Balloon-expandable Endografts Research Articles

Long-term results of balloon-expandable LifePath endografts in abdominal aortic aneurysm: A single-center experience

This retrospective single-center study analyzed long-term results after LifePath (Edwards Lifesciences LLC, Irvine, Calif) endoprosthesis implantation for abdominal aortic aneurysm (AAA), primarily focusing on the wire form fracture issue and consecutive endoleak rate. Between 1999 and 2004, all consecutive patients with LifePath AAA devices in our institution were included in the retrospective analysis. All patients had computed tomography angiography (CTA) imaging preoperatively and image postprocessing. The follow-up using CTA imaging specifically addressed material fatigue (wire form fractures) resulting in migrations and type I endoleaks. During the 6-year study period, which included the 1-year withdrawal and redesign of the device, 51 patients were treated with LifePath AAA endografts. The 30-day mortality was 0%. The perioperative 30-day morbidity was 9.8%. One patient required a primary conversion due to misdeployment of the iliac limbs within the graft main body. The primary endoleak rate was 20.56% (type I, 2%; type II, 19.6%). During the mean follow-up of 40.7 months, 12 patients died, six were lost to follow-up, and 32 underwent subsequent CTA imaging. Eight patients (25%) demonstrated a proximal type I endoleak, seven (22%) had a type II endoleak, and three had a type III endoleak (9%). In nine patients (28.1%), wire form fractures could be detected at image postprocessing. Four patients required a secondary conversion due to endoleak and aneurysm growth (2 type I endoleaks and 2 type III endoleaks). Wire form fracture is the major structural problem in the LifePath balloon-expandable endograft device, resulting in a significant endoleak rate. We must caution those patients with a LifePath device in-situ that careful follow-up must be performed due to material fatigue and they should consider secondary conversion.

Remodeling of the Aortic Neck with a Balloon-Expandable Stent Graft in Patients with Complicated Neck Morphology

Graft migration and other device-related problems are more frequent in abdominal aortic aneurysm (AAA) patients with a complicated neck. We wanted to evaluate the performance of a balloon-expandable stent graft in these cases. Complicated aortic neck morphology was defined as a combination of short (<15 mm) and angulated (>45 degrees) necks with or without circumferential thrombus. Severe aortic angulation was defined as less than 120 degrees. During a 24-month period, 18 consecutive patients with complicated neck anatomy were treated with the Vascular Innovations (VI)-Datascope balloon-expandable endograft. In two patients, a balloon-expandable cuff was implanted to remodel the neck prior to insertion of a bifurcated endograft (Excluder, W.L. Gore & Associates, Flagstaff, AZ). Demographic, procedural, and outcome data were collected prospectively and retrospectively analyzed. All patients had preoperative computed tomographic (CT) angiography to determine aortic neck angulation and were followed with duplex ultrasonography and CT every 3 and 6 months postoperatively to assess aortic neck and sac dilatation, as well as device migration. The VI-Datascope graft consists of an aortounifemoral polytetrafluoroethylene (PTFE) graft sutured to a proximal balloon-expandable stent. The length of the graft is 40 cm; thus, the distal end of the graft always protrudes through the ipsilateral arteriotomy and can be cut to an appropriate length for each patient. The covered portion of the graft was deployed just below the level of the lowest renal artery. The proximal bare metal stent was deployed in the suprarenal area. An endoluminal hand-sewn anastomosis was performed between the aortounifemoral limb and the distal external iliac or the common femoral arteries. An occluder device was placed in the contralateral common iliac artery to prevent retrograde perfusion of the aneurysm. A femorofemoral 8 mm Dacron graft bypass was then performed to establish flow to the contralateral extremity and pelvis. Using this approach, remodeling and straightening of angulated aortic neck morphology were achieved in all cases, including in 44% of patients with severe aortic neck angulation. The average follow-up period was 11.5 months (4-21 months). There was one early occlusion (<30 days after implantation) of the PTFE limb requiring thrombectomy and one late occlusion (6 months after implantation) requiring thrombectomy and implantation of a Viabahn stent graft (W.L. Gore & Associates). Scheduled CT scans did not show any graft migration or proximal neck dilatation. Neither neck dilatation nor endograft migration was observed with the balloon-expandable stent graft. In patients with complicated aortic neck morphology, balloon-expandable stent grafts such as the VI-Datascope graft provide more secure fixation and better long-term outcomes compared with the more commonly used self-expanding endografts.

