Visceral artery pseudoaneurysms occur mostly as a result of inflammation and trauma. Owing to high risk of rupture, they require early treatment to prevent lethal complications. Knowledge of the various approaches of embolization of pseudoaneurysms and different embolic materials used in the management of visceral artery pseudoaneurysms is essential for successful and safe embolization.
We review and illustrate the endovascular, percutaneous and endoscopic ultrasound techniques used in the treatment of visceral artery pseudoaneurysm and briefly discuss the embolic materials and their benefits and risks. INTRODUCTIONAbdominal visceral artery pseudoaneurysms are potentially lethal vascular lesions that arise from splanchnic circulation and the renal artery, as a result of various causes including inflammation, infection, trauma and neoplasm (,). Unlike true aneurysms that have all three arterial wall layers, pseudoaneurysms develop due to disruption of intimal and medial layers of the arterial wall and do not contain any epithelized wall. They are outlined by thin fibrous tissue and usually surrounded by peri-arterial hematoma. Schematic diagram of differences between true aneurysm and pseudoaneurysm.The incidence of rupture of pseudoaneurysms is varies from 2% to 80% depending on the location, with untreated mortality rates reaching up to 100% (,). Due to the high risk of rupture, treatment of these pseudoaneurysms is necessary. Surgery has been the initial treatment option for pseudoaneurysms, however, due to its high invasive nature and risk of complications, radiological intervention is currently the initial treatment of choice (,).
Radiological interventions are minimally invasive and are associated with high success rates and low rates of complications. In this article, we present various techniques of embolization of pseudoaneurysms, embolic materials available and review the performance of each technique and embolic agent. Etiology and PathogenesisPseudoaneurysms result from disruption of the elastic fibers and smooth muscles of the tunica media of the artery, often with interruption of the intima. It has various etiologies such as inflammation (pancreatitis and cholecystitis), infection (abscess), vasculitis, trauma (iatrogenic or penetrating injury), collagen vascular disease, segmental arterial mediolysis and malignancy (,). Essentially all pseudoaneurysms, whether symptomatic or not, need treatment.
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Occasionally, there may be spontaneous thrombosis of a pseudoaneurysm and very rarely, they may undergo spontaneous resolution (,). Clinical PresentationPresentation of pseudoaneurysms may vary from absence of symptoms to life threatening hemorrhage and death. The most common symptom (50–63% cases) results from hemorrhage, presenting as gastrointestinal bleeding due to rupture of pseudoaneurysm arising from celiac, superior mesenteric arteries (SMA), and inferior mesenteric arteries (IMA), hematuria from renal artery pseudoaneurysm and intra-abdominal hematoma (,). Patients with severe hemorrhage may present with hypotension and shock.
Pain is the next common presentation, seen in one third of patients. Uncommonly, hematoma can cause mass effect and present with symptoms like jaundice secondary to common bile duct compression.
Pseudoaneurysms may be incidentally detected in up to one third of patients. Relevant AnatomyAbdominal visceral arteries consist of splanchnic circulation and renal artery. Splanchnic circulation includes celiac trunk, SMA and IMA. It is necessary to understand important collateral pathways for proper management of visceral artery pseudoaneurysms. Common collaterals are 1) between SMA and celiac axis through anterior and posterior pancreatico-duodenal arcades; 2) between branches of gastroepiploic, short gastric and splenic arteries (within the celiac arterial system); and 3) between right and left hepatic arteries.
Variations of arterial anatomy are possible, such as replaced or accessory hepatic arteries that may have retroportal course (retroportal hepatic artery), celiacomesenteric trunk and middle colic artery arising from celiac trunk. Uncommon variations include arc of Buhler (persistence of direct embryological communication between celiac trunk and SMA) and arc of Barkow (anastomosis of the right and left gastroepiploic arteries) (,).
Absence of collateral pathways in the renal arterial system is also an important deciding factor in selecting the embolization technique. ImagingPrior imaging is critical to interventional management of a pseudoaneurysm (,). Ultrasonography, computed tomography (CT) and magnetic resonance imaging are non-invasive imaging techniques that are most commonly employed for the detection and evaluation of pseudoaneurysms. Invasive digital subtraction angiography (DSA) is reserved for specific situations.Ultrasonography is often used as the initial screening tool and may detect large and superficially located pseudoaneurysms and those within the solid organs like liver and spleen (,). A pseudoaneurysm typically appears as an anechoic lesion with thin walls on grey scale scan, which fills with color and shows the characteristic 'yin-yang' flow with bidirectional waveform pattern on duplex color Doppler ultrasound.
