Our Experience with the Low-Profile Braided Occluder: A Case Series of Splenic Artery Embolization in Three Trauma Patients

Abstract

The spleen is the most injured intra-abdominal organ, with splenic injuries constituting 42 to 49% of all abdominal injuries. Due to this vulnerability and the fact that splenic ruptures can potentially result in life-threatening hemorrhage, finding quick and efficient ways to control splenic bleeding in a trauma setting can improve patient outcomes. Recently, the U.S. Food and Drug Administration cleared the low-profile braided occluder (LOBO; Okami Medical, Aliso Viejo, California, United States), a vascular occlusion system designed to rapidly occlude vessels by using a high-density, uniform small pore structure. We present a small case series describing the use of the LOBO device for proximal splenic embolization in three trauma patients. Our report suggests that the LOBO device is safe and efficient for proximal splenic artery embolization as all three of our patients had a successful outcome with no complications; furthermore, we believe using the LOBO device may enhance patient and provider safety by decreasing fluoroscopic time and radiation dose, though further studies are needed to support this.

 

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Keywords

trauma - splenic embolization - interventional radiology - low-profile braided occluder (LOBO)

Introduction

Splenic artery embolization is effective and has the added benefits of preserving splenic tissue and preventing the need for open surgery.[1] Familiarity with the range of commercially available vascular occlusion devices helps to improve outcomes and reduce procedure time, radiation dose, and complications. Common embolization devices in use are coils, vascular plugs, liquid embolic agents, and calibrated microspheres.[2] [3] Recently, the U.S. Food and Drug Administration cleared the low-profile braided occluder (LOBO; Okami Medical, Aliso Viejo, California, United States), a vascular occlusion system designed to rapidly occlude vessels by using a high-density, uniform small pore structure. The larger versions have been approved as recently as 2022. Given its novelty, there remains a scarcity of information in the literature regarding its use, with only two papers discussing it.[4] [5] More clinical data are needed to determine its safety, feasibility, and effectiveness. Herein, we report our single-institution experience with LOBO in three splenic injury cases, with a discussion on our impression of its performance compared with the commonly used devices.

 

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Case 1

A 21-year-old male with no previous medical history, presented as a tier 2 trauma following a motorcycle accident. Hemoglobin was within normal limits, and the patient was hemodynamically stable upon arrival at the emergency department (ED). A physical exam revealed left lower quadrant tenderness and ecchymosis of the left flank. Subsequent imaging showed a grade 4 splenic laceration ([Fig. 1]).

Fig. 1 Abdominal computed tomography (CT) in arterial phase of axial view depicting an inferior splenic hypodense lesion (blue arrow) consistent with a grade 4 splenic laceration.

Following imaging findings, interventional radiology (IR) was consulted for an angiogram and possible splenic artery embolization due to concern for deterioration of hemodynamic status. Selective catheterization of the splenic artery was performed, followed by a digital subtraction angiography (DSA) evaluation, which confirmed the splenic laceration and presence of a possible small pseudoaneurysm ([Fig. 2]).

Fig. 2 Angiogram images. (A) Common hepatic artery (red arrow) and splenic artery (blue arrow) are seen after selection of the celiac artery. (B) Early run of angiogram. (C and D) End of angiogram showing contrast filling into subcapsular hematoma. (E) Red arrow showing presence of a small pseudoaneurysm.

After confirmation of the large laceration and seeing the presence of a pseudoaneurysm, we decided to proceed with proximal occlusion of the splenic vessel. After measuring the splenic artery to determine which size LOBO device to use ([Fig. 3]), the 5F reverse curve catheter (Cook Medical; Bloomington, Indiana, United States) was exchanged for a 5F Envoy catheter (CERENOVUS; California, United States) and the LOBO-7 vascular occlusion plug was placed in the proximal splenic artery between the dorsal pancreatic artery and pancreatic magna ([Fig. 3]). A postembolization angiogram performed from the splenic artery origin showed vascular occlusion of the splenic artery with preserved supply to the spleen through collateral ([Fig. 4]). All catheters were removed, and hemostasis was obtained using a Vascade closure device. The patient tolerated the procedure well and was extubated without any immediate complications.

Fig. 3 (A) Operative planning measuring the splenic artery to select which size low-profile braided occluder (LOBO) device to use. (B) Spot image showing LOBO-7 successfully deployed.

Fig. 4 (A) Image showing the presence of low-profile braided occluder (LOBO) device (red arrow). (B and C) Early and late run of angiogram. (D) Post-LOBO showing a substantial decrease of contrast extravasation into the subcapsular hematoma.

 

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Case 2

A 52-year-old male, with a past medical history of asthma, hypertension, gastroesophageal reflux disease, and erectile dysfunction, had originally presented to an outside hospital with complaints of left upper quadrant abdominal pain. Upon questioning, the patient said that while running the previous day, he tripped and fell onto some tree roots. He had no pain or other symptoms at that time or for the rest of that day, but the pain had acutely worsened the day following the fall. Subsequent imaging at the outside hospital showed a grade 4 splenic laceration and contrast extravasation ([Fig. 5]). The patient was transported to our hospital for further care and embolization by IR. After arriving from the outside hospital, the patient's hemoglobin had fallen from 14.2 to 9.5.

