Jump to
A pseudoaneurysm (PSA) is a contained rupture; there is a disruption in all 3 layers of the arterial wall (Figure 1). PSAs may occur under 4 circumstances: (1) after catheterization (Figure 2); (2) at the site of native artery and synthetic graft anastomosis (eg, aortofemoral bypass graft); (3) trauma; and (4) infection (eg, mycotic PSA) (Figure 3). This review will focus on PSAs that occur after cardiac and peripheral endovascular procedures. PSAs occur when an arterial puncture site does not adequately seal. Pulsatile blood tracks into the perivascular space and is contained by the perivascular structures, which then take on the appearance of a sac. Hematoma and the surrounding tissue form the wall of the PSA.
Figure 1. Artist’s rendition of a postcatheterization PSA with proper placement of the needle for thrombin injection. There is a disruption in all 3 layers of the arterial wall. In essence, this represents a contained rupture.
Figure 2. Arteriogram that demonstrates an axillary artery PSA after a diagnostic arteriographic procedure. Note the disruption in the vessel wall (white arrow) and the larger PSA sac (black arrow).
Figure 3. Ultrasound of a spontaneous PSA in the left brachial artery. Note the absence of a tract. The PSA chamber is directly connected to the brachial artery. This type of PSA must be treated surgically. This patient had infective endocarditis.
Postcatheterization PSA is one of the most common vascular complications of cardiac and peripheral angiographic procedures. The incidence of PSA after diagnostic catheterization ranges from 0.05% to 2%.1 When coronary or peripheral intervention is performed, the incidence increases to 2% to 6%. In 1 series where diagnostic ultrasound was performed on 536 consecutive patients who underwent catheterization, the incidence of PSA was 7.7%, with 83% of the PSAs associated with interventional procedures.2 Despite a low incidence, PSAs are commonly encountered when more complex coronary and peripheral interventions are performed, especially with the use of potent antithrombotic and antiplatelet therapy. Since 1996, the number of peripheral interventions has more than doubled to an estimated 750 000 procedures in 2005.3 In 2003, the Centers for Disease Control/National Center for Health Statistics estimated 1.4 million inpatient diagnostic cardiac catheterization procedures, and 1.2 million angioplasties were performed in the United States.4
It has been suggested that PSAs may thrombose spontaneously. In 1 study, spontaneous thrombosis occurred in 72 of 82 patients with PSA <3 cm at a mean of 23 days,5 whereas in another prospective study only 9 of 16 patients had spontaneous thrombosis at a mean of 22 days. Failure to thrombose was associated with size >1.8 cm and concomitant use of anticoagulation or antiplatelet agents.6 Most of the studies that suggested observation occurred prior to the era of aggressive antithrombotic and dual antiplatelet therapy. The rate of spontaneous thrombosis in patients who take aspirin+clopidogrel or warfarin is really not known. In the absence of severe pain, observation of small PSAs (<2.0 cm) is reasonable. However, if the patient has severe pain, treatment is indicated.
The most catastrophic complication of PSA is rupture. Although the exact rate is unknown, the risk of spontaneous rupture of PSA is related to size >3 cm, presence of symptoms, large hematoma, or continued growth of the sac.5,7,8 Although most postcatheterization PSAs are sterile, infection of a PSA significantly increases the risk of rupture as well as septic emboli.9
Factors Associated With Pseudoaneurysm Formation
Several patient and procedural factors may contribute to the formation of PSA as shown in Table 1.10 Of particular importance is the increased incidence of femoral artery PSAs when the puncture site is not in the common femoral artery, but rather is located in the superficial or deep femoral artery or the external iliac artery.11 The complexity of interventions such as coronary stenting, atherectomy, intraprocedural thrombolytic therapy, and repeat coronary angioplasty has also been shown to increase the risk of vascular complications.12,13 In a meta-analysis of randomized trials, there was no increased vascular complication rate with Angio-Seal (St. Jude Medical, St. Paul, Minn) or Perclose (Abbott Vascular Devices, Redwood City, Calif) for patients who underwent either diagnostic catheterization or percutaneous coronary intervention.14 There was an increase in the vascular complication rate with VasoSeal (Datascope Corp, Montvale, NJ) (odds ratio, 2.25; 95% CI, 1.07 to 4.71). This study did not report the PSA rate, only the total vascular complication rate, a composite of PSA, arteriovenous fistula, retroperitoneal hematoma, femoral artery thrombosis, surgical vascular repair, access site infection, and