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A temporary inferior vena caval filter: the way forward in prophylaxis against pulmonary embolism?
Current Obstetrics & Gynaecology (1997) 7, 171-172 © 1997 Pearson Professional Ltd
Lessons in clinical practice
A temporary inferior vena caval filter: the way forward in prophylaxis against pulmonary embolism?
E. H. Kevelighan, I. Robertson and A. C. Crompton Follow-up was arranged with the haematology clinic, and the patient was advised not to get pregnant while on warfarin and not to use the combined oral contraceptive pill. At 3 months' post delivery she was well and the swelling in her leg had resolved. A thrombophilia and cardiolipin/lupus anticoagulant screen was negative.
CASE REPORT A 23-year-old secundagravid at 38 weeks' gestation was admitted with a swollen and painful right leg. She was anticoagulated with intravenous (i.v.) heparin and a Doppler ultrasound demonstrated extensive ilio-femoral thrombus. The patient had no risk factors (other than pregnancy) for deep venous thrombosis (DVT). Clinically, she was well. Coagulation screens were performed daily and activated partial thromboplastin time (APTT) kept between two and three times the normal control. A temporary caval filter (Antheor) was inserted via the right internal jugular vein under image intensifier control. A cavogram was performed revealing no caval thrombus, and the filter was inserted infrarenally in a satisfactory position. The following morning the patient went into spontaneous labour and delivered a healthy female infant weighing 3.58 kg. Post partum, anticoagulation was maintained with heparin, and warfarin was commenced. The patient became unwell and developed rigors with a pyrexia of 39°C 2 days following delivery. Blood cultures grew Staphylococctts attreus, which was sensitive to flucloxacillin. She was treated with cefuroxime and metronidazole i.v. and improved rapidly. A cavogram 6 days after delivery revealed that there was no evidence of thrombus in the iliac veins. Therefore, the temporary filter was removed using a removal kit. Histology confirmed three fragments of thrombus totalling 6 mm.
DISCUSSION Thromboembolic disease remains the major cause of maternal mortality in the UK, accounting for 27.1% of direct maternal deaths in the triennium 1991-1993.1 Treatment of DVT by anticoagulation alone may not be sufficient to prevent fatal pulmonary embolism7 The use of IVC filters to prevent pulmonary embolism in pregnancy has been widely reported) .4 However, all these cases involved permanent IVC filters, such as Greenfield or Cardial. The major advantage of a temporary filter is that it can be removed, preventing blockage of the blood flow through the vena cava. In a 7-year follow-up of seven types of permanent filters in non-pregnant patients, there was a complication rate of up to 20%. These complications included caval thrombus, penetration through the IVC wall and filter migration; 5persistent leg swelling has also been reported? Many of the filter follow-up studies have been clinical rather than radiological ones, and quote IVC occlusion rates of only 2-3%. 4 It is probable that the true figure is much higher and is not detected clinically owing to the development of collateral circulation when chronic caval occlusion occurs. Antheor temporary filters are designed for a maximum implantation time of 2 weeks. The filter is coated with amorphous carbon, improving the haemocompatibility and delaying the fibrinous reaction at the filter/inferior vena cava wall interface.
E. H. Kevelighan,Clinical Research Registrar, Department of Obstetrics and Gynaecology,L Robertson, Consultant Radiologist, Department of Radiology,A. C. Crompton, Consultant, Department of Obstetrics and Gynaecology,St James's University Hospital, Leeds LS9 7TF, UK Correspondence to: EHK
171
172
Current Obstetrics & Gynaecology to be larger than I cm 3 it is necessary to insert a permanent filter before removing the t e m p o r a r y one. Following removal, anticoagulation should be continued for 3-6 months: similar to cases o f thrombosis where filters are not inserted. In o u r case, the patient was at 38 weeks' gestation and if she had not laboured within 1 week we would have induced labour. It seems preferable to deliver patients with the filter in situ, as the risk o f thrombus release is increased at this time. The advantages o f a temporary filter over its permanent counterpart are: • a reduced risk o f the complications outlined above • many permanent filters are ferromagnetic and, therefore, the patient cannot undergo Nuclear Magnetic Resonance ( N M R ) imaging in the future if required.
Figure Antheor temporary filter with thrombus.
