Bird's Nest Filter Migration to the Right AtriumJohn O. F. Roehm, Jr.Audio Available | Share

Thromboembolic complications are common in patients with advanced malignancies. For these patients anticoagulation with warfarin is often complicated by severe bleeding. For this reason we evaluated the safety and efficacy of the Bird's Nest Filter, a new device capable of preventing migration of thromboemboli to the pulmonary arteries through interruption of the inferior vena cava. We report a series of 31 unselected patients with advanced malignancies and thromboembolic disease in whom the filter was used in lieu of chronic full-dose warfarin anticoagulation. No documented cases of pulmonary emboli occurred after insertion of the filter. Placement of the filter was uncomplicated. Eight patients (25.8%) developed lower-extremity edema. Venous thrombosis distal to the filter was documented in six (19.4%) patients but did not require institution of heparin or warfarin. Two patients (6.5%) required treatment with aspirin for painful lower-extremity thrombophlebitis. No filter migration was documented. We conclude that the use of the Bird's Nest Filter is an option for patients with cancer-related lower-extremity thrombosis who are at risk for pulmonary emboli and are poor candidates for full-dose systemic anticoagulation with warfarin. A prospective randomized trial comparing the filter and the new strategy of low-dose anticoagulation with warfarin will be needed to completely validate this approach.

Permanent ligation of arteries supplying blood to the spinal cord in operations for aortic aneurysm can lead to spinal cord ischemia, which can result in either paraparesis or paraplegia. This report describes a rapid method of intraoperative identification of those arteries that supply the spinal cord by use of an intrathecal platinum electrode to detect hydrogen in solution that has been injected into the aortic ostia. Preservation or perfusion of those identified arteries supplying the spinal cord may decrease the rate of postoperative neurologic complications. Of 28 porcine experiments with postoperative observation for 24 hours, there were 3 initial pilot experiments in which saline saturated with hydrogen was injected into the temporarily cross-clamped aorta. Twenty animals were then randomized to (1) preservation of only the vessels sequentially identified to supply blood to the spinal cord from T-13 to L-5 (n = 10); (2) division of the vessels supplying the spinal cord (n = 10). A further five animals underwent perfusion experiments wherein the identified cord arteries were perfused by a shunt, the other nonsupply arteries were divided, and the aorta was kept clamped for 45 minutes. Spinal motor evoked potentials were elicited with an intrathecal electrode and were highly sensitive for paralysis. Paralysis occurred in 0/3 pilot (p less than 0.013 vs division); 8/10 division; 1/10 preservation (p less than 0.0017 vs division); and perfusion 1/5 (p less than 0.025 vs division). Results of a pilot study in eight humans shows that the technique can be used to rapidly identify segmental arteries supplying the spinal cord, to determine if distal perfusion is supplying the spinal cord with blood flow, and if reattached segmental arteries are patent.

The appearance of the Bird's Nest inferior vena cava filter on magnetic resonance (MR) images of 11 patients is described. No complication or symptomatic filter displacement was encountered as a result of MR imaging performed at 1.5 T. The filters created significant local artifact and distortion on MR images. However, diagnostic MR images of the pelvis, spine, and brain may still be obtained.

The bird's nest inferior vena cava filter, in clinical trial since 1982, has been placed in 568 patients at risk for pulmonary embolism. Of the 481 patients in whom the filter had been in place for 6 months or more, 440 were followed up clinically. The prevalence of clinically suspected recurrent pulmonary thromboembolism was 2.7% (12 patients) and that of inferior vena cava filter occlusion was 2.9% (13 patients). With the initial filter design, filter migration occurred in five patients. No migrations have occurred in the 147 patients treated with the filter after its modification to improve the anchoring system for greater stability. The bird's nest filter has proved safe and effective in the prevention of pulmonary embolism.

The bird's nest filter (Cook, Inc., Blooming-ton, IN) is a transvenous stainless-steel inferior vena caval filter designed for percutaneous introduction. Its design incorporates features to eliminate the technical problems associated with other trans-venous filters and produces an effective non-thrombogenic barrier to potential pulmonary emboli.

The bird's nest filter is a new transvenous stainless steel inferior vena cava filter designed for percutaneous introduction. The filter design eliminates the technical problems associated with other transvenous filters and produces an effective nonthrombogenic barrier to potential pulmonary emboli.

