Preliminary report on prediction of spinal cord ischemia in endovascular stent graft repair of thoracic aortic aneurysm by retrievable stent graft

New Preoperative Spinal Cord Ischemia Risk Stratification Model for Patients Undergoing Thoracic Endovascular Aortic Repair

PURPOSE

Our objective was to determine significant predictors of spinal cord ischemia (SCI) following Thoracic Endovascular Aortic Repair (TEVAR) and to further develop a simple and clinically orientated risk score model.

METHODS

A retrospective review of data from the Society of Vascular Surgery/Vascular Quality Initiative national data set was performed for all patients undergoing TEVAR from January, 2014 to June 2018. Preoperative demographics, procedure-related variables, and clinical details related to SCI were examined. A SCI risk score was developed utilizing a multivariable logistic regression model.

RESULTS

For the 7889 patients in the final analysis who underwent TEVAR during the study period, the mean age was 67.6 ± 13.9, range 18 to 90 years, and the majority was male (65%). Postoperative outcomes included stroke (3.0%), myocardial infarction (2.9%), inhospital mortality (5.4%), transient SCI (1.5%), and permanent SCI (2.1%). Nearly half of the overall cases were performed in high volume centers. Predictors of increased risk for SCI included age by decade (odds ratio [OR]: 1.2), celiac coverage (OR: 1.5), current smoker (OR: 1.6), dialysis (OR: 1.9), 3 or more aortic implanted devices (OR: 1.7), emergent or urgent surgery (OR: 1.5), adjunct aorta-related procedure (OR: 2.5), adjunct not related (OR: 2.6), total estimated length of aortic device (19-31 cm, OR: 1.9 and ≥32 cm, OR: 3.0), ASA class 4 or 5 (OR: 1.6), and procedure time ≥154 minutes (OR: 1.8). Two predictors decreased the risk of SCI, cases from high-volume centers (OR: 0.6) and eGFR ≥ 60 (OR: 0.6). To evaluate the risk score model, probabilities of SCI from the original regression, raw score, and raw score categories resulted in area under the curve statistics of 0.792, 0.786, and 0.738, respectively.

CONCLUSIONS

Spinal cord ischemia remains one of the most feared complications of TEVAR. Incidence of SCI in this large series of patients with TEVAR was 3.6% with nearly 60% being permanent. The proposed model provides an assessment tool to guide clinical decisions, patient consent process, risk-assessment, and procedural strategy.

Artery of Adamkiewicz: a meta-analysis of anatomical characteristics

PURPOSE

The artery of Adamkiewicz (AKA) provides the major blood supply to the anterior thoracolumbar spinal cord and iatrogenic injury or inadequate reconstruction of this vessel during vascular and endovascular surgery can result in postoperative neurological deficit due to spinal cord ischemia. The aim of this study was to provide comprehensive data on the prevalence and anatomical characteristics of the AKA.

METHODS

An extensive search was conducted through the major electronic databases to identify eligible articles. Data extracted included study type, prevalence of the AKA, gender, number of AKA per patient, laterality, origin based on vertebral level, side of origin, morphometric data, and ethnicity subgroups.

RESULTS

A total of 60 studies (n = 5437 subjects) were included in the meta-analysis. Our main findings revealed that the AKA was present in 84.6% of the population, and patients most frequently had a single AKA (87.4%) on the left side (76.6%) originating between T8 and L1 (89%).

CONCLUSION

As an AKA is present in the majority of the population, caution should be taken during vascular and endovascular surgical procedures to avoid injury or ensure proper reconstruction. All surgeons operating in the thoracolumbar spinal cord should have a thorough understanding of the anatomical characteristics and surgical implications of an AKA.

Anaesthetic Management of Planned or Emergency Endovascular Stent Graft Surgery for Thoracic Aneurysms and Dissections

We reviewed the intraoperative anaesthetic management and outcome of seven consecutive cases of endovascular stent graft surgery for thoracic aortic aneurysms or dissections over a period of 20 months in our institution. Seven males (median age 63) underwent endovascular stent graft surgery of the thoracic aorta under general anaesthesia. Four were emergency procedures for acute dissection or leaks of thoracic aneurysms. The duration of the procedures ranged from 120 to 300 minutes. Intraoperative stent migration occurred in one patient. Induced hypotension and immobilization were critical during stent deployment. Six out of the seven patients were discharged home between three to 20 days postoperatively. There was no 30-day mortality. One patient died sixty days postoperatively. Anaemia and respiratory complications were the most common postoperative problems encountered. None of the patients sustained spinal cord ischaemia, acute myocardial infarction or renal impairment. Endovascular stent graft surgery of the thoracic aorta is a relatively new alternative to conventional open surgery. Our experience suggests satisfactory short-term outcome even for patients with acute dissection. However, long-term survival and results require further evaluation.

Endografting of the Aortic Arch

In recent years, endovascular repair with stent-grafts has made great advances as a minimally invasive alternative to conventional open surgery in the treatment of aortic aneurysm and dissection. Although many commercial endograft systems are now used worldwide for the treatment of these pathologies in the abdominal aorta, only a few dedicated stent-grafts have been developed for use in the thoracic aorta. However, these second-generation commercial endografts have almost identical specifications and performance profiles in terms of structure, function, and delivery mechanism as stent-graft systems employed in the abdominal aorta. Thus, endografts have been used in the thoracic aorta with little consideration to the morphological and hemodynamic characteristics specific to the aortic arch and the deployment techniques needed to navigate this curved region of the thoracic aorta. This review will survey the literature on aortic arch stent-graft repair and identify key elements critical to the successful design of an endograft to treat lesions in the aortic arch.

