Deployment Of Thoracic Stent Graft Research Articles

Distribution of Air Embolization During TEVAR Depends on Landing Zone: Insights From a Pulsatile Flow Model

Purpose: To analyze the distribution of air bubbles in the supra-aortic vessels during thoracic stent-graft deployment in zones 2 and 3 in an aortic flow model. Materials and Methods: Ten identical, investigational, tubular, thoracic stent-grafts were deployed in a glass aortic flow model with a type I arch: 5 in zone 2 and 5 in zone 3. A pulsatile pump generated a flow of 5 L/min with systolic and diastolic pressures (±5%) of 105 and 70 mm Hg, respectively. The flow rates (±5%) were 300 mL/min in the subclavian arteries, 220 mL/min in the vertebral arteries, and 400 mL/min in the common carotid arteries (CCAs). The total amounts of air released in each supra-aortic branch and in the aorta were recorded. Results: The mean amounts of air measured were 0.82±0.23 mL in the zone-2 group and 0.94±0.28 mL in the zone-3 group (p=0.49). In the zone-2 group compared with zone 3, the amounts of released air were greater in the right subclavian artery (0.07±0.02 vs 0.02±0.02 mL, p<0.01) and right CCA (0.30±0.8 vs 0.18±07 mL, p=0.04). There were no differences between the groups concerning the mean amounts of air measured in the right vertebral and all left-side supra-aortic branches. The amount of air released in the descending aorta was significantly higher in the zone-3 group vs the zone-2 group (0.48±0.12 vs 0.13±0.08 mL, p<0.01). Small bubbles were observed continuously during deployment, whereas large bubbles appeared more commonly during deployment of the proximal stent-graft end and after proximal release of the stent-graft. Conclusion: Air is released into all supra-aortic branches and the descending aorta during deployment of tubular thoracic stent-grafts in zones 2 and 3 in an aortic flow model. Higher amounts of air were observed in right-side supra-aortic branches during deployment in zone 2, whereas significantly greater amounts of air were observed in the descending aorta during deployment in zone 3.

Transapical Deployment of Thoracic Stent Graft for Ascending Aorta Coronary Bypass Pseudoaneurysm in a Patient with Prosthetic Aortic Valve.

The authors describe the transapical deployment of a thoracic endograft to exclude a saphenous vein graft proximal anastomotic pseudoaneurysm following coronary artery bypass grafting (CABG) in a 63-year-old male with a prosthetic aortic valve. A standard thoracic endograft has been deployed via transapical access after percutaneous transluminal coronary angioplasty of the native vessel perfused by the patent CABG. The procedure was uneventful; an 8-month computed tomography scan showed complete exclusion of the pseudoaneurysm with patency of supra-aortic trunks.

Bubble Counter for Measurement of Air Bubbles During Thoracic Stent-Graft Deployment in a Flow Model

BackgroundThe aim of our study was to describe and validate the use of a bubble counter in an aortic flow model assessing the distribution of air bubbles in the supra-aortic vessel during thoracic stent-graft deployment. Materials and methodsIn an aortic flow model made by glass, identical tubular thoracic stent grafts (Zenith TX2 ProForm; Cook Medical, Bjaeverskov, Denmark) were deployed distal to the left subclavian artery. Four steps were defined during deployment: (1) introduction of the stent graft in the arch; (2) deployment of the stent graft; (3) proximal release of the stent graft; and (4) retrieval of the introduction system. On both sides, the common carotid and the vertebral artery were connected together, and the air bubbles were measured with one bubble counter probe per side. The number of air bubbles, as well as their size and distribution, is analyzed during these four steps for the left and right sides with a bubble counter. ResultsTen thoracic stent grafts were included in the study. The total number of air bubbles measured during all steps was significantly higher on the left side (1091 ± 255 versus 545 ± 288, P < 0.00001). During the third step, significantly higher numbers of bubbles were observed on the left side (P = 0.0000001) compared with the right side. The analysis of all bubbles by size revealed that a higher number of bubbles ranged 100-200 μm (P < 0.02) and 200-300 μm (P < 0.03) on the left side. Small bubbles were observed during all steps of deployment, whereas large bubbles appeared more commonly during the second and third steps. ConclusionsA significant number of air bubbles are released during deployment of tubular thoracic stent grafts distally of the left subclavian artery in an aortic flow model. The distribution of air bubbles is bilateral with a higher number of air bubbles released on the left side.

