.

Real-world data of popliteal artery aneurysm treatment. Analysis of the POPART registry

OBJECTIVE

Popliteal artery aneurysm (PAA) is a rare disease with a prevalence of 0.1-1%. Within the last years, endovascular repair of PAA (ER) has been performed more frequently despite the lack of high-level evidence compared to open surgery (OR). In 2014, the POPART registry was initiated to validate current treatment options in PAA repair.
 METHOD: POPART is a multinational multicenter registry for peri- and postoperative outcome of endovascular and open PAA repair. Data sets are recorded by the online survey tool "SurveyMonkey®". Regular monitoring and plausibility checks of the data sets are performed to ensure reliability. The aim of this study is to present results of the POPART registry, with data of 41 centers.
 RESULTS: From June 2014 to August 2019, a total of 794 cases were recorded in the PAA registry. OR was performed in 662 patients and ER in 106 patients; 23 Patients were treated conservatively. Four of the 106 patients with primary ER underwent conversion to OR. ER patients were significantly older (ER x˜= 71 vs. OR x˜= 67 (p<0.05). There were no other significant differences in demographics or comorbidities and aneurysm morphology between the two groups. 50.3% patients in the OR group were symptomatic; in the ER group 29.2% (p<0.05). Emergency treatment for acute ischemia, critical ischemia or rupture was necessary in 149 patients (22.5%) in the OR group vs. 11 patients (10.3%) in the ER group.
Most frequent complications after surgery were impaired wound healing (OR n=47, 7.1%; ER n=3, 2.8%, p>0.05) and major bleeding (OR n=26, 3.9%; ER n=3, 2.8%, p>0.05). In-hospital length of stay (= 10d [3-65] OR vs. x˜=7d [1-73] ER) was significantly higher in the OR group. Overall patency was 83.2% vs. 44.7% (OR/ER, p<0.005) after 12 months and 74.2% vs. 29.1% (OR/ER, p<0.005) after 24 months. There was a significantly poorer outcome for prosthetic graft compared to autologous vein in the OR group (71.4% vs. 88.1% 12-month primary patency).
 CONCLUSION: 
 In order to evaluate new treatment techniques such as endovascular repair (ER) for PAA, real world data is of essential importance. This analysis of the first results for the POPART registry shows good perioperative results for endovascular treatment of PAA in asymptomatic patients with good outflow vessels. The perioperative complication rate is low and the postoperative hospital stay is shorter than after OR. However, the patency rates after 12 and 24 months are low in the ER group compared to patients treated with open repair. More follow-up data is required for further interpretation; the completion of the data sets in the registry is ongoing.

Early Results after Exclusion of Popliteal Aneurysms with an Endoprosthesis

Objectives

To evaluate safety and efficacy of endoprosthesis implantation for the exclusion of popliteal artery aneurysm (PAA).

Methods

Elective asymptomatic patients with aneurysm > 20 mm and symptomatic patients with endovascular therapy of PAA were included. The proportion of patients with critical limb ischemia (presence of rest pain or tissue loss) was high at 32.1%, 21.6% of the patients had acute ischemia with symptoms persisting shorter than 14 days. The primary study endpoint was the target lesion revascularization (TLR) rate at 12 months. Secondary endpoints included technical success, periinterventional adverse events, primary patency at 6, 12 and 24 months, TLR rate at 24 months, predictors on reintervention, change in in clinical symptoms using the Rutherford-Becker classification (RBC), amputation and mortality rate. One hundred thirty-four patients (68.3±10.6 years, 88.8% male) were treated with a Viabahn^® endoprosthesis (W.L. Gore & Associates Inc., Flagstaff, AZ, USA).

Results

The average aneurysm diameter was 2.5±0.87 cm. In 41%, occlusion of the aneurysm was present. TLR rate was 31.3% and 38.8% after 12 and 24 months, respectively. Primary patency rates were 69.1%, 52.3% and 42.6% at 6, 12 and 24 months, respectively. Univariate logistic regression analysis revealed age as a predictor of reintervention and in the multivariable analysis it was treatment with lysis. An improvement in RBC was seen at all-time points. Two major amputations (1.5%) were performed and the mortality rate at 24 months was 5.2%.

Conclusion

Primary patency rate after endovascular exclusion of PAA is low. However, limb salvage rate is high.

