BB
McGuire, C Kelly.
Department:
Department of Vascular Surgery, Beaumont Hospital, Dublin 9, Ireland.
Correspondence
to:
Email:
barrymcguire2@yahoo.co.uk
SMJ 2006 52(1): 55
Abstract
Introduction:
Acute pulmonary embolism is a serious life-threatening phenomenon.
When anticoagulation is contraindicated, treatment poses a challenge.
Background:
We describe the case of a young girl with recurrent pulmonary emboli
despite the presence of a caval filter and explore the different treatment
options available in this situation.
The
placement of an intra-caval filter often provides a feeling of protection
against further pulmonary emboli, however the incidence of filter thrombosis is
surprisingly quite high. Subsequent pulmonary embolus can occur in up to a third of
these patients which is potentially life threatening.
Conclusion:
We examine the different filters that are commercially available, and the
incidence of thrombosis and embolism associated with them.
Following this, we look at the treatment options available in managing
filter thrombosis and the safety of such intervention.
Introduction
Venothromboembolic
disease is a common phenomenon in the hospital setting.
It is estimated that pulmonary embolism results in 5 to 10% of all
hospital deaths in the United States.1
The age and sex adjusted incidence of pulmonary embolism (PE) is 69 per
100,000.2 The normal
treatment of this condition is anticoagulation, however in situations where
there is a contraindication to anticoagulation an Inferior Vena Cava (IVC)
filter is inserted. This does not
protect completely against pulmonary emboli as demonstrated in this case, in
which a young patient who had placement of an IVC filter developed further
pulmonary emboli.
Case
Report
A 21-year-old female underwent an emergency hemi-colectomy for severe uncontrollable vascular ectasia. Seven months after surgery she developed an acute pulmonary embolus. She was subsequently anticoagulated with warfarin and discharged.
She
presented four days later having again passed large amounts of blood per rectum,
and symptomatic anaemia (Hb 7.2) with an INR of 1.9.
It was necessary to discontinue her anticoagulant therapy and to insert a
Greenfield filter to protect from further PE.
She underwent further colectomy and ileo-rectal anastomosis to remove the
area of vascular abnormality. Nine
days after surgery she developed acute dyspnoea and chest pain. A spiral CT
thorax revealed multiple bilateral PE’s despite the presence of an IVC filter.
She underwent emergency endovascular thrombectomy of clot visible in the
IVC filter and was transferred to the intensive care unit where she eventually
made a full recovery. Haematological investigations were inconclusive.
Discussion
Preventing pulmonary embolisation by interrupting vena caval flow has been attempted since 1893, and intracaval filters have been available for the prevention of pulmonary embolism since the late 1960’s. The main reasons for percutaneous IVC filter insertion are contraindications to, or failure of anti-coagulant therapy. Inferior vena cava filters are effective in trapping clots and protecting against PE3, 4 however, they do not offer complete protection. The rate of IVC filter thrombosis varies widely and ranges from 1.5% to 50%.5,6 In one study, 50% of those with an IVC filter developed filter thrombosis within 6 months of placement7 and a thrombus above the filter and PE was found in 33% of those patients.
The incidence of developing a PE in the presence of an IVC filter ranges from 0 - 3.8% 8,9,10, the lower incidences being associated with the new generation titanium filters.11 This data suggests that, though there may be a contraindication to anti-coagulant therapy at the time of filter placement, the need for anticoagulant therapy must be reassessed as soon as possible, due to the risk of filter thrombosis and pulmonary embolus.
No filter can be designated as superior in safety or efficacy9 and a variety of vena caval filters are available for usage. The choice of filter type depends on physician preference and certain patient variables. Mohan et al12 (1995) found that a higher incidence of filter thrombosis with the use of the Birds Nest Filter (14.6%) versus the Stainless Steel Greenfield Filter (0%), or Titanium Green Field Filter with Modified Hook (3.6%). However, a more recent study (1998), that compared the BNF with the Greenfield Filter, found that the incidence of caval thrombosis is comparable to that of the Greenfield filter.13 Importantly, there was no significant difference in the occurrence of clinically apparent pulmonary embolism during follow up between the different filter types.
Pulmonary emboli and inferior vena caval filter thrombosis in patients with contraindications to anticoagulant therapy is a difficult and challenging problem. When there is an absolute contraindication to anticoagulation the treatment options available are quite limited. These include surgical thrombectomy and endovascular mechanical thrombectomy.
Surgical thrombectomy is highly invasive and requires access to cardiac surgery facilities and mechanical thrombectomy is generally the preferred option. Poon et al14 describe their experience in treating three patients similar to the case described above, using mechanical thrombectomy via the Hydrolyser catheter. There are several commercially available hydrodynamic thrombectomy devices; others include, the Angiojet, Oasis and Clot Buster Amplatz Thrombectomy Device. The authors were able to achieve technical success in recanalization of the thrombosed IVC in all three of the patients in that study, and they found it to be successful in removing the clots around the thrombosed IVC filter. Distal embolization during mechanical thrombectomy is a major concern as the shower of emboli may precipitate fatal pulmonary embolism during the procedure. The in vivo use of the hydrolyser in the treatment of occluded haemolysis shunts revealed an embolization rate of around 2%.15
The authors do not however, suggest that the prophylactic use of a temporary IVC filter during mechanical thrombectomy of a thrombosed IVC filter is an absolute necessity. This also applies to catheter directed thrombolysis, where the rate of distal embolization is high but symptomatic pulmonary embolism is low, and a prophylactic IVC filter is not necessary during thrombolysis.21
In
patients with acute pulmonary embolism, thrombolysis results in a more rapid
resolution of pulmonary emboli than heparin treatment and has a lower composite
endpoint of death/recurrence than heparin treatment.16
The use of thrombolytic agents in their treatment presents a dilemma to
the surgeon. On the one hand,
postoperative pulmonary embolism usually occurs within two weeks of surgery.