Fig. 5 (A and B) Abdominal computed tomography (CT) in axial view with different slices showing a grade 4 splenic laceration. (C) Angiogram showing presence of contrast extravasation.

A joint decision was made between the trauma team and the IR team to proceed with the procedure emergently. Operative planning was done in the IR suite to plan what size LOBO to use ([Fig. 6A]). A LOBO-5 vascular occlusion plug was successfully deployed in the splenic artery between the dorsal pancreatic artery and pancreatic magna ([Fig. 6B]).

Fig. 6 (A) Operative planning measuring the splenic artery to select which size low-profile braided occluder (LOBO) device to use. (B) Spot image showing LOBO-5 successfully deployed.

Following deployment of the LOBO, DSA evaluation was done showing a cease of contrast extravasation into the surrounding hematoma ([Fig. 7]). Right groin puncture site hemostasis was obtained via placement of a 6F AngioSeal closure device. The patient tolerated the procedure well, with an estimated blood loss of less than 20 mL. The trauma team continued to trend hemoglobin following the procedure, and it quickly stabilized.

Fig. 7 Selective selection of the splenic artery after deployment of low-profile braided occluder (LOBO) device showing the lack of contrast extravasation into the perisplenic hematoma.

 

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Case 3

A 59-year-old male, with a past medical history of type 2 diabetes mellitus, coronary artery disease, hypertension, and hyperlipidemia, presented to the ED as a trauma patient following a motor vehicle collision. On route to the hospital, the patient was hemodynamically stable and complained of bilateral shoulder pain, left hip pain, and pain upon left hip palpitation. Subsequent imaging showed a grade 4 splenic laceration and contrast extravasation ([Fig. 8]). IR was consulted and initially decided to proceed with conservative management.

Fig. 8 Abdominal computed tomography (CT) in axial view: (A) red arrow pointing to a hyperdense focus within the splenic laceration, likely representing a pseudoaneurysm versus active extravasation. (B) Grade 4 laceration of the spleen. (C) Angiogram showing presence of contrast extravasation (red arrow).

An acute drop in hemoglobin on hospital day 2 (13.3–8.5) prompted a stat computed tomography (CT) abdomen and pelvis without contrast to evaluate the extent of the splenic injury which showed an interval increase in the size of the perisplenic hematoma compared with day 1 ([Fig. 9]). Due to the acute drop in hemoglobin and the patient's CT findings, the decision was made to proceed with IR intervention. Access to the right common femoral using ultrasound guidance was done. Once the catheter was situated in the splenic artery, a DSA evaluation of the splenic artery was done. Decision was then made to proceed with embolization and operative planning was done to correctly choose the size of the LOBO device as done in the previous two cases. Following the successful placement of the LOBO-5 between the dorsal pancreatic artery and pancreatic magna, another angiographic run of the splenic artery was done ([Fig. 10]). The catheter and sheath were then removed, and hemostasis was achieved using a Vascade closure device. Following the procedure, the hemoglobin had normalized.

Fig. 9 Computed tomography (CT) of abdomen and pelvis showing an increase in the size of the perisplenic hematoma from hospital day 1 (A) to hospital day 2 (B).

Fig. 10 Digital subtraction angiography (DSA) of the splenic artery (A and B) with minimal contrast seen past the low-profile braided occluder (LOBO) occlusive device.

 

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Comparison of LOBO to Amplatzer Vascular Plug and Coils for Proximal Splenic Embolization

Two common embolic agents used for proximal splenic artery embolization include the Amplatzer Vascular Plug (AVP) and vascular coils. The AVP consists of a self-expanding disk made of braided nitinol.[6] While the AVP is widely used and routinely effective, it does have some shortcomings. Multiple studies have shown that when using an AVP for vascular embolization, additional embolic materials, such as coils, or multiple AVPs are often required to achieve complete occlusion, thus leading to increased procedure and fluoroscopic time.[7] [8] [9] [10] Failed embolization attempts and unpredictable occlusion times are other downsides that have been reported.[9] [10] [11] Vascular coils, like the AVP, have defaults as well, including device migration, lack of precision, and the need for multiple coils.[12] [13]

Radiation dose and fluoroscopic time are important considerations when choosing what embolic agent to use, as decreased radiation exposure and fluoroscopy time improve patient and provider safety.[3] To see if the LOBO is potentially more efficient in decreasing fluoroscopic time and dosage compared with AVP or coils for proximal splenic embolization, we compared the three devices ([Table 1]). Findings from a recent meta-analysis[3] were used to gather information on the average fluoroscopic time and radiation dosage when using AVP or coils. These findings were then compared with the average fluoroscopic time and radiation dose from our three present cases.

