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| Journal of Vascular Access 2003; 4: 118 - 122 |
| LatisTM catheter: New technology for thrombectomy of vascular access grafts |
A.F. Schild1, N.M. Baltodano 2, R. Elias 1, J. Livingstone 2, J.K. Raines2
1University of Miami School of Medicine, Miami, Florida
2Miller School of Medicine, University of Miami, Miami FL - USA
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Search Medline for articles by:
 A.F. Schild
N.M. Baltodano
R. Elias
J. Livingstone
J.K. Raines
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ABSTRACT
PURPOSE: The most common complication of vascular access surgery is thrombosis. This study compared the gold standard Fogarty Thrombectomy Catheter, to the new latis Catheter with an advanced monofilament matrix.
METHODS: 30 patients with thrombosed access grafts were randomly assigned to undergo thrombectomy with the Fogarty or latis catheter. An angioscope measured remaining graft thrombi.
RESULTS: Twenty-nine of 30 subjects were successfully thrombectomized. No statistical differences in age, gender, race, or extension graft requirements were found. Catheter use in the latis group was: 1 in 14 procedures, and 2 in 1 procedure; Fogarty group: 1 in 10 procedures, 2 in 3 procedures, and 3 in 2 procedures. The average number of catheter passes was: latis 3.06 (1-6 passes) and Fogarty 4.13 (1-9 passes). A trend in favor of the latis catheter was demonstrated; however, statistical significance was not reached (p = 0.067). The overall 6-month primary patency rates were latis (40%) and Fogarty (30%). The estimated patency at the 50th percentile for latis is 120 days and Fogarty 108 days. Statistical significance was not reached with a p-value of the Log-Rank statistic of 0.68 and a p-value of the Wilcoxon statistic of 0.78.
CONCLUSIONS: The latis and Fogarty catheters are very similar. However, the latis balloon is more rugged with fewer catheters used and reduced number of passes. A difference in primary patency could not be demonstrated. The angioscope identified significant residual thrombus despite no returning thrombus from the catheter. Consequently, our protocol is modified to include the angioscope. (The Journal of Vascular Access 2003; 4: 118-22)
Key Words. Vascular access grafts, Thrombosis, Thrombectomy catheter, Angioscope, Vascular access graft patency, Monofilament matrix
INTRODUCTION
The most common complication of vascular access surgery is thrombosis, with a potential for thrombosis ranging from 50% to 80% per year (1). Thrombosis most often occurs in the area of the venous anastomosis and is usually secondary to neointimal hyperplasia.
For the past 40 years the gold standard for thrombectomy was the Fogarty Thrombectomy Catheter; it has been used in nearly 10 million cases (2). Although introduced in the early 1960s for use during surgery, this balloon thrombectomy catheter, recently has been used as a minimally invasive treatment modality to extract thrombus. When coupled with transluminal angioplasty, it has been an effective alternative to surgical revision (3).
The original Fogarty device consisted of a single lumen catheter with a latex balloon mounted at its distal end (4). The balloon is filled with saline so that it conforms to the endoluminal surface of the artery or vein with circumferential apposition. The balloon is then pulled back to its site of entry into the artery or vein, thereby extracting clot and restoring blood vessel patency. The basic catheter has remained largely unchanged from the original commercially available version (2).
The new latis Catheter incorporates an advanced monofilament matrix intricately woven around a syringe-activated Syntel™ balloon (Fig. 1).
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Fig. 1
The new latis catheter incorporates an advanced monofilament matrix intricately woven around a syringe-activated Syntel™ balloon. |
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The purpose of the monofilament matrix is to engage adherent thrombus and the arterial plug (5).
The purpose of this study was to compare the Fogarty device to the new latis catheter.
METHODS
During a 19-month period, between May 1999 and December 2000, 30 consecutive patients with thrombosed vascular access grafts were randomly assigned to undergo thrombectomy using either the Fogarty Thrombectomy Catheter or the new latis Thrombectomy Catheter (15 patients in each group). Assignments from a sealed envelope were made immediately prior to surgery and accessible to a single member of the research team not in direct contact with study patients. Demographics, medical history, surgical information, and results from follow-up examinations were carefully recorded on case report forms.