blood transfusion.14 In a meta-analysis that was performed by Koreny and associates and involved 30 trials and up to 4000 patients, closure devices showed a relative risk of PSA formation of 1.19 (95% CI, 0.75 to 1.88; P=0.46). However, in the 2 studies that reported intention-to-treat analysis, the occurrence of PSA formation was 5.4 times greater with the use of closure devices compared with manual compression.15 There are no good prospective data to predict who will develop a PSA. However, it makes intuitive sense that the accuracy of the initial puncture and the expertise and duration of compression of the puncture site after the sheath is removed may be important factors in the development of PSAs. Vascular complications are less common when the interventionalist uses ultrasound16 or fluoroscopy with localization of the femoral head17 to puncture the femoral artery in the correct location and with the first attempt (eg, no posterior wall puncture, especially in obese patients and those with weak pulses.18
TABLE 1. Factors Associated With the Formation of Pseudoaneurysm
Diagnosis
The presence of pain or swelling in the groin after catheterization is the most common presentation of a PSA. Swelling from a large PSA or hematoma may also lead to compression of nerves and vessels with associated neuropathy, venous thrombosis, claudication, or, rarely, critical limb ischemia. Local ischemia of the skin may lead to necrosis and infection. On physical examination, there may be a palpable pulsatile mass or the presence of a systolic bruit. However, it should be noted that none of these aforementioned physical findings may be present. Any patient who experiences pain that is disproportionate to that expected after a percutaneous procedure should undergo an ultrasound examination to exclude the presence of a PSA regardless of the presence of a bruit.
The diagnostic examination of choice is duplex ultrasound with a 5- to 7-MHz linear transducer. If the puncture site is high (eg, external iliac artery) or there is extensive hematoma, a lower frequency transducer (curved linear or sector array) may be required to image deeper structures. B-mode scanning alone is unable to differentiate PSA from hematoma (Figure 4). Color Doppler enhances the diagnostic accuracy of ultrasound by identification of pulsatile flow within the sac (Figure 5A).19 The sensitivity of duplex ultrasound to identify a PSA is 94% with a specificity of 97%.20
Figure 4. B-mode ultrasound of PSA with echolucent sac. The only way to tell if this is a PSA or a hematoma is to use color Doppler. If flow is present, it is a PSA. If flow is absent, it is consistent with a hematoma.
Figure 5. A, Color ultrasound of PSA. There are 2 chambers and a long track that connects the artery to each of the chambers. There is marked turbulence (not visualized on this still image) within the track and the chamber. B, When a pulsed-wave Doppler is placed in the PSA tract, one can see the typical “to and fro” signal that indicates that blood flows (often at a very high speed) both into and out of the PSA chamber. This is diagnostic of a PSA.
The typical appearance of a PSA on ultrasound is demonstrated in Figures 4 and 5⇑. The B-mode image shows an echolucent sac that expands and contracts with cardiac contraction (Figure 4). On color Doppler, there is a swirling flow pattern with turbulence in the chamber(s), there may be 1 or more chambers noted. A tract connects the PSA chamber to the feeding vessel (most commonly the common femoral artery) (Figure 5A). When a pulsed wave Doppler is placed within the track, a “to-and-fro” signal is obtained, which signifies that this is in fact a PSA (Figure 5B). In addition to identification of the number, size, and depth of the chambers of the PSA, the depth, width, and length of the tract that connects the artery to the PSA should be identified. It is also important to clearly identify the vessel that feeds the PSA in both transverse and long-axis views as well as record flow in the vessel proximal and distal to the PSA. The venous structures should be clearly identified to rule out the presence of a deep venous thrombosis secondary to prolonged compression on the groin or pressure from an expanding hematoma. There are an increasing number of procedures performed from the arm, which thus increases the likelihood of PSAs in this location. The same principles apply to diagnosis and treatment of PSAs in the arm and leg.
One common mistake during ultrasound examination is to image too superficially. It is important to increase the depth on the ultrasound machine so that deep PSAs (>4 cm from the skin) are not overlooked. A complete examination should include imaging of the mid and distal external iliac artery, common femoral artery, and proximal portions of the superficial femoral and profunda femoral arteries.
