ARTICLE IN PRESS doi:10.1510/icvts.2006.135442
Interactive CardioVascular and Thoracic Surgery 5 (2006) 688–691 www.icvts.org
Institutional report - Vascular thoracic
Endovascular stent-graft treatment of thoracic aortic dissection Jian Yanga,1, Jian Zuoa,1, Lifang Yanga, Weixun Duanb, Lize Xiongb, Minwen Zhengc, Huili Cuia, Dinghua Yia,1,* Department of Cardiovascular Surgery, Xijing Hospital, 15 Chang Le West RD, Xincheng District, Xi’an 710032, People’s Republic of China b Department of Anesthesiology, Xijing Hospital, Fourth Military Medical University, Xi’an, The People’s Republic of China c Department of Radiology, Xijing Hospital, Fourth Military Medical University, Xi’an, The People’s Republic of China
a
Received 23 April 2006; received in revised form 27 July 2006; accepted 2 August 2006
Abstract Endovascular stent-graft implantation technique is a newly developed, effective and less invasive method in treating thoracic aortic dissection (TAD). Our study was designed to further verify the feasibility, the efficacy, and safety of this technique. We present a 4-year follow-up report of endovascular stent-graft treatment over 36 cases of acute TAD patients and 40 cases of chronic TAD patients. The mortality and comorbidity rates were evaluated thoroughly. In our study, the deployment of the stent-grafts was successfully performed in 75 cases. The hospital cumulative 30-day mortality rate was 1.3%. The instant endoleak rate was 15.8% (12 patients). All endoleaks were successfully treated with a second stent. All patients in local anesthesia were transported to the general ward after the intervention and were discharged from hospital within 1 week. Our preliminary results showed endovascular stent-graft implantation technique offered good peri-operative morbidity and mortality rates. Stent-graft placement over TAD produced a low incidence of spinal cord ischemia, cardiac and pulmonary complications, less hospital stay, less blood transfusion and became the first choice of TAD patients in our department. 䊚 2006 Published by European Association for Cardio-Thoracic Surgery. All rights reserved. Keywords: Thoracic aortic dissection; Endovascular treatment; Stent-graft; Electron beam computed tomography
1. Introduction The invention of endovascular stent-graft treatment of thoracic aortic dissection (TAD) is considered an evolutionary step towards less invasive surgical intervention for vascular diseases. Since first being introduced in 1994 by Dake et al. w1x, this technique acquired much recognization and became more and more popular. Thoracic stent-grafts are now used with confidence in the management of a wide variety of thoracic aortic pathologies, including acute and chronic dissection, intramural hematoma, penetrating ulcer, traumatic injuries, and other diseases w2–4x. From April 2002 to March 2006, we treated 76 patients with thoracic aortic dissection with endovascular stent-graft implantation technique. This report presents the experience of a single high-volume center in China over a 4-year period. 2. Material and methods This study was designed as a single center’s (university hospital) experience. Between April 2002 and March 2006, 76 consecutive patients with thoracic aortic dissection (Stanford type B) underwent endovascular stent-graft implantation at Xi Jing Hospital, Xi’an, China. There were 62 male and 14 female patients with a mean age of *Corresponding author. Tel.: q86-29-88563716; fax: q86-29-83210092. E-mail address:
[email protected] (D. Yi). 1 These authors are equal contributors. 䊚 2006 Published by European Association for Cardio-Thoracic Surgery
48.4"12.4 years (28–71 years). The pathology of treatment is listed in Table 1 and medical comorbid condition is listed in Table 2. Eight patients out of the group underwent a previous operation, including 3 Bentall’s procedures, 2 arch replacements, 2 ascending aorta replacements and 1 CABG. All patients routinely underwent a pre-interventional vascular staging that included the use of electron beam computed tomography (EBCT) or magnetic resonance imaging (MRI), transthoracic echocardiography (TTE), and aortography as well as coronary angiography in some cases. Two types of stent-graft systems were used in our study. The TALENT (Medtronic, Sunrise, FL) was used in 15 patients; the AEGIS (Microport, Shanghai, China) was used in 61 patients. All procedures were performed in the catheter room with the patient under epidural anesthesia or local anesthesia. Patients were placed in the dorsal decubitus position. Drapes were arranged to include the abdomen and both groins in the operative field, thus affording access to the common femoral arteries and, if needed, the iliac arteries or the abdominal aorta. Through a left percutaneous brachial access, a 5-F pigtail catheter was introduced to the thoracic aorta for preliminary angiography. Precise location of the primary tear of the dissection and the range of the aneurysm was confirmed by angiography. The diameter of the stent-graft was oversized by 20% in relation to the diameter of the landing zone, to ensure a satisfactory seal. Prior to the deployment of the stent-graft, 1 mgykg or 5000 U heparin was given intravenously. Then the stent-