A New Adjustable Puncture Device for In Situ Fenestration During Thoracic Endovascular Aortic Repair

Purpose: To describe a new adjustable puncture system for in situ fenestration in thoracic endovascular aortic repair (TEVAR). Technique: An adjustable puncture needle for use in conjunction with a steerable 8-F, 55-cm Fustar sheath is demonstrated in a 65-year-old man with acute complicated type B dissection involving the left subclavian artery (LSA). The puncture device features an inflatable balloon at the tip, a central lumen for 0.018-inch guidewires, and a 3-level puncture depth. After thoracic stent-graft deployment at zone 2, the needle/sheath combination was delivered from a left brachial artery access. The needle was adjusted perpendicular to the fabric of the stent-graft with the assistance of the steerable sheath. The balloon at the tip was inflated to center the needle, and the puncture depth was selected on the puncture needle system. Holding the sheath and puncture needle together, a hole was created in the graft fabric. The aperture was sequentially dilated to accommodate the mating stent selected to maintain perfusion to the LSA. This new device has been successfully applied in 6 patients treated with TEVAR for different arch pathologies. Conclusion: This new puncture device could assist in situ fenestration and improve the technical success rate.

Feasibility Study of a Novel Thoraco-abdominal Aortic Hybrid Device (SPIDER-graft) in a Translational Pig Model

The hybrid SPIDER-graft consists of a proximal descending aortic stent graft and a conventional six branched Dacron graft for open abdominal aortic repair. Technical feasibility with regard to avoiding thoracotomy and extracorporeal circulation (ECC) during thoraco-abdominal aortic hybrid repair and peri-procedural safety of this novel device are unknown. This was a feasibility and safety study in domestic pigs (75-85kg). The abdominal aorta including iliac bifurcation, left renal artery, and visceral arteries were exposed via retroperitoneal access. The right iliac branch was first temporarily anastomosed end to side to the distal aorta via partial clamping. During inflow reduction and infra-coeliac cross-clamping, the coeliac trunk (CT) was divided and the proximal stent graft portion of the SPIDER-graft was deployed into the descending aorta via the CT ostium. Retrograde visceral and antegrade aorto-iliac blood flow was maintained via the iliac side branch. The visceral, renal, and iliac arteries were sequentially anastomosed, finally replacing the first iliac end to side anastomosis. Technical success, blood flow, periods of ischaemia, and peri-procedural complications were evaluated after intra-operative completion angiography and post-operative computed tomography angiography. Six animals underwent successful thoracic stent graft deployment and distal open reconstruction without peri-operative death. The median thoracic graft implantation time was 4.5min, and the median ischaemia times before reperfusion were 10min for the CT, 8min for the superior mesenteric artery, 13min for the right renal artery, and 22min for the left renal artery. Angiography demonstrated appropriate graft implantation and blood flow measurements confirmed sufficient blood flow through all side branches. In this translational pig model, thoraco-abdominal hybrid repair using the novel SPIDER-graft was successful in avoiding thoracotomy and ECC. Technical feasibility and safety appear promising, but need to be reassessed in humans.

Magnetic Navigation for Thoracic Aortic Stent-graft Deployment Using Ultrasound Image Guidance

We propose a system for thoracic aortic stent-graft deployment that employs a magnetic tracking system (MTS) and intraoperative ultrasound (US). A preoperative plan is first performed using a general public utilities-accelerated cardiac modeling method to determine the target position of the stent-graft. During the surgery, an MTS is employed to track sensors embedded in the catheter, cannula, and the US probe, while a fiducial landmark based registration is used to map the patient's coordinate to the image coordinate. The surgical target is tracked in real time via a calibrated intraoperative US image. Under the guidance of the MTS integrated with the real-time US images, the stent-graft can be deployed to the target position without the use of ionizing radiation. This navigation approach was validated using both phantom and animal studies. In the phantom study, we demonstrate a US calibration accuracy of 1.5 ± 0.47 mm, and a deployment error of 1.4 ± 0.16 mm. In the animal study, we performed experiments on five porcine subjects and recorded fiducial, target, and deployment errors of 2.5 ± 0.32, 4.2 ± 0.78, and 2.43 ± 0.69 mm, respectively. These results demonstrate that delivery and deployment of thoracic stent-graft under MTS-guided navigation using US imaging is feasible and appropriate for clinical application.

