Stefan Müller-Hülsbeck

Randomized Study to Compare PTA Alone versus PTA with Palmaz Stent Placement for Femoropopliteal Lesions

PURPOSE The purpose of this study was to evaluate whether percutaneous transluminal angioplasty (PTA) combined with Palmaz stent placement provides long-term advantages compared to PTA alone after 34 months of follow-up in the femoropopliteal region. MATERIALS AND METHODS Thirty patients randomized to undergo PTA in combination with stent placement and 23 patients randomized to undergo PTA alone were evaluated. RESULTS Mean follow-up (+/-SD) for the PTA group was 33.8 months (+/- 8.7) and for the Palmaz group 29.1 months (+/- 6.2), with a maximum follow-up period of 39 months for both groups. No significant differences in primary or secondary patency rates could be observed at 12 or 39 months. After 39 months, the primary patency rate for PTA alone was 68.4% and the secondary patency rate was 89.5%; the primary patency rate for PTA with stent placement was 62% and the secondary patency rate was 90%. CONCLUSIONS The results of this study show that even after a long-term follow up of more than 3 years, PTA with stent placement in the femoropopliteal artery does not produce better results than PTA alone, although it does provide better initial luminal gain after the procedure.

Nitinol stent implantation in long superficial femoral artery lesions: 12-month results of the DURABILITY I study.

Purpose: To evaluate the long-term efficacy and integrity of the PROTÉGÉ EverFlex stent in superficial femoral artery (SFA) lesions in symptomatic patients with peripheral artery disease (PAD). Methods: A prospective, multicenter, nonrandomized study enrolled 151 subjects (111 men; mean age 67.8 years, range 42–93) undergoing percutaneous treatment of de novo, restenotic, or reoccluded SFA lesions between August 11, 2006, and June 26, 2007. Subjects were scheduled to receive a single stent and be evaluated through 12 months following the implant procedure. Occlusions were present in 40% of the patients. Mean lesion length was 96.4 mm (range 10–150). Results: A total of 161 stents (158 EverFlex) were implanted in the 151 patients: single stents in 93.4% (141/151) and a second stent in 6.6% (10/151). One-year follow-up information was available for 88.7% (134/151) of the study participants; of the remaining 17 subjects, 6 subjects withdrew from the study, 2 were lost to follow-up, and 9 died. Freedom from restenosis data were available for 99.3% (133/134) of the subjects who completed a 12-month follow-up visit. The mean Rutherford classification fell from 2.8±0.8 (range 1–5) at baseline to 0.6±1.1 (range 0–5) at 12 months. The mean ankle-brachial index rose from 0.6±0.2 (range 0–1.4) at baseline to 0.9±0.2 (range 0–1.2) at 12 months. The rates for freedom from >50% restenosis at 6 and 12 months were 91.3% (95% CI 84.9% to 95.2%) and 72.2% (95% CI 63.8% to 79.6%), respectively. The freedom from target lesion revascularization rate at 12 months was 79.1% (95% CI 71.2% to 85.6%). The 1-year stent fracture rate was 8.1% (95% CI 4.0% to 14.4%). Conclusion: The high freedom from >50% restenosis and low fracture rate at 12 months suggests that the PROTÉGÉ EverFlex stent offers a safe and acceptably efficacious means of treating SFA lesions in symptomatic subjects with PAD.

Endovascular placement of self-expanding nitinol coil stents for the treatment of femoropopliteal obstructive disease

PURPOSE To report on a prospective two-center study to evaluate safety and effectiveness of a self-expanding nitinol coil stent in patients with femoropopliteal obstructive disease. MATERIALS AND METHODS The IntraCoil nitinol stent was used in 37 patients (28 men and nine women; mean age, 62.4 y plus minus 10.7; range, 43-81 y) presenting with high-grade stenoses (n = 23) or short (<3 cm) occlusions (n = 17) of the superficial femoral artery (SFA; n = 33) or popliteal artery (n = 4). Indications for stent placement were significant residual stenosis (>30%) or dissection after angioplasty. Follow-up evaluations with measurement of the Doppler ankle-brachial index (ABI), assessment of Rutherford clinical stage, and color-coded duplex sonography were performed at discharge and 1, 3, 6, 12, and 18 months thereafter. Primary endpoints of the study were immediate technical and clinical success and 1-year patency. RESULTS Initial technical success was achieved in all patients. In 10 patients (27%), more than one 40-mm-long device had to be implanted for total lesion coverage; in three patients (8.1%), stents were placed in two separate segments of the SFA simultaneously. The total number of stents deployed was 50. Stent placement induced an initial improvement of the ABI from 0.54 plus minus 0.2 to 0.92 plus minus 0.11 (P <.01). Follow-up data for 12 months after treatment are available for 29 of 37 patients (78.4%); mean follow-up is 15.6 months (range, 1-26 mo). Primary patency rates at 6 and 12 months were 97.1% (SE = 2.9) and 86.2% (SE = 6.5). The primary assisted patency rate was 100% at 12 months. CONCLUSION Endovascular placement of the IntraCoil self-expanding nitinol coil stent for salvage of failed angioplasty in patients with femoropopliteal obstructive disease is an effective and safe procedure with promising mid-term results.