A filter for the inferior vena cava has been devised for treatment of pulmonary embolism. Percutaneous insertion of the filter is accomplished with the use of a sheath and an 8-F catheter. Therapeutic results involving 28 patients have been excellent. No embolism has recurred; no vena cava thrombosis has developed. Since minor surgery is unnecessary, the procedure saves time and is cost-effective.

All aneurysms of the aorta are now successfully treated by operation; however, the indications, objectives, and results of therapy vary with the type and location of the aneurysm. This report emphasizes current concepts and principles.

A successful operation on a patient with infected right atrial myxoma is presented. The clinical features of cardiac myxoma are discussed, with particular emphasis on the relationship of this lesion to bacterial endocarditis and the differential diagnosis of right atrial myxomas. A careful survey for cardiac myxomas should be conducted in patients with unusual cardiac disease. A careful search for infection in patients with known cardiac myxoma may reveal that infection is more common than previously recognized.

Occlusion of the celiac, superior mesenteric, and inferior mesenteric artery has been studied in 46 patients treated by operation. The condition was acute and was caused by embolic obstruction of the superior mesenteric artery in four cardiac patients and detachment of the inferior mesenteric artery in two patients during removal of infrarenal abdominal aortic aneurysms. The condition was chronic and involved two or all three of the vessels in 40 patient. Embolic obstruction caused severe abdominal pain but few physical signs early in the process,, but the picture of an acute abdomen indicating bowel gangrene developed in a few hours. Ischemia from inferior mesenteric detachment was observed at operation. Patients with chronic obstruction had abdominal pain, weight loss, and diarrhea. Patients with embolic obstruction were treated successfully by embolectomy, and patients developing intraoperative sigmoid ischemia were treated by reattachment of inferior mesenteric arteries to aortic graft. Various procedures were employed in patients with chronic multiple obstruction. However, graft bypass using Dacron tubing was preferable because of its simplicity and because the frequently (48%) associated occlusive disease and aneurysm of the distal aorta were treated at the same time. Confining operation to the abdomen significantly reduced the magnitude of operation and eliminated risks in this age group. Of the 46 patients, 91% survived and were relieved of their symptoms despite associated disease. The 5-year survival rate in this group of patients was 62%.

The scimitar syndrome is a rare but nevertheless important developmental cardiopulmonary abnormality of particular interest to the radiologist because it can be readily recognized on plain roentgenograms. In view of the fact that only 54 cases have been reported in the world literature (1) and 7 patients with this malformation have been studied at the University of Minnesota Heart Hospital, it is appropriate to summarize the radiographic features. The full-blown syndrome, which invariably involves the right lung and its vascular supply, consists of: (a) hypoplasia of the right lung with subsequent dextroposition of the heart into the right thoracic cavity; (b) hypoplasia of the right pulmonary artery; (c) anomalous arterial supply from the abdominal aorta to the right lower lobe; (d), most important of all, anomalous venous drainage of the right lung by a large vein emptying into the inferior vena cava just below or above the right hemidiaphragm (2–5). The clinical features vary considerably with the degree of associated lung hypoplasia which results in repeated respiratory infections. Recurrent bouts of pneumonitis may be the dominant symptom, especially in the pediatric age group (1). On the other hand, in the milder form without significant lung hypoplasia, the abnormality may be discovered as an incidental finding on a chest film. Associated cardiac abnormalities have been rarely reported in the literature, but such intracardiac malformations were encountered in 3 of our patients. Two had ventricular septal defects with pulmonary stenosis, and one had a reversing patent ductus arteriosus (1). Discussion of Radiographic Features Plain Roentgenograms of the Chest: In patients with significant hypoplasia of the right lung, the postero-anterior roentgenogram may show a slightly smaller right bony hemithorax with a generalized shift of the mediastinal structures to the right (6–8) (Fig. 1). Frequently, the right heart border is indistinct (Fig. 1), apparently because of commonly found pleuropericardial adhesions and atelectasis secondary to repeated episodes of pulmonary infection. Pleural changes may be well visualized on the lateral film study, causing indistinctness of the right diaphragmatic contour (Fig. 2). Either the entire right lung may be drained anomalously or only the middle or lower lobes (5, 8). Characteristically, the anomalous vein shows a vertical course toward the right cardiophrenic angle, closely paralleling the right atrium. Due to its gentle curvature, the vein appears quite similar to a curved Moslem sword or scimitar (9). Depending upon the degree of right pulmonary hypoplasia, the vein may project through the right heart or in the right pericardial area. In all our observed cases, the scimitar vein was clearly visible on plain roentgenograms of the chest without laminagraphy, a procedure necessary only in doubtful cases.