The incidence of deep venous thrombosis patients undergoing abdominal aortic aneurysm resection

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1 The incidence of deep venous thrombosis patients undergoing abdominal aortic aneurysm resection in Jeffrey W. Olin, DO, Robert A. Graor, MD, Patrick O'Hara, MD, and Jess R. Young, MD, Cleveland, Ohio Purpose: Fifty consecutive patients undergoing abdominal aortic aneurysm resection were studied prospectively for the presence of deep venom thrombosis (DVT) after surgery. Methods: Bilateral venography was performed 5 days after surgery in all patients. There were 42 men and 8 women, with a mean age of 70 years (range 60 to 83 years). No patients received DVT prophylaxis before surgery. Results: Nine (18%) of 50 patients had a venogram positive for acute DVT. Nine (21%) of 42 men and none of eight women had DVT. Six patients had DVT in the left leg and three patients in the right leg. No patients had symptoms to suggest D~, Seven (78%) of the nine patients with DVT had thrombi in the calf veins and two patients (22%) had thrombi in the more proximal venom segments, representing 14% and 4% of the entire series, respectively. No clinically evident pulmonary emboli were observed. Conclusions: Eighteen percent of 50 consecutive patients undergoing abdominal aortic aneurysm resection had DVT. Because of this high incidence, a study should be undertaken to determine whether DVT prophylaxis can lower the incidence of DVT after abdominal aortic aneurysm resection. (J VASC SURG 1993;18: ) Venous thromboembolism is the third most common cardiovascular disease after ischemic heart disease and stroke) The reported incidence of deep venous thrombosis (DVT) and pulmonary emboli has not changed during the past 30 years? Lindblad et al.2 performed necropsy on 77% of 1293 patients during a 30-year period. During these three decades the incidence of venous thromboembolism, pulmonary embolism, and fatal pulmonary embolism documented at autopsy remained unchanged at 35%, 22%, and 8.9%, respectively. In addition, the mortality rate from pulmonary embolism has not diminished during the last generation.2,~ ' One reason that the incidence of venous thromboembolic disease has not decreased, whereas all other forms of cardiovascular disease have, may be the result of the failure of physicians to use adequate DVT prophylaxis in medical and surgical patients. From the Departments of Vascular Medicine and Vascular Surgery, Cleveland Clinic Foundation. Reprint requests: Jeffrey W. Olin, DO, Cleveland Clinic Foundation, 9500 Euclid Ave., Desk S-60, Cleveland, OH Copyright 1993 by The Society for Vascular Surgery and International Society for Cardiovascular Surgery, North American Chapter /93/$ Anderson et al. 4 studied a total of 2017 patients with multiple risk factors for venous thromboembolism treated in 16 hospitals and demonstrated that prophylaxis for venous thromboembolism was given to only 32% of these high-risk patients. 4 Prophylaxis use varied widely among the different hospitals, ranging from 9% to 56%, and was higher in teaching hospitals compared with nonteaching hospitals (44% vs 19%;p < 0.001). Failure to use DVT prophylaxis occurred despite the enormous body of literature that has demonstrated that prophylaxis reduces the incidence of DVT and fatal pulmonary embolism, s-s Most recommendations regarding prophylaxis for venous thromboembolic disease are directed at patients undergoing general, orthopedic, or neurologic surgery or medical patients confined to prolonged periods of bed rest. There are few recommendations in the literature regarding prophylaxis for patients undergoing peripheral vascular surgery. The incidence of DVT in patients undergoing aortic replacement is not well defined. The paucity of data in the literature assessing the incidence of DVT after aortic surgery used iodine 125-labeled fibrinogen leg scanning as the primary method of diagnosis of DVT To our knowledge, there is no report to date that has used venography to assess the incidence of DVT after aortic surgery, 1037