The peripheral part of a pseudoaneurysm may show variable extent of thrombosis, which appears hypoechoic or echogenic, often with stratification due to thrombosis of different ages. Obesity, bowel gas, operator dependency and deep location of visceral artery pseudoaneurysms result in lower sensitivity of detection. 33-year-old male with confirmed chronic pancreatitis, presenting with high grade fever and hematemesis.Transabdominal ultrasonographic images of right hepatic artery pseudoaneurysm (arrows) showing well defined anechoic lesion on grey scale image (A) with characteristic 'yin-yang' sign on color Doppler (B). Cholangitic abscesses are seen adjacent to pseudoaneurysm (arrowheads).Multidetector CT angiography (CTA) is the most commonly used and most sensitive non-invasive modality for detection of pseudoaneurysms (,).
Routinely, CT should include both arterial and venous phases as some pseudoaneurysms with a narrow neck may not be seen on the arterial phase and opacify only in the venous phase. CTA demonstrates a well defined contrast filled sac with attenuation parallel to adjacent main artery in both the phases. Post-processing with maximum intensity projection and volume rendering better demonstrate the pseudoaneurysm and its origin and improve detection.
Depending on the extent of thrombosis, the sac may show low attenuation areas, usually in the periphery. In addition to the detection of a pseudoaneurysm, CTA provides a road map for intervention and depicts associated anatomical arterial variations. CT angiography in 38-year-old male with acute pancreatitis and melena.Axial images in arterial (A) and venous (B) phases show small pseudoaneurysm arising from splenic artery (arrows) with pancreatic inflammation.
Maximum intensity projections in axial (C) and coronal (D) planes and three-dimensional volume rendered image (E) better demonstrate characteristics of pseudoaneurysm (arrows).MR angiography (MRA) is rarely used for the detection of pseudoaneurysms because of non-feasibility in hemodynamically unstable patient, long scan times and high cost (,). In addition, the spatial resolution of MRA is lower than CTA.
However, absence of ionising radiation and availability of non-contrast techniques have advantages over CT (,). Ghost or pulsatile artefact in the phase encoding direction is an important clue for detection of pseudoaneurysm on MRA.Digital subtraction angiography remains the gold standard for diagnosis. Two main indications of DSA in the setting of pseudoaneurysms are 1) possible embolization of a pseudoaneurysm detected on imaging, and 2) detection of a pseudoaneurysm under high clinical suspicion and normal findings on imaging. DSA has the advantage of real time assessment of hemodynamics of the source vessel, identification of collateral supply and expendability of donor inflow artery. DSA can be used to identify pseudoaneurysms that are not seen in ultrasonography, CTA and MRA, with the advantage of ability to perform concurrent therapeutic intervention. Cone beam CT, also known as rotational angiography, involves the acquisition of angiographic images in different planes by rotating the tube-detector assembly rapidly around the patient.
The images can be viewed in all the three standard planes, facilitating the determination of size and exact origin of the pseudoaneurysm and the course of the inflow artery. Few studies have reported the superiority of cone beam CT over routine DSA images in management of pseudoaneurysms (,).Differentiation of pseudoaneurysm from a true aneurysm is important, as indications for treatment are different in both cases. Presence of irregular outline, eccentric location, saccular shape, eccentric thrombosis and demonstration of etiology on imaging (like inflammation, trauma) may suggest a pseudoaneurysm (,). However, in the absence of an etiology, it may be difficult to differentiate a pseudoaneurysm from a saccular true aneurysm.
Indications for InterventionsPatients presenting with hemorrhage, unstable hemodynamic status and symptoms of mass effect due to a pseudoaneurysm need embolization. However, due to high mortality of rupture, all pseudoaneurysms require treatment as soon as detected (,). Since pseudoaneurysms have thin walls, their size has no correlation with the risk of rupture (,). Small pseudoaneurysms may cause life threatening hemorrhage, while a large pseudoaneurysm may be detected incidentally. However, this is not the case with true aneurysms that need treatment when sized 2 cm or with mass effect (,). Embolization for incidentally detected pseudoaneurysms in asymptomatic patients is still controversial. Due to high risk and mortality of rupture, we embolize all pseudoaneurysms irrespective of whether the patient is symptomatic or not.
