Mind the gap: A novel endovascular technique to repair a transected vessel

Introduction

Traumatic injury to blood vessels has many presentations that can be managed in a variety of ways. During blunt force or penetrating traumas, a damaged vessel can be partially or completely transected leading to extravasation and ultimately failure to perfuse distal vital organs or extremities.^1–3 Depending on the trauma center’s resources and anatomic location of injuries, these can be repaired via primary repair, bypass graft, or endovascular stent graft.

The natural vascular response to injury or insult is vasospasm to prevent bleeding and to allow clotting factors to seal off the vessel. Vasospasm can cause a marked reduction in blood flow, ⁴ but as effective as this natural response is, it can interfere with primary repair by causing retraction of the ends of the vessel. When this occurs, the other options for repair include bypass graft or endovascular stent graft. Surgical bypass may be challenging depending on location of the injury. Endovascular techniques are often employed when primary repair or surgical bypass are not good options.

Endovascular repair of completely transected vessels is much more technically challenging than partial transections. The challenge faced with repairing a complete transection is navigating through active hemorrhage, hematoma, damaged tissue, and essentially an open territory of soft tissue. Compared to partially transected vessel repairs, these have high rates of failure and conversion to open procedures.^2,5,6 Operators historically use wires to traverse the gap of the injured artery and place a covered stent that acts as an artificial vessel. This procedure is typically performed by gaining proximal and distal access to the transected vessel so that a wire can be snared and pulled through the gap. This wire then acts as a rail over which a stent graft is placed.^2–6

The steerable microcatheter (SMC) is a revolutionary device that provides the operator with the ability to rotate the catheter tip up to 180° in multiple planes. The operator steers the catheter tip using a rolling dial at the proximal base. Using small amounts of contrast and an extensive knowledge of anatomy, the SMC can be advanced through the body without using a prefacing wire for guidance.^7,8

Technical note

A 35-year-old male presented with high-grade multi-system trauma shortly following a motorcycle collision. Computed tomography angiogram (CTA) of the chest was significant for transection of the right subclavian artery 2.5 cm distal to the right vertebral artery origin and a massive hematoma in the supraclavicular region, axilla, and chest wall. Of note, there was also suspected injury to the right brachial plexus, later confirmed on MRI. He also sustained additional injuries: cervical spine fractures, grade II dissection of the right V2 vertebral artery, right clavicular and scapular fractures, right ulnar fracture, multiple right rib fractures, right pneumothorax, pelvic fractures, Society of Vascular Surgery (SVS) grade I injury of the descending thoracic aorta, dissection of the celiac axis, American Association for the Surgery of Trauma (AAST) grade II liver injuries, AAST grade I splenic injury, and AAST grade III right renal injury.

After initial resuscitation with 2 L of normal saline, 1 U of fresh frozen plasma and transfusion of 2 U of packed red blood cells in the trauma bay, the patient was hemodynamically stable. The right arm was cool and mottled with visible deformity of the forearm. There were no palpable or dopplerable pulses in the wrist. Motor and sensory exams were deferred since the patient was intubated. The estimated ischemic time to the right upper extremity at this point in time was approximately 1 h.

Given the location of the arterial transection and also presence of a high-grade celiac axis injury which also needed endovascular repair, the decision was made in a multidisciplinary fashion among trauma surgery, vascular surgery, and interventional radiology to proceed with endovascular repair of the axillosubclavian injury.

Under general anesthesia, percutaneous arterial access was obtained by using a 6-French introducer sheath (Terumo Medical Corp, Somerset, NJ) via the right common femoral artery. A 5-French Berenstein diagnostic catheter was negotiated to the aortic arch in standard fashion. Initial subclavian arteriogram demonstrated abrupt cut-off of the right subclavian artery immediately distal to the thyrocervical trunk, compatible with complete transection (Figure 1). Additional access was gained to the right brachial artery in retrograde fashion utilizing a 5-French introducer sheath (Glidesheath Slender; Terumo Medical Corp) under direct ultrasound guidance.

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Figure 1.

Innominate digital subtraction arteriogram (DSA) demonstrating complete transection of the proximal right subclavian artery.

Simultaneous contrast injection through the brachial artery sheath and catheter positioned within the right subclavian artery demonstrated long segment occlusion from the proximal subclavian artery to the third segment of the axillary artery (Figure 2). A 10-mm Amplatz GooseNeck Snare (Medtronic, Minneapolis, MN) was advanced into the distal portion of the subclavian artery. Multiple attempts to snare an angled 0.035-in Glidewire (Terumo Medical Corp) from the retrograde brachial access were unsuccessful. Additional angiographic catheters and wires were also used without success (Figure 3). After 2 h of unsuccessful attempts at crossing the gap, an angled Glidecath (Terumo Medical Corp) was then inserted through the brachial access and navigated to the axillary artery in a retrograde fashion.

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Figure 2.

DSA with simultaneous contrast injection via antegrade and retrograde right upper extremity arterial access demonstrates long segment occlusion from the proximal subclavian artery to the third segment of the axillary artery.

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Figure 3.

Roadmap overlay image showing unsuccessful loop-snare retrieval attempted without the use of a SMC.

