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