Journal of Endovascular Therapy

To evaluate the incidence and natural history of endoleaks following thoracic endovascular aortic repair (TEVAR) of thoracic aortic aneurysm (TAA).

A retrospective review was conducted on 200 TAA patients (122 men; mean age 69±12 years) who underwent elective TEVAR in the descending thoracic aorta between January 2001 and December 2006. The mean aneurysm diameter was 66 mm (range 50–124), and most (75%) of the aneurysms were atherosclerotic in origin. Medical records and multidetector computed tomography studies were evaluated on a 3-dimensional workstation to categorize endoleak, establish morphological characteristics, and assess outcomes. The outcomes following any secondary interventions were noted in the context of endoleak etiology and the magnitude of the intervention.

Over a mean follow-up of 30 months (range 12–73), 39 (19.5%) patients developed an endoleak (33 primary and 8 secondary); 3 people had 2 distinct types of endoleaks. Endoleaks were associated with the presence of a carotid-subclavian bypass (p=0.0001) and lengthy aortic coverage by the stent-graft (p=0.005). The proportion of the 170 patients with a Zenith stent-graft who had an endoleak (17%, n=39) was significantly lower (p<0.01) than the proportion of endoleaks (34%, n=10) in the 30 patients with Gore or Talent devices. Secondary interventions for endoleak were performed in 79% of type I, 24% of type II, and 57% of type III endoleaks.

In this study, 1 in 5 TAA patients with TEVAR had endoleak. Most type I and III endoleaks required secondary intervention, while conservative treatment was most frequent for type II. Characterization of endoleak type was not always precise, and routine surveillance of all patients with endoleak is recommended.

To report the use of an external common femoral to carotid artery shunt in the setting of acute type A aortic dissection associated with carotid occlusion and stroke.

The procedure is illustrated in a 52-year-old man who presented with a type A dissection extending into the innominate trunk, with associated occlusion of the right common carotid artery (CCA). Angiography showed no collateral circulation to the right cerebral hemisphere. To re-establish brain perfusion in this setting, a percutaneous external shunt was installed from the common femoral artery to the right CCA. The 5-F femoral sheath used during diagnostic angiography was replaced by an 8-F femoral introducer securely fixed to the skin with silk sutures. Ultrasound-guided percutaneous CCA access was obtained using an 18-G needle and a 6-F introducer, also sutured to the skin. The ICA and intracranial branches showed no evidence of thrombosis at this level. A plastic tube was used to connect the femoral and carotid sheath side arms to restore ICA flow. Transcranial Doppler showed normal flow at the right middle cerebral artery after shunt placement. The patient was immediately transferred to the operating room for aortic surgery, during which an intrapericardially ruptured aorta was found. The ascending aorta and proximal arch were replaced under cardiopulmonary bypass and circulatory arrest, but the patient died during the procedure due to uncontrolled bleeding.

A temporary percutaneous external femoral-carotid shunt can restore blood flow to the brain whenever the carotid artery is occluded by the dissection flap and adequate collateral flow is absent.

To examine the solid mechanical effects of varying stent design and atherosclerotic plaque stiffness on the biomechanical environment induced in a diseased artery wall model.

Computational modeling techniques were employed to investigate the final radius of the lumen and artery wall stresses after stent implantation. Two stent designs were studied (one stiff and one less stiff). The stenotic artery was modeled as an axisymmetrical diseased vessel with a 20% stenosis by diameter. The material properties of the diseased tissue in the artery models varied. Atherosclerotic plaques half as stiff (0.5×), of equal stiffness (1.0×), or twice as stiff (2.0×) as the artery wall were investigated.

Final lumen radius was dependent on stent design, and the stiffer stent deformed the artery to an approximately 10% greater radius than the more compliant design. Alternatively, circumferential stress levels were dependent on both stent design and plaque material properties. Overall, the stiffer stent subjected the artery wall to much higher stress values than the more compliant design, with differences in peak values of 0.50, 0.31, and 0.09 MPa for the 2.0×, 1.0×, and 0.5× stiff plaques, respectively.

Evidence suggests that a judicious choice of stent design can minimize stress while maintaining a patent lumen in stenotic arteries. If confronted with a rigid, calcified plaque, stent design is more important, as design differences can impose dramatically different stress fields, while still providing arterial patency. Alternatively, stent design is not as much of an issue when treating a soft, lipid-laden plaque, as stress fields do not vary significantly among stent designs.

