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Stent-graft Repair of the Thoracic Aorta: Short-term Results
Stent-graft Repair of the Thoracic Aorta: Short-term Results S. Haulon, MD,1 M. Koussa, MD,1 J.P. Beregi, MD,2 C. Decoene, MD,3 C. Lions, MD,2 and H. Warembourg, MD,1 Lille, France
The purpose of this study was to evaluate clinical feasibility and immediate outcome of stentgraft repair of the thoracic aorta. From December 1999 to January 2001, a total of 14 patients underwent stent-graft repair of the thoracic aorta. The underlying etiologies were traumatic rupture of the aortic isthmus in four cases, Stanford type B dissection in four, thoracic aortic aneurysm in three, penetrating atherosclerotic ulcer in two cases, and postoperative aortoesophageal fistula in one case. Stent-graft placement was performed under angiographic control in all cases in association with transesophageal echography in seven cases. The procedure was performed under emergency conditions in five cases. Thirteen patients presented contraindications for surgery. stent-graft placement was succesful in all cases. No further surgery has been performed in any case. Thus we conclude that endovascular treatment of the thoracic aorta using stent grafts is a promising therapeutic modality in patients with contraindications for conventional surgical treatment.
INTRODUCTION The first aortic lesion to be treated using a covered stent graft was an infrarenal abdominal aortic aneurysm (AAA) in 1991.1 Use of this technique was soon extended to patients with thoracic aortic disease at high risk for surgery. A variety of thoracic lesions have been treated, including rupture of the aortic isthmus,2,3 thoracic aortic aneurysm (TAA),4,5 Stanford type B aortic dissection,6,7 and penetrating atherosclerotic ulcer.8 The anatomical 1
Service de Chirurgie Cardiovasculaire, Hoˆpital Cardiologique, Lille, France. 2 Service de Radiologie Vasculaire, Hoˆpital Cardiologique, Lille, France. 3 Department d¢ Anesthe´sie-Re´animation Chirurgicale, Hoˆpital Cardiologique, Lille, France. Presented at the Sixteenth Annual Meeting of the Socie´te´ de Chirurgie Vasculaire de Langue Franc¸aise, Nice, France, May 31-June 2, 2001. Correspondence to: S. Haulon, MD, Service de Chirurgie Cardiovasculaire, Hoˆpital Cardiologique, CHU de Lille Cedex, France, E-mail: [email protected]. Ann Vasc Surg 2002; 16: 700-707 DOI: 10.1007/s10016-001-0313-3 Annals of Vascular Surgery Inc. Published online: 6 November 2002 700
features of the descending thoracic aorta are especially suited to stent-graft placement. The main advantage of endovascular treatment is its less invasive nature in comparison with traditional surgical treatment. However, routine use of stent grafts for thoracic aortic repair is currently not recommended since follow-up is still insufficient and there are no randomized prospective studies comparing matched endovascular and operative groups. In addition to being a less invasive option, endovascular treatment could provide an alternative for patients who are often poor candidates for conventional open surgical repair because of multiple disease history and risk factors. The purpose of this report is to describe our preliminary experience with the use of stent-graft repair for various diseases of the thoracic aorta in 14 patients.
PATIENTS AND METHODS Patients From December 1999 to January 2001, endovascular treatment of the descending thoracic aorta
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Table I. Contraindications for conventional surgical treatment and delay to treatment in 14 patients with thoracic aortic disease who received a stent graft Aortic lesion
n
Contraindication
Delay to treatment
Type B dissection
4
Rupture of isthmus
4
Aneurysm
3
Penetrating ulcer
2
Iatrogenic injury
1
COPD (n = 2) COPD Recent stroke (21 days) Multiple trauma (n = 3) None COPD (n = 2) Liver cirrhoses (child B) COPD Recent MI (7 days) Recent thoracic surgery
Chronic 1 day 1 day 7 days Chronic Chronic 1 day Chronic 1 day 1 day
Chronic; patient demonstrating progression during follow-up of a known aortic lesion; COPD; severe chronic obstructive pulmonary disease (FEV1 < 1 L); MI; myocardial infarction.
was performed in 14 patients including 10 men and 4 women with a mean age of 45.8 ± 6.6 years (range, 20 to 78 years). The delay to treatment and contraindications for conventional surgery are summarized in Table I. Stanford type B dissection. In four patients in this study, stent-graft repair was used to treat a false lumen aneurysm associated with Stanford type B dissection. In two of these patients, endovascular stent grafting was carried out under emergency conditions involving chest pain, hemothorax, and unstable hemodynamic status. The stent device was delivered to the hospital within 24 h after admission of the patient. In the other two patients, Stanford type B dissection was asymptomatic and the decision to perform stent-graft repair was based on the results of biennial follow-up using CT angiography, which showed the maximum transverse diameter (MTD) of the descending thoracic aorta to be >55 mm. The MTD prior to treatment was 59.4 ± 4.6 mm (range, 53 to 64 mm). Traumatic rupture of the aortic isthmus. In four patients stent-graft placement was performed to treat traumatic rupture of the aortic isthmus (Fig. 1). Three of these patients (multiple trauma victims) presented neurosurgical and abdominal contraindications for extracorporeal circulation with heparinization at 3 mg/kg. Endovascular repair was performed after 7 days on the basis of concerted multidisciplinary assessment between the neurosurgery, anesthesia/intensive care, and vascular surgery departments. Stent-grafting was carried out before neurological, abdominal, or orthopedic intervention. The fourth patient with traumatic rupture of the aortic isthmus was not contraindicated for conventional surgery. Rupture
was discovered coincidentally on a chest X-ray taken 12 years after a vehicular accident. Thoracic aortic aneurysm. In three patients the indication for stent-grafting was thoracic aortic aneurysm (TAA) (Fig. 2). In one of these patients the procedure was carried out under emergency conditions involving chest pain, hemothorax, and unstable hemodynamic status. In the other two patients, the decision to perform stent-grafting was based on CT angiography performed after a chest X-ray revealed the presence of an asymptomatic TAA with an MTD >55 mm. The MTD of the thoracic aorta prior to treatment was 57.3 ± 2.5 mm (range, 55 to 60 mm). Penetrating atherosclerotic ulcer. In two patients stent grafts were used to treat penetrating atherosclerotic ulcer (Fig. 3). In one patient diagnosis was achieved by CT angiography during work-up for atypical thoracic pain. This lesion was uncomplicated. In the second patient, stent-grafting was performed under emergency conditions involving hemothorax and unstable hemodynamic status. Iatrogenic aortic injury. In one patient the indication for stent-grafting was aorto esophageal fistula caused during esophageal surgery for Barrett’s ulcer. Left thoracotomy was contraindicated because the patient had recently undergone two right thoracotomy procedures and presented an unstable hemodynamic status. Diagnosis of the iatrogenic aortic injury was confirmed by CT angiography and conventional angiography. Preoperative Diagnostic Imaging. Helical CT angiography with thoracoabdominal contrast injection was performed in all 14 patients in this series. The diameter of the proximal and distal implantation sites was measured. A stent graft with
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Fig. 2. Helical CT angiography A before and B 1 month after placement of a stent graft for treatment of a thoracic aortic aneurysm.
