Treatment of aortic dissections with a percutaneous intravascular endoprosthesis: comparison of covered and bare stents

Custom-made Stent-Grafts for Aortic Aneurysm Repair Using Gianturco Z Stents and Woven Polyester: Healing in an Animal Model

The purpose of this study was to evaluate the healing at 6 months of aortic stent-grafts custom-made by using Z stents and woven polyester in an animal model. Stent-grafts were built by a published method using autoexpandable stainless steel stents continuously compiled with polyester sutures and covered with a woven polyester membrane. Fourteen stent-grafts of 3 different designs were deployed under fluoroscopic control into the thoracic and the abdominal aorta of 7 adult sheep. At 6 months, all the implants of the sheep that survived the implantation were angiographed and harvested for macroscopy and microscopy. All stentgrafts were implanted successfully and remained patent from then to the explantation procedure. All stent-grafts implanted among the 6 of 7 (86%) animals that survived after the implantation remained patent, stayed free from local complications, and did not migrate during more than 6 months. In all these cases during this period, the implant functioned as a satisfactory aortic substitute while the aortic segment containing the graft kept a normal structure. There was no adverse effects of the presence of the implant upon the aorta or the animal. Stent-grafts home-made according to the described methods gave results at 6 months in this animal model compatible with a safe clinical application among humans.

Malperfusion syndromes in aortic dissections

Aortic dissection remains a challenging clinical scenario, especially when complicated by peripheral malperfusion. Improvements in medical imaging have furthered understanding of the pathophysiology of malperfusion events in association with aortic dissection, including the elucidation of different mechanisms of branch vessel obstruction. Despite these advances, malperfusion syndrome remains a deadly entity with significant mortality. This review presents the latest knowledge regarding the pathogenesis of aortic dissection complicated by malperfusion syndrome, and discusses the diagnostic and therapeutic guidelines for management of this vicious entity.

Muslin-induced intracranial vasculopathic stenosis: a report of two cases

Muslin wrapping is a commonly utilized alternative technique in the treatment of aneurysms that are not amenable to direct clipping. In this case report, we describe two patients from different institutions who both required aneurysm wrapping with gauze/muslin for aneurysm reinforcement. Both patients developed an inflammatory foreign body response to muslin visible on MRI that resulted in a vasculitic stenosis. The onset of TIAs was at 6 months and 1 month postoperatively, respectively. The stenoses rapidly progressed to near occlusion despite antiplatelet therapy, and in one case, an aggressive corticosteroid regimen. One patient eventually developed leptomeningeal collateral flow that allowed tolerance of the stenosis, while the other patient required microsurgical bypass. These cases reports are the first to our knowledge that describe the adverse effects of muslin wrapping without adhesive reinforcement, as well as one of few reports to include follow-up angiographic imaging.

Type B aortic dissections: treating the many to benefit the few?

PURPOSE

It is now more than a decade since aortic stent-grafts were introduced clinically to provide a less invasive and potentially less harmful therapeutic option to treat type B aortic dissections. However, recent publications on best medical treatment and quality of life in patients with chronic type B dissection support conservative treatment due to the low incidence of aneurysm formation, rupture, and disease-related complications. Against this backdrop, we analyzed our experiences and now discuss whether the availability of endografts allowed us to change indications toward a more aggressive endovascular approach to acute and non-complex type B dissections, seeking to determine which patients we should treat and which ones we should observe.

METHODS

Between 1997 and 2008 in our institution in Heidelberg, we treated 172 patients with acute and chronic type B dissections, most (n = 118, 69%) conservatively. However, 54 patients (40 men; mean age 57 years, range 30-82) underwent endovascular repair; 43% (n = 23) were emergency cases. Patients were followed periodically with computed tomographic angiography.

RESULTS

Correct stent-graft deployment was achieved in 50 (93%) patients; the left subclavian artery was intentionally covered in 30 (55%) cases. Two carotid-subclavian bypass grafts were performed at the time of the endovascular repair due to partial coverage of the left common carotid artery. The perioperative complication rate was 19% (n = 10), but there were no neurological sequelae. The 30-day mortality rate was 11% (n = 6). Over a mean 32.1+/-25 months, 4 other patients died (18.5% overall mortality rate); survival estimates by Kaplan-Meier analysis were 80.4% and 66.1% after 1 and 5 years, respectively. Complete false lumen thrombosis was observed in 32 (60%) and a persisting completely patent false lumen in 3. The aortic expansion rate was 31% (17/54) overall. No difference was found between acute and chronic dissections in terms of survival (p = 0.247).

CONCLUSION

Despite a minimally invasive approach, complication and mortality rates for endovascular therapy of type B aortic dissections are considerable. Endografting is limited to symptomatic patients and those with chronic large aneurysmal expansion. At this stage in stent-graft development, asymptomatic patients benefit more from conservative treatment.