Stent-Graft Repair versus Open Surgery for the Descending Aorta: A Case-Control Study

Purpose: To compare the clinical outcomes of open surgery versus endovascular repair in patients with pathologies of the descending thoracic aorta (DTA). Methods: This retrospective study included 44 patients (28 men; mean age 68±12 years, range 37–86) treated for DTA pathologies between 1995 and 2003. Twenty-two patients (15 men; mean age 68±13 years, range 37–86) undergoing stent-graft implantation were matched for sex, age, emergency operation, and comorbidities (coronary artery disease, chronic obstructive pulmonary disease) with a 22-patient contemporaneous surgical cohort (13 men; mean age 69±11 years, range 41–80). Results: Thirty-day mortality was 5% in the stent-graft group and 27% in the open surgery group (p=0.047). The incidences of postoperative stroke and paraplegia were both 5% in the stent-graft group and 9%, respectively, in the open surgery cohort. One patient required a second stent-graft due to an endoleak during the same hospital stay, and 2 reoperations were performed in the standard operation group (p = NS). Lengths of stay in the intensive care unit (ICU) and hospital were 4.3±5.4 and 11.9±15.0 days, respectively, in the stent-graft group and 10.0±7.4 and 21.5±17.4 days, respectively, in the open surgery group (p<0.006). Conclusions: Stent-graft repair was associated with lower 30-day mortality and comparable complication rates in older patients with significant comorbidities and a high percentage of emergency operations compared to open surgery. Stent-graft implantation shortens ICU and hospital stays significantly. In the future, subgroups of patients who may experience the greatest benefit from stent-graft repair in the long term should be defined.

Comparison of various cerebral protection devices used for carotid artery stent placement: an in vitro experiment.

PURPOSE To compare the effectiveness of five basic cerebral protection devices designed for carotid angioplasty in an in-vitro bench-top model. MATERIALS AND METHODS Simulation of embolization from carotid angioplasty (n = 180) was performed with polyvinyl alcohol (PVA) particles (Contour; 150-1,000- micro m) in an open flow model simulating the aortic arch with a carotid bifurcation made from elastic silicone tubes. Particles (150-250 micro m [small], 355-500 micro m [medium], 710-1,000 micro m [large]; 5 mg each) were injected separately into the internal carotid artery (ICA) proximal to the placed protection device. Five devices were tested: the Angioguard (AG), Filter Wire EX (EX(A), EX(B)), Trap, Neuroshield (NS), and GuardWire Plus (GW). Particles getting past the protection device or flowing into the external carotid artery (ECA) were caught in a filter at the end of both arteries and their weight was determined. RESULTS For small, medium, and large particles, the lowest weight of emboli in the effluent of the ICA was obtained with the NS (0.28 mg, 0.18 mg, and 0.07 mg, respectively; P <.001 compared to all other devices except the GW for small particles only). The GW had the highest embolization rate into the ECA for all particle sizes. When combining the particle weights for the different protection devices, the NS showed the lowest weight of emboli into the ICA filter (0.53 mg/3.5%; P <.001 compared to all [>1.1 mg/7.0%]). The GW revealed the highest weight of emboli into the ECA (1.2 mg/7.6%; P <.001 compared to all [<0.59 mg/0.09%]). Effectiveness of the EX(B) device was enhanced when circumferentially deployed under direct view (EX(B), 0.39 mg/2.58%; EX(A), 1.18 mg/7.81%; P <.001). CONCLUSIONS In vitro, none of the tested devices or modifications has the ability to prevent embolization completely. An occlusion balloon leads to increased embolization into the ECA. The effectiveness of the EX might be enhanced with design improvements. During this evaluation, the NS was most effective for preventing PVA particle embolization of the three different particle groups within this in-vitro model.

