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Vascular and Interventional Radiology |
1 From the Departments of Radiology (K.K., M.Z., A.G., O.S., D.S., K.L.), Internal Medicine (F.D.S.), and Cardiology (C.F.), University of Cologne, Joseph-Stelzmann-Strasse, D-50924 Cologne, Germany. Received December 28, 2001; revision requested February 27, 2002; revision received April 4; accepted June 5. Address correspondence to K.K. (e-mail: karsten.krueger@uni-koeln.de).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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MATERIALS AND METHODS: Fifty femoral pseudoaneurysms (37 simple pseudoaneurysms with one lobe and 13 complex pseudoaneurysms with two or three lobes) were treated with US-guided percutaneous thrombin injections. Pseudoaneurysm size, neck length and width, thrombin dose, outcome of therapy, and complications were documented prospectively. Duplex sonographic follow-up examinations were performed at 12–24 hours and 5–7 and 21–25 days. In 25 patients, activated thromboplastin time, Quick test (prothrombin time), thrombin time, fibrinogen, D-dimer, antithrombin III, thrombin–antithrombin III complex, and prothrombin fragments 1 and 2 were determined before and at 2, 5, and 10 minutes after thrombin injection. Differences in results before and those after thrombin injection were evaluated by means of the one-sample t test.
RESULTS: Mean volume of pseudoaneurysms was 5.84 cm3 ± 4.89 (SD). Fifty-eight thrombin injections were performed. Mean thrombin dose was 357 IU ± 291 in simple and 638 IU ± 549 in complex pseudoaneurysms. Primary success rate was 36 of 37 (97%) for simple and eight of 13 (61%) for complex pseudoaneurysms. Reperfusion occurred in four complex pseudoaneurysms (none in simple ones). Secondary success rate was 100%. No thromboembolic, infectious, or allergic complications occurred. During follow-up, reperfusion was detected in one patient with a complex pseudoaneurysm. Levels of thrombin–antithrombin III complex increased significantly (P < .05) after thrombin injection, whereas changes in all other laboratory tests were not significant.
CONCLUSION: US-guided percutaneous injection of thrombin is successful and safe in the management of femoral pseudoaneurysms. The increase of thrombin–antithrombin III complex indicates the possibility of thrombin passage into the arterial circulation.
© RSNA, 2003
Index terms: Aneurysm, femoral, 921.1279, 921.732, 922.1279, 922.732, 923.1279, 923.732 • Aneurysm, therapy, 921.1279, 921.12986, 922.1279, 922.12986, 923.1279, 923.12986 • Interventional procedures, complications, 921.1279, 921.732 • Ultrasound (US), guidance, 921.12986, 922.12986, 923.12986
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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Iatrogenic pseudoaneurysm is one of the most common complications secondary to radiologic and cardiac catheterization (12). While the complication rate for diagnostic examinations is barely 1% (12,13), the incidence increases to 3.2%–7.7% in interventions in which large-bore sheaths are used because of the longer indwelling time and postinterventional anticoagulant and antiplatelet therapies (12,14).
In the management of pseudoaneurysms, ultrasonographically (US) guided compression repair combined with surgical revision has become an established method. Its success rate decreases, however, when anticoagulation is given from over 90% (15) to 62%–73% (16,17). Additionally, not all patients tolerate the compression, which is usually time consuming and can be painful (6,18). The use of thrombin has allowed successful repair of pseudoaneurysm in the inguinal region in 93% (19) to 100% (6,20,21) of patients. Even in patients treated with anticoagulant or antiplatelet therapy, the success rate was higher than that with compression alone (6,9,20,21).
The technique used in the current study to treat pseudoaneurysm with thrombin involves the percutaneous puncture of the pseudoaneurysm lobe. While small volumes of thrombin are injected, the flow within the pseudoaneurysm lobe is visualized directly with color duplex US.
A pseudoaneurysm is characterized by blood inflow from and outflow into the feeding artery. However, the neck of the aneurysm is not compressed regularly during the injection of thrombin. Thus, as a result of injecting thrombin into the pseudoaneurysm lobe, it is likely that thrombin will enter the arterial circulation, which leads to the risk of thrombus formation and allergic reactions.