To report a prospective feasibility study of Cutting Balloon angioplasty (CBA) applied in the predilation phase of carotid artery stenting (CAS) in highly calcified lesions.

From January 2003 to February 2007, 178 consecutive patients (109 men; mean age 73.1±7.3 years) with highly calcified carotid lesions underwent CAS with CBA applied as a pre-specified strategy in the predilation phase of the procedure. All steps in the procedure were performed under cerebral filter protection. The cutting balloon ranged in diameter from 3 to 4 mm and was inflated at nominal pressures in the target lesion. Pre-CBA dilation with a low-profile coronary balloon was performed only when the Cutting Balloon was not able to cross the lesion. Selection of the filters and stents was at the operator's discretion. Primary endpoints were the all stroke and death rates at 30 days and 6 months. Secondary endpoints included Cutting Balloon success (positioning and full balloon inflation), CAS technical success (residual angiographic stenosis <30%), CAS procedural success (technical success and no complications), and in-hospital major complications.

Cutting Balloon success was achieved in all 178 patients. In 32 (18.0%), pre-CBA dilation was necessary due to inability to cross the lesion with the Cutting Balloon initially. CAS technical success was achieved in all patients. One (0.6%) patient suffered transient neurological intolerance due to flow cessation from massive debris in the distal filter; this event was completely resolved after the filter was removed (CAS procedural success 99.4%). One patient suffered a major stroke at day 15 (0.6% 30-day all stroke and death rate). At the 6-month follow-up, 174 (97.7%) patients were evaluated; 1 patient died from myocardial infarction at day 35, and 2 patients died from non-neurological or cardiac causes at days 103 and 158. The cumulative all stroke and death rate was 2.2%.

These data suggest that CBA performed during the predilation phase of CAS in highly calcified lesion is a safe and useful method to prepare this lesion subset for stenting.

To examine the effects of swallowing and side-to-side head turning on stents in the internal carotid artery.

Seven patients (4 men; mean age 76.9 years) who underwent carotid artery stenting for the treatment of atherosclerotic cervical carotid artery disease were examined with cine fluoroscopy. Geometric processing techniques were used to quantify carotid stent deformations due to head turning and swallowing forces. The variables measured included radial, axial, and crush deformations, as well as radii of stent curvatures during tested maneuvers.

Radial deformations of the stented vessels were significantly less than axial and crush deformations, ranging from −10.2% to 15.5%. Axial deformations in response to both swallowing and head turning were positive (average 4.5%, range −14.5% to 14.1%), indicating a general lengthening of the stented vessel due to biomechanical motions. Crush strains exhibited the largest range of all of the deformation modes during both swallowing and head turning. Strain values ranged from −18.7% to 25.9% in the anteroposterior direction and from −25.6% to 21.9% in the lateral direction. Head turning produced fairly symmetrical crushing of the stent. Conversely, swallowing resulted in a preferential medial crush of the stented artery due to contraction of the pharyngeal constrictor muscles. Curvature measurements revealed a tightest radius of curvature of ∼1.5 cm during ipsilateral head turning, with average values during both swallowing and head turning of ∼10 cm.

In general, head turning toward the stented artery produced greater deformation in the vessels than swallowing. Since patients are expected to undergo far more swallowing cycles than head turns, however, the accumulated deformations from swallowing may be more significant and should be considered in the design of fatigue resistant stents for carotid arteries.

To evaluate if there are any differences in duplex ultrasound velocity measurements between native and stented carotid arteries using duplex ultrasound in an animal model.

The common carotid artery of 5 pigs was exposed bilaterally (10 arteries). Diameters and velocities were measured by ultrasound in the proximal, mid, and distal native artery at the intended site of stent implantation. Measurements were repeated after bilateral stent placement (Wallstent versus Precise) under angiographic control. Outcomes of native versus stented arteries and Wallstent versus Precise were statistically compared.

Angiographic measurements matched well with duplex-measured diameters. The mean proximal stent diameter (3.5±0.5 mm) was significantly smaller than the native proximal artery diameter (4.2±0.4 mm, p=0.004), mostly due to narrowing of the Wallstent diameter to 3.2±0.5 mm (p=0.009). Proximal, mid, and distal segments of the Wallstents were narrower than those of the Precise stent, and associated peak systolic velocities (PSV) were higher at the 3 locations versus the Precise stent, although the differences were not statistically significant. Wallstent PSVs were higher than in the native artery at the proximal, mid, and distal segments, respectively; again, the differences were not statistically significant.

