Canine model of acute aortic rupture: treatment with percutaneous delivery of a covered Z stent--work in progress

Endovascular Repair for Acute Rupture of the Descending Thoracic Aorta

Purpose:

To report the endovascular treatment of acute descending thoracic aortic rupture as an alternative to open surgery in high-risk patients.

Methods:

Between November 1999 and April 2001, 10 patients (7 men; median age 75 years) underwent endovascular stent-grafting of the descending thoracic aorta for acute rupture from an aneurysm (n = 7) or blunt trauma (n = 3). All patients were evaluated as high operative risk. The aortic rupture was associated with isolated mediastinal hematomas (n = 7), left hemothorax (n = 2), or aortobronchial fistula (n = 1). The Excluder Thoracic Endoprosthesis was used predominantly.

Results:

The mean interval to the endovascular repair was 45.3 ± 28.4 hours. All stent-grafts were successfully deployed. Two patients required common iliac artery access, and 2 needed covered stents for iatrogenic iliac artery rupture. There was 1 postoperative death (myocardial infarction) and no renal failure, neurological complications, embolization, stent-graft migration, or perigraft leak. One patient died 4 months later from an unrelated cause. At a mean follow-up of 7.9 ± 5.1 months, all aneurysms and rupture sites were excluded with no evidence of endoleak or hematoma.

Conclusions:

Endoluminal treatment is a feasible technique for the management of acute rupture of the descending thoracic aorta. Long-term studies are required to assess the effectiveness and durability of this technique in comparison to open repair.

Endovascular intervention in thoracic arterial trauma

The management of thoracic vascular injury has improved dramatically over the past two decades. The availability of multi-row detector CT has facilitated early diagnosis and incorporation of minimally invasive endograft repair for traumatic aortic injury has improved mortality and paraplegia rates. This review evaluates the available data on stent-graft repair of acute blunt traumatic aortic injury and traumatic great vessel injury with regard to safety and efficacy in comparison with conventional open surgical repair.

Blunt traumatic aortic transection: the endovascular experience

BACKGROUND

Thoracic aortic transection resulting from blunt trauma is usually fatal. It is almost always associated with multiple, complex, nonaortic injuries that could be adversely affected by standard surgical repair of the aorta. Endovascular stenting techniques offer these patients a less physiologically disruptive treatment option. We studied the feasibility and safety of endovascular stent graft placement for treatment of acute traumatic aortic transection.

METHODS

Between 1994 and 2001, 9 patients were treated emergently for aortic transections with stent graft placement. The first patient had a custom-made prototype, and the other 8 patients had the Cook-Zenith thoracic stent graft implanted. All were polyester-covered Z-stent construction and deployed through a femoral 20- to 24-F delivery sheath.

RESULTS

Stent graft placement successfully sealed the aorta in all patients. One patient died as a result of a cerebrovascular accident. One patient required a brachial thrombectomy to relieve arm ischemia. The remaining eight patients were alive and without complications during the follow-up period (mean 21 months).

CONCLUSIONS

Endovascular repair for acute aortic transection is a safe, effective, and timely treatment option. It may be the treatment of choice in patients with extensive associated injuries.

Acute and contained rupture of the descending thoracic aorta: treatment with endovascular stent grafts

PURPOSE

The purpose of this study was to evaluate feasibility and safety of endovascular stent grafting for the treatment of patients with rupture of the descending thoracic aorta.

METHODS

Thirteen patients with rupture of the descending thoracic aorta were treated with endovascular stent grafting. Six patients were treated on the day of diagnosis because their vital signs were unstable, and the other seven patients were treated electively. Five patients had infection or potential infection, and the other eight patients did not. Expanded polytetrafluoroethylene-covered or polyester-covered Z stents were used in all patients.

RESULTS

Stent grafts were successfully placed in all patients. No endoleaks were observed at the end of the procedure. However, rebleeding was observed within 2 weeks of the procedure in two patients with infection. Six patients (46%) died within 5 months of the procedure (mean survival period, 61 +/- 60 days). All five patients with infection (100%) died, and only one of eight patients without infection (13%) died (P <.01). The remaining seven patients are alive during the mean follow-up period of 21 months (overall survival rate, 54%), although additional surgical interventions, including surgical conversion in one case and upper extremity extraanatomic bypass in the other, were necessary in two of these patients.

CONCLUSION

Endovascular stent grafting may be a safe and feasible method for the treatment of rupture of the descending thoracic aorta in selected patients without infection. However, its usefulness in terms of long-term prognosis appears to be extremely limited, especially in patients with infection.

Endoluminal treatment of ruptured abdominal aortic aneurysm with small intestinal submucosa sandwich endografts: a pilot study in sheep

PURPOSE

To evaluate efficacy of small intestinal submucosa (SIS) Sandwich endografts for the treatment of acute rupture of abdominal aortic aneurysms (AAA) and to explore the short-term reaction of the aorta to this material.

METHODS

In eight adult sheep, an infrarenal AAA was created transluminally by dilation of a short Palmaz stent. In six sheep, the aneurysm was then ruptured by overdilation of the stent with a large angioplasty balloon. Two sheep with AAAs that were not ruptured served as controls. A SIS Sandwich endograft, consisting of a Z stent frame with 5 bodies and covered inside and out with SIS, was used to exclude the ruptured and non-ruptured AAAs. Follow-up aortography was done immediately after the procedure and before sacrifice at 4, 8, or 12 weeks. Autopsy and histologic studies followed.