The Use of Rapid Ventricular Pacing to Facilitate Stent Graft Deployment in the Distal Aortic Arch

Systemic hypotension has been traditionally used to facilitate deployment of thoracic stent grafts. Decreasing blood pressure with vasodilating agents further increases cardiac output and, consequently, the cardiac output-mediated windsock effect during deployment. Use of rapid ventricular pacing reduces the windsock effect during stent graft deployment and allows the graft to appose to the aortic wall under zero cardiac output, thus minimizing aortic wall shear stress. In this case we report the use of transvenous rapid ventricular pacing, a safe and reproducible technique to allow precise deployment of a Valiant Captivia stent graft in the distal thoracic arch for a saccular thoracic aneurysm.

An Externalized Transseptal Guidewire Technique to Facilitate Guidewire Stabilization and Stent-Graft Passage in the Aortic Arch

To describe a technique to facilitate passage and stable deployment of thoracic stent-grafts in patients with multiple tortuous aortic segments that may hamper endograft delivery or precise placement because of an unstable position in the aortic arch. The technique of a transseptal through-and-through guidewire is demonstrated in a patient with a ruptured thoracic aneurysm with severe tortuosity of the aorta and a right-sided, severely angulated aortic arch. The transseptal through-and-through guidewire stabilization technique allowed successful passage and deployment of a thoracic stent-graft after debranching of the right common carotid and subclavian arteries. The ruptured thoracic aneurysm was excluded, while the proximal graft edge lined up with the origin of the aberrant left innominate artery. An externalized transseptal guidewire can facilitate endograft passage in tortuous aortic anatomies and optimize control in most severely angulated aortic arches. It may obviate the use of proximal bare stents because the proximal stent-graft is actively conformed to the inner curve of the aortic arch by the stabilizing wire. Transseptal access to the ascending aorta has the potential to become an important tool for endovascular treatment, especially for catheterization of branches and fenestrations in aortic arch stent-grafts.

Incidence of and outcomes after misaligned deployment of the Talent Thoracic Stent Graft System

Various types of device-specific adverse events can occur during deployment of thoracic stent grafts due to the high flow rate and severe aortic angulation that is often encountered in the thoracic aorta. This study assessed the incidence, etiology, and overall effect of misaligned deployment of the Talent Thoracic Stent Graft (TSG) System. Techniques to predict and avoid this complication are discussed. Data collection included pivotal-trial follow-up, direct surveys of centers inside and outside the United States and principal investigators, a targeted literature search, and review of complaint files. Misaligned deployment was considered to occur when the proximal covered or uncovered stent apices of a thoracic stent graft folded back on itself and remained nonparallel to the wall of the aorta after deployment had been completed. Of about 20,305 deployments to date of the Talent TSG, 24 misaligned deployments were identified for an incidence of 0.1%. Nineteen (79%) events occurred during treatment of degenerative aneurysms or penetrating ulcers, four (17%) during treatment of dissections, and the underlying pathology could not be determined for one patient. The misalignment was noted at the proximal end of the stent graft in 15 patients (63%), and the other 9 events (37%) occurred at the graft overlap junction. Two events were treated intraoperatively, with a second overlapping device placed in one patient and a snare used to reposition the proximal stent in another. Adverse clinical events occurred in three patients and included a persistent type I endoleak, continued false lumen perfusion in a patient with dissection, and delayed retrograde type A dissection in a patient undergoing total arch repair. No intraoperative contrast extravasation or computed tomography evidence of perforation was noted. There were no perioperative deaths or cerebrovascular events, with one report of paraplegia among the 24 patients in this series. Misaligned deployment is an unusual phenomenon that tends to occur in the context of certain well-defined anatomic conditions in the thoracic aorta. To date, most of these events have not led to significant adverse sequelae. However, careful patient selection, periprocedural imaging, and case planning can help to identify anatomies in which misaligned opening is likely to occur, allowing physicians to avoid this complication.