Treatment
Until the early 1990s, the only treatment available for PSA was surgery. Since that time, ultrasound-guided compression (USGC) repair, ultrasound-guided thrombin injection (UGTI), and a whole host of other treatment modalities such as FemStop compression devices,21 coil insertion,22 fibrin adhesives,23 or balloon occlusion have been used with variable success. The 3 most common treatment strategies are discussed below in more detail.
Surgical Management
Surgical management of PSA is still an important and necessary management strategy in a minority of patients with PSA (Table 2). Any PSA that occurs at the site of a vascular anastomosis (eg, aortobifemoral bypass) should be repaired surgically because it results from a disruption at the suture site and may be caused by infection. Likewise, spontaneously occurring PSAs are often mycotic (Figure 3) and should be repaired surgically. Compression on underlying structures by an expanding pulsatile mass, which causes claudication, neuropathy, or critical limb ischemia, requires urgent surgical decompression and resection of the PSA. Rarely, the PSA is so large that it has or will cause skin necrosis. In this situation it is imperative to decompress this area surgically.5,10,24 However, surgery is rarely employed to treat the usual postcatheterization PSA. The disadvantages of surgery for the treatment of PSA are that it requires anesthesia and an incision usually in the groin, an area known to become infected easily after a surgical procedure. Lumsden and colleagues reported a surgical complication rate of 20% after PSA repair. Complications included bleeding, infection, neuralgia, prolonged hospital stay, perioperative myocardial infarction, and, rarely, death.25
TABLE 2. Indications for Surgical Repair of Pseudoaneurysm
Ultrasound-Guided Compression
In 1991, Fellmeth and associates introduced a safe and noninvasive method to treat PSA: USGC.26 USGC has been shown to have a success rate of 75% to 98%.27–29 With the use of ultrasound to identify the chamber and tract of the PSA, the ultrasound transducer is positioned and pressure is applied to compress the chamber and tract while flow in the native artery is allowed. Direct ultrasound visualization confirms cessation of flow into the PSA. Compression is usually held for cycles of 10 minutes. This can be repeated until success or until a discretionary failure time. Although it would be advantageous to use manual compression devices, the vertical angle created by the device does not allow selective compression of the PSA chamber and tract. Nonselective compression leads to longer compression times, more discomfort to the patient, and a lower success rate, in addition to an increase in the likelihood of complications such as deep venous thrombosis.29 Body habitus, size, depth, and number of chambers, as well as concurrent anticoagulation may limit the success of USGC.
In patients on anticoagulation, the success has been reported to be in the range of 30% to 73%.27,30 Two series from the same institution evaluated the role of USGC of postcatheterization PSAs in patients who did not receive anticoagulation and in those who did.30,31 In the first 100 cases of postcatheterization PSA, USGC was immediately successful in 94 patients (94%), which included 30 (86%) of 35 patients who received anticoagulation and 64 (98%) of 65 patients who were not on anticoagulation. There were recurrences in a total of 10 patients who subsequently underwent repeat USGC8 or surgery.2 We later demonstrated that USGC was successful in 56 (73%) of 77 patients who received anticoagulation. Seven (12.5%) of these patients required 2 or 3 compression attempts to induce sustained thrombosis.30 There were no significant complications reported in either of these studies.
The main limiting factor in USGC is the time it takes to induce sustained thrombosis. The average compression time to achieve occlusion was 33 minutes with a range of 10 to 120 minutes.31 This is a very painful procedure for the patients, and they often have to be pretreated with narcotic analgesia. In addition, it is hard work for the physician or ultrasound technologist who must apply constant hard pressure over the groin. It is difficult to maintain pressure in the correct position for prolonged periods of time. Rare complications have been reported such as vasovagal reactions, PSA rupture, skin necrosis, and deep vein thrombosis, although we have not experienced this in our large series.30,31
Ultrasound-Guided Thrombin Injection
UGTI has become the treatment of choice for postcatheterization PSAs.32–34 Percutaneous coagulation of a PSA was first reported by Cope and Zeit in 1986.35 The procedure was later adapted to utilize ultrasound guidance with the injection of thrombin.36 It should be noted that this is off-label use of thrombin. There is a warning on the thrombin package that states “for topical use only, not for injection”. The principle of thrombin injection into the PSA chamber is based on the fact that thrombin is important in the conversion of fibrinogen to fibrin. Thus a fibrin clot is formed instantaneously (even in the presence of antiplatelet therapy or anticoagulation therapy) with UGTI, whereas it may take up to several hours with USGC. Success ranges from 91% to 100% in large series.32,37–49 More than 45 individual series have been published on the safety and efficacy of this therapy. The cumulative overall success rate in 1329 PSA injections was 97%. Table 3 reports the success and complications in the largest series.32,37–49
TABLE 3. Summary of Ultrasound-Guided Thrombin Injection Series
Bovine thrombin, manufactured by GenTrac, Inc (Middleton, Wis) and distributed by Jones Pharma Inc (Bristol, Va), is available in a commercial kit, and it is generally reconstituted in normal saline to a concentration of 1000 U/mL. Several authors have advocated lower concentrations of thrombin (eg, 100 U/mL)50,51 or the use of human thrombin because of the theoretical concept that it may produce a lower likelihood of allergic reactions.44,49 In >400 thrombin injections, we have not experienced an allergic reaction to bovine thrombin.