Fig. 1. A Angiography and B helical CT angiography in a patient with post-traumatic rupture of the aortic isthmus. C Control helical CT angiography performed 6 months after stent-graft placement.
a diameter 10% greater than CT angiography measurements was used to ensure firm attachment. Digital angiography with a graduated catheter was performed in the nine patients who underwent elective treatment. Examination included injection of the aortic arch, full length of the aorta, iliac arteries, and femoral bifurcations. Angiography using radio-opaque catheters allowed accurate determi-
nation of the length of the stent graft needed to achieve complete exclusion of the diseased aortic segment. Stent Graft Devices. In 13 cases one Talent LPS thoracic stent graft (Talent, World Medical Inc., Sunrise, FL; Medtronic, Sunnyvale, CA) was used, including 12 standard models and 1 customized model. In the remaining case a Gore Thoracic Excluder stent graft (W.L. Gore and Associates, Flagstaff, AZ) was used. The Talent stent graft consists of a self-expanding nitinol stent with a polyester cover. The Thoracic Excluder stent graft consists of a self-expanding nitinol stent with a polytetrafluoroethylene (PTFE) cover. Mean dimensions of the stent grafts used in this series were as follows: proximal diameter: 36.7 ± 7.7 mm (range, 24 to 46 mm); distal diameter: 34.6 ± 6.6 mm (range, 22 to 44 mm); and length: 96.7 ± 5.9 mm (range, 95 to 101 mm). Placement Technique. Placement procedures were carried out in a surgical setting on a radiolucent surgical table. Monitoring was performed using a Solar monitor (Marquette, Inc., Minster, OH) featuring a electrocardioscope waveform (7 leads) allowing monitoring of the ST segment,
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Fig. 3. Helical CT angiography A before B 3 months after placement of a stent graft for treatment of an atherosclerotic penetrating ulcer of the thoracic aorta.
pulse oxymetry, and continuous analysis of inspired and expired gases (CO2 and halogen). In all patients induction of anesthesia was followed by placement of a catheter in the jugular vein to allow measurement of central venous blood pressure, a catheter in the right radial artery to allow continuous invasive measurement of arterial blood pressure, and a 14-gauge access line in the right arm. In seven patients (50%), a transesophageal echography (TEE) probe was inserted under direct laryngoscopic control. Intraoperative TEE was performed using a System Five ultrasound system (Vingmed GE) with a multi planar probe. Imaging was directed toward the descending thoracic aorta between the ostium of the left subclavian artery and first segment of the abdominal aorta. The operative field and surgical instrumentation were prepared for emergency thoracotomy. If the stent graft was to be placed near the base of the subclavian artery (n = 11), a 0.035 Teflon-coated guide inserted via the left humeral artery was used to mark the location of the ostium of the left subclavian. After longitudinal exposure of the femoral triangle, the right (n = 11) or left (n = 3) common
Stent graft repair of the thoracic aorta 703
femoral artery was dissected and controlled. A 7 French introducer was then placed in the common femoral artery and used to insert a 0.035 Tefloncoated guide wire into the ascending aorta. If necessary, a 5 French pig-tail catheter was used to facilitate insertion. Left oblique anterior arteriography was then performed using the pig-tail catheter located at the level of the innominate artery. A 260-cm-long rigid guide wire (Amplatz, Meditech) was inserted via the femoral introducer into the ascending aorta (n = 12) or right brachial artery (n = 2). Transverse arteriotomy was performed following systemic heparinization at a dose of 0.5 mg/kg and clamp placement on the common femoral artery. The collapsed stent graft inside the catheter was shuttled through the iliac artery into the thoracic aorta on the rigid guide wire. To prevent the stent graft from backsliding when the sheath was removed from the delivery system, systolic blood pressure was reduced to between 60 and 70 mmHg. While maintaining hypotension, the stent graft was expanded along its full length using a compliant balloon catheter built in the delivery system. Hypotensive conditions were maintained using sodium nitroferricyanide and were discontinued after complete deployment of the stent graft. The mean duration of hypotension was 8 min. The mean dose of sodium nitroferricyanide was 2 lg/ kg/mn. Modification of the ST segment was not observed in any patient during hypotension conditions. All phases of stent-graft placement including shuttling, positioning, and deployment were carried out under fluoroscopic and TEE control. Intraoperative TEE was used to check that the stent graft was securely attached to the aortic wall and to detect leaking areas requiring further balloon expansion. After deployment, the pig-tail catheter was repositioned in the aortic arch and arteriography was repeated. All endovascular placement devices were then withdrawn and the arteriotomy was closed. At the end of the procedure, the TEE probe was used to assess myocardial function to detect segmental dyskinesia and volemia by transgastric measurement of left and right ventricular surface and to check the left pleura for effusion. All patients remained in intensive care for 24 h after leaving the operating room. Follow-up Imaging Follow-up examinations using helical CT angiography were performed at 1 week, 1 month, 3 months, 6 months, and 1 year.
