1.Patients and methods:
Medical records, operative records, and discharge summaries of all patients who underwent type A AD surgery with combined cannulation at our institution from January 2017 to June 2019 were reviewed in electronic medical record system and picture achieving and communication system. Records were noted for cannulation sites, surgical procedures, and overall clinical outcomes were reviewed. We were particularly concerned about postoperative lower limb ischemia, stroke, malperfusion, paraplegia, and death - complications that may be related to the cannulation site and retrograde perfusion.
The ethics committee of our institution, Union Hospital of Fujian Medical University in Fuzhou, China, approved this study protocol, Informed consent was waived as it was a retrospective study.
2.Surgical techniques
All patients were under general anesthesia. In order to avoid a malperfusion, the following measures are taken to minimize the risk: 1. Peripheral vascular condition is evaluated by computed tomography images, whether there is occlusive disease and whether there is dissection involvement; 2. Peripheral blood pressure monitoring and oxygen saturation detection were used to evaluate whether there was occlusive disease and dissection involvement. The affected arteries should not be cannulated if a significant stenosis and dissection are identified in the preoperative examinations.
We preferred right axillary artery combined with the right femoral artery cannulation. The surgeons were divided into two groups and started at the same time. During femoral artery cannulation, after a purse-string suture is placed on the exposed femoral artery, a femoral arterial cannula is inserted into the femoral artery by using the Seldinger technique. The right femoral artery is usually cannulated if dissection was absent in the right iliofemoral artery. If both sides are dissected, we exercise great care to make certain that our cannula is placed into the true lumen.
If the vital sign was stable, another group continue on anatomy the right axillary artery, the axillary artery exposure for cannulation was obtained through a 4 - 6 cm incision about 2 cm under the Subclavian fossa. The fibers of the pectoralis major muscle were blunt split. The pectoralis minor muscle is retracted laterally. After exposed the axillary artery, femoral artery clamps are used proximal and distal to the cannulation site. After clamping of the vessel and longitudinal arteriotomy, either direct cannulation with an arterial cannula or anastomosed a Dacron graft end-to-side to the axillary artery with a running 5-0 Prolene suture. Flow is evaluated through the cannula by back bleeding, and if adequate, the cannula is connected to the arterial line and secured to the skin.
Median sternotomy was performed, and venous cannulation was performed with a 2-stage right atrial cannula. or with superior and inferior vena cava cannulation if combined with intracardiac operation. The arterial perfusion line was divided into two branches on the operating table, and "single pump and double tube method" was adopted for management, so as to transfer the position of artery perfusion and protect the cerebral at different stages of the operation.
After cannulation, the position of cannulation was confirmed by observing whether there was a clear blood return, whether the pump pressure was normal, and whether there was a significant increase in the pump pressure after pumping 50 ~ 100ml of liquid to eliminate the possibility of insert to the dissection. The arterial pressure of the radial and dorsal foot arteries, transesophageal echocardiography (TEE) and regional cerebral oxygen saturation were routinely monitored by an anesthesiologist.
After the CPB was initiated, we routinely palpated the aorta and compared the pressures of the radial artery and dorsal foot artery, and evaluated the area ratio of the true lumen and false lumen in the descending aorta with TEE to evaluate whether there is a case of malperfusion. We changed the arterial cannulation site if we suspected that the patients had malperfusion syndrome caused by inadequate perfusion.
During surgery, our brain protection methods were deep hypothermia concomitant with selective antegrade cerebral perfusion (SACP). Also, neuro-protective drugs were administered and the head was cooled with a topical ice hat. The axillary artery is rarely dissected, so we can put the cannula inside the true lumen basically. After establishment of the circulatory arrest, we can find the backflow in the orifice of arch vessels. But if we can find not, we put another cannula inside the orifice of carotid artery13-14.
If the dissection involves only the ascending aorta, the ascending aorta and a hemi-arch replacement are usually performed. For patients with arch department involvement, we usually use triple-branched Stent Graft technology15. During core cooling, the left common carotid and innominate arteries were dissociated from the surrounding tissue. After the ascending aorta was clamped, aortic root manipulations such as aortic valve repair and sinus of Valsalva reconstruction were performed. Then the Dacron tube graft was subsequently continuous anastomosis to the aortic root. When a 22°C rectal temperature was achieved, selective cerebral perfusion via the right axillary artery was started at a rate of 10 to 15 mL/kg/min, and femoral artery perfusion was discontinued. Then the left common carotid artery and innominate artery were cross-clamped, next transected the ascending aorta at the base of the innominate artery. The triple-branched stent graft was inserted and properly positioned. Finally, continuous end-to-end anastomosis was performed between the artificial vessels and intraoperative stents. After the dissection operation and after the air was carefully flushed out, systemic perfusion was resumed, and the patient was rewarmed16-18.
3.Definition of clinical parameters
Early mortality was defined as all-cause mortality either in-hospital or within 30 days of surgery. Transient neurologic dysfunction was defined as the occurrence of post-operative confusion, agitation, and delirium without focal neurologic symptoms. Permanent neurologic injury was defined as the new onset of focal injury (stroke) or global dysfunction (coma) after a surgical repair with and without morphological correlates in a brain computed tomography or magnetic resonance image. Early stroke was defined as permanent neurologic injury being evident after the emergence from anesthesia. Delayed stroke was defined as permanent neurologic injury after first awaking from surgery without a neurological deficit. Acute kidney injury was defined as serum creatinine concentrations over 133 μmol/l or the need of dialysis due to oliguria. Postoperative liver failure was defined as at least having two of the following parameters were concurrently observed: the coagulation abnormality, total bilirubin > 15 mg/dL, liver enzymes levels more than tenfold the upper limit of normal, alteration of consciousness, asterixis.
4.Statistical analysis
Statistical analysis was performed with SPSS ver. 22.0(SPSS Inc., Chicago, IL, USA). Continuous variables with a normal distribution were expressed as mean ± standard distribution. nonnormally distributed data were expressed as median.