A SwiftNINJA® steerable microcatheter (Merit Medical Systems, South Jordan, UT) was then coaxially introduced through the Glidecath via the retrograde brachial artery access and advanced into the soft tissue free-space. After navigating the microcatheter in the desired direction, a 0.018-in microwire was secured with the loop-snare withdrawn through the femoral sheath for “through-and-through” wire access (Figure 4). This “through-and-through” access was obtained within 15 min of using the SMC. After establishing wire access from the right arm to the right groin, a 4-French Quick-Cross catheter (Spectranetics, Colorado Springs, CO) was navigated over the 0.018-in brachial wire from the femoral sheath, and the 0.018-in wire was exchanged for a 260 cm, 0.035-in Amplatz Super Stiff guidewire (Boston Scientific, Marlborough, MA; Figure 5). The femoral access sheath was then upsized to an 8-French, 90 cm Destination sheath (Terumo Medical Corp) and advanced to the proximal subclavian artery. Simultaneous arteriograms via the vascular sheaths redemonstrated abrupt cut off of the subclavian artery with contrast extravasation overlying the comminuted first rib fracture (Figure 6). The size of the vessels and the gap were measured on this arteriogram and confirmed with the pre-operative CTA. Intraoperative heparin was not given due to multiple injuries sustained by this patient. Four Viabahn heparin impregnated covered stents (W.L. Gore & Associates Inc, Flagstaff, AZ; 6 mm × 5 cm, 7 mm × 10 cm, 8 mm × 5 cm, and 9 mm × 5 cm) were successfully deployed across the transection sequentially from distal to proximal (Figure 7), covering the length of the gap and landing in normal vessel distally and proximally, without covering the vertebral artery. The proximal end of the stent was positioned 1 cm distal to the origin of the vertebral artery. The goal was to achieve the shortest possible length of coverage while maintaining an adequate proximal and distal seal with the vessel ends. Angioplasty was then performed throughout the stents. Immediately after angioplasty, displaced thrombus was seen at the distal portion of the stent, which was subsequently aspirated with an 8-French Angiojet device (Boston Scientific; Figure 8). Subsequent completion angiographic images demonstrated complete restoration of flow down the arm without evidence of further contrast extravasation or remnant thrombi, and preserved blood flow to the right vertebral artery (Figure 9). A CTA performed one week later for follow-up of the presenting SVS grade I descending thoracic aortic injury showed patency of the right subclavian stents (Figure 10).

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Figure 4.

Microwire successfully snared when torque applied to the SMC, allowing for advancement of the microwire in the desired direction.

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Figure 5.

Quick-Cross catheter advanced antegrade over the microwire to allow for exchange to a 0.035-in wire.

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Figure 6.

Simultaneous contrast injection via antegrade and retrograde access demonstrates complete occlusion of the proximal subclavian artery, contrast extravasation overlying the comminuted first rib fracture, and filling defects within the subclavian and axillary arteries.

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Figure 7.

Complete endovascular subclavian/axillary artery reconstruction with Viabahn covered stents.

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Figure 8.

DSA following stent deployment and angioplasty showing displaced thrombus at the distal end of the stent, which was subsequently cleared with an 8-French Angiojet device.

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Figure 9.

Early DSA image of completion angiogram demonstrates the proximal landing zone of the stent and preserved patency of the right vertebral artery.

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Figure 10.

CTA of the aorta performed one week after subclavian artery injury demonstrates patency of the subclavian stents.

Results

The right axillosubclavian artery reconstruction was a technical and clinical success. The patient had a dopplerable right radial pulse immediately after the procedure with progression to palpable radial pulse upon discharge. The patient underwent a successful right clavicular and ulnar open reduction and internal fixation two days later with orthopedic surgery, after which he was started on 81 mg of aspirin daily. One week later, 75 mg of clopidogrel was added to his daily antiplatelet regimen, which he was expected to continue for life. He underwent aggressive physiotherapy for six months after he was discharged from the hospital. One year after the axillosubclavian artery reconstruction, his right upper extremity continued to be well perfused on clinical exam, with a 2+ palpable pulse. He did have minimal return of sensation to the right shoulder region but he did not regain any motor function in his right upper extremity, due to his concurrent complete brachial plexus injury.

Discussion

To date, no technical report exists which describes endovascular repair of a transected vessel utilizing a SMC. The repair of traumatic transected vasculature by endovascular stent grafts has become a valuable tool for level I trauma centers in those cases not amenable to surgical repair. Endovascular techniques have been generally accepted to decrease patient morbidity and mortality. The speed of which a procedure or surgery can be performed has been directly correlated with improved patient outcomes.

By using a SMC, procedural time can be potentially reduced by offering the ability to directly steer the catheter through soft tissue. Although using a wire and following it with a catheter has been the cornerstone of endovascular technique, the wire can often be difficult to navigate due to its lack of purposeful maneuverability. This is particularly true when there is no conduit in which the wire can travel, for example, the soft tissues between a transected vessel.

When traversing through post traumatic soft tissue and hematoma, there are often times when multiple probes of the wire do not produce the desirable direction needed to make contact with the distal vessel. Additionally, one may need to make sharp turns which would be impossible using a traditional wire. With the SMC’s ability to turn 180°, it has the ability to make the turns necessary without endlessly probing for the correct path with a wire.

Another advantage of the SMC is the potential procedural time savings which translates to less fluoroscopic radiation exposure to both the patient and medical team.

A limitation of this technique is the operator’s experience with using the device. If the operator is not familiar with how the SMC functions, then the time savings advantage is potentially negated. The other disadvantage of using the SMC is its higher expense compared to traditional wires and catheters. This could potentially be overcome by not relying on the SMC as a “last resort”, but rather the initial device used. Exhausting many wires and catheters could ultimately be more expensive.

Conclusion

Endovascular repair of completely transected vessels can be a technically challenging and tedious endeavor. Although no firm conclusions can be drawn from a single case, the use of a SMC shows potential in reducing procedural time by giving the operator more control navigating between the damaged vessels. Reduced procedural time translates to decreased table time as well as reduced radiation exposure from decreased fluoroscopic time. More experience with the SMC is needed in the realm of acute traumatic vascular injuries to determine its value in endovascular repair of these injures.

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