Principles of InterventionExclusion of the pseudoaneurysm from systemic circulation is the main aim of radiological intervention. This can be achieved by slowing the flow within the pseudoaneurysm (coils, stent grafts), inducing thrombosis (coils and liquid embolics) and stimulating inflammation (coils and liquid agents). An interventional radiologist should consider some important principles while choosing the interventional technique and embolizing agent for managing the pseudoaneurysm, as shown in. Size of pseudoaneurysm & its neckLarge size–option of percutaneous approachWide neck–risk of non target embolization (liquid agents)Parent arteryEnd artery vs.
Artery with rich collaterals–proximal occlusion vs. Sandwich embolizationExpendable vs. Inexpendable artery–parent artery occlusion vs. Preservation approachesTortuous artery–difficult catheterization; consider other approachesLocationProximal–short landing zone poses difficultyPatient's coagulation parametersDeranged–may prolong thrombosis with coils; glue is beneficial. Embolic MaterialsVarious embolic materials used in treatment of visceral artery pseudoaneurysms are coils, liquid embolics (glue, thrombin), gelfoam slurry and vascular plugs (,). The choice of embolics depends on various factors.Coils are permanent embolic agents made of stainless steel that is stiffer or the softer platinum (,).
They are available in various sizes (both length and diameter) and shapes. Fibered coils with multiple soft fibers increase thrombogenicity. Based on method of administration, they can be pushable, injectable or detachable.
Pushable coils are most commonly used. Detachable coils provide better control of deployment and are mostly used in the treatment of intracranial aneurysms. In visceral pseudoaneurysms, they may be used with sac packing or stent assisted coiling techniques (,).
Size (diameter) of the selected coil should be 20–30% larger than the size of the artery to allow adequate coiling and packing. Drawbacks of coils are non-target embolization, pseudoaneurysm rupture, infection and requirement of normal coagulation factors for successful embolization (,).N-butyl cyanoacrylate (glue) is a liquid permanent embolic agent that polymerises to form a cast when it comes in contact with anions (present in blood) (,). Lipiodol® (Geurbet, Hong Kong, China), an iodised oil emulsion, is used as a carrier for glue; when mixed with glue, it acts as a diluting agent that slows the rate of solidification and provides radio-opacification for the solution. Concentration of glue in the glue-lipiodol mixture determines the rate of polymerisation (,). Dextrose (5%), which is non-ionic, is used to flush the catheter before and after the administration of glue to prevent its polymerization within the catheter. Use of glue as an embolic agent requires expertise due to serious potential complications such as non-target embolization and catheter trapping or fragmentation.Lyophilised thrombin derived from human plasma is available in powder form (2500–10000 IU) and mixed with calcium chloride solution prior to use.
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Thrombin injection at a 100–1000 IU/mL concentration, causes activation of coagulation cascade, resulting in polymerization of fibrinogen to form fibrin clot (,). This is usually used for direct percutaneous embolization.
To prevent reflux of thrombin into systemic circulation, the neck of the pseudoaneurysm may be occluded with a balloon catheter placed endovascularly (,). Contraindications to thrombin include history of allergy and local infection. In addition to non-target embolization, allergic reaction, infection and recurrence due to collateral supply or high flow are frequent problems (,).Gelatin sponge, available as sheets or in powder form, is mixed with iodinated contrast medium to make pledgets or gelfoam slurry (,). It is a low cost, temporary embolizing agent that acts by causing mechanical obstruction. It is mainly used in emergency situations to control bleeding. The main disadvantages are non-target embolization and infection.Amplatzer vascular plug (St. Jude Medical, MN, USA) is an expandable three dimensional nitinol mesh occlusive device attached to the delivery system by screw (,).
Once in the desired position, the plug is deployed by unscrewing after unsheathing. The plugs are required to be oversized by a factor of 30–50% with respect to the size of the vessel to be embolized ; and may be used to occlude pseudoaneurysms arising from medium sized vessels (,). The advantages are control in deployment and high success rates. Despite the limitation of high cost of a single plug device, as compared to a coil, it could be cost effective in cases that require multiple coils. Patient PreparationPatient preparation is important prior to all radiological interventions (,).
The blood pressure is required to be within normal limits. The morning dose of anti-hypertensive medication is mandatory in hypertensive patients. Furthermore, if the blood pressure is high, sublingual nifedipine can be given.