Stent Grafts for Thoracic Aortic Pathology: Single-Center Experience in Western Australia

The purpose of this article is to report a single-center experience in treating thoracic aortic pathology with stent grafts. This is a retrospective review of cases done within a period of 30 months.

Between January 2002 and May 2004, 12 patients were treated in our institution with thoracic stent grafts ( n = 12) for various clinical conditions. There were seven men and five women. Three patients required emergency treatment ( n = 3), two for aortic transection and one for iatrogenic injury during lung biopsy. Others were treated electively ( n = 9).

All patients were high risk for open surgery. There was one perioperative death, with a patient with multiple trauma succumbing to head injury 4 weeks after stent graft insertion. There was no incidence of paraplegia. Three patients underwent bypass surgery in the neck to achieve an adequate proximal seal zone prior to stent grafting. One patient with an aneurysm of the descending thoracic aorta required an extension limb below the original graft for an increase in sac size, possibly owing to endotension. Renal failure occurred in one patient and resolved without dialysis. One patient died 18 months after her procedure, possibly owing to aneurysm expansion.

Stent grafts are a viable alternative to open surgery for thoracic aortic pathology in high-risk individuals. Visceral and spinal cord ischemia is less prevalent with stent grafts compared with open surgery. The short-term results are promising. Long-term follow-up is awaited. Stent grafts might have greater impact in the thoracic aorta than the abdominal aorta for which they were initially developed.

Evaluation of spinal cord ischemia with a retrievable stent graft is useful for determining the type of repair for a case of patch aneurysm

Patch aneurysms after thoracoabdominal aortic aneurysm repair are a serious late complication. We treated a patient with patch aneurysm (originating at the artery of Adamkiewicz) involving a portion of an implanted graft from a previous operation. First, thoracic endovascular aneurysm repair was planned. A retrievable stent graft was inserted, and motor-evoked potentials were monitored to evaluate spinal cord ischemia. Significant changes in the motor-evoked potentials were observed, and permanent stent graft placement was abandoned. Later, open surgery was performed. The patient showed no postoperative paraplegia and was discharged in good condition.

Endovascular stent graft repair for thoracic aortic aneurysms: the history and the present in Japan

Stent-grafts for endovascular repair of thoracic aortic aneurysms have been commercially available for more than ten years in the West, whereas, in Japan, a manufactured stent-graft was not approved for the use until March 2008. Nevertheless, endovascular thoracic intervention began to be performed in Japan in the early 1990s, with homemade devices used in most cases. Many researchers have continued to develop their homemade devices. We have participated in joint design and assessment efforts with a stent-graft manufacturer, focusing primarily on fenestrated stent-grafts used in repairs at the distal arch, a site especially prone to aneurysm. In March 2008, TAG (W.L. Gore & Associates, Inc., Flagstaff, Arizona, USA) was approved as a stent graft for the thoracic area first in Japan, which was major turning point in treatment for thoracic aortic aneurysms. Subsequently, TALENT (Medtronic, Inc., Minneapolis, Minnesota, USA) was approved in May 2009, and TX2 (COOK MEDICAL Inc., Bloomington, Indiana, USA) in March 2011. Valiant as an improved version of TALENT was approved in November 2011, and TX2 Proform as an improved version of TX2 began to be supplied in October 2012. These stent grafts are excellent devices that showed good results in Western countries, and marked effectiveness can be expected by making the most of the characteristics of each device. A clinical trial in Japan on Najuta (tentative name) (Kawasumi Labo., Inc., Tokyo, Japan) as a line-up of fenestrated stent grafts that can be applied to distal arch aneurysms showing a high incidence, and allow maintenance of blood flow to the arch vessel was initiated. This trial was completed, and Najuta has just been approved in January of 2013 in Japan, and further development is expected. In the U.S., great efforts have recently been made to develop and manufacture excellent stent grafts for thoracic aneurysms, and rapid progress has been achieved. In particular, in the area of the aortic arch, in which we often experience aneurysmal change, but there are no commercially available devices which are urgently needed. Companies are competing keenly to develop devices. To our knowledge, more than 4 manufacturers are involved in the development of functionally new stent grafts in this area. The introduction of branched stent grafts may not be faraway.

A systematic review of spinal cord injury and cerebrospinal fluid drainage after thoracic aortic endografting

BACKGROUND

The use of thoracic endovascular aneurysm repair (TEVAR) is increasing. Similar to open repair, TEVAR carries a risk of spinal cord ischemia (SCI). We undertook a systematic review to determine whether preoperative cerebrospinal fluid (CSF) drainage reduces SCI.

METHODS

PubMed, the Cochrane Library, and conference abstracts were searched using the keywords thoracic endovascular aortic repair, cerebrospinal fluid, spinal cord ischaemia, TEVAR, and aneurysm. Studies reporting SCI rates and CSF drain rates for TEVAR patients were eligible for inclusion. SCI rates across studies were pooled using random-effects modeling. Study quality was evaluated using the Downs and Black score.

RESULTS

Study quality was generally poor to moderate (median Downs and Black score, 9). The systematic review identified 46 eligible studies comprising 4936 patients; overall, SCI affected 3.89% (95% confidence interval, 2.95.05%-4.95%). Series reporting routine prophylactic drain placement or no prophylactic drain placement reported pooled SCI rates of 3.2% and 3.47%, respectively. The pooled SCI rate from 24 series stating that prophylactic drainage was used selectively was 5.6%.

CONCLUSIONS

Spinal chord injury is uncommon after TEVAR. The role of prophylactic CSF drainage is difficult to establish from the available literature. High-quality studies are required to determine the role of prophylactic CSF drainage in TEVAR.