To our knowledge, there have been no studies to date on the frequency of thrombin extravasation from the pseudoaneurysm lobe, and we should not rule out the fact that thrombin might extravasate during or after injection. Thromboembolic complications after injection of thrombin into the pseudoaneurysm were described in single cases in the literature (5,8,21–24). Indeed, the thrombin antagonist antithrombin III, which circulates in the blood, can completely abolish the clotting effect of thrombin. An increase in blood levels of thrombin would lead to an elevation in the concentration of the thrombin–antithrombin III complex, but this would not lead invariably to simultaneous clot or thrombus formation.
The purpose of this study was to determine the success rate of percutaneous US-guided thrombin injection in the treatment of femoral pseudoaneurysms and to evaluate the effects of thrombin injection on systemic coagulation parameters.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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Imaging and Procedures
Diagnostic imaging and US-guided injection of the pseudoaneurysm were performed with a 5-MHz transducer (Elegra; Siemens Medical Systems, Erlangen, Germany). In nine patients with extensive inguinal hematomas, a 3.5-MHz transducer was also used to achieve better visualization of aneurysmal geometry and the position of the pseudoaneurysm in relation to the artery.
Before the injection, the aneurysmal geometry and position were documented prospectively, along with the following parameters: (a) number of pseudoaneurysm lobes (simple pseudoaneurysm, one lobe; complex pseudoaneurysm, two or more lobes separate from each other; with the lobe located closest to the artery defined as the proximal lobe and that located farthest away defined as the distal lobe), (b) lobe volume (length x height x width x 0.523), (c) position of the pseudoaneurysm lobes in relation to each other in complex pseudoaneurysms, and (d) length and width of the pseudoaneurysm neck.
Lyophilized, sterilized, and virus-inactivated bovine thrombin (1,000 or 5,000 IU) (Jones Medical Industries, St Louis, Mo) was dissolved in 1 mL of isotonic saline (5,000 IU in 5 mL of isotonic saline) and drawn into a 1-mL syringe (ie, 0.1 mL was equivalent to 100 IU of thrombin).
Before the injection, the spectrum and peak blood flow in the ipsilateral anterior and posterior tibial arteries were determined with duplex sonography at the level of the upper subtalar joint. The local anesthetic (Scandicain 1% [5 mL]; AstraZeneca, Wedel, Germany) and thrombin were injected in sterile conditions by one of four interventional radiologists (K.K., M.Z., A.G., O.S.). The thrombin was injected with a 20-gauge spinal needle that was 89 mm long (Dahlhausen, Cologne, Germany) or a 22-gauge polymer-coated Chiba needle that was 90 or 150 mm long (Cook, Mönchengladbach, Germany), which was advanced toward the pseudoaneurysm in a direction that was longitudinal to the transducer. The puncture was made as far caudal from the aneurysm as possible to keep the puncture needle parallel to the transducer surface. This enabled better sonographic identification of the injection needle.
The puncture was depicted in the gray scale without color coding. The tip of the needle was positioned in the lobe of the pseudoaneurysm. The location of the aneurysmal neck opening or the flow patterns within the pseudoaneurysm lobe did not affect positioning of the injection needle. After the position of the needle tip in the pseudoaneurysm lobe was documented with gray-scale and color-coded US, thrombin was injected in incremental doses of 100 IU (0.1 mL) with color-coded US guidance set at a low pulse repetition frequency. The individual injections could be monitored by watching the "bursts of color" at the tip of the puncture needle. The injections were performed one after the other until the color signal had disappeared completely. The thrombin dose was recorded. The pseudoaneurysm neck was not compressed during the thrombin injection.
For the repair of complex (ie, multilobulated) pseudoaneurysms, we tried to puncture the proximal pseudoaneurysm lobe. We assumed that with occlusion of the proximal lobe, the lobes located more distally would also occlude.
If it was technically not possible to puncture the proximal lobe, we punctured the next closest distal lobe. This problem appeared in patients with concomitant inguinal hematomas with the proximal lobe located deep under the skin. In these cases, the puncture angle increased, with the consequence of poor identification of the tip of the puncture needle at US. The technique for injecting thrombin was identical to that described earlier.
Ten minutes after injection, the following parameters (1) were examined with color-coded duplex sonography and documented: (a) extent of thrombosis in the pseudoaneurysm lobe(s), (b) extent of residual perfusion in the pseudoaneurysm lobe(s), (c) perfusion in the neck of the pseudoaneurysm, and (d) perfusion in the artery that fed the pseudoaneurysm.
Additionally, the duplex sonographic determinations of the spectrum and peak blood flow in the ipsilateral anterior and posterior tibial arteries at the level of the upper subtalar joint were repeated. A dressing was wrapped around the thigh, and all patients had bed rest following the procedure until the first sonographic follow-up examination at 12–24 hours after thrombin injection.