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Table 3 Details about the stent-graft implantation
Table 1 Thoracic aortic pathology disease treated with stent-grafts Pathology
n
%
Acute dissection (Penetrating ulcer) (Post-traumatic) Chronic dissection (Para-anastomotic) Total
36 4 3 40 2 76
47.4 5.3 3.9 52.6 2.6 100
graft introducer delivery system was positioned inside the thoracic aorta under fluoroscopic monitoring. After systolic blood pressure was lowered to -80 mmHg by a hypotensive agent, the stent-graft was deployed. Angiography was performed again to ensure that the false aneurysm was properly excluded and also to detect if there were endoleak or any potential stent-graft related complications. If endoleak took place, another stent-graft of the same size or bigger would be additionally deployed to cover the leakage. Finally, after removing the introducer delivery system, the femoral arteriotomy was repaired with interrupted 5-0 polypropylene sutures. After discharge from the hospital, all patients were subjected to a strict follow-up protocol consisting of EBCT scan and complete physical examination at 6 and 12 months post intervenetion and then yearly thereafter. The mean follow-up period in our study was 15 months (range, 2 to 48 months). 3. Results In a 4-year period, 76 TAD patients were managed with stent-graft implantation. The mean duration of the stentgraft procedure and fluoroscopy time were 78 min and 12 min, respectively. In the group, 55 patients did not receive any blood transfusion. The average hospitation time before intervention was 9.3 days. The mean ICU time was 1.2 days. Most of the patients were transported to general wards immediately after the intervention except 3 hemodynamically unstable cases, who were returned to ICU for further treatment (details in Table 3). The mean diameter of the implanted stent used in our study was 35.3 mm and the mean length of the covered area of the stent was 98.5 mm. Among the 76 patients treated interventionally, the deployment of the stent-grafts at the intended position was successfully performed in 75
Duration of the procedure (min) Fluoroscopy time (d) Blood transfusion (ml) Time before intervention (d) Time after intervention (d) ICU stay days (d) Diameter of the stent (mm) Length of the covered area (mm)
Least
Most
Mean
47 5 0 0 5 0 30 98
240 30 2000 46 26 7 42 120
78 12 80 9.3 11.1 1.2 35.3 98.5
cases. One patient with pseudoaneurysm in the LSCA position had difficulty in deploying the stent-graft because the stent became 908 angular kinking inside the descending aorta and the patient was returned to open surgery after aortography (Fig. 1). No strut failure was found in either the TALENT or the AEGIS group. The primary endoleak rate was 15.8% (12 patients) and all endoleaks were categorized as type I endoleak. These patients received a second stentgraft in an overlapping manner immediately after the first stent-graft implantation. All endoleaks were successfully treated with a second stent. In 10 cases, the left subclavian artery (LSCA) was partially or totally occluded, and two carotid-carotid bypasses were set up in advance. No symptom of blood stealing or extremity dysfunction was found (Fig. 2). The mean follow-up period in our study was 15 months (range, 2 to 48 months). Intra-operative mortality was not observed. The hospital mortality and cumulative 30-day mortality rate was 1.3%. One patient, combined with mitral valve insufficiency and aortic valve insufficiency, died because of heart failure 7 days after implantation. The comorbidity included: fever, central nerve system disorder, renal failure etc. Twelve patients (15.8%) presented a postimplantation syndrome, described by Blum et al. w5x, with
Table 2 Medical comorbid conditions Comorbidity
n
%
Hypertension Pleural effusion or hemathorax Diabetes Hepatic cyst Subdural effusion Gross hematuria Emphysema Previous CABG Previous aorta operation Genetic history
28 9 5 2 1 1 1 1 7 2
36.8 11.8 6.6 2.6 1.3 1.3 1.3 1.3 9.2 2.6
Fig. 1. a and b: EBCT image of pseudoaneurysm in the LSCA position. c: DSA image of the LSCA pseudoaneurysm. d: DSA showed the stent became 908 angular kinking inside the descending aorta.
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Fig. 2. a: DSA showing primary tear of 0.5 cm to the opening of the LSCA. b: DSA showing that LSCA was totally occluded after stent-graft implantation.