Popliteal Artery Occlusion with Collateral Blood Flow in a Reducible Knee Dislocation During Pregnancy: A Case Report

CASE

A 29-year-old healthy woman, 19 weeks pregnant, sustained a right posterolateral knee dislocation with multiligamentous injury and a complete occlusive injury to the right popliteal artery yet had adequate distal perfusion. She declined operative management for both the knee dislocation and the arterial injury, and successful collaboration between obstetrical, vascular, and orthopaedic surgical services resulted in limb preservation and restoration of function.

CONCLUSION

This is a unique case of traumatic complete popliteal artery occlusion with adequate collateral arterial perfusion after a reducible posterolateral knee dislocation in a pregnant patient that resulted in limb preservation with nonoperative management.

Hybrid Approach to Popliteal Artery Aneurysm with Thromboembolic Symptoms. A Pilot Study

BACKGROUND

The treatment of patients with thromboembolic symptoms due to a popliteal artery aneurysm (PAA) is still controversial with poor results in terms of primary patency. The aim of our pilot study was to evaluate whether improving the outflow with an endovascular pretreatment consisting in thromboaspiration and angioplasty could positively ameliorate the primary patency of the subsequent femoropopliteal (FP) bypass in symptomatic patients with at least one below the knee (BTK) patent vessel.

METHODS

This is a single-center pilot case-control study that involves patients treated at the Vascular and Endovascular Surgery Unit of Udine, Italy, from January 2015 to November 2019. The inclusion criteria were the presence of thromboembolic symptoms due to PAA distal embolization, associated with the presence of a patent PAA >20 mm and a poor runoff (no more than one patent BTK artery). The case group was treated in a two-step approach: the first step consisted in thromboaspiration followed by BTK angioplasty, when appropriate, and the second one consisted in performing the surgical FP bypass. The control group moved on directly to the open surgical intervention.

RESULTS

The case group was composed of 11 patients, 10 males and 1 female, with a mean age of 69.3 ± 10.8 years. The mean PAA dimension was 32.6 ± 9.9 mm. Particularly, 9 patients were operated on through the medial vascular approach and 2 through the posterior one. The grafts used were 10 polytetrafluoroethylene (PTFE) and 1 great saphenous vein (GSV) in situ. The control group was composed of 11 male patients with a mean age of 75.5 ± 8.7 years, and the mean PAA dimension was 29.8 ± 13.4 mm. All the FP bypasses were approached medially, and the materials used were 10 PTFE and 1 reversed GSV. The median follow-up was 31.5 ± 12.6 months. Primary patency in the case group was 72.7% within one year; on the contrary, it was 27.3% in the control group. The amputation rate was 0% in the case group, 27.3% in the controls. By comparing the 2 groups, we found a higher and significant risk (P = 0.0261) of early FP bypass occlusion and major limb amputation in the control group.

CONCLUSIONS

This pilot study shows encouraging results; the endovascular approach is a safe and repeatable procedure which, improving the runoff in thromboembolic symptomatic PAA, seems to guarantee a better FP graft primary patency.

Contrast-enhanced ultrasound (CEUS) in the diagnostic evaluation of popliteal artery aneurysms, a single-center study

BACKGROUND

Popliteal artery aneurysms (PAA) are the most common peripheral artery aneurysms. Most common cause is arteriosclerosis. Acute thromboembolic limb ischemia and rupture of the PAA depict severe complications. Diagnostic tools for identifying PAAs are (Doppler) ultrasound, CT/MR angiography and DSA.

PURPOSE

The aim of the present retrospective single-center study is to assess the application and safety of CEUS for assessing untreated and treated PAAs.

MATERIALS AND METHODS

13 patients were included in this study on whom CEUS was performed between 2007-2016. CEUS examinations were performed and interpreted by an experienced single radiologist (EFSUMB Level 3).

RESULTS

CEUS allowed for the detection of PAAs in all cases. CEUS allowed for detection of partial thrombosis of PAA in 7/8 of untreated patients, proper exclusion of PAA upon femoro-popliteal bypass in 3 patients, incomplete exclusion of PAA upon femoro-popliteal bypass in 1 patient and ruling out of in-stent stenosis in 1 patient.

CONCLUSION

CEUS is a useful and safe tool for in real-time evaluation of PAAs in the pre-/post-treatment status. In addition to conventional (Doppler) ultrasound and as an alternative tool to more elaborate imaging modalities, CEUS might be integrated in the future diagnostic work-up and follow-up of PAA patients.