Evaluation of the patient's coagulation parameters is necessary. Routine checking of prothrombin time, international normalized ratio and platelet count are sufficient. If deranged, fresh frozen plasma and single donor platelets can be transfused accordingly. Normal blood urea and serum creatinine are necessary; as well as obtaining any history of allergy to iodinated contrast agents. The puncture site requires preparation. In addition, informed consent should be obtained from all patients prior to performing the intervention.
Most of the procedures can be performed under local anesthesia. Endovascular ApproachEndovascular method is the common initial choice for embolization of a pseudoaneurysm. It better defines the vascular anatomy and hemodynamics of blood flow through the pseudoaneurysm prior to embolization and thus, helps in avoiding non target embolization (,).
Problems of endovascular embolization include difficulty in catheterization due to tortuous artery and difficult anatomy, short landing zone with risk of non-target embolization and inability to approach through previously blocked artery in cases of recurrent pseudoaneurysms.Coils or microcoils are the preferred and most widely used agents for embolization of a pseudoaneurysm (,). Coils act by slowing the flow by causing mechanical obstruction, inducing thrombosis via their thrombogenic fibres and by inciting inflammatory reaction. The main aim of coil embolization is occlusion of the pseudoaneurysm and its neck or its exclusion from circulation. Various techniques are described for embolization of a pseudoaneurysm using coils (,). These include sack packing, sandwich technique and proximal delivery.
Sack packing involves filling the pseudoaneurysm with coils or microcoils, typically using a coaxial technique. Sack packing is done for saccular pseudoaneurysms with narrow neck, which allows retention of coils within the sac maintaining the patency of parent vessel (,). The success of this technique depends on the coil packing density, although 80–90% packing is sufficient for pseudoaneurysms (,). There is however, a rare risk of secondary rupture of the pseudoaneurysm.
Sandwich technique is performed for pseudoaneurysms that are likely to have collateral inflow vessels. Here occlusion is done distal, across and proximal to the neck of the pseudoaneurysm blocking the efferent (back door) and afferent artery (front door). Embolization of only the parent or afferent artery will lead to incomplete embolization and recurrence due to retrograde filling from the efferent collateral. The efferent artery or back door is closed first, followed by afferent artery or front door. Splenic, hepatic and gastroduodenal artery pseudoaneurysms require embolization through the sandwich technique. This technique has clinical success rates of 90% (,). Proximal occlusion of parent or inflow artery is done for end arteries like renal arteries (,).
42-year-old male patient with acute pancreatitis, presenting with hematemesis and hemodynamic instability.DSA image showing short necked pseudoaneurysm (arrows) arising from gastroduodenal artery (A, B), which was subsequently packed with microcoils and embolized (C). Sac packing was made possible due to origin from branch of gastroduodenal artery, narrow neck, and ability to enter pseudoaneurysm with microcatheter.
Schematic diagram of sac packing (D). DSA = digital subtraction angiography.
Proximal occlusion. 30-year-old male presenting with hematuria and hypotension after percutaneous nephrolithotomy.A. DSA image showing pseudoaneurysm (arrow) arising from lower pole branch of renal artery. DSA image after embolization with proximal coil placement (arrow). As renal arteries are end arteries, proximal occlusion is sufficient to treat pseudoaneurysm. Schematic diagram of proximal delivery.
DSA = digital subtraction angiographyEmbolization with glue is not performed routinely due to higher risk of complications. However, it is useful when reaching the target site is not possible due to the presence of a tortuous artery, in cases of recurrent pseudoaneurysm after previous coil embolization, and in patients with deranged coagulation parameters, as coils need normal coagulation profile for thrombosis of the pseudoaneurysm (,). Interventional radiologist should understand the hemodynamics of blood flow in the source artery and pseudoaneurysm, in order to decide the glue-lipiodol mixture concentration, and amount and rate of injection, to avoid non target embolization. 26-year-old male patient with chronic pancreatitis, presenting with recurrent melena.A. DSA image showing left gastric artery pseudoaneurysm (arrow). Glue-lipiodol mixture was used to embolize pseudoaneurysm and post embolization DSA image (B) shows glue cast (arrowhead).
Coil placed in previous gastroduodenal artery pseudoaneurysm is also seen (block arrow). As pseudoaneurysm arose from close to celiac artery division, coil would have protruded proximally.