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RESULTS
Early Postoperative Mortality
Stent Graft Placement
Two patients died during the postoperative period. The cause of death was extensive anterior infarction during the first 24 h in the intensive care unit (n = 1) and hemorrhagic stroke 3 days after stentgraft repair (n = 1). The indication for stent-graft repair in both of these patients was Stanford type B dissection.
Endovascular insertion was successful in all 14 cases in this series. Conversion to traditional surgery was not necessary in any case. In two patients (14.3%) dilatation of the iliac artery was necessary to allow shuttling of the delivery system. In two patients (14.3%) removal of the external sheath from the delivery system at the aortic arch level was difficult. To avoid this problem in subsequent cases, release was initiated over a 2-cm segment in the ascending aorta and then the system was repositioned for placement distal to the ostium of the left subclavian artery. In two patients (14.3%) the rigid guide wire was positioned in the right brachial artery because of excessive angulation of the aorta. In 11 cases, intraoperative arteriography and TEE confirmed good immediate results of placement. In three cases, implantation of a second stent graft was scheduled because of the morphological features of the thoracic aorta on the preoperative work-up. In one case persistent, incomplete exclusion of the diseased segment was observed after placement of the first stent graft. This was treated by placement of a second stent-graft. Neurological Morbidity Postoperative complications involving spinal cord ischemia were not observed in any patient in this series. Upon recovery, one patient experienced transient blindness in one eye. Emergency CT scanning of the brain revealed no lesions. Doppler ultrasound of the supraaortic vessels detected a decrease in blood flow in the left common carotid artery due to partial obstruction of the ostium by the covered portion of the stent graft. This was treated by placement of a balloon-expandable stent (Palmaz P204, Cordis). Complications Involving Vascular Exposure No reintervention was required for hemorrhagic or septic complications related to inguinal vascular exposure. Acute lower extremity ischemia was diagnosed 2 days after stent-graft repair in one patient who had required dilation of the iliac artery to allow shuttling of the delivery system. Doppler ultrasound confirmed the absence of flow in the common femoral artery ipsilateral to the vascular exposure route. Reintervention with femorofemoral prosthetic bypass was necessary to restore perfusion in the lower extremity.
Duration of Hospitalization The mean duration of hospitalization was 6.25 ± 1.4 days (range, 5 to 9 days) in the 12 surviving patients. Follow-up The mean duration of follow-up in this preliminary series was 7.25 ± 3.4 months (range, 2 to 12 months) in the 12 surviving patients. No deaths were observed. Helical CT angiography demonstrated reperfusion of the excluded segment in two patients (17%). In one of these patients, the indication for stent-graft repair was aneurysm involving the false channel related to Stanford type B dissection. Endoleakage was due to a tear in the intimal flap at the site of distal implantation of the stent graft. In the second case, the indication for stent-graft repair was a penetrating atherosclerotic ulcer. Endoleakage also involved the distal implantation site of the stent graft, probably because of insufficient deployment of the neck of the stent. No complications were observed during followup in any of the four patients treated for rupture of the aortic isthmus, including the case in which implantation of another stent in the left common carotid artery was required. Complications were observed in one patient treated for aneurysm of a false channel associated with Standford type B dissection. The complication was leakage with persistent perfusion of the false channel and no regression of the diameter of the thoracic aorta. The other patient presented thrombosis of the false channel with a 4-mm reduction in the diameter of the thoracic aorta detected by CT scan at 6 months. Narrowing of the thoracic aorta (>2 mm) was observed in the three patients treated for TAA. All three remained asymptomatic. The diameter of the false periaortic aneurysm decreased (>2 mm) in the three patients treated for penetrating atherosclerotic ulcer. In one patient regression occurred despite residual leakage. No hemorrhagic recurrence or infectious complications were observed during follow-up of the
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Stent graft repair of the thoracic aorta 705
Table II. Postoperative complications and CT angiography findings in 14 patients with thoracic aortic disease treated with a stent graft Aortic lesion
Postoperative complications
Follow-up findings
Type B dissection (n = 4)
Death(MI) Death (hemorrhagic stroke) None None TIA None (n = 3) Acute ischemia (lower extremity) None (n = 2) None None None
— — Residual leak + no change in MTD Regression of MTD Lesion excluded Lesion excluded Regression of MTD Regression of MTD Residual leak + regression of MTD Regression of MTD Lesion excluded
Rupture of isthmus (n = 4) Aneurysm (n = 3) Penetrating ulcer (n = 2) Iatrogenic injury
MI; myocardial infarction; MTD; mean transverse diameter of thoracic aorta; TIA; transient ischemic attacks.
patient treated for iatrogenic aortoesophageal fistula caused during surgical treatment of Barrett’s ulcer. Table II summarizes the postoperative complications and CT angiography findings in the 14 patients in this series.
DISCUSSION Current findings indicate that endografting is a reliable procedure for lesions involving the thoracic aorta. The advantages of this technique are proportional to the surgical risk, with increasing benefit for patients requiring emergency treatment and/or presenting major comorbidity. In our series, the indication for endovascular treatment was based on the presence of one or more contraindications for thoracotomy: severe Chronic obstructive pulmonary disease (COPD) (FEV1 < 1 L), instable coronary insufficiency, and traumatic neurological or abdominal lesions. Despite association with these diseases, morbidity/ mortality after endovascular treatment was comparable to that of elective use of conventional surgery for treatment of aortic isthmus rupture and TAA.9-11 Other advantages of endovascular treatment in these two indications are greater patient comfort (rapid extubation and reduced intensive care) and shorter hospital stays. Since the long-term outcome remains poorly documented, we cannot recommend use of stentgraft repair as first-line treatment for rupture of the aortic isthmus, TAA, and uncomplicated Stanford type B dissections associated with aneurysms involving the false channel in patients without contraindications for thoracotomy. However, our opinion is different with regard to penetrating
atherosclerotic ulcers. In all our patients ulcers were located on the straight segment of the thoracic aorta where stent-graft delivery is easy. The sole purpose of stent-grafting in these patients is to exclude the aortic defect feeding the false aneurysm. Mechanical forces on the stent graft are minimal. As a result, we consider endovascular treatment to be a safe first-line treatment for penetrating atherosclerotic ulcers. Careful preoperative work-up is necessary to confirm the feasibility of stent-graft repair, select the stent graft, and plan the interventional technique. Imaging can be performed using conventional angiography or helical CT angiography. In our patients we used a graduated catheter to calculate the required length of the stent graft, the length of the healthy aorta between the left subclavian artery and proximal neck of diseased aortic segment, and the length of the healthy aorta from the distal neck of the diseased aortic segment to the celiac artery. Angiography also provides information on the morphology of the aortic arch and on the tortuosity and diameter of the iliac arteries. The iliac artery with the straightest and largest lumen should be used to shuttle the delivery system. Dilatation using progressively larger-diameter introducers is necessary if the diameter of the iliac artery is <7 mm. However, dilatation can lead to morbidity of its own, since one of the two patients in whom we performed dilatation required reintervention for acute lower extremity ischemia. Considering the diameter of current stent-graft delivery systems (18 to 24 French), the anatomy of the iliac arteries represents a major limitation for endovascular treatment of thoracic aortic lesions, especially in patients with associated atheromatous plaque. This