Technique of Ultrasound-Guided Thrombin Injection
After informed consent is obtained, duplex ultrasound is performed as previously described. Distal pulses are confirmed manually and documented. The injection site is prepared in a sterile fashion, and local anesthesia is used with 1% to 2% lidocaine infiltrated into the skin and subcutaneous tissue.
Several injection techniques have been reported in the literature, but the technique that we use is the 3-way stopcock technique (Figure 6). This technique alleviates the need to change syringes during the procedure (Table 4).32 Normal saline is placed into a 5-mL syringe via a 22-gauge needle. Three milliliters of bovine thrombin is placed in the other syringe, and they are connected to the 3-way stopcock. For most injections, a 1.5-inch 22-gauge needle is used. If the PSA is deeper than 3.75 cm, a 21 gauge × 9 cm Echotip (Cook Inc., Bloomington, Ind) needle that can be visualized under ultrasound will be used. With the thrombin “off” and the saline “on,” the needle is advanced under ultrasound guidance. The needle and transducer are positioned in parallel to puncture the PSA chamber as superficial and far from the PSA tract as possible. Although the needle tip may sometimes be visualized on B-mode imaging, confirmation of proper needle placement is made with aspiration of arterial blood and small injections of saline to produce a flash of color within the chamber and allow direct visualization of the needle tip. Once appropriately placed, the thrombin port is turned “on” and the saline port “off”. Aliquots of 0.2 mL are injected into the PSA chamber and visualized with color Doppler until no flow is observed. This usually occurs within seconds (Figure 7). The goal is to produce complete obliteration of flow in the chamber and tract. However, if tract flow continues, it usually disappears by the time the ultrasound is performed the next day. Under no circumstances should an injection be made directly into the tract, as this will increase the likelihood of thrombosis of the native artery. There is some controversy about how to approach patients with >1 chamber. Injection into the deeper chamber will almost certainly cause all other chambers to thrombose. However, the needle placement is closer to the native artery, and the potential for complications may be higher. We prefer to inject into the most superficial chamber first. This usually results in thrombosis of all chambers. However, if flow is still present in the deeper chambers, a second injection may need to be performed. Less than 1 mL of thrombin is used in virtually all cases, and many PSAs can be completely thrombosed with as little as 0.2 to 0.4 mL. Steps utilized in the 3-way stopcock technique are summarized in Table 4.
Figure 6. Three-way stopcock for UGTI.
TABLE 4. Three-Way Stopcock Technique
Figure 7. A, PSA that arises from the common femoral artery. There is a thrombus in the PSA (black area around the color), and the color represents flow (2.0×1.8 cm) into the PSA. B, Image after UGTI. Note the thrombus present. There is no flow within the chamber.