Glue was used to fill pseudoaneurysm successfully. DSA = digital subtraction angiographyPseudoaneurysms with wide neck have an increased tendency of migration of embolic material (,). To overcome this, stent graft (covered stent) placement, stent assisted coiling and balloon remodelling techniques are useful. These techniques also help in preserving the patency of parent artery. Stent graft is reserved for larger proximal arterial segments like main hepatic artery, main splenic artery and SMA as the stent deployment system cannot pass through small tortuous arteries (,). This technique has long term patency rates of about 82%.
Recently, flow diverting multi-layered bare stents is available, which facilitate slowing the blood flow within the visceral artery aneurysms and maintaining patency of the parent artery as well as any branches arising from or proximal to the aneurysm. Thrombosis of the aneurysm is seen in a high percentage (over 90%) of treated cases; and furthermore, in stent thrombosis and stenosis are complications seen in. Percutaneous ApproachPercutaneous embolization of pseudoaneurysms is conducted under either ultrasonography or CT guidance (,). It is usually used for cases of failed endovascular approach or pseudoaneurysms not accessible endovascularly (,).
This technique is usually performed for a pseudoaneurysm that is surrounded by solid organ, or a large pseudoaneurysm with adjacent scaffolding structures (,). The pseudoaneurysm is punctured using a 22 G Chiba needle under ultrasonography or CT guidance. Care should be taken to keep the tip of the needle away from the neck, to avoid non-target embolization.
Once within the pseudoaneurysm, embolizing agent is slowly injected preferably under guidance, until thrombosis of the pseudoaneurysm occurs. Thrombin, glue and occasionally coils are used as embolic materials (,).
Complications include rupture of the pseudoaneurysm, non-target embolization, and recurrence. Percutaneous approach for pseudoaneurysm embolization. 34-year-old female patient with pancreatitis, presenting with hemodynamic instability. DSA showed spastic splenic artery, which could not be catheterized.A.
Schematic illustration. Axial CTA image showing PsA arising from tortuous splenic artery (arrow). Ultrasonographic images showing anechoic PsA with color filling on Doppler image (arrow). Ultrasonography image after percutaneous embolization with glue showing thrombosis of PsA (arrow). CTA = CT angiography, DSA = digital subtraction angiography, PsA = pseudoaneurysm. EUS guided thrombin injection.
27-year-old male patient with pancreatitis, presenting with hematemesis. DSA and ultrasonography did not demonstrate pseudoaneurysm.A. Schematic diagram. Axial CT image in venous phase showing pseudoaneurysm (arrow) within pancreas.
EUS with color Doppler showing pseudoaneurysm with peripheral thrombus (arrows). Needle placed in pseudoaneurysm under EUS guidance prior to thrombin injection.
EUS image showing thrombosed pseudoaneurysm after thrombin injection (arrows). A = artery, DSA = digital subtraction angiography, EUS = endoscopic ultrasonography, PsA = pseudoaneurysm. ComplicationsComplications can be grouped into puncture site, intervention site and post-embolization complications (,).Puncture site complications include bleeding, hematoma, pseudoaneurysm formation, arterial thrombosis, arterio-venous fistula and nerve damage (,). Most of these complications are rare if proper puncture and compression after the procedure is done. Closure devices may also be used for hemostasis with good results.
Bleeding, which is more common with supra-inguinal punctures, should be managed by local compression, resuscitation and if necessary, balloon placement from contralateral side. Pseudoaneurysm formation is most often due to inadequate compression and use of anticoagulants, and is managed by ultrasound guided manual compression or percutaneous thrombin injection. Arterial thrombosis may require thrombolysis or thrombectomy.Intervention site complications include rupture of the pseudoaneurysm, arterial dissection, non-target embolization, distal migration of coil and straight deployment of coil (,). Rupture of a pseudoaneurysm during embolization is life threatening and immediate steps should be taken to control the bleeding. In these cases, immediate patient resuscitation with fluids is required; and an attempt must be made to occlude the site of rupture with glue or gelfoam.
Mostly this is sufficient, especially if rupture occurs during endovascular embolization. Rupture during percutaneous or EUS approach requires immediate endovascular or surgical treatment in hemodynamically unstable patients. Arterial dissection is often resolved by infusion of heparinised saline; however, stenting may be necessary if it involves a major artery.
Non-target embolization may result in end organ damage causing tissue infarction. Often, expectant management is sufficient. Splenic infarction may cause persistent pain or abscess, which may need splenectomy.