All the procedures were performed by a single surgeon (AFS) at University of Miami Jackson Medical Center. During the surgical procedures the type of catheter used, number of passes required to clear thrombus, and the number of catheters used was recorded. After each catheter pass, a 2.3 mm angioscope (Applied Medical Corp., Avenida Empresa, CA, USA) was used to determine the amount of thrombus still present in the graft (6). The entire graft length and the venous anastomosis were visualized and photographed. We were careful to always remove the arterial plug. When thrombus was no longer evident by angioscopic inspection and the graft exhibited good flow characteristics, no additional catheter passes were performed. In each group we carefully recorded the number of catheters used and the number of passes necessary to reach this endpoint.
Follow-up visits in our clinic were performed at one week, one month, three months, and six months after surgery.
Statistical calculations were made using the standard Statistical Analysis System(SAS) (7). The Fogarty and latis treatment groups were compared and analyzed. Comparisons of continuous data obtained from the two treatment groups were performed using the t test; categorical data were compared using chi-square tests or two-tailed Fischer’s exact tests.
A data set that included time to event (graft occlusion, graft removal, completion of follow-up, death, or transplant), a binary event indicator, patient identification, and treatment group was created from case report forms prepared specifically for this study.
The LIFETEST procedure was used to develop Kaplan-Meier survival curves that compared primary patency for the two treatment groups. For purposes of this study, primary patency is defined as the period between thrombectomy and occlusion.
The protocol was approved by the Institutional Review Board of the University of Miami School of Medicine. Written Informed Consent was obtained by the investigators.
The patient population was consecutive; no subject was excluded on the basis of age or comorbid condition. The suggested reporting standards from the ad hoc committee of the ISCVS/SVS were followed (8).
RESULTS
During the study period 30 subjects presented for thrombectomy of upper extremity access grafts; 29 were successfully thrombectomized. These subjects were randomized to either the Fogarty or latis Thrombectomy Catheter groups with 15 subjects in each group.
In addition to the thrombectomy, 17 subjects required an extension graft to a more proximal vein. There were 7 extensions in the latis group and 10 extensions in the Fogarty group. No participants were lost to follow-up. The mean age in the Fogarty group was 53.7 years and 57.2 years in the latis group. There were no statistical differences in age (p = 0.42), gender (p = 0.71), race (p = 0.17), or extension graft requirement (p = 0.46). In the latis group we had more individuals with hypertension only; in the Fogarty group we had more individuals with hypertension and diabetes. This led to a borderline statistical difference in co-morbid conditions when the two groups were compared (p = 0.047). We feel the two groups are clinically comparable (Tab. I).
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Table I
Patient Demographics
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In the latis group, 14 of 15 procedures required only one catheter. The remaining procedure required two catheters. In the Fogarty group, one catheter was used in 10 cases. Two catheters were required in three cases and two cases required three catheters. The latis group demonstrated reduced catheter use, however, the difference did not reach statistical significance (p = 0.065). The average number of catheter passes to provide complete thrombus removal for the latis group was 3.06 with a range of one to six passes. In the Fogarty group the average number of catheter passes was 4.13 with a range of two to nine passes. This also demonstrated a trend in favor of the latis catheter, however, statistical significance was not reached (p = 0.067). Catheter use and pass data are given in Table II.
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Table II
Catheter Passes / Usage
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A survey provided by our purchasing department suggested the average cost of the latis catheter is $85 and the average cost of the Fogarty catheter is $48. For our study of 15 subjects in each group, we used 16 latis catheters and 22 Fogarty catheters (Tab. II). This means we spent $1360 for latis catheters and $1056 for Fogarty catheters.
Therefore, in this series using the latis catheter added approximately $20 in cost to each procedure.