An experimental model of Stanford type B aortic dissection

PURPOSE

To create an experimental model of aortic dissection with a long-lasting patent false lumen as a proper animal model for development of less-invasive treatment for aortic dissection.

MATERIALS AND METHODS

Fifteen adult beagle dogs (weight, 10-12 kg) were used. The descending aorta was exposed by a left thoracotomy at the sixth intercostal space. The entry for the aortic dissection was created surgically just distal to the origin of the left innominate artery and the reentry was 5 cm distal to the entry point. Normal saline solution was injected into the aortic wall (ie, media) between these two points to create the dissection. The dogs were followed up at 1 day, 3 months, 1 year, and 2 years.

RESULTS

All 12 surviving dogs had completely patent true and false lumina without any thrombi. Microscopic examination showed that the dissection was created in the tunica media layer, making it identical to aortic dissection in humans. Color Doppler imaging confirmed the patency of the true and false lumina and the relatively narrowed true lumen.

CONCLUSION

In this canine model of aortic dissection, the false lumen has excellent long-term patency and the dissection plane is histologically similar to that in human aortic dissection. This model may contribute to the development of new treatments for Stanford type B aortic dissection.

Type A Dissection Following Endovascular Thoracic Aortic Stent-Graft Repair

PURPOSE

To describe our experience with endovascular stent-graft repairs in the thoracic aorta focusing on the secondary complication of type A dissection.

METHODS

Between January 1996 and April 2004, 73 patients were treated for traumatic thoracic aortic rupture (n=15), type B dissection (n=22), or atherosclerotic descending thoracic aortic aneurysms (TAA, n=36). A retrospective review of the records found 5 (6.8%) patients (3 men; median age 64 years, range 43-87) who experienced a type A dissection at a median 20 days (range 2-124) after thoracic stent-graft repair for 3 type B dissections, 1 TAA, and a late type I endoleak that appeared 28 months after initial stent-graft repair of a traumatic dissection.

RESULTS

In 3 patients (2 dissections, 1 endoleak), a tear in the aortic wall at the proximal stent-graft was responsible for a retrograde type A dissection. Underlying disease was the cause of the type A dissection in the 2 other patients (1 dissection, 1 TAA) and was unrelated to the stent-grafts. Three patients underwent open surgery at 3, 26, and 124 days after stent-graft placement; 2 procedures were successful, but the third patient died 3 months later due to multiorgan failure. Two type A dissections were untreated: one patient died from cardiac tamponade 14 days after successful stent-graft exclusion of the type I endoleak; the other patient refused further treatment and survived. The procedure-related mortality following acute retrograde type A dissection was 40%.

CONCLUSIONS

Endovascular stent-graft repair of the thoracic aorta is associated with lower morbidity and mortality rates than surgical repair, although potentially lethal complications, acute or delayed, may occur.

An endovascular stent relieves celiac and mesenteric ischemia in acute aortic dissection

We report the case of a 63-year-old patient with bowel ischemia related to an acute type B dissection. The patient was successfully treated with a covered stent graft inserted at the level of the descending thoracic aorta.

Contemporary management of acute aortic dissection

The development of endovascular techniques has introduced a new dimension to the management of acute aortic dissection. Conventional therapy has traditionally been relegated to patients who experience severe clinical sequelae; unfortunately, clinicians have not been able to accurately predict the clinical consequences of a dissection. However, recent attention to true and false lumen characteristics, the distal extent of the dissection, and branch vessel involvement has demonstrated that these independent predictors of outcome can serve as surrogate indications for endovascular or surgical treatment. We review the pathophysiological mechanisms associated with the sequelae of aortic dissection and summarize the treatment paradigms we have developed.

Conventional repair and operative stent-grafting for acute and chronic aortic dissection

Conventional graft replacement of the ascending aorta and surgically endovascular stent-grafting of the proximal descending aorta were performed concomitantly in a 82-year-old woman with an acute DeBakey type II aortic dissection and a chronic DeBakey type IIIb aortic dissection. Postoperative computed tomography and angiography showed the adequately replaced ascending-aortic prosthesis, the well-expanded stent-graft, and the thrombosed false lumen in the descending aorta.

Treatment of chronic aortic dissection by transluminal endovascular stent-graft placement: preliminary results

PURPOSE

To investigate efficacy of stent-graft repair for the treatment of patients with chronic aortic dissection.

MATERIALS AND METHODS

Fifteen patients with chronic aortic dissection were treated with endovascular stent-grafts. Entry tears were located in the descending thoracic aorta in all patients. The mean maximum diameter of the descending thoracic aorta was 47 mm +/- 8. The mean diameter of the true lumen at the same level was 20 mm +/- 5. The mean interval between diagnosis and stent-graft procedure was 32 months +/- 91. Stent-grafts were fabricated from expanded polytetrafluoroethylene and Z-stents.