Bowel ischemia may require surgical intervention. Distal migration of coil occurs due to smaller size of coil and straight deployment occurs due to oversized coil. Complications of embolization.A. Coil embolization of pseudoaneurysm (arrow) with distal migration (arrowhead) into gastroepiploic artery due to undersize of coil. Oversized coil resulting in its straight deployment in inflow artery (arrowheads).
Arrow shows splenic artery pseudoaneurysm. Gastroduodenal artery pseudoaneurysm (arrow) with dissection (arrowhead). Rupture of renal artery pseudoaneurysm (arrow) with extravascular perinephric leakage of contrast (arrowheads). Non-target embolization due to reflux of glue (arrowheads) into splenic artery branches. Arrow points to splenic artery pseudoaneurysm. A = artery, GDA = gastroduodenal artery, PsA = pseudoaneurysmPost-embolization complications include secondary infection (commonly in gelfoam slurry due to trapped air bubbles) and embolization syndrome (pain, fever and vomiting). Recurrence of the pseudoaneurysm may occur secondary to its incomplete exclusion or collateral supply, and rarely migration of coils, and needs repeat embolization.An algorithm for embolization of visceral artery pseudoaneurysms is shown in.
Follow-UpFollow up is an important and integral part of management of pseudoaneurysms. Established imaging protocol for follow up of pseudoaneurysms after embolization is currently not available in the literature (,). Mostly, clinical assessment of symptoms of hemorrhage and vital parameters is sufficient to evaluate recurrence. Assessment by an imaging modality is also often necessary after embolization.
For pseudoaneurysms visible on ultrasonography, follow up with the same modality 24–48 hours after the procedure and possibly one month later is adequate. CTA is usually not required in asymptomatic patients, but becomes necessary when there is a strong clinical suspicion of recurrence and when pseudoaneurysm is inaccessible by ultrasonography.
Endovascular approach is the treatment of choice for recurrent pseudoaneurysms, and in failed cases, percutaneous or EUS approach may be attempted. Thus, follow up evaluation varies from case to case and initially includes clinical assessment, followed, if necessary, by ultrasonography or CTA. CONCLUSIONAll visceral artery pseudoaneurysms should be treated due to high mortality of rupture cases. Radiological intervention is the treatment of choice. The approach, technique and agents chosen vary with size of the pseudoaneurysm and its neck, location of the pseudoaneurysm, type of the source vessel, presence of collateral supply and individual preference and expertise of the interventionist. Endovascular approach is the preferred technique in most cases.
Percutaneous and EUS guided techniques are reserved for specific situations.
DSA SA58 carbine with rail interface, Leupold Mk4 CQ/T and Laser Devices MOLAD three-way targeting laser/white light. BOTTOM: SA58 carbine finished in Lauer Custom “Afghan Camo” Duracoat and EOTech Holosight.More and more police departments throughout the United States are choosing 5.56x45mm (.223 Remington) carbines for patrol.
This trend has been driven by a number of factors, not the least of which is the increased use of body armor by the “bad guys” and the increased lethality offered by the rifle caliber cartridge. Although the.223 is the primary small arms cartridge of the US military, the fact is that it is actually a “varmint cartridge” and in many states is illegal for deer hunting because the.223 lacks the terminal ballistics to ensure a clean kill of a deer. Given that a human is essentially a deer-sized target, state game laws prohibiting the use of the.223 for deer hunting calls to question its utility for law enforcement use. Indeed, the.223 has not acquitted itself especially well in Afghanistan, where reports are coming to light of enemy soldiers being shot repeatedly with M4 carbines and continuing to fight.
The.223’s lack of performance was also documented in the book Blackhawk Down, where it was noted in several instances that Somali gunmen were shot with M4 Carbines, but kept coming, necessitating that they be hit repeatedly to be stopped. Informal feedback from Afghanistan indicates that many wounds inflicted by the standard 62-grain military bullets are similar to those of a.22 Magnum. This lack of terminal ballistics has driven the special operations forces to adopt a new round for the M4, the Mark 262 Mod 0 5.56mm cartridge that fires a 77-grain bullet.