Endovascular management of chronic aortic dissection in patients with Marfan syndrome

Marfan syndrome patients are prone to aortic dilatation, dissection, and rupture. Success of aortic root replacement has generated a cohort of patients surviving longer and presenting with distal aortic dissection and enlargement. Thoracic endovascular stent-graft repair (TEVR) is being increasingly utilized to exclude aneurysms resulting from chronic aortic dissection. This report explores the role of TEVR in Marfan patients with this pathology. Review of a prospectively maintained database identified seven patients with Marfan syndrome offered endovascular repair of aneurysmal chronic aortic dissection. All patients had previous aortic root repair. Talent or Valiant (Medtronic Vascular, Santa Rosa, Calif) aortic stent-grafts were used to occlude the dissection entry tear and cover the thoracic aorta. Electronic data, case notes, and radiological surveillance were analyzed. Seven consecutive patients (six male; mean age, 45.9 +/- 10 years, range, 29 to 63) underwent successful thoracic stent-graft deployment. Mean aortic aneurysmal diameter was 63.4mm (+/-11.2) with six of seven dissections extending to the aortic bifurcation. No perioperative neurological events occurred. Thirty-day mortality was 1/7 (14%) due to congestive cardiac failure. At median 16 month follow-up, two of six cases (33%) required intervention for endoleak. Aortic false lumen thrombosis (FLT) occurred in 5/6 (83%) cases and partial FLT occurred in 1/6 (17%). All thoracic aortas continued to dilate during follow-up. Crude median aortic growth rate was 7.2 mm/year (range, 3.5 to 19 mm). TEVR in Marfan syndrome patients with chronic aortic dissection is technically feasible. However, post intervention surveillance confirms that the aorta continues to dilate despite graft deployment and false lumen thrombosis. Endovascular repair may offer a viable option in patients who have contraindications to open surgery, but longer follow up of more patients is required to define the place of this therapy.

Endovascular total aortic arch replacement by in situ stent graft fenestration technique

Open surgical total aortic arch replacement is a demanding procedure which carries a substantial morbidity and mortality. A less invasive endovascular option is endovascular stent grafting using in situ fenestrations. After thoracic stent graft deployment in the arch, fenestrations are made for the major arch vessels. During this procedure, antegrade cerebral perfusion is maintained using a temporary bypass from the left femoral artery to both carotids perfusing both the anterior and posterior cerebral circulation. The endovascular technique and devices used are herein described.

High-Dose Adenosine-Induced Asystole Assisting Accurate Deployment of Thoracic Stent Grafts in Conscious Patients

Adenosine has been used to induce asystole and assist deployment of endoluminal grafts. However, application of high-dose adenosine in conscious patients has not been described. In this prospective study, we administered high-dose adenosine in patients undergoing thoracic stent grafting. Asystole duration in relationship to the dosage of adenosine, safety, and side effect profiles was investigated. All patients who underwent thoracic stent grafting between 1998 and 2006 were the potential study subjects. They received monitored anesthesia care and local anesthesia unless contraindicated. Adenosine was given via rapid intravenous bolus immediately prior to the deployment of the stent graft. Every patient received a dose of 36 mg. If needed, a second dose of 18 mg was given. Duration of asystole was recorded after each administration. Patients' vital signs before and after administration were also documented. Side effect profiles were collected intra- and postoperatively. A total of 46 patients received adenosine (34 men, 12 women). Mean age was 60.4 +/- 17.5 years. American Society of Anesthesiologists scores were II in one patient (2%), III in six patients (13%), and IV in 39 patients (85%). Eighteen patients received a single dose of 36 mg adenosine, 15 were given a second dose of 18 mg, and 13 received nonstandard dosages. Asystole durations were 18.8 +/- 8.8 and 11.6 +/- 5.5 sec for 36 and 18 mg, respectively. Technical success was achieved in all cases. The differences achieved statistical significance (p = 0.0009). There were no severe cardiac or pulmonary complications. High-dose adenosine can be given safely in conscious patients. The dose-response was predictable and reproducible. The dosages used in our study induce sufficient duration of asystole, which ensured accurate deployment of thoracic stent grafts.

