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SURGICAL TREATMENT OF SUPERIOR VENA CAVA OBSTRUCTION DUE TO MALIGNANT TUMOR
SURGICAL T R E A T M E N T OF SUPERIOR V E N A CAVA OBSTRUCTION D U E T O M A L I G N A N T T U M O R Robert Allansmith,
M.D.,*
San Jose, Calif.
obstruction of the superior vena cava is associated with a rapid rise of the venous pressure of the upper half of the body. The signs and symp toms characteristic of the clinical picture are well known and these are related to the obstruction of the venous flow. If the obstruction is of gradual onset, or if the obstruction is above the level of the azygous vein, a collateral circulation will develop, permitting the blood to find its way back to the heart. In a previous paper by Allansmith and Richards, 1 the problem of superior vena cava obstruction as related primarily to benign lesions, was taken up in detail. The surgical approach to relief of the obstruction in 21 cases was de scribed. The cause of the obstruction, type of graft, and site of shunt to the heart was summarized. At this time, long-term follow-up studies are not avail able on all of these patients, but it is known that most of the grafts and prostheses eventually became obstructed. The initial relief of symptoms sometimes was lifesaving, however, and enough time was gained so that an efficient col lateral circulation could be developed. Intrathoracic malignant tumors are frequently associated with a rise in the venous pressure of the upper half of the body, both early and late in their course. A venous pattern on the chest wall is sometimes the first sign of an intrathoracic tumor, and may be found before the tumor is visible on the chest film. Partial obstruction of the superior vena cava may be the rule rather than the exception in the advanced stages of intrathoracic neoplasm. Although the neck veins may be prominent and the venous pressure somewhat elevated, the alarming symptoms associated with an acute obstruction of the vena cava are absent, and, if the patient is cyanotic or short of breath, the cause is probably related to invasion of the lung, rather than to the venous obstruction. On the other hand, acute obstruction of the superior vena cava may occur if an intrathoracic malignant tumor invades the vena cava causing a thrombosis of the lumen. The alarming rise of the venous pressure in the upper half of the body to 600 to 1,000 mm. of saline is associated with massive edema of the upper half of the body, acute shortness of breath, and somnolence. In order to save these patients, they must be propped upright and a phlebotomy of 500 to
A
CUTE
Received for publication Nov. 3, 1961. •Address: 606 Medico Dental Bldg-., San Jose, Calif. 258
Vol. 44, No. 2 August, 1962
SUPERIOR V E N A CAVA OBSTRUCTION
259 UK,U
1,000 c.c. must be carried out promptly. Administration of nasal oxygen par tially relieves the shortness of breath, and vigorous treatment with diuretics helps to overcome the cerebral edema. This type of vena cava obstruction may occur with a small tumor, which may not be detectable in the chest films because of the widening of the vena caval silhouette. While bronchoscopy may be performed with the patient in the upright position, the edema of the larynx and tracheobronchial tree may cause obstruc tion of the airway, and trauma to the mucosa, which is already engorged with blood, may cause bleeding which is difficult to control. A scalene node biopsy, or even a tracheotomy, in a patient whose venous pressure is above 600 mm. of saline, may be associated with a serious hemorrhage. CASE REPORT The following case report is t h a t of a 48-year-old crane operator, who had been in excellent general health. Six weeks prior to his admission to the hospital, a cough de veloped, productive of small amounts of bright red blood. At the same time, he began to notice swelling of his face and neck, so t h a t he was unable to button his shirt collar. The veins of his neck and chest wall became prominent, and he began to have episodes of somnolence. When the p a t i e n t was first seen in the hospital he had the typical facies of superior vena cava obstruction. The venous pressure was 600 mm. of saline, and he had to remain constantly in the upright position in order to breathe. A bronchoscopy was done with t h e patient in the upright position under a local anesthetic. Marked edema and engorgement of the mucosa were encountered, but there was no evidence of a tumor. A chest film revealed a widening of the superior mediastinal shadow, consistent with distention of the superior vena cava, and a minimal infiltration of the medial aspect of the upper lobe of the right lung was noted. The surgeon was very reluctant to perform a major operation on this poor risk patient if the cause of the obstruction was a malignant tumor. I n spite of t h e high venous pressure, a right scalene biopsy was performed. The venous bleeding and edema of the structures in the neck made the procedure difficult, but several enlarged lymph nodes were obtained. There was no evidence of tumor in any of these nodes. Since acute vena caval obstruction of this type had been reported due to conditions other than malignancy, the chest was opened through a sternum-splitting incision which was extended into the right fifth interspace. As is characteristic of operations performed under such circumstances, it is impossible to control (completely) the hemorrhage until the obstruction has been relieved. The veins bleed under a pressure t h a t would do credit to an artery, and even the veins of the bone marrow spurt blood. Enough of the bleed ing can be controlled using electrocoagulation, bone wax, and packs to make the operative field reasonably clean. An anaplastic carcinoma of the upper lobe of t h e right lung was found, and this was growing into the adjacent vena cava, causing complete obstruction. Mediastinal nodes were not found, and there was no other-evidence of tumor in the right hemithorax. A woven Teflon graft, supported by rigid Teflon rings, was sutured to the upper part of the vena cava at t h e junction of the innominate veins above, and to the antero-lateral wall of the right atrium below. As soon as the shunt was opened, the venous pressure dropped rapidly and it was possible to control all of the bleeding in the surgical wound. Immediately after the operation the venous pressure was normal, and the patient was able to lie in the recumbent position. There was a weight loss of seventeen pounds by diuresis. At the end of one week, radiotherapy with the linear accelerator was started. He received 5,000 rads to the tumor through opposing anterior and posterior ports. Therapy was continued over 31 days, during which time he was an outpatient.