There is also experimentation underway for a new cartridge in the 6mm range for special operations use in the M4 carbine.For law enforcement use,.223 ammunition such as Black Hills 77-grain, Hornady’s TAP, or Winchester Ranger should be adequate for most situations, but there are times when a patrol carbine in a larger caliber is desirable, particularly in departments whose jurisdiction encompasses rural areas where distances are greater than in cities and units which require a weapon with terminal ballistics beyond those of the.223. For these situations, the.308 cartridge is an obvious choice. The ability of the.308 to penetrate targets that would defeat the.223 bullet is a clear advantage, although in some instances and with some types of ammunition, the.308 would overpenetrate. For law enforcement use,.308 match ammunition is probably a reasonable choice because its terminal ballistics are far superior to the.223.As overpenetration and ricochet are significant issues with law enforcement, it is well worth noting that limited penetration.308 ammunition is available from Black Hills Ammunition, which solves overpenetration concerns regarding the.308, while at the same time delivering very impressive terminal ballistics.
When fired into ten percent ordnance gelatin, Black Hills Limited Penetration.308 Match penetrated no deeper than 10 to 12 inches and left a very large permanent wound cavity. In our accuracy testing, this ammunition performed as well as standard match ammunition from both Black Hills and other manufacturers. The “downside” to Black Hills Limited Penetration ammunition is that it’s more expensive compared to standard.308 ammunition. With several agencies examining the potential of.308 patrol carbines, other manufacturers are developing not only limited penetration ammunition, but frangible ammunition as well.When it comes to selecting a patrol carbine in.308, one of the best is manufactured by DSA, Inc.
Of Barrington, Illinois. DSA makes what are arguably the highest quality FAL rifles in a variety of models that should satisfy any department’s requirements. The FAL is one of the few.308 rifles available as a lightweight carbine. The FAL design is a proven one and the rifle at one time was so widely used that it was referred to as “The Free World’s Right Arm.” Over 90 different countries adopted the FAL as their standard infantry rifle and it is still serving as such in some nations. The FAL carbine is extremely reliable and well suited for use as a patrol carbine, if the decision is made to go with a weapon that is more powerful than the.223. It handles extremely well and is only marginally heavier than most.223 carbines.
With their short 16-inch barrels, DSA’s carbines are also no larger than most.223 LE carbines.Author sends rounds downrange from SA58 Afghan Camo carbine. Gun DetailsFor the purposes of this evaluation, DSA provided us with two carbines that are intended for law enforcement use. Both are fitted with 16-inch barrels, but here the similarities end. One little FAL was fitted with a fluted barrel and MIL-STD-1913 rail mount receiver cover. It was then sent to Steve Lauer of Lauer Custom Weaponry for finishing using his proprietary Duracoat process in Desert Camouflage.Duracoat is an epoxy finish that adheres to metal, wood or synthetic materials and is highly resistant to oils, heat, marring or scratching. We should note that camouflage is being increasingly used by manufacturers and by the military.
The latter usually simply paint their weapons with standard issue camouflage paint. When the paint begins to chip, it is a simple matter to touch it up with spray cans. For a more durable finish, however, Duracoat seems to be about the best of its type available. In our experience, Duracoat seems almost impervious to rubbing or scratching.Like the rest of the rifle, the bolt of our carbine is finished in Duracoat and after several hundred rounds shows no signs of wearing away. Perhaps the best aspect of Duracoat is that it can be applied in a home environment, meaning that it isn’t necessary to send one’s firearm to Lauer to have the finish applied, although better results might be obtained by letting Lauer do the work. Duracoat is available in over 20 colors and can be applied in virtually any pattern imaginable.Duracoat finish in camouflage is permanent, which brings up the question as to why camouflage in the first place? News photos from Afghanistan show special operators with their weapons painted in camouflage colors.
For the operator, this is a virtual necessity because nothing in nature is black with straight lines. A black rifle or carbine stands out like the proverbial sore thumb; hence, camouflage is applied so that the weapon blends in with its background. The same rule is applicable to law enforcement users, who may wish to decrease their threat profile by making their “long gun” blend in with its background. The second DSA FAL carbine was furnished in standard black. It also had the MIL-STD-1913 receiver cover, along with the company’s FAL Rail Interface forearm.