706 Haulon et al.
problem can be circumvented by shuttling the prosthesis through the common iliac artery or aorta or by using the carotid artery approach. Helical CT angiography allowing transverse sections and three-dimensional reconstruction enable good assessment of the aortic wall and accurate measurements of various thoracic aortic diameters. To ensure good exclusion and attachment of the stent graft in the diseased segment of aorta, the proximal and distal diameters of the stent grafts should be 10% larger than the diameter of the aorta at the level of the distal and proximal implantation zones. In our series, reliable measurements were obtained for all aortic diseases (n = 10) except dissection, since only 1 of the 10 patients in our series presented residual leakage that was likely due to insufficient expansion of the lower part of the stent graft. Accurate measurement was difficult in patients with aneurysm of the false channel of a Stanford type B dissection (n = 4). At the beginning of our experience, we used greatly oversized stent grafts in relation to the false channel so that the lumen of the real channel expanded and thus compressed and caused thrombosis in the false channel. During follow-up one patient treated in this way developed a tear in the intimal flap between the two channels, thus allowing high-flow revascularization of the false channel. Since the occurrence of that complication, stent-graft size has been calculated on the basis of aortic arch diameter plus 10%. Angiography and helical CT scanning allow precise measurement of the pathological aortic segment and location of the stent-graft implantation sites. In cases involving a short proximal neck, obstruction of the subclavian artery is possible. At the other end, the risk for spinal cord ischemia is greatest in cases requiring exclusion of an aortic segment between T8 and T12.12 However, this risk seems lower for endovascular than conventional operative treatment.6 Selective angiography to locate the artery of Adamkiewicz was not performed in any case in this series. Intraoperative TEE provides useful information at various steps of stent-graft placement.13-16 The diseased aortic segment as well as the minimal length of the aorta to be covered with the stent graft can be defined, studied, and located with respect to the left subclavian artery. These data can be compared with similar measurements made using angiography and helical CT angiography. Intraoperative TEE allows visual control during guide-wire placement, which can be especially important in patients with pseudoaneurysms or false channels. The TEE probe can also serve as a fluoroscopic
Annals of Vascular Surgery
landmark during stent-graft release. During placement of stent grafts (except for PTFE models), TEE can be used to determine proper deployment, absence of flow in the excluded zone, and absence of residual leakage. At the end of the procedure, complete echocardiography can be performed to assess myocardial function and left pleural status. Another benefit of TEE is that the number of injections of iodinated contrast material is reduced. Endovascular treatment can be proposed for first-line management of patients with contraindications for conventional surgical treatment, especially under emergency conditions. In our experience, intraoperative TEE provided a range of data useful for guiding and checking endovascular treatment as well as for controlling the hemodynamic status of the patient. Larger studies and longer follow-up will be necessary, however, define the indications for endovascular treatment in terms of type of aortic lesion and physiological status of the patient.
This study was funded by donations from MENERT 2693.
REFERENCES 1. Parodi JC, Palmaz JC, Barone HD. Transfemoral intraluminal graft implantation for abdominal aortic aneurysm. Ann Vasc Surg 1991;5:491-499. 2. Rousseau H, Soula P, Perreault P, et al. Delayed treatment of traumatic rupture of the thoracic aorta with endoluminal covered stent. Circulation 1999;99:498-504. 3. Deshpande A, Mossop P, Gurry J, et al. Treatment of traumatic false aneurysm of the thoracic aorta with endoluminal grafts. J Endovasc Surg 1998;5:120-125. 4. Mitchell RS, Dake MD, Semba CP, et al. Endovascular stentgraft repair of thoracic aortic aneurysms. J Thorac Cardiovasc Surg 1996;111:1054-1062. 5. Temudom T, D’Ayala M, Marin ML, et al. Endovascular grafts in the treatment of thoracic aortic aneurysms and pseudoaneurysms. Ann Vasc Surg 2000;14:230-238. 6. Nienaber CA, Fattori R, Lund G, et al. Nonsurgical reconstruction of thoracic aortic dissection by stent-graft placement. N Engl J Med 1999;340:1539-1545. 7. Dake MD, Kato N, Mitchell RS, et al. Endovascular stentgraft placement for the treatment of acute aortic dissection. N Engl J Med 1999;340:1546-1552. 8. Murgo S, Dussaussois L, Golzorian J, et al. Penetrating atherosclerotic ulcer of the descending thoracic aorta: treatment by endovascular stent-graft. Cardiovasc Intervent Radiol 1998;21:454-458. 9. Jacobs MJ, Meylaerts SA, de Haan P, et al. Strategies to prevent neurologic deficit based on motor-evoked potentials in type I and II thoracoabdominal aortic aneurysm repair. J Vasc Surg 1999;29:48-59. 10. Safi HJ, Subramaniam MH, Miller CC, et al. Progress in the management of type I thoracoabdominal and descending thoracic aortic aneurysms. Ann Vasc Surg 1999;13:457462.