Mechanical thrombectomy of major and massive pulmonary embolism with use of the Amplatz thrombectomy device.

Müller-Hülsbeck S, Brossmann J, Jahnke T, et al. Mechanical thrombectomy of major and massive pulmonary embolism with use of the Amplatz thrombectomy device. Invest Radiol 2001;36:317–322. rationale and objectives. To evaluate the feasibility of mechanical thrombectomy with the Amplatz thrombectomy device (ATD) in restoring patency of acutely thrombosed pulmonary arteries resulting from pulmonary embolism for the improvement of patient outcome. methods. Mechanical thrombectomy with the ATD (8F) was performed in nine consecutive patients with angiographically documented thrombus in the left or right pulmonary artery resulting from deep vein thrombosis (n = 4) or unknown cause (n = 5). results. The Miller index decreased from 18 to 11. In all patients, the majority of the thrombus in the pulmonary artery was cleared after a mean activation time of the ATD of 367 seconds. Thrombectomy was performed with the ATD alone (n = 4) or with additional long-term fibrinolysis therapy (n = 5) with infusion of recombinant tissue-type plasminogen activator. Pulmonary arterial pressure decreased from a mean of 57 mm Hg before mechanical thrombectomy to 55 mm Hg directly after the procedure and to 39 mm Hg after termination of the recombinant tissue-type plasminogen activator infusion. conclusions. Mechanical thrombectomy with the ATD in patients with minor and major pulmonary embolism is technically feasible and safe. It is a potential alternative to drug-mediated thrombolysis and surgery. However, the incremental benefit of the ATD over conventional treatments could be shown only in a randomized controlled study.

Rheolytic hydrodynamic thrombectomy for percutaneous treatment of acutely occluded infra-aortic native arteries and bypass grafts: midterm follow-up results.

RATIONALE AND OBJECTIVES To evaluate the efficacy of a rheolytic thrombectomy catheter (RTC) for treatment of acutely occluded infra-aortic native arteries and bypass grafts and to determine midterm primary patency, death, and amputation-free survival rates. METHODS From March 1995 to September 1997, 112 patients with occluded arteries or bypass grafts were primarily treated with RTC at two centers. Thrombus removal was evaluated by two angiographers. RESULTS More than 75% of the thromboembolic material could be removed with RTC alone. Mean activation time of RTC was 280 +/- 163 seconds. Residual mural or organized thrombi (29%) required adjunctive fibrinolytic therapy or aspiration thrombectomy. Remaining stenoses were treated with percutaneous transluminal angioplasty and additional stent implantation. For acute reocclusions, surgical intervention was required. Technical success after the entire procedure was 88.4%. RTC-associated complications included distal embolization, dissection, vessel perforation, and technical failure of RTC. Mean follow-up time was 14.8 months +/- 11.5, rates of primary patency, secondary patency, death, and amputation-free survival were 60%, 84%, 16%, and 75% after 2 years, respectively. CONCLUSIONS RTC is a rapid and efficient technique for mechanical thrombectomy of acutely thrombosed native leg arteries and bypass grafts. Midterm results are comparable to the results of alternative treatment modalities such as Fogarty balloon thromboembolectomy or local fibrinolysis.

PTFE-covered self-expanding nitinol stents for the treatment of severe iliac and femoral artery stenoses and occlusions: final results from a prospective study.

Purpose: To evaluate the technical performance, safety, and 1-year clinical efficacy of polytetrafluoroethylene (PTFE)-covered nitinol stents in the treatment of atherosclerotic iliac and superficial femoral artery (SFA) disease. Methods: The multicenter, prospective, nonrandomized COVENT study involved 98 patients (70 men; mean age 64±10 years) who received PTFE-covered nitinol stents in 107 arteries (60 iliac and 47 SFAs) after predilation. The average lesion length was 50 mm in the SFA and 45 mm in the iliac arteries. Postdilation was performed when necessary. Duplex ultrasound and ankle-brachial index (ABI) were performed at discharge and at 1, 6, and 12 months in follow-up. Results: In total, 130 stents were placed successfully in 97 (99%) of 98 patients. One stent was misplaced during deployment and required subsequent surgical removal. The average stenosis grade was reduced from 98% to 6% in the SFAs and from 96% to 4% in the iliac arteries after covered stent placement. There was a significant rise of the mean ABI from 0.64 at baseline to 0.97 and 0.95 at 1 and 12 months, respectively (p < 0.001). There were 7 primary covered stent occlusions (6.5% of 107 stented lesions: 3 not treated, 2 bypassed, 2 dilated or stented) and 5 (4.7%) recurrent in-stent occlusions (1 bypassed, 2 dilated, 2 untreated) during the 1-year follow-up. Primary patency rates were 92% at 6 months and 89.8% at 12 months for the entire cohort. Secondary patency rates were 98% and 95.6%, respectively. No statistically significant differences were observed in the primary patency rates for the SFAs (89.3% at both 6 and 12 months) versus the iliac arteries (94.3% at 6 months and 90.7% at 12 months). Conclusions: Primary implantation of PTFE-covered nitinol stents in the iliac and superficial femoral arteries is technically feasible, safe, and effective, with excellent 1-year patency.