Thromboendarterectomy and circulatory arrest

Thromboendarterectomy remains a high-risk procedure. The use of circulatory arrest as a technique to allow pulmonary artery visualization is associated with cerebral and organ damage secondary to the ischaemic insult. Application of techniques learned from thoracic aortic stenting and minimal invasive valvular surgery may mean that circulatory arrest becomes an uncommon accompaniment to thromboendarterectomy.

Transapical wire-assisted endovascular repair of thoracic aortic dissection

PURPOSE

To describe a technique for transapical wire-assisted endograft deployment under rapid ventricular pacing for a type B dissection involving the proximal left subclavian artery and extending to the aortic bifurcation.

CASE REPORT

A 58-year-old man presented with a symptomatic thoracic aneurysm as a complication of a chronic type B dissection, with a short proximal neck in zone 1. After arch vessel debranching, the patient underwent endoluminal repair with deployment of a closed web, tapered Valiant thoracic endograft over a through-and-through wire from the left groin to the apex of the left ventricle, using rapid ventricular pacing to reduce cardiac output. The remaining dissected aorta was covered with a second Valiant endograft down to the distal third of the descending thoracic aorta and bare Z stents down to the aortic bifurcation to re-expand the true lumen. A freeflow Valiant endograft was deployed as a proximal extension to treat a proximal type I endoleak. The recovery was complicated by retrograde type A aortic dissection, considered secondary to the bare stent. The complication was repaired surgically; postoperative computed tomography after recovery was unremarkable.

CONCLUSION

Transapical wire-assisted deployment with rapid ventricular pacing is feasible and may provide improved stability for stenting within the aortic arch. The use of a stent-graft with a proximal bare stent is associated with a higher risk of retrograde extension of the dissection and warrants lifelong imaging follow-up.

Thoracic endovascular aortic repair with homemade stent grafts: early and mid-term outcomes

PURPOSE

We reviewed our experience with homemade stent grafts in the repair of a variety of thoracic aortic lesions. The objective of this study was to assess the early and mid-term outcomes of this therapy.

METHODS

From 1999 to 2007, homemade stent grafts were inserted in 88 patients with an atherosclerotic aneurysm, dissection, pseudoaneurysm, trauma, or rupture in the thoracic aorta. The endoprostheses were stainless steel Z-stents covered by a polyester graft, and were custom-designed for each patient.

RESULTS

Placement of stent grafts was technically successful in 81 of the 88 patients (92%). Within 30 days after treatment, 3 patients died, 3 had a cerebral infarction, and 3 had onset of paraplegia or paraparesis. Primary endoleaks were observed in 8 patients (9%). During the mean follow-up period of 32 ± 26 months, 7 patients had persistent endoleaks and 7 had stent-graft migration. The aneurysm-related mortality rate was 7%. The rate of freedom from open-surgery conversion at 32 months was 89.0%.

CONCLUSIONS

Our early experience with elective and emergency thoracic endovascular aortic repair using homemade stent grafts provided therapeutic benefits to high-risk patients. Endoleaks and stent-graft migrations were the factors most commonly responsible for secondary intervention in the mid-term period. Careful follow-up of patients treated with this approach is needed to avoid major complications in the long term.

Staged hybrid repair using telescoped stent graft fixation for aortic arch and descending aortic aneurysms

Staged repair of extensive thoracic aortic aneurysms is complicated, with a high incidence of interval rupture between stages. We describe the systematic staged hybrid procedure of a previous endovascular repair of a descending aortic aneurysm and open surgical repair of an aortic arch aneurysm. In the second-stage arch repair, the stent graft was easily retracted and fixed, without dissection, around the aortic arch aneurysm distal side. Extensive thoracic aortic aneurysms were managed without interim rupture or neurologic deficits. This approach avoided the potential for interim rupture because recovery from the first-stage endovascular repair was shorter than that from open repair.

[Traumatic thoracic aorta rupture: preclinical assessment, diagnosis and treatment options]

Traumatic aortic rupture is a life-threatening injury which is frequently associated with blunt thoracic trauma or found coincidentally in heavily traumatized patients. Depending on the degree of disruption of the damaged aortic wall, vascular injury is associated with a high primary mortality rate and a significant risk of secondary aortic rupture. Early clinical signs which may indicate a ruptured thoracic aorta are left sided thoracic pain, reduced ventilation, tachycardia and dyspnoe as well as hypotension in the lower extremities. The primary aim for emergency treatment is to maintain vital organ function and to hemodynamically stabilize the patient. Surgical treatment was previously performed by either direct aortic suture or segmental alloplastic graft interposition using the clamp and sew technique with or without extra-anatomic shunts or extracorporeal circulation. However, endovascular stent graft implantation has now become another treatment option for traumatic aortic rupture. According to the reported data and our own experience there is increasing evidence that endovascular aortic repair might become the treatment of choice for patients with traumatic aortic rupture, with the option of an early, less invasive intervention thus avoiding thoracotomy. Regular follow-up is necessary to detect possible stent graft migration or leakage which could require additional endovascular or open surgical re-interventions.

Spinal cord ischemia after endovascular repair of the descending thoracic aorta in a sheep model

OBJECTIVES

Spinal cord ischemia remains a devastating complication after thoracic aortic surgery. The aim of this study was to investigate the pathophysiology of spinal cord ischemia after thoracic aortic endografting and the role of intercostal artery blood supply for the spinal cord in a standardized animal model.

METHODS

Female merino sheep were randomized to either I, open thoracotomy with cross-clamping of the descending aorta for 50 min (n=7), II, endograft implantation (TAG, WL Gore & Ass.), (n=6) or III open thoracotomy with clipping of all intercostal arteries (n=5) . CT-angiography was used to assess completion of surgical protocol and assess the fate of intercostal arteries. Tarloy score was used for daily neurological examination for up to 7 days post-operatively. Histological cross sections of the lumbar, thoracic and cervical spinal cords were scored for ischemic damage after stained with Hematoxylin-Eosin, Klüver-Barrrera and antibodies. Exact Kruskall-Wallis-Test was used for statistical assessment (p<0.05).

