An Experimental Evaluation of Device/Arterial Wall Compliance Mismatch for Four Stent-Graft Devices and a Multi-layer Flow Modulator Device for the Treatment of Abdominal Aortic Aneurysms.

OBJECTIVE/BACKGROUND: To investigate experimentally the arterial wall/device compliance mismatch of four stent-graft devices and a multilayer flow modulator within the supra- and infrarenal locations for the treatment of abdominal aortic aneurysms (AAA). METHODS: Five devices (MFM, EndurantII, Excluder, Zenith, and Fortron) were tested under physiological flow conditions within a flow simulator system comprising of a patient-specific thin-walled flexible AAA perfusion model with replicated intraluminal thrombus, supported by the spinal column. Devices were submitted to circumferential force tests and implanted in the perfusion model for circumferential arterial pressure/diameter measurements. Parameters, including radial resistive force, supra-/infrarenal compliance, pulsatile arterial energy loss (PAEL), pulse wave velocity (PWV), and wave reflection coefficient (Γ), were computed to characterise the devices' performance. RESULTS: The Zenith and EndurantII devices had the highest radial resistive force (up to 3 N/cm), while the Fortron device had the lowest (0.11 N/cm). Supra- and infrarenal compliance varied between 6.9-5.1 × 10(-4)/mmHg and 4.8-5.4 × 10(-4)/mmHg, respectively. Two devices (EndurantII and Excluder) significantly decreased infrarenal compliance by 13-26% (p < .001). Four devices increased the PAEL by 13-44% (p < .006). The PWV ranged from 10.9 m/s (MFM; p = .164) to 15.1 m/s (EndurantII; p < .001). There was an increase of 8-238% (p < .001) in the reflection coefficient for all devices. CONCLUSION: Commercially available endovascular devices lower the aortic wall compliance after implantation. The MFM was found to be the most compliant in the suprarenal region, while the Fortron device was the most compliant in the infrarenal region. Choosing the most compliant devices for treating AAAs produces positive gains in the aortic elastic recoil, thus minimising the device related complications.

Novel sealing concept in the Endologix AFX unibody stent-graft.

A major ongoing challenge for the endograft industry has been to create an endograft that assures the same reliable aneurysm seal afforded by surgical resection and suturing of a prosthetic graft to the abdominal aortic wall. The focus of these developmental efforts has always been the proximal neck, where the endo-graft must be firmly affixed to the aorta to prevent device movement and seal against leakage. The two mechanisms of fixation and seal, however, apply to both the proximal and the distal landing zones. Today's bifurcated stent-graft is configured much as it was two decades ago, with a short main body and long limbs, one of which must be mated to the main body after its deployment. The unibody Powerlink endograft made by Endologix, with its long main body and two innate limbs, is deployed so that it rests on the native aortoiliac bifurcation, the first and still only bifurcated endograft design to use anatomical fixation for stabilization and separate seal from fixation. The original Powerlink stent-graft has several design features that have allowed engineers to evolve new sealing technology that is featured on the company's latest iteration, the AFX Endovascular AAA System. This article reviews the approaches taken to enhance the device's ability to reduce type I endoleaks and provides some insight into the challenges of creating the perfect seal for an aortic stent-graft.

Indications for coronary artery bypass grafting in 2009: what is left to surgery.

Coronary artery bypass grafting (CABG) remains the most common procedure performed by cardiac surgeons, yet it is clear that the landscape of coronary intervention is constantly changing as new technology is introduced and data from countless studies continues to be published. However, no single study will be able to clearly define the indications for surgical versus percutaneous revascularization in every clinical scenario given the complexity of this disease as well as that of the patients it afflicts. Moreover, the significant improvements in percutaneous therapy, medical therapy management, perioperative care and secondary prevention after revascularization have decreased the morbidity and mortality of coronary artery disease making comparison between therapies far more difficult. Based on the available literature to date, surgical revascularization (CABG) provides significant benefit in certain patient populations; particularly those with comorbid conditions (for example diabetes, left ventricular [LV] dysfunction) and with more severe disease (for example left main, three-vessel). The goal of this article is to outline the current for surgical revascularization (CABG) understanding that coronary artery disease will continue be an important cause of morbidity and mortality and further study and re-evaluation of these recommendations will likely be necessary as time goes on.

Thoracic endografting is rapidly approaching trim time.

Thoracic aortic endografting is proving to be extremely useful for correcting a variety of lesions with few complications, and several devices have recently been approved by the Food and Drug Administration (FDA). Endovascular intervention avoids sternotomy or thoracotomy, chest tubes, respirators, general anesthesia, and blood loss is limited. Compared with traditional open surgery, complications such as paraplegia, renal failure, and cardiac and pulmonary difficulties are minimized; hospital and rehabilitation times are also reduced. There is no Level-1 evidence of endografting's efficacy in the thoracic aorta, and the pathologies encountered in this vascular territory are complex and often associated with other injuries or lesions, making randomized comparisons between open and endovascular procedures virtually impossible. Nevertheless, series results from centers of excellence indicate thoracic aortic endografting in patients with favorable anatomy and pathology for a specific device yields excellent results. Thoracic aortic endografting is an important alternative to open repair and will likely become the preferred treatment modality as additional devices become available and more experience is achieved in this vascular region.