Owing to the increased risk of D V T associated with pregnancy, and the likelihood o f the filter (if permanent) remaining in situ for 50-60 years, it seems probable that such patients are at a higher risk o f caval occlusion and possible death. Venous access (usually femoral or internal jugular) is determined by the site o f the venous thrombosis. In this case, the risk o f dislodgement o f embolus during catheter manipulation was felt to be appreciable, therefore,, the internal jugular route was preferred. Despite strict aseptic precautions, infection remains a risk and in this case the septicaemia was probably a result of infection at the insertion site. At removal on the 6th day, the femoral and iliac veins were clear and the filter had trapped fragments o f thrombus (Figure). I f the vena cava and filter are patent, the filter is removed by simple traction on the filter catheter. I f the vena cava is patent, but the filter contains thrombus estimated to be less than 1 cm 3 (as in this case); the filter is removed with the removal kit. This technique allows the temporary filter to be closed inside the IVC and then removed in the closed position. In the unlikely scenario where the vena cava is thrombosed or the filter contains thrombus estimated
Recently, p e r m a n e n t retrievable vena caval filters have been introduced. These may be removed within 2 weeks o f insertion or can be left in situ permanently. Such a filter m a y well represent the best way fonvard in the management o f women at 'high risk' o f pulm o n a r y embolism during pregnancy. Although a randomized controlled trial with filters would be unethical, utilizing t e m p o r a r y or retrievable filters instead o f permanent ones appears to be a logical progression with respect to the safety o f IVC filters in pregnancy. REFERENCES 1. Department of Health, Welsh Office,Scottish OfficeHome and Health Department, Department of Health and Social Services, Northern Ireland Report on confidential enquiries into maternal deaths in the United Kingdom 1991-1993. HMSO, London, 1996 2. Golueke PJ, Garrett "~W,Thompson JE, Smith BL, Talkington CM. Interruption of the vena ¢ava by means of the Greenfield filter: expanding the indications. Surgery 1988; 103:111-117 3. Hux CH, Wapner RJ, Chayeu B, Ratten P, Jarrell B, Greenfield L. Use of Greenfieldfilter for thromboembolic disease in pregnancy.Am J Obstet Gynaeeo! 1986; 155: 734-737 4. Narayan H, Cullimore J, Krarup K, Thurston H, MacVicar J, Bolia A. Experiencewith the cardial inferior vena cava filter as prophylaxis against pulmonary embolismin pregnant women with extensivedeep venous thrombosis. Br J Obstet Gynaecol 1992; 99:637-640 5. Ferris EJ, McCowan TC, Carver DC, McFarland DR. Percutaneous inferior vena caval filters: follow-up of seven designs in 320 patients. Radiology 1993; 188: 851-856 6. RoehmJOF, Johnsrude IS, Barlh MH, Gianturco C. The Bird's Nest inferior vena cava filter: progress report. Radiology 1988; 168:745-749
Lessons in clinical practice
A temporary inferior vena caval filter: the way forward in prophylaxis against pulmonary embolism?
E. H. Kevelighan, I. Robertson and A. C. Crompton Follow-up was arranged with the haematology clinic, and the patient was advised not to get pregnant while on warfarin and not to use the combined oral contraceptive pill. At 3 months' post delivery she was well and the swelling in her leg had resolved. A thrombophilia and cardiolipin/lupus anticoagulant screen was negative.
CASE REPORT A 23-year-old secundagravid at 38 weeks' gestation was admitted with a swollen and painful right leg. She was anticoagulated with intravenous (i.v.) heparin and a Doppler ultrasound demonstrated extensive ilio-femoral thrombus. The patient had no risk factors (other than pregnancy) for deep venous thrombosis (DVT). Clinically, she was well. Coagulation screens were performed daily and activated partial thromboplastin time (APTT) kept between two and three times the normal control. A temporary caval filter (Antheor) was inserted via the right internal jugular vein under image intensifier control. A cavogram was performed revealing no caval thrombus, and the filter was inserted infrarenally in a satisfactory position. The following morning the patient went into spontaneous labour and delivered a healthy female infant weighing 3.58 kg. Post partum, anticoagulation was maintained with heparin, and warfarin was commenced. The patient became unwell and developed rigors with a pyrexia of 39°C 2 days following delivery. Blood cultures grew Staphylococctts attreus, which was sensitive to flucloxacillin. She was treated with cefuroxime and metronidazole i.v. and improved rapidly. A cavogram 6 days after delivery revealed that there was no evidence of thrombus in the iliac veins. Therefore, the temporary filter was removed using a removal kit. Histology confirmed three fragments of thrombus totalling 6 mm.