RESULTS

Incidence of paraplegia was 100% in group I and 0% in group II (p=0.0004). When compared to the endovascular group, there was a higher rate of histological changes associated with spinal cord ischemia in the animals of the control group (p=0.0096). Group III animals showed no permanent neurological deficit and only 20% infarction rate (p=0.0318 compared to group I).

CONCLUSIONS

In sheep, incidence of histological and clinical ischemic injury of the spinal cord following endografting was very low. Complete thoracic aortic stent-grafting was feasible without permanent neurologic deficit. Following endovascular coverage or clipping of their origins, there is retrograde filling of the intercostal arteries which remain patent.

Neurological Complications Following Endoluminal Repair of Thoracic Aortic Disease

Open surgery for thoracic aortic disease is associated with significant morbidity and the reported rates for paraplegia and stroke are 3%-19% and 6%-11%, respectively. Spinal cord ischemia and stroke have also been reported following endoluminal repair. This study reviews the incidence of paraplegia and stroke in a series of 186 patients treated with thoracic stent grafts. From July 1997 to September 2006, 186 patients (125 men) underwent endoluminal repair of thoracic aortic pathology. Mean age was 71 years (range, 17-90 years). One hundred twenty-eight patients were treated electively and 58 patients had urgent procedures. Anesthesia was epidural in 131, general in 50, and local in 5 patients. Seven patients developed paraplegia (3.8%; two urgent and five elective). All occurred in-hospital apart from one associated with severe hypotension after a myocardial infarction at 3 weeks. Four of these recovered with cerebrospinal fluid (CSF) drainage. One patient with paraplegia died and two had permanent neurological deficit. The rate of permanent paraplegia and death was 1.6%. There were seven strokes (3.8%; four urgent and three elective). Three patients made a complete recovery, one had permanent expressive dysphasia, and three died. The rate of permanent stroke and death was 2.1%. Endoluminal treatment of thoracic aortic disease is an attractive alternative to open surgery; however, there is still a risk of paraplegia and stroke. Permanent neurological deficits and death occurred in 3.7% of the patients in this series. We conclude that prompt recognition of paraplegia and immediate insertion of a CSF drain can be an effective way of recovering spinal cord function and improving the prognosis.

Assessment of Spinal Cord Circulation and Function in Endovascular Treatment of Thoracic Aortic Aneurysms

BACKGROUND

In thoracic stent graft repair, the importance of segmental artery (SA) occlusion and the role of blood pressure management during the intraoperative and directly postoperative period are not clear. To study these aspects in relation to spinal cord ischemia, our protocol in the endovascular treatment of descending thoracic aneurysms covering segmental arteries T8 and lower includes preoperative assessment of the spinal cord circulation using magnetic resonance angiography, intraoperative cerebrospinal fluid drainage, and spinal cord function monitoring using motor evoked potentials (MEPs).

METHODS

Thirteen patients with thoracic aortic aneurysms and dissections needing stent graft coverage of T8 and lower were included. In 9 patients, spinal cord circulation was evaluated preoperatively by magnetic resonance angiography. In 12 patients, MEPs were recorded during the endovascular procedure. A combination of both techniques was used in 8 patients.

RESULTS

The distal stent graft landing zone covered the intercostal arteries up to T10 in 4 patients, up to T11 in 7 patients, up to T12 in 1 patient, and all SAs to the aortic bifurcation in 1 patient. In 6 patients, the SA feeding the Adamkiewicz artery was covered by the stent graft. In three patients, intersegmental collaterals were present to the SA feeding the Adamkiewicz artery. The MEPs decreased to 50% and 30% in 2 patients, recovering to levels above 50% by elevation of the mean arterial pressure. Postoperatively, no signs of paraplegia were present.

CONCLUSIONS

We believe that the presence of intersegmental collaterals decreases the risk of spinal cord ischemia during endovascular thoracic aortic aneurysm repair. Monitoring of MEPs during endovascular thoracic procedures shows no decrease in most cases. However, if a decrease of MEPs occurs, this can be reversed by elevation of the mean arterial pressure.

Thoracic stent-graft

The stent-graft is a device constructed from a stent and vascular graft and is inserted by means of an interventional procedure under imaging guidance. In 1986, Balko et al. reported the first stent-graft experiment, in which a Z stent covered with polyurethane was inserted into an animal aorta. In the early 1990s, Parodi et al. reported clinical introduction of the stent-graft for abdominal aortic aneurysm. In comparison to the abdominal aortic stent-graft, the thoracic stent-graft has several disadvantages, including difficulties associated with the aortic arch curvature and the relatively large caliber of the stent-graft, and the risk of central nervous system or spinal complication. However, the thoracic stent-graft is advantageous because of minimal procedural invasiveness in comparison to surgical graft replacement. In 1994, Dake et al. reported transluminal placement of an endovascular stent-graft for thoracic aortic aneurysm, and Kato et al. reported use of a stent-graft for aortic dissection and suggested that the stent-graft could be considered an alternative to surgical treatment.

