Triple-branch Stent Graft Placement and Total-arch Replacement for the Treatment of Acute DeBakey I Aortic Dissection

The purpose of this study is to compare triple-branched stent placement with total-arch replacement in the treatment of acute DeBakey I aortic dissection . The investigators design optimal effect compare prospective, multi-center, randomized, open-label, parallel-group, non-inferiority clinical trial.

From November 2015, 90 consecutive patients with acute DeBakey I aortic dissection from five-centers in China were treated with triple-branched stent placement or hemi-arch replacement. The distribution of the patients adopts the dynamic random variance minimization random method. About half of the patients will be assigned to the the stent-graft group, the other to the hemi-arch group.

In all cases, surgery was performed under general anesthesia with tracheal intubation and cardiopulmonary bypass (CPB). During surgery arterial pressures at the upper and lower limbs were monitored. An esophageal echocardiography probe was placed routinely, and a sternal incision was performed. To establish CPB, the perfusion tube was placed in the right axillary artery and the drainage tube was placed in the superior and inferior vena cava through the right atrium. The CPB flow rate was of 2.4-2.6 L/kg/min. Intermittent cold blood cardioplegia was perfused through the left and right coronary arteries for myocardial protection.

In stent-graft group , the innominate artery and the left common carotid artery were fully isolated during the CPB cooling process. The ascending aorta proximal to the innominate artery was occluded, and the ascending aorta was transected slightly above the sinus tube connection; the left and right coronary arteries were directly perfused with blood-containing cold cardioplegia. Proximal procedures such as aortic valve repair, sinus reconstruction, and root replacement were performed first. Afterwards, the stumps were reconstructed. The reconstructed aortic root stump was anastomosed with a Dacron graft of corresponding size using 4-0 polypropylene suture (ascending aorta replacement). The nasopharyngeal temperature was then decreased to 25° (usually a rectal temperature of 27-29°C), the aortic perfusion flow was set to 10-15 ml/kg/min, and the innominate artery and the left common carotid artery were occluded 5-6 cm above the aortic arch. The aortic occlusion clamp was removed and a half aortic arch transection was made about 2 cm proximal to the innominate artery. Through the incision, the true lumens of the aortic arch, the proximal descending aorta, and the three aortic branches were identified. The triple-branched stent graft was inserted into the true lumens of the aortic arch and proximal descending aorta; the three stent graft branches were then placed into the corresponding true lumens of the aortic arch branch vessels followed by the sequential release of the vascular stent backbone and the branch stents in the left subclavian artery, the left common carotid artery, and the innominate artery. A catheter with a balloon or a probe was used to expand the vascular stents and the graft and branches were examined for kinks or folding of the backbone. A sandwich reconstruction was performed between the aortic stump, the aortic external Dacron graft, and the proximal stentless suture zone of the intraluminal artificial vessel backbone. The reconstructed stump was anastomosed with the Dacron graft that replaced the ascending aorta using 4-0 polypropylene suture. The occlusions of the left common carotid artery and the innominate artery were then relieved, and air was fully flushed out from the heart and the aorta. The right axillary artery perfusion was stopped, and systemic perfusion via an aortic perfusion tube at the artificial portion of the ascending aorta was performed. The patient was rewarmed after oxygen debt repayment, followed by the cardiac resuscitation.

In total-arch group , the ascending aorta proximal to the innominate artery was blocked during the CPB cooling process, and the ascending aorta was incised and transected slightly above the sinus tube connection. The left and right coronary arteries were directly perfused with blood-containing cold cardioplegia. As in stent-graft group , proximal procedures were performed first. The reconstructed aortic root stumps were sutured with Dacron graft using 4-0 polypropylene suture (ascending aorta replacement). The nasopharyngeal temperature was then decreased to 25° (usually a rectal temperature of 27-29°C) and the aortic perfusion flow was set to 10-15 ml/kg/min. The innominate artery and the left common carotid artery were clamped 5-6 cm above the aortic arch and the aortic occlusion clamp was removed. Half aortic arch resection was performed along the greater curvature of the aortic arch at 1 cm proximal of the innominate artery to the lesser curvature of the aortic arch at the origin of the descending aorta. Stumps between the dissection slices were lined with cotta slices and reconstructed using the sandwich method and then anastomosed with an Dacron graft of the corresponding size and shape using 4-0 polypropylene suture. Finally, the proximal end was anastomosed with the artificial blood vessel using 4-0 polypropylene suture. Air was fully flushed from the heart and aorta. The right auxiliary artery perfusion was stopped and systemic perfusion via an aortic perfusion tube at the artificial blood vessel of the ascending aorta was performed. The patient was rewarmed after oxygen debt repayment, followed by cardiac resuscitation.

Telephone contact was maintained with the patients after discharge. At 3,6,12 months postoperatively , patients received a follow-up examination, chest radiography, echocardiography, bilateral carotid artery Doppler examinations and CT angiography (CTA) examinations Numerical data were expressed as percentages, and comparisons between groups were performed with the chi-square test. Quantitative data were expressed as mean ± standard deviation; the independent sample t test was used for group comparisons and the paired t-test was used to compare the groups before and after surgery. The primary end point is the occluded rate of the false lumen one year postoperatively. The secondary end point are the survive rate ,complication, reoperation rate, the growth rate of thoracic descending aorta, security index perioperatively, life quality postoperatively.Statistical analysis were performed with SPSS 11.5 software. A value of P \< 0.05 was considered statistically significant.

Eligibility Criteria:
Inclusion Criteria:

* age\<65 years
* acute DeBakkey I aortic dissection is confirmed by CTA
* cardiac function is NYHA I-II
* the onset time\< 2 weeks
* the patient or family members can understand the research plan and will participate in this study and provide a written informed consent

Exclusion Criteria:

* Dissection involved the superior mesenteric artery, renal artery and coronary artery, which affect the body's viscera function seriously. The principal researcher from different centre need judge the patients' condition.
* there is a serious complication of nervous system, such as coma, paraplegia, etc
* pregnant or lactating women
* anyone with severe emphysema, interstitial pneumonia or ischemic heart disease cannot tolerate surgery
* subjects with contraindications of heart surgery, anesthesia and extracorporeal circulation
* subjects had significant or progressive of heart disease, according to the experience of the researchers,whose life expectancy is less than 1 year, or placement of triple- branched stent graft will induce unacceptable risk to the subjects
* anyone with serious mental illness, drug abuse, alcoholism, prison inmates, a lack of ability to care for, or can not express the informed consent
* subjects are incompliance or can't complete the research
* anyone is involved in the other clinical trial
* other reasons are not suitable for clinical trials, according to the researchers