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11. Svensson LG, Crawford ES, Hess KR, et al. Variables predictive of outcome in 832 patients undergoing repairs of the descending thoracic aorta. Chest 1993;104:12481253. 12. Ishimaru S, Kawaguchi S, Koizumi N, et al. Preliminary report on prediction of spinal cord ischemia in endovascular stent-graft repair of thoracic aortic aneurysm by retrievable stent-graft. J Thorac Cardiovasc Surg 1998;115:811-818. 13. Ferrari E, Taillan B, Drai E, Morand P, Baudouy M. Investigation of the thoracic aorta in cholesterol embolism by transoesophageal echocardiography. Heart 1998;79:133136.
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14. Fattori R, Caldarera I, Rapezzi C, et al. Primary endoleakage in endovascular treatment of the thoracic aorta: importance of intraoperative transesophageal echocardiography. J Thorac Cardiovasc Surg 2000;120:490-495. 15. Moskowitz DM, Kahn RA, Konstadt SN, et al. Intraoperative transoesophageal echocardiography as an adjuvant to fluoroscopy during endovascular thoracic aortic repair. Eur J Vasc Endovasc Surg 1999;17:22-27. 16. Orihashi K, Matsuura Y, Sueda T, et al. Echocardiographyassisted surgery in transaortic endovascular stent grafting: role of transesophageal echocardiography. J Thorac Cardiovasc Surg 2000;120:672-678.
The purpose of this study was to evaluate clinical feasibility and immediate outcome of stentgraft repair of the thoracic aorta. From December 1999 to January 2001, a total of 14 patients underwent stent-graft repair of the thoracic aorta. The underlying etiologies were traumatic rupture of the aortic isthmus in four cases, Stanford type B dissection in four, thoracic aortic aneurysm in three, penetrating atherosclerotic ulcer in two cases, and postoperative aortoesophageal fistula in one case. Stent-graft placement was performed under angiographic control in all cases in association with transesophageal echography in seven cases. The procedure was performed under emergency conditions in five cases. Thirteen patients presented contraindications for surgery. stent-graft placement was succesful in all cases. No further surgery has been performed in any case. Thus we conclude that endovascular treatment of the thoracic aorta using stent grafts is a promising therapeutic modality in patients with contraindications for conventional surgical treatment.
INTRODUCTION The first aortic lesion to be treated using a covered stent graft was an infrarenal abdominal aortic aneurysm (AAA) in 1991.1 Use of this technique was soon extended to patients with thoracic aortic disease at high risk for surgery. A variety of thoracic lesions have been treated, including rupture of the aortic isthmus,2,3 thoracic aortic aneurysm (TAA),4,5 Stanford type B aortic dissection,6,7 and penetrating atherosclerotic ulcer.8 The anatomical 1
Service de Chirurgie Cardiovasculaire, Hoˆpital Cardiologique, Lille, France. 2 Service de Radiologie Vasculaire, Hoˆpital Cardiologique, Lille, France. 3 Department d¢ Anesthe´sie-Re´animation Chirurgicale, Hoˆpital Cardiologique, Lille, France. Presented at the Sixteenth Annual Meeting of the Socie´te´ de Chirurgie Vasculaire de Langue Franc¸aise, Nice, France, May 31-June 2, 2001. Correspondence to: S. Haulon, MD, Service de Chirurgie Cardiovasculaire, Hoˆpital Cardiologique, CHU de Lille Cedex, France, E-mail: [email protected]. Ann Vasc Surg 2002; 16: 700-707 DOI: 10.1007/s10016-001-0313-3 Annals of Vascular Surgery Inc. Published online: 6 November 2002 700
features of the descending thoracic aorta are especially suited to stent-graft placement. The main advantage of endovascular treatment is its less invasive nature in comparison with traditional surgical treatment. However, routine use of stent grafts for thoracic aortic repair is currently not recommended since follow-up is still insufficient and there are no randomized prospective studies comparing matched endovascular and operative groups. In addition to being a less invasive option, endovascular treatment could provide an alternative for patients who are often poor candidates for conventional open surgical repair because of multiple disease history and risk factors. The purpose of this report is to describe our preliminary experience with the use of stent-graft repair for various diseases of the thoracic aorta in 14 patients.
PATIENTS AND METHODS Patients From December 1999 to January 2001, endovascular treatment of the descending thoracic aorta
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Stent graft repair of the thoracic aorta 701
Table I. Contraindications for conventional surgical treatment and delay to treatment in 14 patients with thoracic aortic disease who received a stent graft Aortic lesion
n
Contraindication
Delay to treatment
Type B dissection
4
Rupture of isthmus
4
Aneurysm
3
Penetrating ulcer
2
Iatrogenic injury
1
COPD (n = 2) COPD Recent stroke (21 days) Multiple trauma (n = 3) None COPD (n = 2) Liver cirrhoses (child B) COPD Recent MI (7 days) Recent thoracic surgery
Chronic 1 day 1 day 7 days Chronic Chronic 1 day Chronic 1 day 1 day
Chronic; patient demonstrating progression during follow-up of a known aortic lesion; COPD; severe chronic obstructive pulmonary disease (FEV1 < 1 L); MI; myocardial infarction.