2 1038 Olin et al. JOURNAL OF VASCULAR SURGERY December 1993 Table I. Demographics and past medical history of 50 patients undergoing abdominal aortic aneurysm resection Patient data n % Sex Male 42 Female 8 Age (yr) Mean 70 Range Medical history Prior venous throm- 0 boembolism Hypertension 27 Coronary artery disease 37 Stroke 4 Diabetes 1 Obesity 8 Current smoker 19 Past smoker The purpose of this study is to determine the incidence of DVT in patients undergoing abdominal aortic aneurysm resection. PATIENTS AND METHODS Fifty consecutive patients undergoing abdominal aortic aneurysm resection were studied prospectively for the presence of DVT after abdominal aortic aneurysm resection. After informed consent was obtained, all patients underwent bilateral ascending venography 5 days after surgery. Venograms were reviewed independently by a member of the section of interventional angiography and a member of the vascular medicine department. There was agreement in the interpretation of all venograms. Tourniquets were applied to fill all of the deep calf veins as much as possible. Spot films were obtained in all patients. A venogram was considered positive for an acute thrombns only if an intraluminal filling defect was demonstrated on more than one view. Failure to fill a vein with contrast material adequately was not considered to represent an acute DVT in the absence of an intraluminal filling defect. Prophylaxis for DVT was not administered to any patient before or after abdominal aneurysm resection. The demographics and past medical history of the patient population is shown in Table I. All patients underwent either aortobiiliac grafting, aortobifemoral grafting, or the placement of an aortic interposition graft. The synthetic graft material used was knitted Dacron in 38 patients and woven Dacron in 12 patients. Statistical analysis. The Fisher exact test was Table II. Incidence of DVT in patients undergoing abdominal aortic aneurysm resection DVT Patient data n % Total (n = 50) 9 18 Male (n = 42) * Female (n = 8) 0 Proximal DVT 2 22 Calf DVT 7 78 Right-leg DVT Left-leg DVT Male versus female: p = 0.322, Fisher exact test. used to detect differences in the incidence of DVT between men and women and between those patients who received protamine sulfate and those who did not. The Wilcoxan rank sum test was used to determine other differences that might have occurred occurred between patients who had DVT and those who did not. RESULTS Nine (18%) of 50 patients had DVT as determined by ascending venography (Table II). None of the eight women in this study had DVT. There was no significant difference between the incidence of DVT in men and women. Deep venous thrombosis was present in the calf veins in seven patients (14%) and in the proximal venous segments (popliteal, superficial femoral, common femoral, or iliac) in two patients (4%). Seventy-eight percent of thrombi were confined to the calf veins and 22% to the proximal veins. All nine patients who had DVT were symptom free (i.e., no calf tenderness, swelling, dilated superficial veins, suffusion). Clinically apparent pulmonary emboli were not observed in any patient. The DVT occurred in the left leg in 66.7% of the patients and in the right leg in 33.3%. Table III outlines several factors that may be important in the formation of intraoperative venous thrombosis. There was no difference in any of these factors in the patients who had DVT compared with those patients who did not. DISCUSSION This is the first study to document the incidence of DVT after abdominal aortic aneurysm resection by venography 5 days after surgery. The sensitivity and specificity ofvenography are superior to those of any of the noninvasive methods available to detect DVT

3 Volume 18, Number 6 Olin et al. I039 Table III. Possible intraoperative factors contributing to DVT DVT (n = 9) No DVT (n = 41) p Value Clamp time (min) Right leg 90 (35-334) 92 (37-334) NS Left leg 81 (18-375) 82 (22-375) NS Total intraoperative heparin (units) NS Estimated blood loss (ml) NS Blood product replacement (ml) Packed red blood cells (36 patients) NS Platelets (6 patients) NS Fresh-frozen plasma (16 patients) NS Autotransfusion (46 patients) NS Protamine sulfate (n) Yes 7 33 NS No 2 8 NS NS, Not significant. Table IV. Summary of studies that attempted to determine the incidence of DVT after abdominal aortic surgery Incidence of D VT Method of Author/yr No. patients diagnosis of D VT n % Angelides et ai,9/ Satiani et al} / lennings et al.n/ Reilly et a1.12/ Sch66n et al.la/ Cass et ai}4/ Olin et al./ SI-labeled fibrinogen leg scanning; venography obtained if there was extension of radioactivity above the knee 12SI-labeled fibrinogen and impedance plethysmography; venography obtained if ~2sI was positive 12SI-labeled fibrinogen leg scanning I-labeled fibrinogen leg scanning and 6 6 Doppler evaluation; venography in all patients with positive results of noninvasive tests 12~I-labeled fibrinogen leg scanning, per fusion lung scan, and venous emptying time Leg swelling and 12SI-labeled fibrinogen 7 23 leg scanning Ascending venography 9 18 if proper technique is used and acute DVT is diagnosed only when an intraluminal defect is present. Table IV shows the incidence of DVT in patients undergoing aortic surgery in other published reports. 914 Each of these series used 12SI-labeled fibrinogen leg scanning alone or leg scanning combined with Doppler, impedance plethysmography, or venography when the leg scan was positive. 12aIlabeled fibrinogen leg scanning is useful in detecting thrombi in the calf and the distal portion of the thigh. A delay in diagnosis of DVT of up to 48 hours may occur because the labeled fibrinogen must be incorporated into an actively forming thrombus to be detected as a hot spot on the scan. False-positive results can occur as a result of previous surgical incisions, a large wound, or areas of inflammation or hematoma} s This technique generally has a high degree of sensitivity for calf thrombi yet it fails to detect thrombi in the iliofemoral region in approximately 30% of patients. There may be a high false-positive rate with the use of lzsi-labeled fibrinogen leg scanning as is demonstrated in some of the reports in Table IV. In the study of Satiani et al. 1 there was an abnormal 125I-labeled fibrinogen leg scan in 17 of 138 limbs. However, the venogram was abnormal in only three patients. Two of these patients had an equivocal venogram for acute thrombus and one was clearly positive} Reilly et al}2 detected an abnormal ~2SI-labeled fibrinogen leg scan in 17 of 100 patients who underwent aortoiliac reconstructive surgery. However, the venogram was

4 1040 Olin et al. December 1993 positive in only six of these patients, giving an incidence of DVT of 6%. In their series one patient had a normal fibrinogen leg scan and Doppler examination, yet an abnormal venogram. In the two previously mentioned studies, the 12SI-labeled fibrinogen leg scan overestimated the likelihood of DVT. In addition, Iz~I-labeled fibrinogen leg scanning may not detect up to 15% of patients with venographically proved DVT. 12 Because this noninvasive modality is inadequate to detect iliofemoral DVT, duplex ultrasonography should be performed in conjtmction with leg scanning in an attempt to identify proximal venous thrombosis. Because of these limitations, we currently believe that the most effective way to determine the incidence of DVT after abdominal aortic aneurysm resection is to perform venography on every patient. Venography is the best test for detecting not only calfthrombi but also thrombi in the thigh and pelvis. In this series the overall incidence of DVT was nine (18%) of 50 patients. None of the women had DVT, but there was no statistical difference in the incidence of DVT between the men and the women. Most of the thrombi in this series were confined to the calf (78%). Although some investigators believe that postoperative calf vein thrombosis need not be treated, ~6 we generally do not agree with this approach. Philbrick and Becket 17 reviewed 20 relevant English-language articles published since 1942 regarding the natural history of calf vein thrombosis. This review suggests that calf vein thrombosis propagates to the proximal venous system in up to 20% of cases. If proximal propagation occurs, there is a 50% chance of the thrombus embolizing to the pulmonary vasculature, yielding a 10% risk of pulmonary embolism associated with calf DVT. There is evidence that treatment with standard anticoagulation (heparin and warfarin) prevents extension, embolization, and recurrence of DVT. For these reasons, as well as the unchanging death rate of pulmonary embolism during the last 40 years, 2'3 we believe that most patients with calf vein thrombosis should be treated. If a patient with calf DVT is at an increased risk for bleeding with anticoagulants, serial duplex ultrasonography is a reasonable alternative to identify the 20% of calf vein thrombosis that may propagate to the proximal veins. All of the patients with DVT in this series were treated with heparin followed by warfarin for 3 months. In the event of a significant contraindication to anticoagulation, we would have placed an inferior vena caval filter if a proximal venous thrombosis was present. If antico- agulation was contraindicated in the patient who had a calf venous thrombosis, serial duplex scanning would have been performed in an attempt to detect thrombus propagation to the proximal venous segments. Although not statistically significant, DVT occurred more often in the left leg compared with the right leg. This may be related to the normal anatomy in which the right iliac artery may compress the left iliac vein. 18 This may result in stasis of blood flow in all segments of the vein distal to the compression. There was no difference in the clamp time, intraoperative heparin dosage, estimated blood loss, type of blood product replacement, use ofprotamine sulfate, and the development of DVT. This report is the first to demonstrate the incidence of DVT after abdominal aortic aneurysm surgery with venography in every patient. The next important step would be to perform a randomized trial of DVT prophylaxis (subcutaneous heparin, low molecular weight heparin, or pneumatic compression stockings) versus placebo to determine if this high incidence of DVT (18%) can be lowered to more acceptable levels. We thank Carol Pirzada, RN, for data collection. REFERENCES 1. Goldhaber SZ. Pulmonary embolism and thrombolysis: a clarion call for international collaborationl J Am Coil Cardiol 1992;19: Lindblad B, Sternby H, Bergqvist D. Incidence of venous thromboembolism verified by necropsy over 30 years. Br Med J 1991;302: Lilienfeld DE, Chan E, Ehland J, et al. Mortality from pulmonary embolism in the United States: Chest 1990;98: Anderson FA, Wheeler B, Goldberg RJ, et al. Physician practices in the prevention of venous thromboembolism. Ann Intern Med 1991;115: National Institutes of Health Consensus Development Panel. Prevention of venous thrombosis and pulmonary embolism. JAMA 1986;256: Collins R, Scrimgeor A, Yusuf S, Peto R. Reduction in fatal pulmonary embolism and venous thrombosis by perioperative administration of subcutaneous heparin. N Engl ] Med 1988;318: Hull RD, Raskob GE, Hirsh J. Prophylaxis of venous thromboembolism: a review. Chest 1986;89(suppl):374S- 81S. 8. Halkin H, Goldberg J, Modan M, Modan B. Reduction of mortality in general medical inpatients by low dose heparin prophylaxis. Ann Intern Med 1982;96: Angelides NS, Nicolaldes N, Fernandes J, et al. Deep venous thrombosis in patients having aortoiliac reconstruction. Br J Surg 1977;64: Satiani B, Kulms M, Evans WE. Deep venous thrombosis

5 Volume 18, Number 6 Olin et al following operations upon the abdominal aorta. Surg Gynecol Obstet 1980;151: Jennings S, Cass A], Heather BP, Greenhalgh RM. Coagulation changes during major surgery and relationship to postoperative deep vein thrombosis. J Cardiovasc Surg 1981;22: Reilly MK, McCabe CJ, Abbott WM, et al. Deep venous thrombosis following aortoiliac reconstructive surgery. Arch Surg 1982;117: Sch66n IM, Holm ], Lindberg B, et al. Hemodynamic findings before and after resection of abdominal aortic aneurysm. Acta Chit Scand 1984;150: Cass AJ, Jennings SA, Greenhalgh RM. Leg swelling after aortic surgery. Int Angiol 1986;5: Hirsh J, Genton E, Hull R. Diagnosis of venous thromboembolism. New York: Grune & Stratton, 1981: Softs MM, Ranval TJ, Nix ML, et al. Is anticoagulation indicated for asymptomatic postoperative calf vein thrombosis? J VASC SURG 1992;16: Philbrick IT, Becker DM. Calf deep venous thrombosis: A wolf in sheep's clothing? Arch Intern Med 1988;148: Cockett FB, Lea Thomas M, Negus D. Iliac vein compression: its relation to iliofemoral thrombosis and the postthrombotic syndrome. Br Med J 1967;2:14-9. Submitted Nov. 30, 1992; accepted Jan. 25, 1993.