Evaluation of thrombogenicity by indium-111 platelet scintigraphy in endografting for abdominal aortic aneurysms

Obstruction of the endograft limb by thrombosis has often been reported and may cause fatal complications such as leg necrosis or myonephropathic metabolic syndrome. The purpose of this study was to evaluate endograft antithrombogenicity by indium-111 platelet scintigraphy. Seventeen patients with abdominal aortic aneurysms were treated by endografting. Thirteen patients were treated with conventional open surgery using an artificial graft. The endograft was constructed from a self-expanding Z-shaped stent and woven polyester fabric. Autologous platelets labeled with indium-111 were injected at 2 weeks postoperatively. At 24 hours and 72 hours postinjection, the ratio of scintillation count of the endograft or graft to that of the native artery was calculated to assess platelet deposition. The normalization ratio was calculated as follows: (scintillation count per pixel of endograft or graft/circumference)/(scintillation count per pixel of the native femoral artery). Platelet factor 4 and beta-thromboglobulin were measured to evaluate the systemic platelets activity at 2 weeks postoperatively. There was no significant difference in platelet counts or labeling efficiency between the groups. The ratio was significantly higher in the endografting group than in the open surgery group at 72 hours postinjection (2.5-0.7 vs 3.9-1.1, P<.001). There was no significant difference in platelet factor 4 and beta-thromboglobulin between the groups. Although there was no difference in systemic platelet activity, endografting was associated with lower antithrombogenicity. It remains unclear whether lower antithrombogenicity causes thromboembolism as a complication of the procedure. The authors recommend the administration of antiplatelet drugs to prevent endograft obstruction in patients with very narrow iliac arteries.

Initial and Midterm Results for Repair of Aortic Diseases With Handmade Stent Grafts

BACKGROUND

The purpose of this study was to determine the initial and midterm results for repair of thoracic and abdominal aortic diseases using handmade stent-grafts (SGs).

METHODS AND RESULTS

Between 1999 and 2004, 41 consecutive patients (31 patients with thoracic and 10 patients with abdominal aortic disease) underwent endovascular stent-graft repair using handmade SGs. The follow-up averaged 24.8+/-17.6 months. The technical and initial clinical success rates were 82.9% (34/41) and 80.5% (33/41), respectively. Primary type I or III endoleaks occurred in 12.2% (5/41) of the patients. The hospital mortality rate was 4.9% (2/41). Persistent type I or III endoleaks occurred in 9.8% (4/41) and SG migrations occurred in 4.9% (2/41) of the patients. Open surgical conversion was undertaken in 12.2% (5/41) of the patients because of an endoleak and/or migration. The mean change observed in the aneurysm diameter was -6.2+/-10.5 mm, and shrinkage in the diameter occurred in 51.4% (18/35) of the cases. There was 1 patient death because of aneurysm rupture. Neither stent fracture nor graft hole was observed. The overall clinical success rate during follow-up was 78.0% (32/41).

CONCLUSION

The initial and midterm results obtained after repair of the aortic diseases using handmade SGs were considered to be satisfactory. More surgical experience and long-term patient follow-up are both required to further reassess the effect of this treatment.

Onlay Patch for Complete Intercostal Artery Preservation During Thoracic and Thoracoabdominal Aortic Aneurysm Repair

BACKGROUND

Replacement of the thoracic aorta is associated with a potential for interruption of the blood supply to the spinal cord leading to paralysis. Techniques have been proposed to ameliorate this risk, including reimplantation of the intercostal arteries. We present a technique to simplify this approach.

METHODS

In patients with extensive aneurysmal disease, a standard approach to the thoracic aorta via a left thoracotomy is performed. The patient is placed on full cardiopulmonary bypass with moderate hypothermia. The proximal anastomosis is performed unclamped with circulatory arrest. After completing the proximal and distal anastomosis separately, an onlay patch of Dacron is created and placed along the entire back wall of the aorta to cover all of the intercostal arteries. A side-to-side anastomosis between the patch and the distal graft is then performed and subsequently the anastomosis tested by retrograde flow.

RESULTS

The technique allows direct inspection of all suture lines, tested to an adequate pressure, so that postoperative bleeding is minimal.

CONCLUSION

Techniques to lessen the risk of paraplegia associated with aortic surgery include reimplantation of the intercostal arteries. This technique allows each suture line to be tested and easily visually inspected prior to closure of the chest.

Spinal cord ischemia after elective stent-graft repair of the thoracic aorta

OBJECTIVES

Neurologic deficit after endovascular treatment of the thoracic aorta is a complication reported with variable frequency that may be associated with severe morbidity and mortality. The mechanism of spinal cord ischemia appears to be multifactorial and remains ill-defined. We reviewed our experience to investigate the determinants of paraplegia after stent-graft repair of the thoracic aorta, identify patients at risk, and assess the effectiveness of ancillary techniques.

METHODS

Over a 5-year period (June 1999 to December 2004), 103 patients underwent elective endovascular repair of the thoracic aorta at a university referral center. Indications for treatment were atherosclerotic aneurysms in 88 patients, chronic type B dissection in 10 patients, and penetrating aortic ulcer in 5 patients. Four of the 103 patients affected with thoracoabdominal aortic aneurysms had hybrid procedures and were excluded from the cumulative analysis. Twelve patients with zone 0 and zone 1 aortic arch aneurysms were operated on with synchronous or staged surgical aortic debranching. Preoperative cerebrospinal fluid (CSF) drainage was instituted in seven selected patients. Neurologic deficits were assessed by an independent neurologist and classified as immediate or delayed. Patient demographics and perioperative factors related to the endovascular procedure were evaluated by using univariate statistical analyses.

RESULTS

A primary technical success was achieved in 94 patients (94.9%). At a mean follow-up of 34 +/- 14 months, a midterm clinical success was obtained in 90 patients (90.9%). Four patients (4.04%) had delayed neurologic deficit that completely resolved after the institution of CSF drainage, steroids administration, and arterial pressure pharmacologic adjustment. None of the four patients who underwent hybrid procedures for thoracoabdominal aortic aneurysms had paraplegia or paraparesis. Univariate analyses identified only a perioperative lowest mean arterial pressure (MAP) of <70 mm Hg as a significant risk factor (P < .0001).