was performed in 14 patients including 10 men and 4 women with a mean age of 45.8 ± 6.6 years (range, 20 to 78 years). The delay to treatment and contraindications for conventional surgery are summarized in Table I. Stanford type B dissection. In four patients in this study, stent-graft repair was used to treat a false lumen aneurysm associated with Stanford type B dissection. In two of these patients, endovascular stent grafting was carried out under emergency conditions involving chest pain, hemothorax, and unstable hemodynamic status. The stent device was delivered to the hospital within 24 h after admission of the patient. In the other two patients, Stanford type B dissection was asymptomatic and the decision to perform stent-graft repair was based on the results of biennial follow-up using CT angiography, which showed the maximum transverse diameter (MTD) of the descending thoracic aorta to be >55 mm. The MTD prior to treatment was 59.4 ± 4.6 mm (range, 53 to 64 mm). Traumatic rupture of the aortic isthmus. In four patients stent-graft placement was performed to treat traumatic rupture of the aortic isthmus (Fig. 1). Three of these patients (multiple trauma victims) presented neurosurgical and abdominal contraindications for extracorporeal circulation with heparinization at 3 mg/kg. Endovascular repair was performed after 7 days on the basis of concerted multidisciplinary assessment between the neurosurgery, anesthesia/intensive care, and vascular surgery departments. Stent-grafting was carried out before neurological, abdominal, or orthopedic intervention. The fourth patient with traumatic rupture of the aortic isthmus was not contraindicated for conventional surgery. Rupture
was discovered coincidentally on a chest X-ray taken 12 years after a vehicular accident. Thoracic aortic aneurysm. In three patients the indication for stent-grafting was thoracic aortic aneurysm (TAA) (Fig. 2). In one of these patients the procedure was carried out under emergency conditions involving chest pain, hemothorax, and unstable hemodynamic status. In the other two patients, the decision to perform stent-grafting was based on CT angiography performed after a chest X-ray revealed the presence of an asymptomatic TAA with an MTD >55 mm. The MTD of the thoracic aorta prior to treatment was 57.3 ± 2.5 mm (range, 55 to 60 mm). Penetrating atherosclerotic ulcer. In two patients stent grafts were used to treat penetrating atherosclerotic ulcer (Fig. 3). In one patient diagnosis was achieved by CT angiography during work-up for atypical thoracic pain. This lesion was uncomplicated. In the second patient, stent-grafting was performed under emergency conditions involving hemothorax and unstable hemodynamic status. Iatrogenic aortic injury. In one patient the indication for stent-grafting was aorto esophageal fistula caused during esophageal surgery for Barrett’s ulcer. Left thoracotomy was contraindicated because the patient had recently undergone two right thoracotomy procedures and presented an unstable hemodynamic status. Diagnosis of the iatrogenic aortic injury was confirmed by CT angiography and conventional angiography. Preoperative Diagnostic Imaging. Helical CT angiography with thoracoabdominal contrast injection was performed in all 14 patients in this series. The diameter of the proximal and distal implantation sites was measured. A stent graft with
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Fig. 2. Helical CT angiography A before and B 1 month after placement of a stent graft for treatment of a thoracic aortic aneurysm.
Fig. 1. A Angiography and B helical CT angiography in a patient with post-traumatic rupture of the aortic isthmus. C Control helical CT angiography performed 6 months after stent-graft placement.
a diameter 10% greater than CT angiography measurements was used to ensure firm attachment. Digital angiography with a graduated catheter was performed in the nine patients who underwent elective treatment. Examination included injection of the aortic arch, full length of the aorta, iliac arteries, and femoral bifurcations. Angiography using radio-opaque catheters allowed accurate determi-
nation of the length of the stent graft needed to achieve complete exclusion of the diseased aortic segment. Stent Graft Devices. In 13 cases one Talent LPS thoracic stent graft (Talent, World Medical Inc., Sunrise, FL; Medtronic, Sunnyvale, CA) was used, including 12 standard models and 1 customized model. In the remaining case a Gore Thoracic Excluder stent graft (W.L. Gore and Associates, Flagstaff, AZ) was used. The Talent stent graft consists of a self-expanding nitinol stent with a polyester cover. The Thoracic Excluder stent graft consists of a self-expanding nitinol stent with a polytetrafluoroethylene (PTFE) cover. Mean dimensions of the stent grafts used in this series were as follows: proximal diameter: 36.7 ± 7.7 mm (range, 24 to 46 mm); distal diameter: 34.6 ± 6.6 mm (range, 22 to 44 mm); and length: 96.7 ± 5.9 mm (range, 95 to 101 mm). Placement Technique. Placement procedures were carried out in a surgical setting on a radiolucent surgical table. Monitoring was performed using a Solar monitor (Marquette, Inc., Minster, OH) featuring a electrocardioscope waveform (7 leads) allowing monitoring of the ST segment,
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Fig. 3. Helical CT angiography A before B 3 months after placement of a stent graft for treatment of an atherosclerotic penetrating ulcer of the thoracic aorta.
pulse oxymetry, and continuous analysis of inspired and expired gases (CO2 and halogen). In all patients induction of anesthesia was followed by placement of a catheter in the jugular vein to allow measurement of central venous blood pressure, a catheter in the right radial artery to allow continuous invasive measurement of arterial blood pressure, and a 14-gauge access line in the right arm. In seven patients (50%), a transesophageal echography (TEE) probe was inserted under direct laryngoscopic control. Intraoperative TEE was performed using a System Five ultrasound system (Vingmed GE) with a multi planar probe. Imaging was directed toward the descending thoracic aorta between the ostium of the left subclavian artery and first segment of the abdominal aorta. The operative field and surgical instrumentation were prepared for emergency thoracotomy. If the stent graft was to be placed near the base of the subclavian artery (n = 11), a 0.035 Teflon-coated guide inserted via the left humeral artery was used to mark the location of the ostium of the left subclavian. After longitudinal exposure of the femoral triangle, the right (n = 11) or left (n = 3) common
Stent graft repair of the thoracic aorta 703
femoral artery was dissected and controlled. A 7 French introducer was then placed in the common femoral artery and used to insert a 0.035 Tefloncoated guide wire into the ascending aorta. If necessary, a 5 French pig-tail catheter was used to facilitate insertion. Left oblique anterior arteriography was then performed using the pig-tail catheter located at the level of the innominate artery. A 260-cm-long rigid guide wire (Amplatz, Meditech) was inserted via the femoral introducer into the ascending aorta (n = 12) or right brachial artery (n = 2). Transverse arteriotomy was performed following systemic heparinization at a dose of 0.5 mg/kg and clamp placement on the common femoral artery. The collapsed stent graft inside the catheter was shuttled through the iliac artery into the thoracic aorta on the rigid guide wire. To prevent the stent graft from backsliding when the sheath was removed from the delivery system, systolic blood pressure was reduced to between 60 and 70 mmHg. While maintaining hypotension, the stent graft was expanded along its full length using a compliant balloon catheter built in the delivery system. Hypotensive conditions were maintained using sodium nitroferricyanide and were discontinued after complete deployment of the stent graft. The mean duration of hypotension was 8 min. The mean dose of sodium nitroferricyanide was 2 lg/ kg/mn. Modification of the ST segment was not observed in any patient during hypotension conditions. All phases of stent-graft placement including shuttling, positioning, and deployment were carried out under fluoroscopic and TEE control. Intraoperative TEE was used to check that the stent graft was securely attached to the aortic wall and to detect leaking areas requiring further balloon expansion. After deployment, the pig-tail catheter was repositioned in the aortic arch and arteriography was repeated. All endovascular placement devices were then withdrawn and the arteriotomy was closed. At the end of the procedure, the TEE probe was used to assess myocardial function to detect segmental dyskinesia and volemia by transgastric measurement of left and right ventricular surface and to check the left pleura for effusion. All patients remained in intensive care for 24 h after leaving the operating room. Follow-up Imaging Follow-up examinations using helical CT angiography were performed at 1 week, 1 month, 3 months, 6 months, and 1 year.