DISCUSSION Thromboembolic disease remains the major cause of maternal mortality in the UK, accounting for 27.1% of direct maternal deaths in the triennium 1991-1993.1 Treatment of DVT by anticoagulation alone may not be sufficient to prevent fatal pulmonary embolism7 The use of IVC filters to prevent pulmonary embolism in pregnancy has been widely reported) .4 However, all these cases involved permanent IVC filters, such as Greenfield or Cardial. The major advantage of a temporary filter is that it can be removed, preventing blockage of the blood flow through the vena cava. In a 7-year follow-up of seven types of permanent filters in non-pregnant patients, there was a complication rate of up to 20%. These complications included caval thrombus, penetration through the IVC wall and filter migration; 5persistent leg swelling has also been reported? Many of the filter follow-up studies have been clinical rather than radiological ones, and quote IVC occlusion rates of only 2-3%. 4 It is probable that the true figure is much higher and is not detected clinically owing to the development of collateral circulation when chronic caval occlusion occurs. Antheor temporary filters are designed for a maximum implantation time of 2 weeks. The filter is coated with amorphous carbon, improving the haemocompatibility and delaying the fibrinous reaction at the filter/inferior vena cava wall interface.
E. H. Kevelighan,Clinical Research Registrar, Department of Obstetrics and Gynaecology,L Robertson, Consultant Radiologist, Department of Radiology,A. C. Crompton, Consultant, Department of Obstetrics and Gynaecology,St James's University Hospital, Leeds LS9 7TF, UK Correspondence to: EHK
171
172
Current Obstetrics & Gynaecology to be larger than I cm 3 it is necessary to insert a permanent filter before removing the t e m p o r a r y one. Following removal, anticoagulation should be continued for 3-6 months: similar to cases o f thrombosis where filters are not inserted. In o u r case, the patient was at 38 weeks' gestation and if she had not laboured within 1 week we would have induced labour. It seems preferable to deliver patients with the filter in situ, as the risk o f thrombus release is increased at this time. The advantages o f a temporary filter over its permanent counterpart are: • a reduced risk o f the complications outlined above • many permanent filters are ferromagnetic and, therefore, the patient cannot undergo Nuclear Magnetic Resonance ( N M R ) imaging in the future if required.
Figure Antheor temporary filter with thrombus.
Owing to the increased risk of D V T associated with pregnancy, and the likelihood o f the filter (if permanent) remaining in situ for 50-60 years, it seems probable that such patients are at a higher risk o f caval occlusion and possible death. Venous access (usually femoral or internal jugular) is determined by the site o f the venous thrombosis. In this case, the risk o f dislodgement o f embolus during catheter manipulation was felt to be appreciable, therefore,, the internal jugular route was preferred. Despite strict aseptic precautions, infection remains a risk and in this case the septicaemia was probably a result of infection at the insertion site. At removal on the 6th day, the femoral and iliac veins were clear and the filter had trapped fragments o f thrombus (Figure). I f the vena cava and filter are patent, the filter is removed by simple traction on the filter catheter. I f the vena cava is patent, but the filter contains thrombus estimated to be less than 1 cm 3 (as in this case); the filter is removed with the removal kit. This technique allows the temporary filter to be closed inside the IVC and then removed in the closed position. In the unlikely scenario where the vena cava is thrombosed or the filter contains thrombus estimated
Recently, p e r m a n e n t retrievable vena caval filters have been introduced. These may be removed within 2 weeks o f insertion or can be left in situ permanently. Such a filter m a y well represent the best way fonvard in the management o f women at 'high risk' o f pulm o n a r y embolism during pregnancy. Although a randomized controlled trial with filters would be unethical, utilizing t e m p o r a r y or retrievable filters instead o f permanent ones appears to be a logical progression with respect to the safety o f IVC filters in pregnancy. REFERENCES 1. Department of Health, Welsh Office,Scottish OfficeHome and Health Department, Department of Health and Social Services, Northern Ireland Report on confidential enquiries into maternal deaths in the United Kingdom 1991-1993. HMSO, London, 1996 2. Golueke PJ, Garrett "~W,Thompson JE, Smith BL, Talkington CM. Interruption of the vena ¢ava by means of the Greenfield filter: expanding the indications. Surgery 1988; 103:111-117 3. Hux CH, Wapner RJ, Chayeu B, Ratten P, Jarrell B, Greenfield L. Use of Greenfieldfilter for thromboembolic disease in pregnancy.Am J Obstet Gynaeeo! 1986; 155: 734-737 4. Narayan H, Cullimore J, Krarup K, Thurston H, MacVicar J, Bolia A. Experiencewith the cardial inferior vena cava filter as prophylaxis against pulmonary embolismin pregnant women with extensivedeep venous thrombosis. Br J Obstet Gynaecol 1992; 99:637-640 5. Ferris EJ, McCowan TC, Carver DC, McFarland DR. Percutaneous inferior vena caval filters: follow-up of seven designs in 320 patients. Radiology 1993; 188: 851-856 6. RoehmJOF, Johnsrude IS, Barlh MH, Gianturco C. The Bird's Nest inferior vena cava filter: progress report. Radiology 1988; 168:745-749