RESULTS

Stent-grafts were placed successfully in all patients. Two stent-grafts were required in one patient. Entry closure and thrombosis of the false lumen of the descending thoracic aorta were also achieved in all patients. No procedure-related complications were observed except for postimplantation syndrome, including fever and leukocytosis. The diameter of the true lumen was significantly increased (mean, 31 mm +/- 6) at the level of the descending thoracic aorta (P <.01) and the diameter of the aorta was significantly decreased (mean, 44 mm +/- 8) at the same level (P <.01). There were no deaths and no instances of aortic rupture during the subsequent average follow-up period of 24 months. Secondary stent-graft procedures were required to treat the abdominal component of dissection during follow-up in one patient.

CONCLUSIONS

Stent-graft repair of chronic aortic dissection is a safe and effective method and may be an alternative to surgical graft replacement in selected patients. However, further evaluation is mandatory before this method is widely employed.

Elective endovascular treatment of descending thoracic aortic aneurysms and chronic dissections with stent-grafts

PURPOSE

To report our experience of endovascular stent-graft placement in patients with descending thoracic aortic dissections and aneurysms and to evaluate the feasibility, safety, and clinical outcomes of the treatment.

MATERIALS AND METHODS

Stent-grafts were placed in the descending thoracic aortas of 23 patients with saccular aneurysms (n = 11) and Stanford type B chronic aortic dissections of the descending thoracic and abdominal aorta (n = 12). All stent-grafts were individually constructed of self-expandable stainless steel stents covered with polytetrafluoroethylene. Vascular access was achieved through the femoral artery in all patients. Clinical status of each patient was monitored and postoperative CT was performed within 1 month of the procedure and at 3-12-month intervals after the procedures.

RESULTS

Successful exclusion of the primary entry tears of dissections and the inlets of saccular aneurysms was achieved in all but two patients with aortic dissection. The overall technical success rate was 91.3% (dissection: 10 of 12 = 83%; aneurysm: 11 of 11 = 100%). All patients in whom technical success was achieved showed complete thrombosis and significant decrease in diameter of the thoracic false lumen (preoperative: 5.3 cm +/- 0.9; postoperative: 4.3 cm +/- 0.9; P = .004) or aneurysm sac (preoperative: 5.3 cm +/- 1.7; postoperative: 2.8 cm +/- 2.5; P = .001). In addition, five patients demonstrated complete resolution of the dissected thoracic false lumen (n = 2) and aneurysm sac (n = 3). However, in all patients with aortic dissection, the abdominal aorta was not significantly changed in size (P = .302) and shape and their false lumen flows remained persistent. Immediate postoperative complications were detected in 12 patients (52%); 10 had fever, leukocytosis, and elevation of C-reactive protein, another had wound infection, and another had transient abdominal pain. Three patients died 2, 3, and 12 months after the procedure: one from septic shock, another from underlying mediastinitis, and the other from an unexplained cause. The remaining 20 patients were well after the procedure (1-9 days; mean, 3 days), without any stent-graft-related complications or discomfort (follow up period: 10-65 mo; mean: 25.1 mo +/- 15.6). The cumulative survival rate after the stent graft was 100% at 30 days and 91% at 12 months.

CONCLUSIONS

For treatment of aortic dissection and saccular aneurysm of the descending thoracic aorta, endovascular stent-graft repair may be a technically feasible and effective treatment modality.

Less invasive therapy using endovascular stent graft repair and video-assisted thoracoscopic surgery for ruptured acute aortic dissection

We report a 75-year-old man with a ruptured acute thoracic aortic dissecting hematoma treated using endovascular stent grafting and video-assisted thoracoscopic surgery. This less invasive therapy is a good therapeutic option even in ruptured acute aortic dissections, particularly given the difficulty of surgery.

Treatment of chronic type B aortic dissection with endovascular stent-graft placement

A 74-year-old man with chronic aortic dissection was treated with an endovascular stent graft, fabricated from expanded polytetrafluoroethylene and a Z-stent. It was placed in the true lumen to close an entry tear. Closure was obtained immediately and thrombosis of the false lumen at the descending thoracic aorta was observed on computed tomography (CT) obtained 1 week later. No procedure-related complications developed. The patient is doing well with no adverse events including aortic rupture or aortic branch ischemia.

Aortic stent grafting and side-branch embolization in an expanding chronic type B dissection

OBJECTIVE

This is a report of endovascular treatment of a case of type B thoracoabdominal aortic dissection in a patient with progressive dyspnea, dorsolumbar pain, and expanding aortic diameter over a 1-year period.

METHODS

Pretreatment imaging evaluation showed that the false lumen supplied only the celiac trunk. Endovascular treatment combined (1) embolization of the first segment of the celiac trunk to avoid distal back-flow into the false lumen and (2) stent grafting to occlude the initial entry tear.

