Collateral Lymphatico-Venous Communications After Experimental Obstruction of the Thoracic Duct

SINCE Kinmonth established the technic for cannulating the peripheral lymphatics in 1954 there has been increasing interest in contrast radiography of the lymphatic system (13, 14). The clinical usefulness of this method has been established (5, 25, 28, 29). Although the collateral pathways of the lymphatic system have been studied by many investigators (1, 9, 12, 15, 16, 20, 21, 23, 26, 27), the radiographic demonstration of collateral channels and lymphatico-venous communications in vivo has been uncommon (6, 7, 11, 30). The present study was designed to investigate the mode of collateral lymphatic flow following thoracic duct ligation in the experimental animal, using contrast lymphangiography and cineradiography. Methods and Material Adult mongrel dogs weighing 15 to 20 kg were anesthetized with 250 mg/kg of Diabutol. Initially the spermatic lymph trunks were injected because of the absence of nodes interposed between the injection site and the cisterna chyli. The dissection of these lymphatics proved tedious and time-consuming, however, and, as a consequence, the hindfoot was employed as the site of injection. One-half cubic centimeter of Evans blue was introduced into the interdigital spaces in order to stain the lymphatics. Immediately thereafter, the lymphatic channel was dissected. The mesenteric lymphatics were also injected to clarify the patterns of the mesenteric lymphatic circulation. A 25- or 30-gauge needle connected to appropriate polyethylene tubing was inserted into the lymphatic and taped in place. Ethiodol, emulsified Ethiodol, and Thorotrast were all utilized as contrast agents to demonstrate the lymphatics. Among these, Ethiodol proved most satisfactory. A simple weight-driven mechanical injector was adjusted for needle size and lymphatic resistance at a pressure below that causing extravasation in the soft tissues of the extremity. When radiographs of the abdomen and chest demonstrated filling of the thoracic duct, ligature was carried out with the aid of image amplification. Chlorophyllized “green” Ethiodol aided in identifying the terminal portion of the duct. Fluoroscopy and cine radiography confirmed the correct location of the ligature. The rates of progress, pathways of circulation, injection pressures, and parallel measurements of intralymphatic pressures on the initial study were compared with subsequent lymphangiograms obtained from three to ten weeks later. In the first two cases, daily follow-up films of the chest and abdomen were taken for one week in order to evaluate the changes in the lymphatics and nodes. Thoracic duct ligation was performed on 11 dogs. All had an initial control lymphangiogram, and 9 had subsequent lymphangiograms from three to ten weeks later. Two dogs had three studies at intervals of three weeks. Results The normal anatomy of the thoracic duct of the dog showed surprisingly few variations in this series.