Comparison of Second-Generation Stents for Application in the Superficial Femoral Artery: An In Vitro Evaluation Focusing on Stent Design

Purpose: To examine and compare in an ex vivo study different nitinol stent designs intended for the superficial femoral artery (SFA) with regard to the appearance of fracture. Methods: Seven different 8-x40-mm nitinol stents were evaluated (Misago, Absolute, Smart, Luminexx, Sentinol, Lifestent NT, and Sinus-Superflex). Finite element analysis (FEA) was used for digitalized stent design comparison; the strain during stent movement was calculated for bending, compression, and torsion. Additional mechanical fatigue tests for bending (70°), compression (40%), and torsion (twisted counterclockwise by 180°) were performed up to 650,000 cycles or until a fracture was observed. Results: The FEA bending test showed that only the Misago, LifeStent, and Absolute stents presented no zones of high strain; in the torsion test, the Smart stent also had no zones of high strain. Macroscopic evaluation after mechanical bending indicated that the LifeStent performed the best (no stent fracture after 650,000 cycles). Misago and Absolute stents showed fractures at 536,000 cycles and 456,667 cycles, respectively (range 320,000–650,000 cycles). After compression and torsion testing, Misago showed no stent fracture after 650,000 cycles. The worst performing stent was Luminexx during all test cycles. Conclusion: The 7 SFA stents showed differences in the incidence of high strain zones, which indicates a potential for stent fracture, as demonstrated by the mechanical fatigue tests. Differences in stent design might play a major role in the appearance of stent strut fracture related to restenosis and reocclusion.

Stent placement versus balloon angioplasty for the treatment of obstructive lesions of the popliteal artery: a prospective, multicenter, randomized trial

Background— Stenting has been shown to improve patency after femoral artery revascularization compared with balloon angioplasty. Limited data are available evaluating endovascular treatment for obstructive lesions of the popliteal artery. Methods and Results— This prospective, randomized, multicenter trial compared primary nitinol stent placement to percutaneous transluminal balloon angioplasty in patients with peripheral artery disease Rutherford-Becker class 2 to 5 who had a de novo lesion in the popliteal artery. The primary study end point was 1-year primary patency, defined as freedom from target-lesion restenosis (luminal narrowing of ≥50%) as detected by duplex ultrasound. Secondary end points included target-lesion revascularization rate and changes in Rutherford-Becker class. Provisional stent placement was considered target-lesion revascularization and loss of primary patency. Two hundred forty-six patients were included in this trial. The mean target-lesion length was 42.3 mm. One hundred ninety-seven patients were available for the1-year follow-up. The 1-year primary patency rate was significantly higher in the group with primary nitinol stent placement (67.4%) than in the percutaneous transluminal balloon angioplasty group (44.9%, P=0.002). Target-lesion revascularization rates were 14.7% and 44.1%, respectively (P=0.0001); however, when provisional nitinol stent placement was not considered target-lesion revascularization and loss in patency, no significant differences prevailed between the study groups (67.4% versus 65.7%, P=0.92 for primary patency). Approximately 73% of patients in the percutaneous transluminal balloon angioplasty group and 77% in the nitinol stent group showed an improvement of ≥1 Rutherford-Becker class (P=0.31). Conclusions— Primary nitinol stent placement for obstructive lesions of the popliteal artery achieves superior acute technical success and higher 1-year primary patency only if provisional stenting is considered target-lesion revascularization. Provisional stenting as part of a percutaneous transluminal balloon angioplasty strategy has equivalent 1-year patency and should be preferred over primary stenting. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00712309.