RESULTS

Endograft placement was successful in all eight sheep. Both ruptured and non-ruptured AAAs were successfully excluded. Three animals with AAA rupture developed hind leg paralysis due to compromise of the arterial supply to the lower spinal cord and were sacrificed 1 day after the procedure. In five animals, three with rupture and two controls, follow-up aortograms revealed no aortic stenoses and no perigraft leaks. Gross and histologic studies revealed incorporation of the endografts into the aortic wall with replacement of SIS by dense neointima that was completely endothelialized in areas where the endograft was in direct contact with the aortic wall. In central portions of the endograft, in contact with the thrombosed aneurysm, endothelialization was incomplete even at 12 weeks.

CONCLUSION

The SIS Sandwich endografts effectively excluded simple AAAs and ruptured AAAs. They were rapidly incorporated into the aortic wall. A detailed long-term study is warranted.

Aortoesophageal fistula-relief of massive hematemesis with an endovascular stent-graft

A 59-year-old man with an esophageal carcinoma developed massive hematemesis due to aortoesophageal fistula after irradiation therapy reached 58 Gy. Emergent treatment with an endovascular stent-graft was successfully performed and the patient followed an uneventful course until he died of pneumonia 4.5 months later, which was caused by a tracheoesophageal fistula. Stent-graft repair is a safe and effective method to treat aortoesophageal fistula and may be an alternative to surgical resection.

1997 SCVIR Gary J. Becker Young Investigator Award paper. A transluminally created abdominal aortic aneurysm model

PURPOSE

To develop a stable, transluminally created abdominal aortic aneurysm (AAA) within a live animal model.

MATERIALS AND METHODS

Eight mongrel dogs were utilized to evaluate a new, catheter-based technique for the creation of an AAA. With use of a standard angioplasty balloon and a balloon-expandable intravascular metallic stent, the infrarenal abdominal aorta was overdilated to twice its measured diameter into a fusiform shape AAA in eight dogs. At 30 days, aortography was performed, the dogs were killed, and the aorta was resected and evaluated for histopathology.

RESULTS

Seven of the eight dogs that underwent transluminal AAA creation survived the initial procedure. A stable, fusiform AAA was successfully created in these seven dogs. At 30 days, repeat angiography and histologic examination confirmed that the seven AAAs were still twice the diameter of the normal aorta (a four-fold increase in luminal area), that the branch arteries remained patent, and that the lumen was endothelialized. One of the eight dogs was killed 9 hours after the procedure because of inability to awaken from anesthesia. Gross and histopathologic results in this one dog also demonstrated an intact aorta containing an AAA.

CONCLUSIONS

A stable, infrarenal AAA model can be successfully created in the canine species with use of standard catheter-based techniques and equipment. This model can be used to test emerging endovascular treatments of AAA.

Acute rupture of the descending thoracic aorta: repair with use of endovascular stent-grafts

PURPOSE

To describe the use of endovascular stent-grafts to treat acute ruptures of the descending thoracic aorta as an alternative to surgery in high-risk patients.

MATERIALS AND METHODS

From July 1992 to August 1996, 95 patients underwent stent-grafting of the descending thoracic aorta for a variety of lesions. Of these, 11 patients with acute (< or = 7 days) rupture from aneurysms (n = 8) or trauma (n = 3) underwent repair with use of endovascular stent-grafts. Rupture was confirmed with preoperative imaging studies and occurred in the mediastinum (n = 9), the pleural space (n = 1), or the lung (n = 1). All patients were considered high surgical risk due to generalized cardiopulmonary disease and/or previous thoracotomies. Stent-grafts were constructed from Z stents covered with polyester fabric and delivered through a catheter under fluoroscopic control from a remote access site.

RESULTS

Stent-graft deployment was successful in all patients. There were no complications of perigraft leak, stent migration, paraplegia, or intraoperative death. Two patients died in the follow-up period: one of ventricular perforation during unrelated thoracic surgery for tumor resection (day 1) and one of cardiac arrest (day 28). All others are alive (mean follow-up, 15.1 months).

CONCLUSION

For acute rupture of the thoracic aorta, endovascular stent-graft repair is technically feasible and may be a therapeutic alternative to a surgical interposition graft in patients considered high risk for conventional thoracotomy. Long-term studies are necessary to determine the role of stent-grafts in preventing future aortic rupture.

Mathematical formulation for computing the performance of self expanding helical stents

Stents are cylindrical devices implanted inside pathologic tubular passages within the body. The stents, which are made of metal or plastic, keep the passage open for flow (of blood, urine, air etc.) by applying radial pressure on the passage walls. In most cases the stents are selected empirically for each application. We introduce here a mathematical formula for computing the radial pressure induced by self expanding helical stents. The formula was verified experimentally for an urological stent using a special device. The results correlate well with the theoretical predictions (R = 0.997; y = 1.017 x -0.06 kg; SEE = 0.034, for forces and R = 0.9988; y = 1.04 x +8.7 mmHg; SEE = 25.3 for pressures). This formula can potentially serve as an analytical tool for selecting the most suitable stent for a given application.

Noncoronary vascular stenting

The aim of this report is to review the current state of the art with respect to noncoronary vascular stenting. A review of the literature was performed, examining the historical aspects of stent design and usage, as well as the currently available designs and their respective functions. When appropriate, we note our personal experience with stent placement in each anatomic site. Currently available stents take many forms: balloon-expandable, self-expanding, and shape-memory alloy. Varied design modifications have been made to maximize the open area, to limit the surface area of the prosthesis, to increase (or decrease) flexibility, and to increase (or decrease) stent plasticity and elasticity. Modifications to minimize thrombogenicity are also underway. The clinical uses of the currently available stents in multiple anatomic locations will be discussed. Intravascular stents are an addition to the arsenal available for prolonging blood vessel patency.