We spoke to Dr. Protto to learn more about her presentation at CIRSE 2022.
Embolisation in bleeding: stent-graft
Minimally invasive endovascular interventions for treating acute bleeding have become widely adopted in the last decades due to advances in technology that have enabled a radical expansion of indications .
Independent of the site and etiology of the bleeding, spontaneous, iatrogenic or traumatic, the endovascular approach is a treatment alternative that has proven to be fast, safe and effective. The use of endovascular techniques obviates the need for surgical exploration, reducing morbidity and mortality. Angiography can also be used as a diagnostic tool followed by swift treatment of the bleeding . However, in the majority of cases, if the patient is stable, computed tomography angiography (CTA) should be used to evaluate the source of bleeding, helping in the planning of patient management  (Fig. 1).
An interventional radiologist has many different tools to treat arterial injuries, which can be divided into two main categories:
- Embolisation materials (particles, coils, plugs, and liquid embolics), which usually lead to complete occlusion of the vessel
- Stent-grafts ,i.e., metallic intravascular stents covered with a fabric of either expanded polytetrafluoroethylene (ePTFE) or Dacron, which preserve the arterial patency (Fig. 2)
Thus, it is essential to learn which device/embolic material should be preferred in different cases to achieve the best result.
The first step is to decide if the injured artery can be sacrificed. Arteries with ample collateral circulation can usually be occluded without causing ischaemic damage to the vascularised structures. On the other hand, patency should be preserved in case of a main supplying artery, such as the carotid, hepatic, or superficial femoral artery.
Once the stent-graft approach has been chosen, the second step would be to pick between a balloon-mounted or self-expanding stent. The first one is mounted over a percutaneous transluminal angioplasty (PTA) balloon, which allows the precise deployment, i.e. near a bifurcation or vessel origin. However, the delivery system is quite rigid and more difficult to navigate in tortuous vessels; thus, it is usually deployed in large or medium-sized vessels. The self-expanding stent is sheathed in a retractable delivery system; the deployment is less precise and has to be monitored under fluoroscopy. Moreover, some stents can shorten during deployment; consequently, a longer size may have to be preferred. The delivery system is more flexible, allowing this device to be used in vessels that are more tortuous and in the extremities near the joints (Fig. 3). To reach sufficient sealing and wall apposition, the oversizing of a self-expandable covered stent should be at around 20%.
The use of a stent-graft is an effective method to treat pseudoaneurysms, extravasation, dissection flaps, arteriovenous fistulae, and partial or complete transection while preserving the patency of the injured vessel (Fig. 4). Those injuries are often seen in trauma patients with the specific characteristics depending on the mechanism of the trauma, i.e. whether it is direct or indirect blunt trauma or direct penetrating trauma. However, 30-40% of peripheral vascular injuries are iatrogenic and the possibility to treat those lesions endovascularly is especially appealing . In addition, a major advantage of using minimally invasive techniques is the possibility to treat using percutaneous distant access under local anesthesia, thus avoiding the risks of open surgery .
Regardless of the site of the lesion, the procedure has to be planned carefully using contrast-enhanced multidetector computed tomography (MDCT) and multiplanar reformatting with maximum intensity projection (MIP). Evaluation of the diameter and length of the injured vessel segment is of central importance when planning the sizing of a peripheral stent-graft device, the access site, and the possible use of a closure device (Fig. 5).
After the procedure, the most common complications are access-site bleeding, acute or delayed stent thrombosis, stent fracture and infection. The clinical presentation in the case of early or late stent occlusion depends on the location of the stent. Especially in small diameter arteries, the risk of thrombosis is high. In some occasions, acute occlusion can lead to catastrophic outcomes, such as in the case of carotid artery stenting; thus, single or dual antiplatelet therapy should be taken into consideration.
Figures: Please click on the images to expand
Figure 3. 72-year-old man. Popliteal aneurysm open surgery repair, one week later patient arrives in the ER with swallowed knee and at US 5x5x10 cm hematoma. (a) CT showing bleeding at the upper anastomosis, (b) Angiography showing the bleeding, (c,d) Post-deployment angiography, Viabahn 8×50 mm.
Figure 4. Schematic representation of typical arterial vessel injuries: (1) simple contusion, (2) contusion with intimal injury and thrombosis, (3) contusion with secondary aneurysm, (4) simple laceration, (5) laceration with partial wall loss, (6) incomplete transection, (7) complete transection, (8) pseudoaneurysm, and (9) arteriovenous fistula (6).
Figure 5. 72-year-old woman one month post Whipple, (a) bleeding of a branch of the right hepatic artery, which originated from the SMA, (b) Post-deployment angiography, Viabahn 6mm x 50mm (c) Control CTA 2 months later.
Tampere University Hospital, Tampere/FI
Dr. Sara Protto is an interventional radiologist based in Finland at Tampere University Hospital. She received her medical degree from the University of Pavia in 2007 and completed her radiology training in 2014 at Tampere University Hospital. During her residency, she has received a CIRSE grant and had the possibility to work in Klagenfurt with Prof. Klaus Hausegger.
In 2019, she received the subspecialty in IR from the Finnish IR society and the EBIR. She has been actively involved in the European Trainee Forum, where she served as deputy chairperson between 2018 and 2020, focusing on promoting IR between students and a particular interest in encouraging women to undertake this career.
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