Endovascular Repair of a Ruptured Descending Thoracic Aortic Aneurysm in a Patient with an Ascending Aortic Aneurysm: Hybrid Open Arch Reconstruction with Simultaneous Thoracic Stent-Graft Deployment within Elephant Trunk

Endovascular repair of the thoracic aorta is now widely practiced. The extension of this technique to emergent settings is in evolution. Pathology of the ascending and transverse aortic arch may preclude thoracic aortic stent grafting due to the lack of a proximal seal zone. Several hybrid open/endovascular approaches have been described. We recently encountered the difficult case of a contained rupture of a 6.8 cm descending thoracic aortic aneurysm in a 60-year-old patient with aneurysmal degeneration of the ascending and transverse aortic arch. This patient was treated with a hybrid approach of open ascending and transverse arch reconstruction along with simultaneous stent-graft repair of the descending thoracic aorta. The open repair established an excellent proximal landing zone by use of the "elephant trunk" technique. This technique also allowed direct suture fixation of the stent graft to the arch graft to prevent stent-graft migration. This hybrid surgical approach was successful and avoided the cumulative morbidity that a left thoracoabdominal approach would have added to the sternotomy. Further creative uses of these hybrid techniques will undoubtedly serve a larger role in the treatment of thoracic aortic pathology.

A Laparoscopic Approach to the Abdominal Aorta for Thoracic Stent-Graft Deployment:Evaluation in a Porcine Model

PURPOSE To develop laparoscopic techniques for aortic stent-graft placement as an alternative to the femoral approach. METHODS Endovascular stent-grafts were placed in 8 pigs via a totally laparoscopic retroperitoneal approach. After needle puncture, a guidewire was inserted into the abdominal aorta, followed by an 18-F sheath through which a Talent stent-graft was deployed in the descending thoracic aorta without aortic clamping. All the endovascular tools were inserted into the retroperitoneal area via the ports. After the sheath was withdrawn, hemostasis was achieved by suturing the aortic puncture under aortic cross-clamping. After sacrificing the animals, the thoracic aorta was removed to verify the position and deployment of the stent-grafts. RESULTS Seven (87.5%) of 8 procedures were successfully completed; the first animal died from hemorrhage due to inadvertent injury to the posterior infrarenal aortic wall. The accurate deployment and position of the stent-grafts were verified visually after sacrifice. Mean (+/- SD) procedural, implantation, and aortic cross-clamping times were 205 +/- 56, 22 +/- 9, and 30 +/- 19 minutes, respectively. Mean blood loss was 120 +/- 56 mL. CONCLUSIONS Thoracic aortic stent-grafting using a laparoscopic approach to the infrarenal aorta is feasible. More studies will be required to define the place of combined endovascular and laparoscopic procedures as an alternative to the femoral surgical approach for stent-graft placement.

A laparoscopic approach to the abdominal aorta for thoracic stent-graft deployment: evaluation in a porcine model.

To develop laparoscopic techniques for aortic stent-graft placement as an alternative to the femoral approach. Endovascular stent-grafts were placed in 8 pigs via a totally laparoscopic retroperitoneal approach. After needle puncture, a guidewire was inserted into the abdominal aorta, followed by an 18-F sheath through which a Talent stent-graft was deployed in the descending thoracic aorta without aortic clamping. All the endovascular tools were inserted into the retroperitoneal area via the ports. After the sheath was withdrawn, hemostasis was achieved by suturing the aortic puncture under aortic cross-clamping. After sacrificing the animals, the thoracic aorta was removed to verify the position and deployment of the stent-grafts. Seven (87.5%) of 8 procedures were successfully completed; the first animal died from hemorrhage due to inadvertent injury to the posterior infrarenal aortic wall. The accurate deployment and position of the stent-grafts were verified visually after sacrifice. Mean (+/- SD) procedural, implantation, and aortic cross-clamping times were 205 +/- 56, 22 +/- 9, and 30 +/- 19 minutes, respectively. Mean blood loss was 120 +/- 56 mL. Thoracic aortic stent-grafting using a laparoscopic approach to the infrarenal aorta is feasible. More studies will be required to define the place of combined endovascular and laparoscopic procedures as an alternative to the femoral surgical approach for stent-graft placement.