ALLANSMITH
260
J. Thoracic and Cardiovas. Surg.
The only complication of t h e operation and radiotherapy was a deep stitch abscess in the central p a r t of the midline sternal wound. This was treated conservatively over a period of weeks, and eventually healed. Four months postoperatively he continued to do well and a bronchoscopy revealed no evidence of tumor. At t h a t time a chest film showed only a small density or scar adjacent to the mediastinum on the right. The venous pressure continued to be normal. A superior vena cavagram revealed the graft to be well preserved and free from any obstruction or irregularity. There was some evidence of reoanalization of the superior vena cava.
Fig. 1.—Four months postoperatively the vena cavagram revealed a well functioning graft. There is also some evidence of reoanalization of the superior vena cava which had been completely obstructed by tumor at the time of operation. Six months postoperatively he was again admitted to the hospital following a con vulsive seizure. Seven months postoperatively he died from complications secondary to a large cerebral metastasis. Autopsy revealed an entirely p a t e n t Teflon graft, well lined, with a smooth endothelial surface. There was no evidence of narrowing at either end, although there was dense scarring in the mediastinum incident to the irradiation therapy. The vena cava showed some evidence of reoanalization, having a lumen approximately the size of a pencil. There was no evidence of tumor or infection in the thoracic cavity, although the irradiation change was extensive. There was no evidence of tumor in the primary or secondary bronchi of t h e upper lobe of t h e right lung. A large cerebral metastasis and an adrenal metastasis were the only evidences of residual tumor. DISCUSSION
This case illustrates the use of a bypass graft as a lifesaving procedure in the presence of a superior vena cava obstruction due to a malignant tumor. It
Vol. 44, No. 2 August, 1962
SUPERIOR VENA CAVA OBSTRUCTION
261
has been the experience of the author that the cause of the acute complete vena cava obstruction is related to the growth of the tumor through the vena cava wall obliterating the lumen, rather than to external pressure on the vena cava from the tumor. In this instance, the vena cava was completely blocked by tumor and a positive biopsy was obtained by opening the vena cava. Irradiation to tolerance with the linear accelerator had not caused any narrowing or throm bosis in the Teflon graft. In spite of dense scarring and post-irradiation change in all of the surrounding structures, the Teflon graft, supported with rings of rigid plastic, resisted the encroachment of the scar tissue.
Fig- 2.—Reinforced Teflon graft. Note the rigid plastic rings sutured to the woven Teflon graft in order to preserve the lumen when the graft is inserted into the vena cava, a low pressure system.
Description of the Graft.—A graft of woven Teflon, % inch in diameter and 7 inches long, was reinforced by sliding rigid plastic rings over the outside of the graft and suturing them with 5-0 black silk sutures, so that they sup ported the graft wall. The rings measured y2 inch in internal diameter, 2 mm. in thickness, and 2 mm. in width. These were sutured at intervals of 1 cm. along the graft. One ring at each end was immediately adjacent to the anas tomosis to the superior vena cava above, and to the heart below. The replacement or bypass of vital veins of the body presents a problem which has not been successfully solved. The surgical failures attributed to thrombosis and stricture formation are related to the slow flow and low pressure in the veins. In 1955, Deterling and Bohnslay 2 reported the use of vessel grafts and plastic prostheses for relief of superior vena cava obstruction. After initial good results, all of the grafts and prostheses became obstructed. Blum, Medl, and Keefer 3 used aortic homografts in the postrenal inferior vena cava in 1956. Their results were disappointing. Homografts and silicone rubber tubes were used experimentally by Ohara and Sakai* in 1957. Their efforts to find a suit able vein replacement met with little success, and thrombosis and stenosis oc curred in all cases. In the experimental work of Deterling and Bohnslay, 2 aortic homografts were found superior to autologous jugular veins, Ivalon, woven nylon, and Dacron. There was a 40 per cent narrowing of the lumen due to constriction in those few which remained patent. In 1955, Sauvage and Wesolowski 5 studied anastomoses and grafts in the venous system with