Color-coded duplex sonography was performed to determine the same parameters at 12–24 hours after the first thrombin injection. If there was still evidence of perfusion in one of the pseudoaneurysm lobes, we injected another dose of thrombin as described earlier. If the pseudoaneurysm neck was still open, a new dressing was applied, and the patients were assigned bed rest. Whenever thrombin injections were repeated or the pseudoaneurysm neck was open, color-coded duplex sonography was repeated after 12–24 hours.
Primary success of pseudoaneurysm repair was defined as complete obliteration of the pseudoaneurysms at the follow-up examination at 12–24 hours after the initial thrombin injection. Secondary success of therapy was defined as complete obliteration of the pseudoaneurysm after one or more thrombin injections.
Follow-up
Color-coded duplex sonography was performed by one of the four interventional radiologists at 5–7 days and 21–25 days after successful repair of the pseudoaneurysm. We documented the extent of thrombosis in the pseudoaneurysm lobe(s); the extent of residual perfusion in the pseudoaneurysm lobe(s); perfusion in the neck of the pseudoaneurysm and in the feeding artery; the volume of thrombosed pseudoaneurysm lobes; and symptoms reported by the patients, including signs of inflammation and new occurrence or exacerbation of claudication symptoms.
Determination of Coagulation Parameters
In the first 25 patients in our study (seven with complex and 18 with simple pseudoaneurysms), blood was drawn (D.S., F.D.S., K.K.) from a cubital vein immediately before the initial thrombin injection and at 2, 5, and 10 minutes after injection. The method was standardized. A 21-gauge needle was inserted after a brachial tourniquet was applied at a maximum pressure of 40 mm Hg. The first 5 mL of blood was discarded before each blood drawing. The activated partial thromboplastin time was measured to register if there was any activation of the intrinsic coagulation cascade. The Quick test (prothrombin time) was performed to register any activation of the extrinsic pathway of the coagulation cascade.
Since the conversion of prothrombin to 
-thrombin involves cleavage of prothrombin fragments 1 and 2 (1), we also measured them to rule out any elevations in endogenous thrombin production (25,26). Likewise, prothrombin fragments 1 and 2 can increase by means of thrombin-induced positive feedback activation of prothrombin. Thrombin–antithrombin III complex was tested, and D-dimers were measured to account for both plasmin and thrombin activity. The following parameters were also determined: thrombin time and fibrinogen and antithrombin III levels.
Platelet count, hemoglobin, and hematocrit were determined only once before therapy. In five patients who underwent intraarterial angiography the day before therapy but without development of a pseudoaneurysm, blood was drawn from a cubital vein four times, as described earlier, to exclude the possibility that the technique of blood sampling influences the results of the coagulation parameters prothrombin fragments 1 and 2 and thrombin–antithrombin III complex.
Statistical Analysis
A one-sample t test was performed to compare the mean difference of the coagulation parameters at 2, 5, and 10 minutes after thrombin injection with the values before injection of thrombin. Results are presented with 95% CIs. Owing to the design of our study, all P values are explorative. Summary statistics cited in the text are given as the mean ± SD. The volumes of the pseudoaneurysms were correlated with the total amount of thrombin. Furthermore, the maximum difference in thrombin–antithrombin III complex before versus that after injection of thrombin was correlated with the amount of thrombin. Differences with a P value of less than .05 were regarded as statistically significant.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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The volume of pseudoaneurysms was 5.84 cm3 ± 4.89; minimum volume, 0.57 cm3; maximum volume, 23.06 cm3 (simple pseudoaneurysms: 5.88 cm3 ± 4.90; minimum, 0.57 cm3; maximum, 23.06 cm3; complex pseudoaneurysms: 5.74 cm3 ± 5.08; minimum, 2.04 cm3; maximum, 22.0 cm3). The length of the pseudoaneurysm neck ranged between 0 and 31 mm; mean length, 8.6 mm ± 6.4 (simple pseudoaneurysms: length range, 0–31 mm; mean 9.49 mm ± 6.43; complex pseudoaneurysms: length range, 0–19 mm; mean, 6.29 mm ± 6.17). The width of the pseudoaneurysm neck ranged between 2.0 and 8.4 mm; mean width, 4.1 mm ± 1.85 (simple pseudoaneurysms: width range, 2.0–8.4 mm; mean, 4.34 mm ± 2.02; complex pseudoaneurysms: width range, 2.0–5.2 mm; mean, 3.35 mm ± 0.99).