CONCLUSION

Perioperative hypotension (MAP <70 mm Hg) was found to be a significant predictor of spinal cord ischemia; hence, careful monitoring and prompt correction of arterial pressure may prevent the development of paraplegia. When the latter occurred, reduction of the CSF pressure by drainage was useful. Patients with a previous or synchronous abdominal aortic repair may also benefit from CSF drainage as a perioperative adjunct.

Long-term results of endoluminal grafting for descending thoracic aortic aneurysms

OBJECTIVE

This paper describes the long-term results of endoluminal grafting (EG) for the treatment of descending thoracic aortic aneurysms (dTAA).

METHODS

Until July 2004, EG for dTAA has been applied in 45 cases (male/female, 29/16, 49-86 years old, mean age 67 years old). Locations included the proximal dTAA in 24 cases, and middle or distal dTAA in 21 cases. The stent-grafts (SGs) were constructed of Gianturco Z-stents covered with woven polyester grafts.

RESULTS

Deployment of the SGs was successful in 43 of 45 cases (96%) and complete thrombosis of the aneurysm was achieved in 39 cases (87%). Six minor endoleaks (13%), one migration (2%) and one conversion to surgery (2%) occurred. There was no instance of paraplegia nor hospital death. Over a mean 48 month follow-up (range 3 to 90), there were three persistent endoleaks (6%), four secondary endoleaks (8%), one breakage of wire frame (2%). Four cases were converted to open surgery due to secondary endoleak. There were two aneurysmal ruptures at the site where EG was not performed. The cumulative survival rate was 95.6 +/- 4.4% at 12 months, 85.7 +/- 5.4% at 24 months, and 82.4 +/- 6.1% at 36 and 60 months.

CONCLUSION

These results demonstrated that EG is safe and effective in selected dTAA patients. Improvements in patients selection, surgical techniques and equipment will reduce EG related complications and conversion to open repair over the course of the evaluation.

An experimental study of a new pull-through technique for aortic arch aneurysm in a porcine model

A new pull-through technique for placement of the aortic arch stent-graft was developed. Self-expandable curved stents (Matsui-Kitamura stents) were used on 4 pigs. With use of the endoscopic system, the sheath insertion was performed at the ascending aorta. By this pull-through method from the ascending aorta to the femoral artery, the stent was deployed into the aortic arch. All stents were successfully deployed into the correct position, and they fitted into the curvature of the aortic arch wall. By this method, stent-grafting for aortic arch aneurysm is expected to be performed with more accuracy and safety.

Endografting of the aortic arch

In recent years, endovascular repair with stent-grafts has made great advances as a minimally invasive alternative to conventional open surgery in the treatment of aortic aneurysm and dissection. Although many commercial endograft systems are now used worldwide for the treatment of these pathologies in the abdominal aorta, only a few dedicated stent-grafts have been developed for use in the thoracic aorta. However, these second-generation commercial endografts have almost identical specifications and performance profiles in terms of structure, function, and delivery mechanism as stent-graft systems employed in the abdominal aorta. Thus, endografts have been used in the thoracic aorta with little consideration to the morphological and hemodynamic characteristics specific to the aortic arch and the deployment techniques needed to navigate this curved region of the thoracic aorta. This review will survey the literature on aortic arch stent-graft repair and identify key elements critical to the successful design of an endograft to treat lesions in the aortic arch.

Stent-Graft Repair of Thoracic Aortic Aneurysms

Endovascular treatment of aortic disease has emerged as an alternative mode of treatment that is particularly attractive for patients with severe comorbidities who would not be ideal candidates for open surgery. Actually, short-term morbidity and mortality rates, of large series, compare favorably with those from surgery, and stent-graft placement is proving to be a safe, minimally invasive, and effective treatment for thoracic aortic diseases. However, although endoluminal interventions are minimally invasive, they are associated with complications, as are surgical methods. In this article, indications, technical aspects, and results of endovascular TAA repairs will be reviewed. We will also examine the advantages and limitations of stent-graft treatment. Finally, we will discuss the management of complications following aortic stent-graft implantation. We intentionally do not cover the topic of thoracic dissection, as it is being covered in another article in this volume.

Upper and lower spinal cord blood supply: the continuity of the anterior spinal artery and the relevance of the lumbar arteries

OBJECTIVE

Thoracic and thoracoabdominal aortic repair are still complicated by spinal cord ischemia and paraplegia. The aim of the present article is to present the results of an anatomical study conducted by means of both postmortem injection of the vertebral artery and perfusion of the abdominal aorta.

METHODS

The spinal cord blood supply was investigated in 51 Caucasian cadavers: in 40 cases a methylene blue solution was hand-injected into the vertebral artery, whereas in the remaining 11 cases the abdominal aorta was perfused with a methylene blue solution by means of a roller pump. The level and side of the arteria radicularis magna and the continuity of the anterior spinal artery were recorded.

RESULTS

The anterior spinal artery was a continuous vessel without interruptions along the spinal cord in all 51 cases. The arteria radicularis magna level was variable, ranging from T9 to L5. The arteria radicularis magna arose from a lumbar artery in 36 cases (70.5%) and it was left-sided in 32 cases (62.7%).

CONCLUSIONS

The anterior spinal artery constitutes an uninterrupted pathway between the vertebral arteries, the arteria radicularis magna, and the posterior intercostal and lumbar arteries. Moreover, the arteria radicularis magna arises from a lumbar artery in most of cases. Therefore, the sacrifice of the intercostal arteries during a thoracic aorta repair could be justified, at least from an anatomical standpoint. However, if an extended thoracoabdominal aortic repair is planned, it may be prudent to preserve the blood flow from the lumbar arteries.