Impact of endovascular repair for abdominal aortic aneurysms in octogenarians.

A total of 50 consecutive patients (86% male; median age, 82 years) underwent endovascular repair of abdominal aortic aneurysms (AAAs) ranging from 4.0 to 9.0 cm (median, 5.2 cm). Efficacy of aneurysm exclusion was assessed by angiography, duplex scan, and/or contrast-enhanced computed tomography (CT). Acute technical success was 82%. Access failed in one patient, and immediate conversion to open operation was required in two patients. Improper deployment of the endoluminal graft (ELG) across the renal arteries occurred in one patient. The median operation time, estimated blood loss, packed red blood cells received, contrast volume, and length of intensive care and hospital stay were 128 min, 200 mL, 0.1 unit, 297 mL, 0.9 days, and 3 days, respectively. ELG limb thrombosis was seen in one patient. There were 4 (8%) early endoleaks, and 2 endoleaks were discovered in other patients at 3 and 6 months. Local/vascular and remote/systemic postoperative complications were seen in 13 (26%) and 9 (18%) patients, respectively. At a median follow-up of 11 months (range 2 to 36 months), clinical success was 78%. The aneurysm sac diameter (n = 49) decreased from a preoperative median of 5.2 to 4.7 cm (p = 0.0001). Technical success was high, and results at 11 months were satisfactory. Long-term outcomes require further study.

Postoperative morbidity of closely staged bilateral carotid endarterectomies: an intersurgical interval of 4 days or less.

The purpose of this study was to determine if there is increased morbidity and mortality with bilateral carotid endarterectomies (CEAs) done with an intersurgical period of less than 4 days compared to historical groups of unilateral CEAs, or those with a greater intersurgical delay. From January 1991 to July 1998, 1390 carotid endarterectomies were performed, of which 154 (11.1%) were closely staged bilateral CEAs. Seventy-seven patients (51 male, 26 female; mean age 72.5 years) underwent bilateral CEAs within 4 days or less. Immediate and 30-day postoperative morbidity, including neurologic deficits, cranial nerve deficits, and mortality, were documented. Although controversial, there is no increased morbidity or mortality with bilateral CEAs done with an intersurgical delay of less than 4 days, when compared to the unilateral CEA historical groups.

Endovascular repair of AAA rupture 20 months after endoluminal stent-grafting.

PURPOSE: To demonstrate the feasibility of endovascular repair of a ruptured abdominal aortic aneurysm (AAA) previously treated with an endoluminal stent-graft. CASE REPORT: An 84-year-old man with a 9.5-cm AAA underwent endoluminal repair with an Endologix stent-graft, but a type I endoleak was detected postprocedurally. The patient was discharged and lost to follow-up. Twenty months later, he suffered an aneurysm rupture, which was repaired using endovascular techniques. Although he had a postoperative course complicated by aspiration pneumonia and renal failure, he recovered fully and was discharged from the hospital with no evidence of endoleak on the postprocedural imaging studies. CONCLUSIONS: Late ruptures after endoluminal AAA stent-grafting can be successfully treated with endovascular techniques.

Current status of carotid bifurcation angioplasty and stenting based on a consensus of opinion leaders.

OBJECTIVE: Carotid bifurcation angioplasty and stenting (CBAS) has generated controversy and widely divergent opinions about its current therapeutic role. To resolve differences and establish a unified view of CBAS' present role, a consensus conference of 17 experts, world opinion leaders from five countries, was held on November 21, 1999. METHODS: These 17 participants had previously answered 18 key questions on current CBAS issues. At the conference these 18 questions and participants' answers were discussed and in some cases modified to determine points of agreement (consensus), near consensus, (prevailing opinion), or divided opinion (disagreement). RESULTS: Conference discussion added two modified questions, placing a total of 20 key questions before the participants, representing four specialties (interventional radiology, seven; vascular surgery, six; interventional cardiology, three; neurosurgery, one). It is interesting that consensus was reached on the answers to 11 (55%) of 20 of the questions, and near consensus was reached on answers to 6 (30%) of 20 of the questions. Only with the answers to three (15%) of the questions was there persisting controversy. Moreover, both these differences and areas of agreement crossed specialty lines. Consensus Conclusions: CBAS should not currently undergo widespread practice, which should await results of randomized trials. CBAS is currently appropriate treatment for patients at high risk in experienced centers. CBAS is not generally appropriate for patients at low risk. Neurorescue skills should be available if CBAS is performed. When cerebral protection devices are available, they should be used for CBAS. Adequate stents and technology for performing CBAS currently exist. There were divergent opinions regarding the proportions of patients presently acceptable for CBAS treatment (<5% to 100%, mean 44%) and best treated by CBAS (<3% to 100%, mean 34%). These and other consensus conclusions will help physicians in all specialties deal with CBAS in a rational way rather than by being guided by unsubstantiated claims.

