Abstract
The off-the-shelf multibranched thoracic endograft (t-branch) was created to overcome the limitations of the custom-made multibranched endograft. Consequently, symptomatic and ruptured thoracoabdominal aortic aneurysms can be treated with this device. The system has a fixed proximal diameter of 34 mm and a distal diameter of 18 mm. The t-branch will be deployed before the transaxillary delivery of the bridging endografts to avoid a long occlusion time of the limbs and the hypogastric arteries. Additionally, a 48-hour monitoring in an intensive care unit with invasive arterial blood pressure monitoring to keep the mean pressure between 80 and 90 mm Hg, selective use of cerebrospinal fluid drainage only to patients with clinical signs of neurological deficits are recommendations to prevent and minimize the risk of postoperative spinal cord ischemia.
Keywords
bridging devices, multibranched thoracic endograft, pararenal aortic aneurysms, thoracoabdominal aortic aneurysms
To overcome the delay of custom manufacturing and to offer an off-the-shelf solution for use in urgent conditions, a new device was designed, the t-branch thoracic endograft. This off-the-shelf device has an introduction delivery system that consists of a 22-French (22F) Flexor introducer sheath (7.3-mm inner diameter [ID] and 8.5-mm outer diameter [OD]) and a Captor hemostatic valve (Cook Medical, Bloomington, Indiana, USA). The system has a fixed proximal diameter of 34 mm and a distal diameter of 18 mm. Cook Medical provides a universal distal body at four different sizes, with proximal diameter (D) always 22 mm; lengths (L) of 81, 98, 115, and 132 mm; and 20F delivery system ( Fig. 12.1 ).
The device was created to overcome the limitations of the custom-made multibranched endograft. Consequently, symptomatic and ruptured thoracoabdominal aortic aneurysms (TAAAs) can now be treated with this device.
Anatomic Requirements
- 1.
Proximal to aneurysm. The device requires a 25-mm-long segment of nonaneurysmal thoracic aorta for proximal fixation, with an angle of less than 90 degrees relative to the long axis of the aneurysm, length of at least 25 mm, and diameter measured outer wall to outer wall no greater than 30 mm and no less than 24 mm. Alternatively, the device may be attached to a preexisting thoracic endovascular graft.
- 2.
Visceral vessel anatomy
- a.
Four indispensable arteries
- b.
Aortic diameter greater than 25 mm at the region of the branches
- c.
Target vessel accessible from antegrade approach
- d.
Celiac and superior mesenteric artery (SMA) 6 to 10 mm in diameter
- e.
Renal arteries 4 to 8 mm in diameter
- f.
Distance between the cuff and the corresponding arterial orifice less than 50 mm
- g.
The line between the cuff and the arterial orifice, as projected onto the vessel wall, deviates no more than 45 degrees from the long axis of the aorta.
- a.
- 3.
Access
- a.
Adequate iliac/femoral access compatible with a 22F (8.5-mm OD) delivery system
- b.
Brachial, axillary, or subclavian access vessel size compatible with the delivery profile of a 10F or 12F introducer sheath (3.3- or 4-mm OD).
- a.
Procedure
Case Presentation
A 72-year-old male patient presented with a 6.8-cm type V TAAA ( Fig. 12.2 ), based on the Crawford Classification modified by Safi and Miller. The patient had a previous myocardial infarction and coronary stent placement, chronic obstructive pulmonary disease (GOLD III), arterial hypertension, and diabetes mellitus type 2.
Procedural Steps
Step 1. Anesthesia and approach
All patients undergo general anesthesia and a totally percutaneous approach using the Prostar XL 10F vascular closure device (Abbott Vascular, Redwood City, California, USA).
Importance of Activated Clotting Time (ACT) Measurement
Heparin is administered at a dose of 100 IU/kg body weight, aiming for an ACT of at least 250 seconds. ACT measurements should be performed every 30 minutes.
Step 2. Small or stenotic iliac vessels
In elective, asymptomatic patients with small or stenotic iliac vessels, a 10-mm Dacron bypass graft (e.g., B. Braun, USA) can be implanted between the common iliac and the common femoral artery 3 to 4 weeks before planned aneurysm repair. A two-stage approach avoids severe surgical bleeding from the high-dose heparinization needed for the endovascular repair. In these patients the device is implanted through a small cutdown in the groin.
Step 3. Advancement of 22F sheath to assess trackability of access vessels
A 22F Check-Flo Introducer sheath (Cook Medical) is always advanced through the iliac arteries to assess the ability of the branched endograft to pass through the external and common iliac arteries ( Fig. 12.3 ).
If this maneuver is successful, the procedure continues with SMA precannulation with a Shepherd Hook catheter (Boston Scientific, Natick, Massachusetts, USA) placed in the contralateral groin. Alternatively, Syngo fusion imaging (Siemens, Munich, Germany) can be used to accurately identify the target vessels.
In patients with TAAA involving the arch or descending aorta, the proximal thoracic component can be implanted in a staged approach. In this case, and if the patient is asymptomatic, we prefer a staged procedure with an interval of at least 6 to 8 weeks between the implantation of the thoracic device and the t-branch.
Step 4. Advancement of device at least 10 to 20 mm above orifice of respective target vessel
The t-branch is advanced and deployed by withdrawing the outer sheath so that the branches are located at least 10 to 20 mm above the orifice of each respective target vessel, previously marked with the catheter placed into the involved target vessels.
Step 5. Release of reducing ties and deployment of device
The reducing ties are released, and the aortic endograft repair is completed with the implantation of the distal component (tube or bifurcated device). All sheaths are removed, with suture closure of femoral arterial puncture sites. We completely deploy the t-branch before the transaxillary delivery of the bridging endografts to avoid a long occlusion time of the limbs and the hypogastric arteries. This should minimize the risk for paraplegia. Fig. 12.4 shows the deployed t-branch with all markers in the ventral face of the device.