Table 1 Comparison between the LOBO, AVP, and coils for average fluoroscopic time and dosage

Embolization device used	LOBO	AVP	Coils
Fluoroscopic time (min)	12 (n = 3)	14.65 (n = 42)	27 (n = 42)
Radiation dose (mGy)	766 (n = 3)	849 (n = 68)	2,198 (n = 68)

Abbreviations: AVP, Amplatzer Vascular Plug; LOBO, low-profile braided occluder.

The average fluoroscopic time and radiation dose for the LOBO device was shorter than the averages reported in the recent meta-analysis; however, the small sample size for the LOBO group prevents us from making a strong argument that the LOBO device is significantly more efficient at decreasing fluoroscopic time and radiation dosage compared with AVP and coils. Future studies with a greater sample size are needed to explore this topic.

 

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Discussion

The spleen is the most injured intra-abdominal organ, with splenic injuries constituting 42 to 49% of all abdominal injuries.[14] [15] Due to this vulnerability and the fact that splenic ruptures can potentially result in life-threatening hemorrhage, finding quick and efficient ways to control splenic bleeding in a trauma setting can improve patient outcomes.[16] [17] Further importance should be given to splenic preservation through methods such as splenic artery embolization, as the spleen helps with immune function and prevents overwhelming infection from encapsulated organisms.[17] [18] Splenic artery embolization is routinely performed by IR physicians, individuals who are specialized in performing minimally invasive procedures using medical imaging guidance. Compared with conventional open surgery, IR procedures are associated with less pain, faster recovery time, decreased risk of infection, and better long-term outcomes.[19] [20] [21] This article enhances the literature by describing the use of a novel device for vessel occlusion while also capturing its safety and effectiveness. Additionally, this is the first article that discusses the usage of the LOBO device in the setting of splenic trauma, thus adding another intriguing detail to the report.

Proximal and distal splenic artery embolization are both embolization approaches that can be used to treat splenic injuries, with proximal being the most used.[16] Proximal splenic artery embolization has been associated with more effective hemorrhage control and smaller volumes of splenic infarct compared with distal embolization.[17] [22] Additionally, proximal embolization is less technically challenging and performed in a less amount of time compared with distal embolization[22]; therefore, the choice to proceed with proximal splenic embolization in the present cases was made.

Using the LOBO device in the high-flow and often tortuous splenic artery, we noticed its high trackability and easy delivery mechanism. The occlusion was complete and immediate in all three cases. High-density braiding design eliminates the need for reinforcement with coils, which is necessary in many cases of plug embolization of splenic artery using older designs that have larger pores. We did not encounter the problem of migration and recanalization, which sometimes occur with designs using a polytetrafluoroethylene membrane.[23] The proximal and distal markers are easy to visualize; however, we used magnification in some cases for better visibility and precise placement.

The LOBO device offers efficient embolization due to its unique design. The LOBO is built with patented HDBRAID technology that, when compared with conventional braid, houses a more consistent pore size and higher wire count, which allows for a faster and more complete occlusion. The multiple disc design of the LOBO also enhances the device's success by providing robust stability and precluding the need for proximal coil packing, which is often needed when using other occlusion devices. There are currently four different models of the LOBO device: LOBO-3, LOBO-5, LOBO-7, and LOBO-9. LOBO-3 and LOBO-5 have a three-disc design, with each disc providing two occlusion layers, while LOBO-7 and LOBO-9 have a two-disc design, with each disc providing four occlusion layers. Which model to use is governed by vessel size ([Table 2]). In the present cases, a LOBO-7 was used in the first case due to vessel diameter being 5.57 mm while a LOBO-5 was used in cases 2 and 3 due to vessel sizes being 4.01 and 4.43 mm, respectively.

Table 2 LOBO model specifications in regards to vessel and catheter dimensions

Model	Vessel size	Catheter specifications
LOBO-3	1.5–3 mm	0.027 microcatheter
LOBO-5	3–5 mm	0.028 microcatheter
LOBO-7	5–7 mm	0.056 catheter
LOBO-9	7–9 mm	0.070 catheter

Abbreviation: LOBO, low-profile braided occluder.

This article discusses impactful and novel literature in the realm of a significant topic, but an important limitation that decreases the generalizability of the findings is the scarcity of subjects, with only three being reported in the present article and all patients coming from a single institution. To account for this limitation, future studies should consist of larger and more diverse patient populations from multiple institutions.

 

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Conclusion

In conclusion, we present a small case series describing the use of the novel LOBO device for embolization of the splenic artery in three trauma patients presenting with splenic lacerations. Our report suggests that the LOBO device is safe and efficient for splenic artery embolization as all three of our patients had a successful outcome with no complications. Our findings also suggest that using the LOBO device may result in greater patient and provider safety by decreasing fluoroscopic time and radiation dose. Future studies should consist of a larger and more diverse patient population from multiple institutions.

 

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Conflict of Interest

None declared.

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Publication History

Article published online:
24 October 2024