Two-Stage Combined Endovascular and Surgical Approach for Recurrent Thoracoabdominal Aortic Aneurysm

PURPOSE

To present a 2-stage combined endovascular and surgical approach for recurrent thoracoabdominal aortic aneurysm (TAAA).

CASE REPORT

A 78-year-old man with previous surgical repairs of infrarenal abdominal and descending thoracic aortic aneurysms was referred for dysphagia due to an enlarging 9-cm aneurysm extending from the mid thoracic to the suprarenal aorta. Because no suitable endograft was available, an open repair was attempted, but the presence of a "frozen" chest made the redo procedure extremely difficult. A 2-stage treatment was thus decided upon. First, a retrograde bifurcated bypass graft was implanted from the abdominal aortic graft to the superior mesenteric and celiac arteries. Twenty days later, the TAAA was successfully excluded with a stent-graft, during which spinal fluid drainage was performed to prevent paraplegia. At 6 months, computed tomography showed patency of the endoprosthesis and visceral grafts. At 1 year, the patient remains asymptomatic.

CONCLUSIONS

This case illustrates that a 2-stage combined endovascular and surgical approach may be a safe and effective alternative to reoperation for recurrent TAAA.

Emergent endovascular stent-graft placement to treat ruptured Stanford type B acute aortic dissection

Uncomplicated Stanford type B acute aortic dissection, for which medical treatments are effective in most cases, is associated with a better prognosis than Stanford type A dissection. However, ruptured Stanford type B dissection still is associated with high mortality, because of the risks of open surgery and the complications of the disease. We report successful stent-graft placement in two patients with acute type B dissection with rupture, and discuss the advantages of stent-graft placement to treat ruptured acute type B dissection.

Endovascular Treatment of the Descending Thoracic Aorta

OBJECTIVES

to report our initial experience with endovascular stent graft repair of a variety of thoracic aortic pathology.

DESIGN

retrospective single center study.

MATERIAL AND METHODS

between February 2000 and January 2002, endovascular stent graft repair was performed in 26 patients: traumatic aortic isthmus rupture (n=3), Type B dissection (n=11) and descending thoracic aortic aneurysm (n=12). The deployed stent graft systems were AneuRx-Medtronic (n=1), Talent-Medtronic (n=13) and Excluder-Gore (n=12).

RESULTS

successful deployment of the stent grafts in the intended position was achieved in all patients. No hospital mortality neither paraplegia were observed. Late, non procedure related, death occurred in four patients (15%). Access artery complications with rupture of the iliac artery occurred in two patients and were managed by iliac-femoral bypass. The left subclavian artery was overstented in seven patients (27%). Only the first patient received a carotido-subclavian bypass. The mean maximal aortic diameter decreased significantly in patients treated for descending thoracic aneurysm. Only one patient had an endoleak type II after 6 months without enlargement of the aneurysm. Complete thrombosis of the thoracic false lumen occurred in all but one patient treated for Type B dissection 6 months postoperatively. Two patients underwent a consecutive stent graft placement, due to a large re-entry tear distal to the first stent graft.

CONCLUSIONS

endovascular stent graft repair for Type B dissection, descending thoracic aneurysm and aortic isthmus rupture is a promising less-invasive alternative to surgical repair. Further studies are mandatory to determine its long-term efficacy.

Descending thoracic aortic diseases: stent-graft repair

PURPOSE

To evaluate endovascular treatment of descending thoracic aorta with commercially available self-expanding stent-grafts.

MATERIALS AND METHODS

Seventy patients with aortic dissection, intramural hemorrhage, degenerative and posttraumatic aneurysm, penetrating atherosclerotic ulcer, and pseudoaneurysm underwent endovascular treatment. Eleven patients had impending rupture and were treated on an emergency basis. Stent-grafts were customized or selected on the basis of spiral computed tomographic (CT) or magnetic resonance (MR) imaging measurements. Preprocedure diagnostic angiography was performed in patients with aortic dissection and in other selected patients. All procedures were performed in an operating room and monitored with digital subtraction angiography (DSA) and transesophageal echocardiography (TEE). Follow-up was at 1, 3, 6, and 12 months after treatment and yearly thereafter.

RESULTS

Stent positioning was technically successful in 68 cases. At DSA and TEE, complete aneurysm or false-lumen exclusion was achieved in 66 (97%) cases. No intraoperative mortality or complications occurred. In-hospital complications included transient monoparesis (one patient) and extension of dissection into ascending aorta (one patient) that was repaired surgically. Early endoleak was observed in five (7%) patients: In three (type 2), endoleak resolved spontaneously; in one (type 1), it was persistent; and in one (type 1), treatment was converted to surgery. At long term, one (1%) patient died of aortic rupture; another, of respiratory insufficiency. Five (7%) late endoleak (type 1, one caused by migration of the stent) cases were observed. In three (4%), endovascular treatment was successful; in two (3%), surgery was performed. In one patient with persistent postimplantation syndrome, treatment was converted to surgery after successful aneurysm sealing. Procedure failure (ie, aortic disease-related mortality or conversion to surgery) occurred in six (9%) patients.

CONCLUSION

Endovascular stent-graft repair is less invasive in patients with chronic and acute descending thoracic aortic aneurysm and dissection.