Fifty-eight thrombin injections were performed (38 injections in 37 simple pseudoaneurysms and 20 in 13 complex pseudoaneurysms). In 36 of 37 (97%) simple pseudoaneurysms (Figure), only one thrombin injection (eight of 13 [62%] of complex pseudoaneurysms) was necessary. One simple and three complex pseudoaneurysms required two injections, and two complex pseudoaneurysms required three injections. It was possible to safely deploy the tip of the needle into the lobe in all simple pseudoaneurysms. In complex pseudoaneurysms, the tip of the needle was deployed in the medial or distal lobe in three of 13 cases because the tip of the needle could not be deployed safely into the proximal lobe.
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Primary success rate was 61% (eight of 13) in complex pseudoaneurysms. In five patients, the pseudoaneurysm was still perfused. In one of the three patients in whom the tip of the needle could not be deployed safely into the proximal lobe, it was still open at 12–24 hours of follow-up. In four patients, reperfusion of a previously thrombosed lobe was observed at 12–24 hours after therapy and was limited exclusively to the proximal lobe. Three of these pseudoaneurysms were initially thrombosed successfully by means of direct injection of thrombin into the proximal lobe. At 10 minutes following the initial treatment, residual perfusion (corresponding to only partial thrombosis of the lobe) of the proximal aneurysm lobe remained in one complex pseudoaneurysm. At 12 hours, this lobe was completely obliterated. Secondary therapeutic success was registered in 100% of the pseudoaneurysms.
The total amount of thrombin required for primary and secondary repair of the pseudoaneurysm ranged from 100 to 1,500 IU. The mean thrombin dose was 357 IU ± 291 (100–1,500 IU) in simple and 638 IU ± 549 (150–1,500 IU) in complex pseudoaneurysms. There was no correlation between the size of the pseudoaneurysm lobe and the thrombin dose (correlation factor, r = 0.07).
The pseudoaneurysm neck was still perfused in six of 50 (12%) pseudoaneurysms immediately after successful thrombosis of the pseudoaneurysm lobe. In pseudoaneurysms in which primary repair was successful, the neck was occluded in 100% at the first duplex sonographic follow-up.
No major differences were observed in the peak flow rate in the anterior and posterior tibial artery before and after injection of thrombin (anterior tibial artery, 64.7 cm/sec ± 31.6 before injection and 64.2 cm/sec ± 28.3 after; posterior tibial artery, 55.0 cm/sec ± 25.2 before injection and 62.3 cm/sec ± 31.0 after). Occlusion of an artery that was perfused before treatment was not observed.
Follow-up
The follow-up examinations were performed in 48 of 50 (96%) patients after 5–7 days (first examination) and in 46 (92%) patients after 21–25 days (second examination). At the first follow-up examination, the pseudoaneurysm, including the neck, was completely obliterated in 49 of 50 patients (100% [37 of 37] of simple pseudoaneurysms and 92% [12 of 13] complex pseudoaneurysms). Partial reperfusion of the proximal pseudoaneurysm lobe occurred in one complex pseudoaneurysm, which had thrombosed spontaneously with primary treatment (ie, after injection of thrombin into the distal pseudoaneurysm lobe). At the 12-hour examination, both pseudoaneurysm lobes were thrombosed. Subsequently, the patient underwent aortic valve surgery with standard anticoagulation therapy. After a second thrombin injection, the aneurysm occluded permanently. At the second follow-up examination, all pseudoaneurysms were completely obliterated.
The volume of the thrombosed pseudoaneurysm lobes decreased to 5.9 cm3 ± 6.2 at the first examination and to 3.7 cm3 ± 5.1 at the second examination. There were no clinical or sonographic signs of an infection or any recurrence or exacerbation of arterial occlusive disease.