On the other hand, recent surgery is considered a contraindication for
the use of thrombolytics. Previous
attempts at thrombus destruction via systemic thrombolysis failed to
convincingly demonstrate sufficient benefit to outweigh the risks of bleeding17,
and is not practiced anymore. Molina
et al18, developed a protocol for treating pulmonary embolism
patients who have recently undergone surgery.
In this study, thirteen patients were treated for angiographically proven
pulmonary embolism within 14 days of surgery via catheter directed thrombolysis.
Complete lysis of every embolus was achieved, and no deaths or bleeding
complications occurred.
Conclusion
This
case demonstrates thrombosis of an IVC filter and subsequent pulmonary emboli.
Endovascular mechanical thrombectomy has been shown to be a safe and effective
means of clearing the thrombus from the IVC filter. It is imperative however,
that the need for anticoagulation be reassessed as soon as possible in patients
even with an IVC filter.
References
1.
Westrich GH, Rana AJ. Techniques in Orthopaedics, 16(3): 279-290
2
Lee AY, Hirsch J. Annual Review of Medicine. 53:15-33, 2002.
3
Cardiovascular & Interventional Radiology. 21 (6): 464 - 9, 1998 Nov
- Dec.
4.
Athanasoulis CA, Kaufman JA, Halpern EF et al. Inferior vena caval filters:
review of a 26-year single-center clinical experience.Radiology 2000
Jul;216(1):54 - 66
5
Schutzer R, Ascher E, Hingorani A, et al. Preliminary results of the new 6F
TrapEase inferior vena cava filter. Ann Vasc Surg. 2003 Jan; 17(1):103-6. Epub
2003 Jan 24.
6
Tardy B, Mismetti P, Page Y et al. Symptomatic inferior vena cava filter
thrombosis: clinical study of 30 consecutive cases. European Respiratory
Journal. 9(10): 2012-6, 1996 Oct.
7
Tardy B, Mismetti P,
Page Y et al. Symptomatic inferior vena cava filter thrombosis: clinical study
of 30 consecutive cases. European
RespiratoryJournal. 9(10):2012-6,1996 Oct.
8
Carlin AM, Tyburski JG, Wilson RF et al. Prophylactic and therapeutic inferior
vena cava filters to prevent pulmonary emboli in trauma patients.
Archives of Surgery. 137(5):521-5; discussion 525-7, 2002 May.
9
Streiff MB. Vena caval filters: a comprehensive review.
Blood 2000 Jun 15;95(12): 3669-77
10
Nicholson AA, Ettles
DF, Paddon AJ et al. Long-term
follow-up of the Bird's Nest IVC Filter. Clinical
Radiology. 54 (11): 759 -
64, 1999 Nov.
11
Becker DM, Philbrick JT, Selby JB (1992). Inferior
Vena Cava Filters: Indications, Safety, effectiveness. Arch Intern med
152:1985-1994
12
Mohan CR, Hoballah JJ,
Sharp WJ et al. Comparative
efficacy and complications of vena caval filters.
J Vasc Surg 1995
Feb;21(2):235-45; discussion 245-6.
13
Thomas JH, Cornell
KM, Siegel EL et al. Vena caval occlusion after bird's nest filter placement.
American Journal of
Surgery. 176(6): 598-600, 1998 Dec.
14
Poon WL, Luk SH, Yam
KY et al. Mechanical thrombectomy in inferior vena cava thrombosis after caval
filter placement: a report of three cases.
Cardiovasc Intervent Radiol
(2002) 25:440-443
15
Overbosch EH, Pattynama PMT, Aarts HJCN, et al. (1996) Occluded hemodialysis
shunts: Dutch multicenter experience with the hydrolyser catheter. Radiology
201:485 - 488.
16
Agnelli G, Becattini
C, Kirschstein T. Thrombolysis vs
heparin in the treatment of pulmonary embolism: a clinical outcome-based
meta-analysis. Archives
of Internal medicine. 162(22):2537-41, 2002 Dec 9-23.
17
TennArmon MP,
Whitaker SCant WG. Catheter-directed
thrombolysis of iliofemoral deep vein thrombosis. A new approach via the
posterior tibial vein. Eur
J Vasc Endovasc Surg 13, 413-416 (1997)
18 Molina JE, Hunter DW, Yedlicka JW et al. Thrombolytic therapy for postoperative pulmonary embolism. American Journal of Surgery. 163(4):375-80;discussion 380-1, 1992 Apr.