Stent placement caused anatomical and hemodynamic alterations. Narrowings and associated increased velocities were noted. Such alterations, however, were stent-type dependent and did not justify a general approach to new velocity criteria indiscriminately applied to all stents.

To demonstrate that results similar to high-volume academic centers can be achieved in the community setting when treating abdominal aortic aneurysm (AAA) using endovascular techniques, given appropriate volume and skill sets.

A retrospective review was conducted of 342 consecutive patients who underwent endovascular aneurysm repair (EVAR) by surgeons in a community hospital group from October 1999 through September 2005. In this population, 245 (71.6%) patients were treated with EVAR and 97 (28.4%) with open surgical repair. Of the 245 EVAR patients (203 men; mean age 73.4±9.2 years), 218 AneuRx, 19 Ancure, 6 Excluder, and 2 Zenith stent-grafts were implanted by 2 vascular surgeons to exclude AAAs with a mean diameter of 54±11 mm. Patients were followed postoperatively with office visits and computed tomography at 1, 6, and 12 months and annually thereafter.

Technical success was achieved in 99.6% (244/245) with 1 intraoperative conversion. Mean operative time was 131±57 minutes, with a mean contrast load of 161.6±65.5 mL. Thirty-five (14.3%) patients required intraoperative blood transfusion. Length of stay was 2.3±4.5 days. Thirty-day mortality was 0.8% (2/245). Secondary procedures were required in 15 (6.1%) patients. Kaplan-Meier estimates of freedom from secondary interventions were 98%, 98%, 95%, and 90% at 12, 24, 36, and 48 months, respectively. At the same time points, freedom from surgical conversion was 99%, 99%, 97%, and 96%, and freedom from aneurysm-related death was 97%, 96%, 96%, and 96%.

Endovascular AAA repair provides a less invasive method of managing aortic disease with resultant low perioperative mortality. Results in our community hospital demonstrate that this technology can be applied outside an academic environment in nearly three quarters of the population with excellent short and long-term results.

To evaluate the splanchnic and limb metabolic effects of open repair (OR) of abdominal aortic aneurysms (AAA) versus endovascular aneurysm repair (EVAR) in a pilot study utilizing microdialysis.

Nine AAA patients (8 men; mean age 74 years, range 61–85) were treated with EVAR and 9 had an OR (5 men; mean age 70 years, range 55–85). In the EVAR cases, which were performed percutaneously, the external iliac artery was obstructed by the introducer to a mean functional stenosis of 70% (52%–100%). Catheters for microdialysis were placed subcutaneously above the ankle of the right leg and freely in the abdominal cavity to measure the levels of lactate and pyruvate. The lactate/pyruvate ratio was calculated as a measure of ischemia. Measurements started at the end of surgery and continued for 2 days. Mean values were compared using the Mann-Whitney U test.

The mean value of intraperitoneal lactate during the first day after EVAR was 1.5±0.7 mM versus 2.6±0.8 mM after OR (p=0.019). The lactate/pyruvate ratio was 10.2±2.2 after EVAR and 12.3±2.6 after OR (p=0.113). Leg lactate mean values were 4.2±2.0 mM after EVAR versus 1.8±0.6 mM after OR (p<0.001). The lactate/pyruvate ratio was 20.1±8.3 for EVAR and 13.7±3.3 for OR (p=0.040). These differences between EVAR and OR continued for the second day.

Intraperitoneally, metabolism was slightly increased after OR; however, it was not suggestive of splanchnic ischemia. Leg findings reflected a more extensive ischemia after EVAR over 48 hours, which was a somewhat unexpected finding that may be related to the introducer's impact on blood flow to the limb during the intervention. Although no clinical consequences were recorded, the finding suggests some benefit of minimizing as much as possible the time of reduced perfusion to the limb.

To demonstrate the absence of bleeding from a ruptured abdominal aortic aneurysm (AAA) without evidence of endoleak following endovascular aneurysm repair (EVAR).

A 72-year-old woman developed aneurysm enlargement 4 years after EVAR of an infrarenal AAA. During surgical exploration for abdominal pain and presumed aneurysm rupture, the ruptured aneurysm sac was found to be filled with gelatinous material without evidence of thrombus or active bleeding.

This case provides insight into the natural history of endotension and indicates that conservative management even in the face of an expanding aneurysm is a valid management option for selected patients.