Determination of Coagulation Parameters
The results of the different coagulation tests before injection of thrombin and at 2, 5, and 10 minutes after injection are summarized in Table 1. The mean platelet count was 217.2 nL ± 57.9 (normal, 150–400 nL), mean hemoglobin level was 14.0 x g/dL ± 1.15 (SI unit conversion factor, 10 x g/L) (normal, 13.5–18.0 g/dL), and the mean hematocrit level was 40.0% ± 3.51 (SI unit conversion factor, .01) [proportion of 1.0]) (normal, 42%–50%). In 16 of the 25 (64%) patients, thrombin–antithrombin III complex was already elevated above normal values before thrombin was injected (in 10 patients [40%], prothrombin fragments 1 and 2 were elevated). The mean value of D-dimers was slightly above the upper limit of the normal range. Thrombin–antithrombin III complex was the only parameter with significant increase after thrombin injection compared with that before injection. There was no correlation between the maximum difference in thrombin–antithrombin III complex before versus after thrombin injection and the amount of thrombin (r = -0.19). The increase in prothrombin fragments 1 and 2 was not significant (P > .05).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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Compared with the success rate of compression therapy, that of percutaneous thrombin injection into pseudoaneurysm lobes is higher. In the study by Paulson et al (2), obliteration of the pseudoaneurysm by means of US-guided compression was successful in 74% of patients and in 96% when thrombin was used. The percentage of patients with anticoagulant therapy was significantly higher in the thrombin group than in the compression group. Brophy et al (6) treated patients in whom compression therapy failed with thrombin. In all patients (n = 15), the injection of thrombin was successful despite anticoagulant therapy. Likewise, in comparative studies conducted by Pezzullo et al (18) and Taylor et al (19), thrombin therapy led to successful obliteration of pseudoaneurysms more frequently than did compression.
In our study, we were able to show that the US-guided injection of bovine thrombin into the pseudoaneurysm lobe is a practical and safe method for managing femoral pseudoaneurysm. In addition, changes in systemic coagulation parameters after thrombin injection presumably indicate that thrombin passes into the arterial blood stream, with the risk of thromboembolic and allergic complications.
Various suggestions about the way to perform the thrombin injection are contained in the literature. The merits of the percutaneous method with one injection needle were proved in our study, as well as in most of the publications. In our opinion, it is not necessary to inject the thrombin via a percutaneous (5,30) or arterial catheter advanced through the femoral artery and placed into the pseudoaneurysm lobe. In individual cases, an insufflated balloon is deployed in the vessel to occlude the neck of the pseudoaneurysm and thereby prevent thromboembolic complications (31,32). In our opinion, it is not necessary to inject larger thrombin doses (ie, as a bolus containing, for example, 500 IU, as suggested in the literature [33]). In seven of the patients in the current study, injection of 100 IU alone led to permanent obliteration of the pseudoaneurysm.
The geometry of the pseudoaneurysm affected the success rates in the current study, which confirmed the high success rate for simple pseudoaneurysms in a recently published article (9). The size of the pseudoaneurysm lobe and anticoagulation had no effect on their success rates. In another report, Kang et al (7) postulate that the thrombin dose is dependent on the size of the pseudoaneurysm lobe. This hypothesis could not be confirmed by the results in our study or those in the study of Sheiman and Brophy (9).
In our study, one patient had residual perfusion of a simple pseudoaneurysm that had thrombosed by the time of follow-up. This observation supports the theory proposed by Sheiman and Brophy (9) that if there is residual perfusion in the lobe of a simple pseudoaneurysm, a wait-and-see approach should be taken as the pseudoaneurysm may still thrombose spontaneously. On the basis of the results of our study, this approach can be taken when there is also residual perfusion of the pseudoaneurysm neck. In a series by Paulson et al (2), perfusion of the pseudoaneurysm neck occurred in six of 26 treated pseudoaneurysms, four of which had thrombosed spontaneously by the time of follow-up. In the study conducted by Kang et al (8), the neck of the pseudoaneurysm thrombosed spontaneously in six of nine patients.
Our experience has shown that it is technically more difficult to inject thrombin in complex than in simple pseudoaneurysms. This is a result of the obviously more complex geometry and the fact that the angle of puncture is usually steeper, which makes positioning of the tip of the needle harder. In our study, reperfusion of a previously thrombosed lobe occurred only in complex pseudoaneurysms. Higher reperfusion rates of the proximal pseudoaneurysm lobe have been described in the literature (9). In that study, reperfusion occurred in four of nine patients with complex pseudoaneurysms and spontaneous thrombosis of the proximal lobe after puncture of only the distal lobe. The authors concluded that thrombi that develop in the proximal lobe under these conditions have a higher sensitivity to thrombolytic agents and heparin than that of thrombi in simple aneurysm. In contrast, reperfusion also occurred in our study when the proximal lobe was punctured directly and thrombin was injected there.
We ensured sterile conditions during the injection and did not encounter local infections after thrombin treatment of pseudoaneurysms. Nevertheless, local infections are conceivable. A groin abscess after percutaneous thrombin injection was described recently in the literature (10).