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RESULTS
Early Postoperative Mortality
Stent Graft Placement
Two patients died during the postoperative period. The cause of death was extensive anterior infarction during the first 24 h in the intensive care unit (n = 1) and hemorrhagic stroke 3 days after stentgraft repair (n = 1). The indication for stent-graft repair in both of these patients was Stanford type B dissection.
Endovascular insertion was successful in all 14 cases in this series. Conversion to traditional surgery was not necessary in any case. In two patients (14.3%) dilatation of the iliac artery was necessary to allow shuttling of the delivery system. In two patients (14.3%) removal of the external sheath from the delivery system at the aortic arch level was difficult. To avoid this problem in subsequent cases, release was initiated over a 2-cm segment in the ascending aorta and then the system was repositioned for placement distal to the ostium of the left subclavian artery. In two patients (14.3%) the rigid guide wire was positioned in the right brachial artery because of excessive angulation of the aorta. In 11 cases, intraoperative arteriography and TEE confirmed good immediate results of placement. In three cases, implantation of a second stent graft was scheduled because of the morphological features of the thoracic aorta on the preoperative work-up. In one case persistent, incomplete exclusion of the diseased segment was observed after placement of the first stent graft. This was treated by placement of a second stent-graft. Neurological Morbidity Postoperative complications involving spinal cord ischemia were not observed in any patient in this series. Upon recovery, one patient experienced transient blindness in one eye. Emergency CT scanning of the brain revealed no lesions. Doppler ultrasound of the supraaortic vessels detected a decrease in blood flow in the left common carotid artery due to partial obstruction of the ostium by the covered portion of the stent graft. This was treated by placement of a balloon-expandable stent (Palmaz P204, Cordis). Complications Involving Vascular Exposure No reintervention was required for hemorrhagic or septic complications related to inguinal vascular exposure. Acute lower extremity ischemia was diagnosed 2 days after stent-graft repair in one patient who had required dilation of the iliac artery to allow shuttling of the delivery system. Doppler ultrasound confirmed the absence of flow in the common femoral artery ipsilateral to the vascular exposure route. Reintervention with femorofemoral prosthetic bypass was necessary to restore perfusion in the lower extremity.
Duration of Hospitalization The mean duration of hospitalization was 6.25 ± 1.4 days (range, 5 to 9 days) in the 12 surviving patients. Follow-up The mean duration of follow-up in this preliminary series was 7.25 ± 3.4 months (range, 2 to 12 months) in the 12 surviving patients. No deaths were observed. Helical CT angiography demonstrated reperfusion of the excluded segment in two patients (17%). In one of these patients, the indication for stent-graft repair was aneurysm involving the false channel related to Stanford type B dissection. Endoleakage was due to a tear in the intimal flap at the site of distal implantation of the stent graft. In the second case, the indication for stent-graft repair was a penetrating atherosclerotic ulcer. Endoleakage also involved the distal implantation site of the stent graft, probably because of insufficient deployment of the neck of the stent. No complications were observed during followup in any of the four patients treated for rupture of the aortic isthmus, including the case in which implantation of another stent in the left common carotid artery was required. Complications were observed in one patient treated for aneurysm of a false channel associated with Standford type B dissection. The complication was leakage with persistent perfusion of the false channel and no regression of the diameter of the thoracic aorta. The other patient presented thrombosis of the false channel with a 4-mm reduction in the diameter of the thoracic aorta detected by CT scan at 6 months. Narrowing of the thoracic aorta (>2 mm) was observed in the three patients treated for TAA. All three remained asymptomatic. The diameter of the false periaortic aneurysm decreased (>2 mm) in the three patients treated for penetrating atherosclerotic ulcer. In one patient regression occurred despite residual leakage. No hemorrhagic recurrence or infectious complications were observed during follow-up of the
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Table II. Postoperative complications and CT angiography findings in 14 patients with thoracic aortic disease treated with a stent graft Aortic lesion
Postoperative complications
Follow-up findings
Type B dissection (n = 4)
Death(MI) Death (hemorrhagic stroke) None None TIA None (n = 3) Acute ischemia (lower extremity) None (n = 2) None None None
— — Residual leak + no change in MTD Regression of MTD Lesion excluded Lesion excluded Regression of MTD Regression of MTD Residual leak + regression of MTD Regression of MTD Lesion excluded
Rupture of isthmus (n = 4) Aneurysm (n = 3) Penetrating ulcer (n = 2) Iatrogenic injury
MI; myocardial infarction; MTD; mean transverse diameter of thoracic aorta; TIA; transient ischemic attacks.
patient treated for iatrogenic aortoesophageal fistula caused during surgical treatment of Barrett’s ulcer. Table II summarizes the postoperative complications and CT angiography findings in the 14 patients in this series.