The latis group had a slightly better graft patency pattern. The overall 6-month primary patency rates were 40% for the latis group and 30% for the Fogarty group. The estimated patency at the 50th percentile for the Fogarty group is 108 days. The 50th percentile for the latis group is 120 days. This did not reach statistical significance with a p-value of the Log-Rank statistic of 0.68 and a p-value of the Wilcoxon statistic of 0.78 (Fig. 2).
We experienced one adverse event. During a thrombectomy there was disruption of an arterial anastomosis in the latis group; this was successfully repaired.
DISCUSSION
This study was unique for two reasons. First, we systematically and routinely used a state-of-the-art angioscope (9). Second, we evaluated a new technology for thrombectomy of access grafts.
With the angioscope we were able to visualize the lumen of the graft on an intraoperative video monitor after each catheter pass. This was instructive in determining the effectiveness of the two catheters and provided general insight into the mechanics of graft cleaning. Figure 3 illustrates a luminal view with significant residual thrombus after two passes of a Fogarty catheter. Figure 4 illustrates a similar view after two passes of a latis catheter. Figure 5 illustrates a clean lumen after four passes using the latis catheter.
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Fig. 3
Luminal view of graft after two passes of a Fogarty catheter illustrating significant residual thrombus. |
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Our thrombectomy protocol, when not using the angioscope, is to continue to pass a thrombectomy catheter until no further thrombus is returned. When using the angioscope, on several occasions, we identified significant residual thrombus despite no returning thrombus from the catheter. On the basis of these findings, we have modified our thrombectomy protocol for access grafts to include use of the angioscope.
Failing to remove the arterial plug will result in graft failure often within 24 hours. Figure 6 illustrates a typical arterial plug removed from an occluded access graft.
In our series of 30 cases, 17 or 57%, required an extension graft to a more proximal vein. Whereas, there is a trend toward performing thrombectomy in interventional radiology suites, extension grafting can only be performed in the operating room.
The latis and Fogarty catheters are very similar regarding their use and handling in the operating room. We feel the latis balloon is more rugged and in the long run will result in less catheters used due to less balloon ruptures. However, in our study the overall cost of using the latis catheter was slightly more (~$20 on a procedural basis) than the Fogarty catheter. We also feel the number of passes required for successful thrombectomy will be reduced with the latis catheter. We could not demonstrate a statistically significant difference in primary patency, although the trend was in favor of the latis catheter.
Adddress for correspondence:
A. Frederick Schild, MD, FACS
Professor of Surgery
Department of Surgery (R-310)
University of Miami
East Tower 3016A
1611 NW 12th Avenue
Miami, FL 33136
305-585-5286
fschild@med.miami.edu
REFERENCES
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2. Hill B, Fogarty TJ. The use of the Fogarty catheter in 1998. Cardiovasc Surg 1999; 7: 273-8.
3. Schwartz CI, McBrayer CV, Sloan JH, Meneses P, Ennis WJ. Thrombosed dialysis grafts: comparison of treatment with transluminal angioplasty and surgical revision. Radiology 1995; 194: 337-41.
4. Fogarty TJ, Cranley JJ, Krause RJ, et al. A method for extraction of arterial emboli and thrombi. Surg Gynecol Obstet 1963; 116: 241-4.
5. Applied Medical. Applied LatisTM Graft Cleaning Catheter. In: sales brochure 2001 http://www.appliedmd.com
6. Vesely TM, Hovsepian DM, Darcy MD, Brown DB, Pilgram TK. Angioscopic observations after percutaneous thrombectomy of thrombosed hemodialysis grafts. J Vasc Interv Radiol 2000; 11: 971-7.
7. Statistical Analysis System. Cary NC: SAS Institute, Inc 1988.
8. Sidawy AN, Gray R, Besarab A, et al. Recommended standards for reports dealing with arteriovenous hemodialysis accesses. J Vasc Surg 2002; 35: 603-10.
9. Holzenbein TJ, Miller A, Gottlieb MN, Gupta SK. The role of routine angioscopy in vascular access surgery. J Endovas Surg 1995; 2: 10-25.
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