It was interesting for us that thrombin–antithrombin III complex increased significantly during the minutes after thrombin injection. In principle, there are several possible reasons for this finding. The first reason is that thrombin passes from the lobe of the pseudoaneurysm into the feeding artery and binds to antithrombin III. The second reason is that thrombin binds to antithrombin III within the lobe of the pseudoaneurysm, which results in the formation of thrombin–antithrombin III complex and its passage into the arterial circulation. The third reason is that thrombin is absorbed from the surface of the pseudoaneurysm cavity into the venous drainage. We have not directly proved the passage of thrombin into the feeding artery. However, the risk remains that thrombin enters the feeding artery for three reasons, as described in the literature (5,10,21,23,24): (a) There is a characteristic inflow and outflow of blood within the neck of the pseudoaneurysm, (b) thrombus formation within the lobe of the aneurysm after injection of thrombin usually takes some time, and (c) thrombus formation as a complication of thrombin injection occurred within the feeding artery.
To our knowledge, one angiographically verified thrombosis of the profunda femoris artery has been described in the literature (5). In this case, thrombin was dissolved in a relatively large volume of 10 mL and injected into the pseudoaneurysm. In seven additional cases in which thromboembolic complications occurred, three patients had to undergo surgery (23,24), the thrombus resolved spontaneously in three patients (10,21), and one patient underwent local thrombolysis treatment (24). Two further thromboembolic complications described in the literature occurred in pseudoaneurysms that extended off the brachial artery (8,22). In one case, thrombin was injected partly into the pseudoaneurysm neck and partly into the artery (8).
The results of our study emphasize the importance of antithrombin III as a thrombin-neutralizing factor that can abolish the clotting effect of thrombin. Further investigations are needed to determine whether the blood level of antithrombin III should be measured routinely before thrombin treatment.
Baseline levels of thrombin-antithrombin III complex and prothrombin fragments 1 and 2 were increased in 64% and 40%, respectively, of the patients in our study but not in the five patients without a pseudoaneurysm. These findings can be interpreted as a result of endogenous thrombin production because of activated coagulation. Thrombus forms spontaneously within the lobe of pseudoaneurysms, as is demonstrated by the facts that some pseudoaneurysms are partially thrombosed at the time of diagnosis or small pseudoaneurysms have a tendency toward spontaneous occlusion (34,35).
The question of thrombin extravasation is also important with regard to the risk of allergic complications of thrombin therapy. A case of allergic urticaria after thrombin treatment of a pseudoaneurysm was published recently (36). In another patient, long-term fever after thrombin injection was interpreted as allergic response to bovine thrombin (24). Additionally, antibodies to bovine factor V can be produced that, in turn, can be accompanied by a cross-reaction with human factor V of the coagulation cascade (37,38). Hence, in addition to the allergic risk, there is also a risk of other disturbances of blood clotting. No hemorrhaging occurred after injection of thrombin in the patients in our study nor has any been reported as of April 2002. The recommendations given in the literature for documenting previous thrombin exposure should be complied by documenting the type and nature of thrombin exposure and keeping mandatory records of the batch numbers.
Treatment of patients after thrombin therapy and follow-up are still being studied. Data in our study and those in the literature indicate support for bed rest of less than 12 hours. No recurrent perfusions were observed in patients with simple pseudoaneurysms who received only 6 hours (2) or even 1 hour (9) of bed rest. Results are different for complex pseudoaneurysms. Our results indicate that bed rest of 12 hours is required. Sheiman and Brophy (9) recommend bed rest of more than 6 hours.
In our study, no serious complications were observed at the follow-up examinations in the patients with simple pseudoaneurysms. In one of our patients with a bilobulated pseudoaneurysm, partial reperfusion of the proximal lobe was diagnosed 6 days after the 12-hour follow-up had showed complete obliteration. The literature also contains a report of a patient who had late reperfusion after 4 days (39). This leads us to conclude that US and clinical examinations are recommended to exclude reperfusion or procedure-related complications.
In conclusion, US-guided percutaneous injection of thrombin for the management of pseudoaneurysms is an effective, timesaving, and safe procedure. In our study, pseudoaneurysm geometry proved to be a key factor influencing the primary success of the treatment. Changes in systemic coagulation parameters allow the interpretation that thrombin passes into the arterial blood stream and that there is a risk of thromboembolic and allergic complications.
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FOOTNOTES |
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REFERENCES |
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