Patients and methods
The medical records, operative records, and discharge summaries of all patients who underwent TAAD surgery with combined cannulation at our institution from January 2017 to June 2019 were reviewed in an electronic medical record system and picture achieving and communication system. The records were reviewed, and cannulation sites, surgical procedures, and overall clinical outcomes were noted. We were particularly concerned about postoperative lower limb ischaemia, stroke, malperfusion, paraplegia, and death - complications that may be related to the cannulation site and retrograde perfusion.
The ethics committee of Union Hospital of Fujian Medical University approved this study protocol. Informed consent was waived due to the retrospective nature of the study.
Surgical techniques
All patients were placed supine under general anaesthesia. To avoid malperfusion, the following measures are taken to minimize the risk: 1. the peripheral vascular condition was evaluated by computed tomography images to assess whether there was occlusive disease or dissection involvement; and 2. peripheral blood pressure monitoring and oxygen saturation detection were used to evaluate whether there was occlusive disease or dissection involvement. The affected arteries were not cannulated if significant stenosis or dissection were identified in the preoperative examinations.
We preferred right axillary artery combined with 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 was placed on the exposed femoral artery, a femoral arterial cannula was inserted into the femoral artery by using the modified Seldinger technique. The right femoral artery was usually cannulated if dissection was absent in the right iliofemoral artery. If both sides were dissected, we exercised great care to ensure that our cannula was placed into the true lumen.
If vital signs were stable, another group continued the procedure, and axillary artery exposure for cannulation was obtained through a 4–6 cm incision approximately 2 cm under the subclavian fossa. The fibres of the pectoralis major muscle were bluntly divided. The pectoralis minor muscle was retracted laterally. After exposing the axillary artery, femoral artery clamps were used proximal and distal to the cannulation site. While clamping the vessel and longitudinal arteriotomy, either direct cannulation with an arterial cannula or end-to-side anastomosis with a Dacron graft to the axillary artery with a running 5–0 Prolene suture was carried out. Flow was evaluated through the cannula by blood return, and if flow was sufficient, the cannula was 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 in the case of a combined intracardiac operation. The arterial perfusion line was divided into two branches on the operating table, and the “single pump and double tube method” was adopted for management to transfer the arterial perfusion position and protect the cerebral tissue at different stages of the operation.
After cannulation, the cannulation position was confirmed by observing whether there was clear blood return, whether the pump pressure was normal, and whether there was a significant increase in the pump pressure after pumping 50 ~ 100 ml of liquid to eliminate the possibility of insertion into the dissection. The arterial pressure of the radial and dorsal foot arteries as well as transesophageal echocardiography (TEE) and regional cerebral oxygen saturation were routinely monitored by an anaesthesiologist.
After CPB was initiated, we routinely palpated the aorta and compared the pressures of the dorsal foot artery and radial artery, monitored regional cerebral oxygen saturation and evaluated the area ratio of the true lumen and false lumen in the descending aorta with TEE to evaluate whether there was malperfusion. If the patient was suspected of having intraoperative organ malperfusion due to cannulation of the arterial cannula into the false lumen, we changed the location of the arterial cannula.
During surgery, our brain protection methods were deep hypothermia concomitant with selective antegrade cerebral perfusion (SACP). Additionally, neuroprotective drugs were administered, and the head was cooled with a topical ice hat. The axillary artery was rarely dissected, so we could simply place the cannula inside the true lumen. After circulatory arrest was established, we routinely assessed the backflow in the orifice of the arch vessels and monitored regional cerebral oxygen saturation. If the backflow was reduced or the regional cerebral oxygen saturation value was decreased, we placed another cannula inside the orifice of the carotid artery to prevent decreased cerebral perfusion, which would lead to brain dysfunction [
13,
14].
If the dissection involved only the ascending aorta, the ascending aorta and a hemi-arch replacement were routine used. For patients with aortic arch involvement, we usually used triple-branched stent-graft technology [
15]. During the cooling phase of core body temperature, the innominate artery and the left common carotid artery were dissociated from the surrounding tissues. After the ascending aorta was clamped, aortic root manipulations such as aortic valve repair and aortic sinus reconstruction were performed, and then the Dacron tube graft was subsequently continuously anastomosed 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. With the innominate artery and left common carotid artery cross-clamped, the ascending aorta was transected at the base of the innominate artery. Then, 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 rewarmed [
16‐
18].
Definition of clinical parameters
Early mortality was defined as all-cause mortality either in-hospital or within 30 days of surgery. Temporary neurologic dysfunction was defined as the presence of postoperative agitation, transient delirium, and confusion without focal neurologic symptoms. Permanent neurologic injury was defined as the new onset of permanent neurologic deficits, including coma or stoke after surgical repair with or without morphological correlates in a brain magnetic resonance or computed tomography image. Early stroke was defined as evident permanent neurologic injury after emergence from anaesthesia. Delayed stroke was defined as permanent neurologic injury after first awakening from surgery without neurological deficits. Acute kidney injury was defined as serum creatinine concentrations over 133 μmol/l or the need for dialysis due to oliguria. Postoperative liver failure was defined as the concurrent observation of at least two of the following parameters: coagulation abnormalities, total bilirubin > 15 mg/dL, liver enzyme levels more than tenfold the upper limit of normal, alteration of consciousness, and asterixis.