Safety, efficacy, and durability of carotid artery stenting for restenosis following carotid endarterectomy: a multicenter study.

PURPOSE: To present the results of a multicenter registry established to collect data on carotid stent procedures in patients with restenosis following carotid endarterectomy. METHODS: The procedural details, outcomes, and late follow-up results were collected from 14 centers in the United States. Thirty-day and late stroke and death rates were analyzed. RESULTS: Three hundred and thirty-eight patients (201 men; 71 +/- 8 years) underwent carotid stenting in 358 arteries. The average duration from carotid endarterectomy was 5.5 +/- 7.3 years. Sixty-one percent of the patients were asymptomatic. The overall 30-day stroke and death rate was 3.7%. The minor stroke rate was 1.7% (6/358), and the major nonfatal stroke rate was 0.8% (3/358). The fatal stroke rate was 0.3% (1/358), and the nonstroke-related death rate was 0.9% (3/338). There was 1 (0.3%) fatal and 1 (0.3%) nonfatal stroke during the follow-up period. The overall 3-year rate of freedom from all fatal and nonfatal strokes was 96% +/- 1% (+/- SE). CONCLUSIONS: Carotid artery stenting can be performed in patients with restenosis following carotid endarterectomy with 30-day complication rates comparable to those of most published studies on repeat carotid endarterectomy. Results of late follow-up suggest that this technique is durable and efficacious.

Transrenal fixation of aortic endografts: intermediate follow-up of a single-center experience.

PURPOSE: To examine the fate of the renal ostia following transrenal fixation of endovascular aortic stent-grafts. METHODS: Thirty-five patients (29 men; mean age 75 years) undergoing endovascular repair for abdominal aortic aneurysms (AAAs) had transrenal fixation of the uncovered proximal stent due to a short (< 1.5 cm long) or conical neck or a periprocedural endoleak. Eighteen (51%) patients were hypertensive; 7 (20%) had renal artery stenoses (RAS). Outcome measures included blood pressure, serum creatinine, computed tomography, and renal artery duplex scans. RESULTS: Two patients with > or = 60% RAS had renal stents placed during the endograft procedure; the other 5 RAS patients were normotensive and their renal lesions were not treated. Overall technical success was 82.9% (29/35). One (2.9%) case was converted due to graft twisting. There were 5 (14.2%) early endoleaks. Transient postoperative creatinine elevations were observed in 5 (14.2%) cases. Over a median 11-month period (range 2-24), no secondary endoleaks or silent renal artery occlusions were seen. One normotensive patient with an untreated > or = 60% renal lesion developed hypertension and severe stenosis (99%) at 4 months; stenting through the interstices of the transrenal stent was performed. No disease progression was seen in the other 6 RAS patients. CONCLUSIONS: In the intermediate period, transrenal fixation appears to have no adverse effects on renal blood flow. Moreover, in patients with no evidence of renal disease or preoperative RAS < 60%, it does not precipitate or cause progression of renal stenosis. However, patients with preoperatively documented RAS > or = 60% are a concern and mandate further study.

Global experience in cervical carotid artery stent placement.

The purpose of this article is to review and update the current status of carotid artery stent placement in the world. Surveys to major interventional centers in Europe, North and South America, and Asia were initially completed in June 1997. Subsequent information from these 24 centers in addition to 12 new centers has been obtained to update the information. The survey asked the various questions regarding the patients enrolled, procedure techniques, and results of carotid stenting, including complications and restenosis. The total number of endovascular carotid stent procedures that have been performed worldwide to date included 5,210 procedures involving 4,757 patients. There was a technical success of 98.4% with 5,129 carotid arteries treated. Complications that occurred during the carotid stent placement or within a 30-day period following placement were recorded. Overall, there were 134 transient ischemic attacks (TIAs) for a rate of 2.82%. Based on the total patient population, there were 129 minor strokes with a rate of occurrence of 2.72%. The total number of major strokes was 71 for a rate of 1.49%. There were 41 deaths within a 30-day postprocedure period resulting in a mortality rate of 0.86%. The combined minor and major strokes and procedure-related death rate was 5.07%. Restenosis rates of carotid stenting have been 1.99% and 3.46% at 6 and 12 months, respectively. The rate of neurologic events after stent placement has been 1.42% at 6-12-month follow-up. Endovascular stent treatment of carotid artery atherosclerotic disease is growing as an alternative for vascular surgery, especially for patients that are high risk for standard carotid endarterectomy. The periprocedure risks for major and minor strokes and death are generally acceptable at this early stage of development and have not changed significantly since the first survey results. Cathet. Cardiovasc. Intervent. 50:160-167, 2000.