RESULTS

The treatment resulted in technical and clinical success. The patient remains asymptomatic 12 months after treatment.

CONCLUSION

Stent grafting offers an interesting therapeutic alternative to exclude the initial entry tear in aortic dissection and may be combined with other endovascular procedures.

Endovascular stent-graft placement for the treatment of acute aortic dissection

BACKGROUND

The standard treatment for acute aortic dissection is either surgical or medical therapy, depending on the morphologic features of the lesion and any associated complications. Irrespective of the form of treatment, the associated mortality and morbidity are considerable.

METHODS

We studied the placement of endovascular stent-grafts across the primary entry tear for the management of acute aortic dissection originating in the descending thoracic aorta. We evaluated the feasibility, safety, and effectiveness of transluminal stent-graft placement over the entry tear in 4 patients with acute type A aortic dissections (which involve the ascending aorta) and 15 patients with acute type B aortic dissections (which are confined to the descending aorta). Dissections involved aortic branches in 14 of the 19 patients (74 percent), and symptomatic compromise of multiple branch vessels was observed in 7 patients (37 percent). The stent-grafts were made of self-expanding stainless-steel covered with woven polyester or polytetrafluoroethylene material.

RESULTS

Placement of endovascular stent-grafts across the primary entry tears was technically successful in all 19 patients. Complete thrombosis of the thoracic aortic false lumen was achieved in 15 patients (79 percent), and partial thrombosis was achieved in 4 (21 percent). Revascularization of ischemic branch vessels, with subsequent relief of corresponding symptoms, occurred in 76 percent of the obstructed branches. Three of the 19 patients died within 30 days, for an early mortality rate of 16 percent (95 percent confidence interval, 0 to 32 percent). There were no deaths and no instances of aneurysm or aortic rupture during the subsequent average follow-up period of 13 months.

CONCLUSIONS

These initial results suggest that stent-graft coverage of the primary entry tear may be a promising new treatment for selected patients with acute aortic dissection. This technique requires further evaluation, however, to assess its therapeutic potential fully.

Autologous vein-covered stent repair of a cervical internal carotid artery pseudoaneurysm: technical case report

OBJECTIVE AND IMPORTANCE

Stenting of a cervical internal carotid pseudoaneurysm is presented using a stent covered with saphenous vein. This procedure resulted in immediate exclusion of the aneurysm and maintained patency of the carotid artery.

CLINICAL PRESENTATION

A gunshot to the neck resulted in airway obstruction and respiratory arrest with neurological injury in a male patient. Angiographic investigation revealed an enlarging cervical internal carotid pseudoaneurysm, possibly the source of a cerebral embolism. Anticoagulation had to be stopped because of bleeding complications. A decision was made to conduct definitive percutaneous treatment of the pseudoaneurysm.

TECHNIQUE

A Palmaz stent (JJIS, Warren, NJ) was covered with saphenous vein harvested from the patient's leg. Using standard technique and a simple innovation for stent construct introduction into the sheath, the vein-covered stent was placed across the opening of the aneurysm and dilated into position with a balloon.

CONCLUSION

Immediate exclusion of a cervical internal carotid pseudoaneurysm was performed using an autologous vein-covered stent. One-month follow-up confirmed continued exclusion of the pseudoaneurysm and carotid patency without stenosis.

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.

Aortic dissection: percutaneous management of ischemic complications with endovascular stents and balloon fenestration

PURPOSE

The purpose of this study was to evaluate endovascular stenting (EVS) and balloon fenestration (BF) of intimal flaps for the management of lower extremity, renal, and visceral ischemia in acute or chronic aortic dissection.

METHODS

Twenty-two patients (16 male, 6 female) with a median age of 53 years (range 35 to 77 years) underwent percutaneous treatment for peripheral ischemic complications of 12 type A (five acute, seven chronic) and 10 type B (nine acute, one chronic) aortic dissections.

RESULTS

Ten patients had leg ischemia, 13 had renal ischemia, and 6 had visceral ischemia. Sixteen patients were treated with EVS including 11 with renal, 6 with lower extremity, 2 with superior mesenteric artery, and 2 with aortic stents. Three patients had BF of the intimal flap, and three had BF in combination with EVS. Revascularization with clinical success was achieved in all 22 patients. Two patients died 3 days and 13.4 months after the procedure was performed, respectively. Of the remaining 20 patients, 1 is lost to follow-up, and 19 have persistent relief of clinical symptoms. Mean follow-up time is 13.7 months (range 1.1 to 46.5 months). One case was complicated by guidewire-induced perinephric hematoma.

CONCLUSION

EVS and BF provide a safe and effective percutaneous method for managing peripheral ischemic complications of aortic dissection.