This enables one to add any number of accessories, such as lasers, white lights and vertical handgrips. The second carbine also came equipped with an integral muzzle brake and grip sleeve. Both carbines were fitted with a “Snap Sling” tactical multi-position heavy duty 1.5-inch wide sling that carries the carbine “hands free” across the chest in a ready position but allows deployment directly into firing position with no adjustments. This is thanks to a metal clip that keeps the sling snug and in an upright position against the user’s body, but releases the sling for instant use as the carbine is brought to a firing position against the shoulder.Optics DetailsWe fitted the desert camouflage carbine with an EOTech Holosight that we sent to Steve Lauer so that it matched the carbine. The Holosight uses a laser to project a holographic reticle onto a window of hardened glass in much the same way that a heads-up display weapons sight is used in fighter aircraft. The Holosight ring subtends 65 MOA and the aiming dot of one MOA.
The “dot and ring” holographic image is parallax free and can be used even if the glass is partially obscured or broken. The night vision capable Holosights have ten levels of night vision intensity built in. The Holosight has no illuminating signature, as it does not project any light forward towards the target.We also equipped the black DSA carbine with an optical sight, the Leupold’s Mark4 CQ/T 1-3x optic. Like the Holosight, the CQ/T uses a “dot and ring” reticle that’s etched onto the glass.
The ring subtends 18 inches at 25 yards and six feet at 100 yards when the scope is set on 3x. The dot is three MOA at 3x and nine MOA at 1x. The CQ/T is especially well suited to a.308 carbine like the DSA because it can be used from CQB ranges out to medium ranges of 200 yards and beyond.
Both sights offer the user the advantage of rapid target acquisition. To use either sight, all that’s necessary is to look at the target with both eyes open and raise the rifle to a firing position. The reticle is almost instantly superimposed over the target by the shooter’s eye. Since the eye has only to accommodate two elements, the reticle and target, sight alignment is automatic and instinctive with sights such as the Holosight and CQ/T.In addition, we installed DSA’s “black” carbine with the latest product from Laser Devices, the innovative MOLAD, or Multi-Operational Laser Aiming Device. This unique device incorporates a high-intensity (95 lumen) white light, a visible laser aimer, an IR laser aimer and LED illuminator in an extremely lightweight and compact package.
The white light can be focused from a narrow spot to a diffuse beam to illuminate a broader area. The MOLAD is activated via toggle switches on either side of the housing, or via a remote press pad. The MOLAD is completely waterproof and the laser aimers are fully adjustable for windage and elevation.
Besides the rifle mount we used, the MOLAD can be quickly attached or detached from any MIL-STD-1913 rail mounting system. Because of its light weight and compact size, the MOLAD is particularly well suited for handgun applications. Mounting and removal is accomplished via proprietary rail “grabbers” that can be released by simply pressing them. There are no screws, knobs or levers to worry with. Once the “grabbers” are locked in place, unintentionally pressing both to cause the MOLAD to fall off is virtually impossible.
Because it incorporates three different types of illumination, the MOLAD enables an operator to move from low light using night vision to a bright white tactical light at the touch of a finger. Further, the MOLAD can be switched between any possible operational configuration via the rotary mode switch. Changing from IR to visible light is accomplished via a small recessed toggle switch at the right side of the device. The MOLAD weighs only 7.5 ounces, 4.5 inches in length, 2 inches high and 1.5 inches wide. We predict that the versatile MOLAD will find widespread acceptance in the military and law enforcement communities.
Tools of the trade: SA58 Rail Interface carbine, SWAT gear and test ammo from various manufacturers.We evaluated DSA’s carbines at 50 yards because the vast majority of law enforcement engagements take place within this distance. Instead of structured testing from a bench rest or the prone position, we conducted our test firing over the hood of a police cruiser, a much more realistic scenario for carbines such as these. The DSA carbines delivered excellent accuracy and flawless performance, although the short barrel length made for a distinct muzzle blast. We obtained our best accuracy with Black Hills, Hornady Tactical Application Police (TAP) and Remington match ammunition, although the carbines delivered acceptable accuracy with all types of ammunition tested.
Complete accuracy results can be found in the chart.In the final analysis, DSA’s FAL carbines are the ideal size and weight for patrol carbines. The proven.308 cartridge is available in a great variety of law enforcement loads, including both limited penetration and frangible loadings for those situations where overpenetration or ricochets are concerns.
Even in these specialized loads, the.308 outperforms the diminutive.223 in terms of both range and terminal ballistics.DSA’s carbines are especially useful for agencies that operate in both urban and rural environments. They should be one of the first choices for agencies whose jurisdictions encompass only rural areas where a compact powerful carbine is a virtual necessity due to possible encounters with large dangerous targets of both the four and two-legged varieties.