elevated inflammatory parameters such as leukocytosis, elevated creactive protein levels and slight back pain, which normalized with some nonsteroidal anti-inflammatory drugs between 5 and 20 days. One patient had acute renal failure and recovered after hemodialysis in one week. One patient had post-interventional left side hemathorax and recovered after surgery. No permanent neurological deficit was postoperatively diagnosed in any of the 76 patients. Follow-up results showed thrombosis formed and most aneurysm diminished or decreased in size by half at one year after stent implantation (Fig. 3). 4. Discussion Although dramatic improvement in operative techniques, anesthesiologic methods, and medical therapy has been gained in recent years, TAD still remains a therapeutic dilemma. Thanks to the pioneering work of Dake and colleagues in Stanford, endovascular technology now represents a potential alternative to open surgery and medical preservative therapy in selected TAD patients w1x. One of the major advantages of this technique lies in the fact that extracorporeal circulation and deep hypothermic circulatory arrest with their inherent risks can be avoided. Vascular stent-graft technology can maintain blood flow to vital arteries while excluding the aneurysm from the circulation. In addition, stent-graft placement over the intimal tear can prevent the development of the aneurysm by facilitating complete thrombosis of the false lumen w6,7x. Patients with acute or chronic dissection usually manifested with different symptoms and were diagnosed easily. In our study, EBCT found obvious entries in 52 patients and there was no obvious entry in the other 24 patients. DSA
Fig. 3. a: EBCT image of penetrating ulcer and intramural hematoma before stent-graft implantation. b: EBCT scan 6 months postoperatively. The hematoma diminished.
verified the results of EBCT and found another two entries. The implantation of stent-graft was usually easily performed in patients with obvious entries. While in patients without obvious entries, the exclusion of the TAD always became difficult and required a thorough consideration of the length of the aneurysm, the relationship with LSCA or renal artery, and also the experience of the operator. After the implantation, re-aortography was compulsory to detect any endoleaks or remaining entries. According to the pre-operation precise evaluation of TAD, there are several crucial parameters that determine the results of the stent-graft technique. These parameters may include: the diameter of the normal aorta proximal to the aneurysm, the distance from the intimal entry to the orifice of the LSCA and the position, diameter and the length of the aneurysm etc. According to our experience, the diameter of the stent-graft should be 2–6 mm or 20% bigger than the diameter of the proximal normal aorta and the length of the stent-graft usually varies from 10–12 cm. We believe that a 10–12 cm long graft would be enough and it can fully cover the entry of the dissection and need not be as long as the whole dissected aorta or the aneurysm, because thrombus will soon form in the false lumen of the aneurysm after the stent-graft intervention. Excessive stent-graft may exclude many intercostal arteries from the true lumen and increase the possibility of paraplegia w8x. Another important consideration is the distance from the intimal entry to the orifice of the LSCA. In our study, the average distance from the intimal entry to the orifice of the LSCA is 5.6 cm (0 to 10 cm). LSCA was excluded in 10 patients (13%). There were two cases of brachial arteriovenous fistula related to the stent-graft technique. But none of them had the symptom of blood stealing or upper limb ischemia. So we believe that most LSCA can be excluded safely and without complications. But, in order to be safe, when LSCA is in great possibility to be excluded, it is routine that we assess the patency of the carotid artery, the vertebral artery and the situation of the Willis’ Circle before the interventions. In some special cases when the left common carotid artery was involved in the aneurysm and was in great possibility to be excluded, we would set up a carotid-carotid bypass in advance. The last important consideration in the patient’s preoperative profile requiring careful attention relates to renal dysfunction, because postoperative renal failure after stent-graft implantation continues to be a significant and potential lethal complication w9x. Moreover, the incidence of worsening renal function increases two- to three-fold in those patients with pre-existing renal insufficiency. In our study, one patient with pre-operative renal insufficiency got acute renal failure, and the patient gradually recovered after 7day hemodialysis. Endoleak and too big a diameter of the stent-graft remain the shortcomings of the technology w2,10x. Endoleak after stent-graft implantation can cause progressively enlargement of the TAD and even rupture. While applying the stent-graft, endoleak usually takes place between the graft and the aortic wall (Type I or II). If endoleak was found before the end of the operation, additional stent should be needed. The additional stent should be of the same size as, or a little bigger than, the original one. Once it fails
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again, open surgery of thoracic aorta replacement should be compulsory. In our study, 30 patients underwent the stent-graft implantation in epidural anesthesia and 46 patients in local anesthesia. Firstly, we used epidural anesthesia on all patients. With the accumulation of experience and being more familiar with the anatomy and pathology of the disease, we tried more local anesthesia on patients. From January 2004 onwards, we used local anesthesia instead of epidural anesthesia in most patients. Local anesthesia had the advantages of being easier to handle, having less effect on the blood pressure, heart rates and being less invasive and became our first choice. All patients in local anesthesia were transported to the general ward immediately after the interventional procedure and were discharged from hospital in -1 week. In conclusion, our preliminary experience shows that the endovascular stent-graft technology offered good perioperative morbidity and mortality rates, especially in an emergency situation. Stent-graft placement over TAD produced a low incidence of spinal cord ischemia, cardiac and pulmonary complications, less hospital stay, less blood transfusion and has become the first choice of TAD patients in our department. References w1x Dake MD, Miller DC, Semba CP, Mitchell RS, Walker PJ, Liddell RP. Transluminal placement of endovascular stent-graft for the treatment
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