Results of Thrombin Injection
The primary success rate is very high at 91% to 100% (Table 3). In our early series of 70 consecutive patients who underwent UGTI, the PSA arose from the distal external iliac artery in 11%, common femoral artery in 65%, superficial femoral artery in 16%, profunda femoral artery in 4%, and brachial artery in 3%. A total of 66 of 70 patients (94%) had complete thrombosis of the PSA with thrombin injection; 20 of 21 anticoagulated patients (95%) had successful thrombin injections.32 In this early series, 2 of the failures were in patients after aortic stent graft insertion, and the PSA tract was short and wide. The third failure was the first patient in the series and was likely a technical failure as a result of inexperience with the technique. Occasionally, the majority of the PSA thromboses but a small portion remains patent. In these situations, we use compression immediately after thrombin injection to manually disperse the thrombin into the open portion of the PSA.52
After cessation of the flow in the PSA, preservation of distal pulses should be documented if they were present prior to injection. Pulsed-wave and color Doppler flow should be documented in the artery and vein proximal and distal to the PSA and compared with images recorded prior to the intervention. Although bedrest is not required after injection, it is advisable to recommend avoidance of strenuous activity for 24 hours. We treat many of these patients as outpatients and let them ambulate immediately after the procedure. There is a recurrence rate of 0% to 9% when imaged the next day (Table 3). A follow-up duplex ultrasound is obtained within 24 to 72 hours after thrombin injection. Recurrence of PSA can be treated with a second (or third) injection with excellent results.
The most serious complications associated with thrombin injection are the development of deep venous thrombosis (if the thrombin is inadvertently injected into the vein), pulmonary embolism,45 or thrombosis of the artery (if thrombin is injected into the PSA tract or the artery itself). This is most likely to occur if an injection is made directly into the neck of the PSA.36,41 Although some clinicians take the patient immediately to surgery should this complication occur, other patients have been observed while anticoagulated and reported spontaneous resolution with no significant clinical sequelae.46,53,54 Although it has been suggested that short wide tracts may increase the risk of thrombin injection, we have not altered our indications on the basis of the tract anatomy and have not experienced an increased complication rate in our large series.
Allergic reactions and anaphylaxis have been reported in patients previously exposed to bovine thrombin.42,55,56 Pope and Johnston recommend skin testing in patients with prior exposure to bovine thrombin;55 this has not been observed in most reports and rarely skin testing is performed. There have been previous reports of antibodies that form against bovine factor V contamination of thrombin preparations. This has potential for serious hemorrhagic complications in humans; however, it has not been observed in any of the series of patients treated with UGTI. The overall complication rate from UGTI is 1.3% with an embolic rate of 0.5% (Table 3). There is a definite learning curve, and the reported embolic complications are quite rare as one gains more experience with the technique of injection.
Contraindications to Ultrasound-Guided Thrombin Injection
Thrombin injections should only be performed in patients who develop PSA secondary to a catheterization procedure. If a PSA occurs spontaneously, a mycotic PSA (Figure 3) should be suspected, and UGTI should not be undertaken. Additionally, a PSA that occurs at the anastomosis of a synthetic graft and native artery should be treated surgically and not with UGTI. The size of the PSA chamber is not, in of itself, a contraindication to UGTI. However, if the PSA is large enough to cause skin necrosis or compression of nerves or blood vessels, then surgery should be performed instead of thrombin injection (Table 2).
Special Circumstances
Occasionally a PSA is noted on the completion angiogram, prior to removal of the sheath. If this occurs, there are several techniques that can be utilized to correct the situation at that time. Covered stents and coils have been utilized with good results.57,58
Prevention
There are no prospective studies that have addressed measures to prevent the formation of PSA. More complex procedures and more potent antithrombotic therapy have led to the occurrence of more frequent PSA formation. The most important strategies to prevent PSA formation are:
Assure a needle puncture in the proper location with the use of either fluoroscopy or ultrasound, thus achieve vascular access on the first puncture without access through the posterior wall.
Appropriate groin compression after sheath removal. Adherence to the first makes this accomplishment easier.
Conclusion
PSAs are common after catheterization procedures. Duplex ultrasound is the diagnostic method of choice because it is noninvasive, accurate, and cost-effective. Surgical repair of PSAs is rare but is indicated in patients who exhibit rapid expansion, infection, compression syndrome, or failure of UGTI. UGTI has an excellent primary success rate of 97% and a low complication rate of ≤1.3%. Proper technique with adequate ultrasound visualization of thrombin injected into the PSA will minimize embolic complications. Although USGC is safe and successful, procedural limitations have made UGTI the technique of choice for first-line management of PSAs that occur after percutaneous catheterization procedures.
Acknowledgments
Disclosures
None.
References
This Issue
Jump to
Article Tools
Share this Article
- Contemporary Management of Postcatheterization PseudoaneurysmsPermalink:
