Prophylactic Interruption of the Inferior Vena Cava

A Retrospective Evaluation

David Rosenthal, MD, Boston, Massachusetts

David Cossman, MD, Boston, Massachusetts

Gary Matsumoto, MD, Boston, Massachusetts

Allan D. Callow, MD, Boston, Massachusetts

Sudden, unexpected, and occasionally fatal postop- erative pulmonary embolism may be a tragic com- plication of many surgical procedures. The reported incidence of fatal pulmonary embolism after surgery is as low as 0.5 to 3 per cent [I], but may increase to 5 or 6 per cent [z] after difficult gynecologic, ortho- pedic, or general surgical procedures. The incidence of pulmonary embolism after aortic surgery has not been established. Patients with a history of deep vein thrombosis, varicose veins, or previous pulmonary embolism, or those sustaining operative trauma to major veins, are at an even greater risk [3].

The precise incidences of deep vein thrombosis and pulmonary embolism in postoperative patients are not known; however, autopsy series [4] and ra- dioactive labeling studies [5] have demonstrated a startlingly high rate of occurrence of both. The fate of a single thrombus in the lower extremity in a postoperative patient is unknown and makes deter- mination of appropriate clinical treatment uncertain. For example, considerable confusion exists regarding the significance of thrombi in the soleal veins of the calf. Some clinicians [6] may ignore them. Others [ 7,8] believe they may be potential foci for thrombus extension into the popliteal system and possible pulmonary embolism. Anticoagulation therapy may therefore be justified. Results of increasingly sensi- tive methods of detecting small venous thrombi only add to the debate concerning appropriate therapy,

From the Vascular Service, Department of Surgery, Tufts-New England Medical Center Hospital, and the Department of Surgery, Tufts University School of Medicine, Boston, Massachusetts. This work was supported in part by NIH-GFtS Grant #27222. the New England Medical Center Hospital Free Fund #25280, and a contribution from Mr. and Mrs. Isaac Harter.

Reprint requests should be addressed to Allan D. Callow, M), Department of Surgery, Tufts-New England Medical Center, 171 Harrison Avenue, Boston, Massachusetts02111.

an issue especially important in the postoperative vascular surgical patient in whom anticoagulation may be hazardous.

Recently, regimens designed to test the effective- ness of perioperative low dose heparin have been shown to be valuable in preventing pulmonary em- bolism [9, IO]. Heparin in low doses, however, is in- adequate to treat established deep vein thrombosis or pulmonary embolism. Prophylactic interruption of the inferior vena cava in conjunction with aortic surgery has several advantages. Should deep vein thrombosis develop in the postoperative patient, prophylactic interruption of the inferior vena cava would serve as an already established therapy against pulmonary embolism, thus obviating the need for anticoagulant therapy with its potential hazards of early postoperative hemorrhage [II], immune- mediated thrombocytopenia [12], and late postop- erative pseudoaneurysm formation [13].

Material and Methods

To determine the effects of prophylactic inferior vena caval interruption in association with abdominal aortic surgery, the charts of 160 patients were retrospectively analyzed. Sixty-three patients who underwent aortic pro- cedures without inferior vena caval interruption from 1966 to 1976 were compared with ninety-seven patients with similar operations from 1970 to 1976 who had prophylactic inferior vena caval interruption. Since 1970 all patients have had prophylactic inferior vena caval interruption. Patients were excluded from this study if they died from causes unrelated to venous disease (proven by autopsy) or if prolonged hospitalization and bed rest (more than 10 days) were required to treat major nonvenous complica- tions.

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Rosenthal et al

Figure 1. Adams-De Weese vena caval clip.

The Adams-DeWeese clip (Jobst Institute, Toledo, OH) (Figure 1) is U shaped, having one smooth limb and one serrated limb with teeth 3.5 mm apart. When the clip is approximated transversely around the inferior vena cava, it divides the inferior vena cava into four or five channels, each measuring approximately 3 mm in diameter [ 141. The infrarenal vena cava should be exposed and surrounded with an umbilical tape prior to systemic heparinization. After insertion of an aortic graft, the clip is passed around the vena cava and secured in place. The clip should be placed immediately below the renal veins and situated away from the aortic anastomosis (Figure 2.)

The patients in each group were comparable in terms of sex, age, and type of procedure performed. Ninety-seven patients (69 males, 28 females) underwent surgery with inferior vena caval interruption; thirty-six underwent re- section of an abdominal aortic aneurysm and sixty-one were operated on for aortoiliac occlusive disease. The av- erage age of the group was sixty-six years. Sixty-three pa-

TABLE I Postoperative Venous-Related Complications

RENAL YE/N.9

GOMADAL VEIM

GRAF7

Figure 2. Placement of vena caval clip immediately below the renal veins, situated away from the aortic anastomo- sis.

tients (48 males, 15 females) underwent surgery without interruption of the inferior vena cava; twenty-seven were operated on for abdominal aortic aneurysms and 32 for aortoiliac disease. The average age of this group was sixty-five years. Neither group received anticoagulant therapy preoperatively. Both groups received intravenous heparin during surgery. Neither group was “reversed” with protamine sulfate. All operations were performed with general endotracheal anesthesia.

Clinical suspicion of deep vein thrombosis (leg edema, tenderness, a positive Homan’s sign) or pulmonary em- bolism (tachypnea, hemoptysis, or chest pain) was docu- mented by phlebography and pulmonary anteriography, respectively. Patients were evaluated for leg edema, deep vein thrombosis, and pulmonary embolism in the imme- diate postoperative period and during the follow-up period (range 1 to 72 months; median 20 months). Leg edema was considered significant when an increase of more than 3 cm in the circumference of the calf or midthigh was docu- mented.

All patients were examined on an outpatient basis after discharge. Two patients in the group with the inferior vena

PE DVT

Soleopopliteal lliofemoral

Prophylactic Inferior caval clip and three in the group without the clip were lost

Vena Cava Clip No WC Clip to follow-up.

(n = 97) (n = 63)

0 6 (lo%)* Results

10 (10%) 6 (10%) 4 3 No patients in the group with the inferior vena 6 3 caval clip had a pulmonary embolus. In contrast, six

Leg edema 5 (5%) 0 Total venous morbidity 15 (15%) 12 (20%)

Note: IVC = inferior vena caval; PE = pulmonary embolism; DVT = deep vein thrombosis.

+ Pulmonary embolism determined as cause of death at autopsy in 1 patient.

patients in the group without the inner vena cava clip (10 per cent) had a pulmonary embolism (Table I), one of whom died as a result, as confirmed by au- topsy. Five of six patients had pulmonary emboli within a thirty day postoperative period. Four of five

390 The American Journal of Surgery

Prophylactic IVC Interruption

TABLE II Venous Disease History/Postoperative Complications

Prophylactic IVC Clip (n = 82) No WC Clip (n = 54) No. of Patients Comolications No. of Patients Comolications

PE DVT

Varicose veins

Total

Previous Venous Disease (n = 12) 2 0 6 1 (leg edema)

1 (DVT) 4 2 (leg edema)

12 4 No Previous Venous Disease (n = 70)

7 (DVT) 2 (leg edema)

Previous Venous Disease (n = 7) 0 4 3 (DVT)

3 1 (PE)

7 4 No Previous Venous Disease (n = 47)

5 (PE) 3 (DVT)

Note: IVC = inferior vena caval; PE = pulmonary edema; DVT = deep vein thrombosis.

patients’ pulmonary emboli occurred within five days in postoperative venous morbidity between the group postoperatively. with the clip and the group without it.

Deep vein thrombosis occurred in ten patients in the group with the inferior vena caval clip (10 per cent). Four thromboses occurred in the soleopopliteal system and six in the iliofemoral system. Postoper- ative deep vein thrombosis developed in six patients in the group without the clips (10 percent): three cases in the soleopopliteal system and three in the iliofemoral system.

Leg edema with no phlebographic evidence of deep vein thrombosis occurred in five patients in the group with the inferior vena caval clip (5 per cent). Leg edema without deep vein thrombosis did not occur in the other group. Three patients had persisting leg edema after six months; in only one was it not con- trolled with elastic stockings. Thus, there was an overall complication rate of 15 per cent in the group with theinferior vena caval clip and 20 per cent in the group without the clip.

Of patients in both groups in whom complications developed, twelve in the group with the inferior vena cava clip and seven in the group without the clip gave a history of previous venous disease. (Table II.) Of the group with the clip, six patients had a history of deep vein thrombosis; in one patient, leg edema de- veloped and in another deep vein thrombosis devel- oped postoperatively. Leg edema developed post- operatively in two of four patients with a history of varicose veins. Although two additional patients gave a history of previous pulmonary embolism, neither had a pulmonary embolism postoperatively.

Eleven patients in the group without the clip re- quired heparin for treatment of deep vein thrombosis or pulmonary embolism postoperatively. Six patients in the group with the clip received heparin for deep vein thrombosis to prevent extension of thrombus and potential postphlebitic sequelae. Two patients with soleal vein deep vein thrombosis were not given heparin, and treatment was limited to limb elevation and bed rest. Since 1972, heparin, 30,000 USP units/l 5 per cent dextrose in water, was administered by an IVAC (IVAC Corporation, La Jolla, CA) constant infusion pump. (Prior to 1972, heparin, 5,000 USP units, was administered subcutaneously every 4 hours.) The infusion was regulated to maintain par- tial thromboplastin time at twice the control level. A total of four complications (23 per cent) occurred, two necessitating cessation of the heparin therapy. Complications consisted of one wound hematoma, two retroperitoneal hemorrhages, and one instance of gross hematuria. There were no complications related to the placement or the presence of the infe- rior vena caval clip itself.

Comments

In the group without the inferior vena caval clip, deep vein thrombosis developed in the postoperative period in three of four patients with a history of previous deep vein thrombosis. One of three patients with varicose veins had a postoperative pulmonary embolus. In those patients with no history of venous disease, there was no statistically significant increase

Kakkar and co-workers [3,10] have identified several factors that predispose surgical patients to venous thromboembolic complications. These in- clude previous venous disease, cardiac disease, and diabetes mellitus. A history of one or more of these risk factors classifies the patient as a “high risk” for venous thromboembolic complications. The majority of our vascular surgical patients are in this high risk category. (Table III.)

Moran, Kahn, and Callow [15] and Miles, Rich- ardson, and Wayne [16] reported on the use of pro- phylactic inferior vena caval interruption on a se-

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Rosenthal et al

TABLE III Predisposing Factors to Venous Thromboembolism

Risk factors

Prophylactic IVC Clip (n = 97;

mean age, 66 vr)

Major Previous DVT Previous PE Varicose veins Previous MI CHF

Total

Minor Diabetes Chronic obstructive lung

disease Hypertension Previous limb fractures Previous malignant

disease

6 (6%) 2 (2%) 4 (4%)

14 (14%) 13 (13%)

39%

22 (22%) 17 (27%) 23 (23%) 15 (24%)

18 (18%) 3 (3%) 4 (4%)

t1 (17%) 2 (3%) 2 (3%)

No IVC Clip (n = 63;

mean age,

65 yr)

4 (6%) 0 3 (5%) 9 (14%)

11 (17%) 42%

Total 70% 74%

Note: IVC = inferior vena caval; DVT = deep vein thrombosis: PE = pulmonary embolism; MI = myocardial infarction; CHF = congestive heart failure.

lective basis. Patients considered to be in a high risk category (previous history of deep vein thrombosis and/or pulmonary embolism) underwent placement of an inferior vena caval clip at the time of abdominal surgery. None of these patients suffered a postop- erative pulmonary embolus. Routine prophylactic inferior vena caval interruption, however, was not performed.

Our data indicate that use of the prophylactic clip only in those patients considered to be at high risk for pulmonary embolism will exclude the “average” patient who might have a pulmonary embolism in the postoperative period. In this series, pulmonary em- boli developed in five of six patients with no previous record of venous-related disease in the group who did not receive a clip, one of whom died as a result.

Abdominal aortic surgery can be considered a predisposing factor for thromboembolic complica- tions. Trauma to the vena cava, iliac, or vertebral veins, retroperitoneal dissection, venous stasis due to aortic cross clamping, lymphatic interruption, and prolonged operating time also enhance the develop- ment of thromboembolic disease. Intraoperative heparinization may hinder the development of thromboemboli, but this has not been clinically proven. Provided that complications such as deep vein thrombosis or leg edema due to the inferior vena caval clip itself do not negate its benefit, prophylactic interruption of the inferior vena cava would be jus-

tifiable in the previously asymptomatic patient undergoing aortic surgery. The value of the prophy- lactic inferior vena caval clip in preventing pulmo- nary embolism is significant by chi-square analysis (p < 0.001).

In this series the incidence of postoperative deep vein thrombosis was identical (10 per cent) and similar in location (Table I) in both groups, suggesting that the inferior vena caval clip was not the cause of deep vein thrombosis. Leg edema was more common in the group with the inferior vena cava clip. Of the five patients in whom leg edema developed, three had a history of venous-related disease. (Table II.) Persistent leg edema after twenty-four months in our series was a significant problem in only one patient.

The surgeon may avoid complications associated with anticoagulation in the postoperative period, especially in patients with vascular prostheses, if the vena cava has been prophylactically interrupted. In this series, 17 of 160 patients required postoperative heparin therapy either for deep vein thrombosis or pulmonary embolism. Of these seventeen patients, a complication developed in four (23 per cent) from postoperative heparinization. Two patients in the group without the inferior vena caval clip required cessation of heparin therapy, leaving them unpro- tected against pulmonary embolism. Although it has been our policy to heparinize patients with an inferior vena caval clip in place, when deep vein thrombosis develops this may be unnecessary, and other less hazardous forms of therapy are currently being evaluated. Low molecular weight dextran [17] and/or anti-inflammatory agents combined with limb ele- vation and bed rest may be adequate immediate treatment. This form of treatment cannot be advo- cated -until longer trials have shown that postphle- bitic syndrome is not a problem.

Summary

One hundred sixty patients were retrospectively evaluated to determine the effect of prophylactic inferior vena caval interruption in association with aortic surgery. Sixty-three patients underwent aortic procedures without inferior vena caval interruption and ninety-seven patients underwent placement of an Adams-DeWeese clip as prophylaxis against pulmonary embolism.

Pulmonary embolism occurred in 10 per cent of the group without the clip and in no patients in the group with the clip. The incidence of deep vein thrombosis was identical in both groups (10 per cent). The 6 per cent rate of early (within 6 months) postoperative leg edema in the group with the inferior vena caval clip

392 The American Journal of Surgery

Prophylactic IVC Interruption

was a significant problem in only one patient after twenty-four months. Prophylactic interruption of the inferior vena cava has been shown to be a safe method of decreasing the incidence of pulmonary embolism without increasing the incidence of ve- nous-related complications.

Acknowledgments: We wish to thank Drs. Ralph A. Deterling, Jr and Thomas F. O’Donnell for al- lowing their patients to be included in this study and for their editorial assistance with the manuscript.

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