Endovascular stent grafting of descending thoracic aortic aneurysms

The treatment of descending thoracic aortic aneurysms using endovascular stents is one of the more recent advances in treatment and is receiving increasing attention as it is a less invasive alternative to open surgical repair. Although the technology is still primitive, significant improvements have lately been made in the design and deployment of the endovascular stent-grafts. Aortic stent-grafts were used initially to exclude abdominal, and later thoracic, aortic true and false aneurysms. These prostheses have been increasingly used to treat aneurysms, dissections, and traumatic ruptures of the descending thoracic aorta with good early and mid-term outcomes. Although the long-term outcome of patients with aneurysms of the descending thoracic aorta after stent graft implantation has not been investigated, continued refinement of the endovascular approaches has decreased the need for conventional open thoracic aortic aneurysm repair, especially in patients who are at a high risk for standard surgery because of advanced age or the presence of comorbid diseases. The placement of endoluminal stent-grafts to exclude the dissected or ruptured site of thoracic aortic aneurysms is a technically feasible and relatively safe procedure. With the rapid development of endovascular approaches, the treatment of the descending thoracic aortic aneurysms might alter even more, but an extended follow-up is necessary to determine the longer term outcome. Historical perspectives, advantages, device considerations, complications, and current perspectives of the endovascular stent grafting of the descending thoracic aortic aneurysms are elaborated on.

Endovascular treatment of thoracic aortic pathology: feasibility and mid-term results

OBJECTIVE

to report our experience with 21 consecutive patients treated with a thoracic stent-graft.

DESIGN

retrospective analysis.

MATERIALS AND METHODS

Between October 1998 and February 2002, 21 patients (12 male), mean age 55.6 years (range 19-86 years), were treated for aorticortic pathology localized to the descending aorta (18 patients), the aortic arch (2 patients) and the ascending aorta (1 patient) and comprising true aneurysms (8 patients), false aneurysms (6 patients), traumatic rupture (4 patients), mycotic aneurysms (2 patients), and ruptured aneurysm (1 patient). Plain chest X-rays and computed tomography was performed at 3, 6 and 12 months postoperatively and then annually.

RESULTS

the median (range) operation time was 85min (50-305min), hospital stay 6 days (3-63 days) and follow-up 24 months (5-44 months). Complications occurred in 5 patients and comprised intraoperative migration (1), type I endoleak (1), type II endoleak (1), ischemic myelopathy (1), pneumonia (2), suture granuloma (1) and common femoral artery dissection (1).

CONCLUSIONS

stent-grafting can be successfully employed to treat a wide range of thoracic aortic pathologies with a mortality, morbidity and resource utilization that is considerably less than that associated with conventional surgery. However, long term follow-up on safety and efficacy is needed.

Blood coagulation and fibrinolytic response after endovascular stent grafting of thoracic aorta

OBJECTIVE

Thrombosis is common in aneurysms immediately after stent-grafting, because of exclusion from systemic blood flow. We studied changes in blood coagulation and the fibrinolytic system in patients with thoracic aortic aneurysm or dissection after stent-grafting to examine risk for consumption coagulopathy.

METHODS

Thirty-one thoracic aortic aneurysms were treated with stent-grafting (aneurysm group), and 29 aortic dissections were treated with entry closure with stent-grafting (dissection group). The stent-graft was constructed from a self-expanding Z stent and thin-walled woven polyester fabric. Platelet count, fibrinogen, antithrombin III (AT III), and thrombin-AT III complex were assayed as markers of coagulation. Plasminogen, alpha(2)-plasmin inhibitor, alpha(2)-plasmin inhibitor-plasmin complex, fibrin degradation products fragment E (FDP-E), and fibrin degradation products d-dimer were monitored as markers of fibrinolysis. Blood samples were collected before surgery and on postoperative days 1, 3, 7, and 14.

RESULTS

In both groups platelet count significantly decreased on postoperative days 1 and 3, and increased on postoperative day 14. AT III significantly decreased on postoperative day 1, but recovered after postoperative day 7. FDP-E significantly increased on postoperative day 1 in both groups. There was significant correlation of aneurysm diameter with alpha(2)-plasmin inhibitor-plasmin complex, fibrin degradation products, and d-dimer in the dissection group on postoperative day 1.

CONCLUSIONS

Activation of coagulation and fibrinolysis was observed after stent-grafting to treat thoracic aortic aneurysm and aortic dissection. However, no patients exhibited consumption coagulopathy postoperatively. Therefore we believe there is little risk for consumption coagulopathy after stent-grafting.

Management of traumatic rupture of the thoracic aorta in pediatric patients

BACKGROUND

Traumatic rupture of the thoracic aorta (TRA) in the pediatric population is uncommon. Management of TRA in general has evolved to include selective nonoperative and endovascular stent graft approaches, although operative repair remains the standard.

METHODS

We conducted a retrospective chart review of patients younger than 16 years of age admitted to a single institution between March 1985 and February 2002.

RESULTS

Of 160 patients admitted with TRA, 11 were younger than 16 (11.9 +/- 3.5) years of age. Concomitant injuries included closed head injury (5 patients) and acute lung injury (6 patients). All were started on beta-blockers when the diagnosis was suspected. Laparotomy was required in 3 patients and orthopedic procedures in 5 patients. Six underwent operative repair (two primary repairs), with no mortality. Cross-clamp time was 30.4 +/- 2.6 minutes. One patient (operated on without bypass) was partially paralyzed. Two patients were managed nonoperatively, 1 with an intimal arch injury, who on subsequent follow-up has demonstrated healing, and 1 who died of head injury. Three patients were managed by endovascular stent grafts, 2 who died of closed head injury and 1 who at 1-year follow-up has fully recovered. The endovascular stent grafts were placed through the femoral artery in 2 patients and through an iliac conduit in 1 patient. No patient died of rupture.

CONCLUSIONS

The approach to pediatric TRA should be identical to the adult, with early institution of beta-blockers. Depending on the clinical setting, a spectrum of options should be considered, including operation, non-operation, and endovascular stent graft, although the choice of the latter must be tempered by the lack of long-term follow-up data.