DISCUSSION Current findings indicate that endografting is a reliable procedure for lesions involving the thoracic aorta. The advantages of this technique are proportional to the surgical risk, with increasing benefit for patients requiring emergency treatment and/or presenting major comorbidity. In our series, the indication for endovascular treatment was based on the presence of one or more contraindications for thoracotomy: severe Chronic obstructive pulmonary disease (COPD) (FEV1 < 1 L), instable coronary insufficiency, and traumatic neurological or abdominal lesions. Despite association with these diseases, morbidity/ mortality after endovascular treatment was comparable to that of elective use of conventional surgery for treatment of aortic isthmus rupture and TAA.9-11 Other advantages of endovascular treatment in these two indications are greater patient comfort (rapid extubation and reduced intensive care) and shorter hospital stays. Since the long-term outcome remains poorly documented, we cannot recommend use of stentgraft repair as first-line treatment for rupture of the aortic isthmus, TAA, and uncomplicated Stanford type B dissections associated with aneurysms involving the false channel in patients without contraindications for thoracotomy. However, our opinion is different with regard to penetrating
atherosclerotic ulcers. In all our patients ulcers were located on the straight segment of the thoracic aorta where stent-graft delivery is easy. The sole purpose of stent-grafting in these patients is to exclude the aortic defect feeding the false aneurysm. Mechanical forces on the stent graft are minimal. As a result, we consider endovascular treatment to be a safe first-line treatment for penetrating atherosclerotic ulcers. Careful preoperative work-up is necessary to confirm the feasibility of stent-graft repair, select the stent graft, and plan the interventional technique. Imaging can be performed using conventional angiography or helical CT angiography. In our patients we used a graduated catheter to calculate the required length of the stent graft, the length of the healthy aorta between the left subclavian artery and proximal neck of diseased aortic segment, and the length of the healthy aorta from the distal neck of the diseased aortic segment to the celiac artery. Angiography also provides information on the morphology of the aortic arch and on the tortuosity and diameter of the iliac arteries. The iliac artery with the straightest and largest lumen should be used to shuttle the delivery system. Dilatation using progressively larger-diameter introducers is necessary if the diameter of the iliac artery is <7 mm. However, dilatation can lead to morbidity of its own, since one of the two patients in whom we performed dilatation required reintervention for acute lower extremity ischemia. Considering the diameter of current stent-graft delivery systems (18 to 24 French), the anatomy of the iliac arteries represents a major limitation for endovascular treatment of thoracic aortic lesions, especially in patients with associated atheromatous plaque. This
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problem can be circumvented by shuttling the prosthesis through the common iliac artery or aorta or by using the carotid artery approach. Helical CT angiography allowing transverse sections and three-dimensional reconstruction enable good assessment of the aortic wall and accurate measurements of various thoracic aortic diameters. To ensure good exclusion and attachment of the stent graft in the diseased segment of aorta, the proximal and distal diameters of the stent grafts should be 10% larger than the diameter of the aorta at the level of the distal and proximal implantation zones. In our series, reliable measurements were obtained for all aortic diseases (n = 10) except dissection, since only 1 of the 10 patients in our series presented residual leakage that was likely due to insufficient expansion of the lower part of the stent graft. Accurate measurement was difficult in patients with aneurysm of the false channel of a Stanford type B dissection (n = 4). At the beginning of our experience, we used greatly oversized stent grafts in relation to the false channel so that the lumen of the real channel expanded and thus compressed and caused thrombosis in the false channel. During follow-up one patient treated in this way developed a tear in the intimal flap between the two channels, thus allowing high-flow revascularization of the false channel. Since the occurrence of that complication, stent-graft size has been calculated on the basis of aortic arch diameter plus 10%. Angiography and helical CT scanning allow precise measurement of the pathological aortic segment and location of the stent-graft implantation sites. In cases involving a short proximal neck, obstruction of the subclavian artery is possible. At the other end, the risk for spinal cord ischemia is greatest in cases requiring exclusion of an aortic segment between T8 and T12.12 However, this risk seems lower for endovascular than conventional operative treatment.6 Selective angiography to locate the artery of Adamkiewicz was not performed in any case in this series. Intraoperative TEE provides useful information at various steps of stent-graft placement.13-16 The diseased aortic segment as well as the minimal length of the aorta to be covered with the stent graft can be defined, studied, and located with respect to the left subclavian artery. These data can be compared with similar measurements made using angiography and helical CT angiography. Intraoperative TEE allows visual control during guide-wire placement, which can be especially important in patients with pseudoaneurysms or false channels. The TEE probe can also serve as a fluoroscopic
Annals of Vascular Surgery
landmark during stent-graft release. During placement of stent grafts (except for PTFE models), TEE can be used to determine proper deployment, absence of flow in the excluded zone, and absence of residual leakage. At the end of the procedure, complete echocardiography can be performed to assess myocardial function and left pleural status. Another benefit of TEE is that the number of injections of iodinated contrast material is reduced. Endovascular treatment can be proposed for first-line management of patients with contraindications for conventional surgical treatment, especially under emergency conditions. In our experience, intraoperative TEE provided a range of data useful for guiding and checking endovascular treatment as well as for controlling the hemodynamic status of the patient. Larger studies and longer follow-up will be necessary, however, define the indications for endovascular treatment in terms of type of aortic lesion and physiological status of the patient.
This study was funded by donations from MENERT 2693.
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11. Svensson LG, Crawford ES, Hess KR, et al. Variables predictive of outcome in 832 patients undergoing repairs of the descending thoracic aorta. Chest 1993;104:12481253. 12. Ishimaru S, Kawaguchi S, Koizumi N, et al. Preliminary report on prediction of spinal cord ischemia in endovascular stent-graft repair of thoracic aortic aneurysm by retrievable stent-graft. J Thorac Cardiovasc Surg 1998;115:811-818. 13. Ferrari E, Taillan B, Drai E, Morand P, Baudouy M. Investigation of the thoracic aorta in cholesterol embolism by transoesophageal echocardiography. Heart 1998;79:133136.
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14. Fattori R, Caldarera I, Rapezzi C, et al. Primary endoleakage in endovascular treatment of the thoracic aorta: importance of intraoperative transesophageal echocardiography. J Thorac Cardiovasc Surg 2000;120:490-495. 15. Moskowitz DM, Kahn RA, Konstadt SN, et al. Intraoperative transoesophageal echocardiography as an adjuvant to fluoroscopy during endovascular thoracic aortic repair. Eur J Vasc Endovasc Surg 1999;17:22-27. 16. Orihashi K, Matsuura Y, Sueda T, et al. Echocardiographyassisted surgery in transaortic endovascular stent grafting: role of transesophageal echocardiography. J Thorac Cardiovasc Surg 2000;120:672-678.