Aortic Neck Dilatation and Endograft Migration Are Correlated With Self-Expanding Endografts

To compare self-expanding and balloon-expandable stent-grafts in terms of aortic neck dilatation and endograft migration. Two-hundred and forty-two patients (178 men; mean age 68 years, range 56-91) underwent elective endovascular repair of abdominal aortic aneurysm. Two-hundred self-expanding (115 Excluder, 48 Endologix, 23 Vanguard, 10 Anaconda, and 4 Talent) and 42 balloon-expandable (Lifepath) endografts were used. All patients underwent contrast-enhanced computed tomography (CT) prior to the intervention, at 1, 3, and 6 months after the procedure, and annually thereafter. Comparison was made between the first and the last follow-up CT scans. Fifty-five (27.5%) of the 200 patients treated with self-expanding endografts had aortic neck dilatation compared to only 3 (7.1%) of the 42 patients treated with balloon-expandable endografts (p = 0.023). Forty-nine (24.5%) patients in the self-expanding group versus only 3 (7.1%) patients of the balloon-expandable group presented with endograft migration (p = 0.034); all had dilated necks. The difference between the means of neck dilatation for the Lifepath balloon-expandable stent-graft and the Excluder self-expanding endoprosthesis was statistically significant (p = 0.011, 95% CI 0.07 to 0.91). Aortic neck dilatation following endovascular AAA repair appears to be correlated with self-expanding endografts, which may contribute to a higher incidence of graft migration compared to that occurring with balloon-expandable endografts.

Intravascular Ultrasound Evidence for Stabilization of Compensatory Enlargement of the Femoropopliteal Segment after Endograft Placement

To document whether the vasodilatory response seen at the anastomotic segment 6 months after placement of a balloon-expandable endograft in the femoropopliteal segment progresses between 6 and 24 months. Twelve patients (9 men; median age 65 years, range 47-75) treated with an investigational polytetrafluoroethylene (PTFE) endograft for obstructive disease of the femoropopliteal segment were studied with intravascular ultrasound (IVUS) immediately after placement and at 6 months (first follow-up period) and 24 months (second follow-up period). Matched IVUS cross sections derived from the endograft and the anastomotic segment were analyzed for changes in lumen (LA), vessel (VA), and plaque areas (PLA). Five patients had complete IVUS surveillance at both the first (mean 8 months, range 7-9) and second (mean 25 months, range 23-26) follow-up periods; 1 patient was lost to follow-up during the second interval, and another 6 were excluded owing to graft occlusion (n = 4) or no IVUS surveillance available (n = 2) during the second follow-up period. Matched IVUS cross sections derived from the endograft showed no significant change in LA during both follow-up periods (-8% and +1%, respectively). There was no evidence for intimal hyperplasia or endograft recoil. During both follow-up periods, IVUS cross sections derived from the anastomotic segment revealed significant increases in LA (+37% and +8%, respectively) and VA (+26% and +6%, respectively) (both p < 0.05). The change in PLA during both follow-up periods was not significant (+13% and +3%, respectively). The PTFE endograft seems to inhibit both intimal hyperplasia and constrictive remodeling. The short-term (6-month) vascular dilatory response seen at the anastomotic segment tends to stabilize at 2 years. Therefore, this endovascular anastomosis acts as an "ideal" end-to-end anastomosis.

Adenosine-Induced Transient Cardiac Asystole Enhances Precise Deployment of Stent-Grafts in the Thoracic or Abdominal Aorta

Purpose: To present a cardiac asystole technique that assists in the accurate deployment of stent-grafts during endovascular repair of thoracic or abdominal aortic aneurysms. Technique: In the anesthetized patient, trial doses of intravenous adenosine are delivered until a ≥ 20-second period of asystole is recorded. The endograft procedure then proceeds until the device is ready for deployment. The predetermined dose of adenosine is administered, and the device is deployed during asystole. Adenosine-induced transient asystole has been utilized in 16 patients undergoing balloon-expandable endograft exclusion of 6 thoracic aortic and 10 abdominal aortic aneurysms. Asystole lasted for 20 to 30 seconds, during which time the devices were accurately deployed without interference from the aortic flow. There were no clinical sequelae of this technique in any patient. Conclusions: Pharmacologically induced transient asystole appears to be a safe maneuver to preclude endograft movement by systolic blood flow. The technique permits precise placement of balloon-expandable stent-grafts and is applicable to self-expanding devices as well. Interventionists may wish to incorporate adenosine-induced asystole into their aortic aneurysm exclusion procedures.

Endovascular Graft Placement in Experimental Dissection of the Thoracic Aorta

To test the effectiveness of endoluminal exclusion of the false lumen in experimental thoracic aortic dissection by occlusion of the entry site with a balloon-expandable endograft. Thoracic aortic dissections were induced surgically in six beagles. The endograft consisted of an ultrathin, 12-mm-wide polyester tube sutured over a Strecker stent that was already crimped onto an angioplasty balloon. Fluoroscopic and intravascular ultrasonographic (IVUS) guidance were used. Endografts were introduced by means of femoral arteriotomy, via a 12-F sheath positioned in the aorta, and were then expanded on the angioplasty catheter. IVUS and aortography showed an extensive thoracic dissection in all animals. Only four of six endografts were successfully placed. At 1 month, all thoracic endografts were patent, but the false lumen was never thrombosed. IVUS scans demonstrated a malpositioned endograft in two cases and persistent reentry in all cases. Endovascular grafting of the aorta was feasible in experimental thoracic aortic dissection, but thrombosis of the false lumen was not achieved.