ALLANSMITH
262
J. Thoracic and Cardiovas. Surg.
special reference to growth changes. The intrathoracie venae cavae were grafted with Orion cloth or aortic homografts, but all of the grafts became constricted or totally obliterated. Ashburn, Sewell, and Huggins, 6 in 1956, used homologous arteries in the vena cava, but all of their grafts showed stenosis of the distal anastomosis within 5 months. In 1956, Egdahl and Hume 7 reported experimental work, including nonsuture blood vessel anas tomoses, using polyethylene tubing as the prosthetic material. The results with the polyethylene were unsatisfactory. Using perforated polyethylene tubing, there was short-term success when the tubes were lined with a venous homograft. The superiority of the perforated polyethylene tubing over the solid tubing wa's due to external vascularization, through the perforations of the tubes. The above review indicates that, clinically and experimentally, a completely satisfactory graft replacement for the vital veins has not been developed. In 1957, MacLean and co-workers,8 used an Ivalon-Lucite prosthesis to replace the intrathoracie inferior vena cava. They presented a follow-up study of early work done with molded Ivalon in their laboratory and stated that stenosis or complete obstruction developed within 10 months in all cases. They also reported the unsuccessful attempt to use fresh aortic homografts to re place 2 to 4 cm. segments of intrathoracie inferior vena cava. The Ivalon-Lucite prosthesis was made by wrapping a thin layer of Ivalon over a glass rod, approximately the size of the inferior vena cava. Lucite rings, 2 mm. in width and 2 mm. thick, were slipped over the Ivalon and spaced at intervals of 0.5 cm. A second layer of Ivalon was then wrapped over the Lucite rings and a prosthesis was completed by compressing with a gauze bandage and boiling. As long as one of the Lucite rings was included in the anastomosis at either end of the prosthesis, the grafts remained patent and were successful in resisting collapse due to fibrous constriction of the sur rounding tissues. Follow-up studies with veno grams revealed that, if stenosis or obstruction occurred, it took place early in the postoperative course. There was very little change after the first 4 months. SUMMARY
Replacement of the vital veins in the body in the past has been unsuccess ful clinically and in the laboratory. The use of a woven Teflon graft supported by rigid plastic rings has over come this problem. At the end of 7 months, when the patient died from a cerebral metastasis, the graft showed no evidence of constriction or thrombus formation at autopsy. It may be noted that the graft survived irradiation to tolerance with the linear accelerator, even though there was marked irradiation fibrosis of all of the surrounding tissues. REFERENCES 1. Allansmith, E., and Bichards, V.: 353-359, 1958.
Superior Vena Caval Obstruction, Am. J. Surg. 96:
Vol. 44, No. 2 August. 1962
SUPERIOR V E N A CAVA OBSTRUCTION
263 ^
u o
2. Deterling, R., and Bohnslay, S.: Use of Vessel Grafts and Plastic Prostheses for Relief of Superior Vena Cava Obstruction, Surgery 38: 1008, 1955. 3. Blum, L., Medl, W., and Keefer, E. B. C : Aortic Homograft Substitution for the Postrenal Inferior Vena Cava, A. M. A. Arch. Surg. 72: 567, 1956. 4. Ohara, I., and Sakai, T.: Transplantation of the Large Venous System W i t h Various Blood Vessel Substitutes, Surgery 42: 929, 1957. 5. Sauvage, L., and Wesolowski, S.: Anastomosis and Grafts in the Venous System With Special Reference to Growth Changes, Surgery 37: 714, 1955. 6. Ashburn, E., Sewell, W., and Huggins, C : Experimental Replacement of the Superior Vena Cava W i t h Homologous Arteries, and Report of a Case of Malignant Ob struction Replaced W i t h a Heterologous Artery, J . THORACIC SURG. 3 1 : 618, 1956. 7. Egdahl, R., and Hume, D.: Nonsuture Blood Vessel Anastomosis—An Experimental Study Using Polyethylene as the Prosthetic Material, A. M. A. Arch. Surg. 72: 232, 1956. 8. MacLean, L., Phibbs, C , Flom, R., and Brainard, J.: Replacement of Vital Veins, A. M. A. Arch. Surg. 149: 549, 1959.
M.D.,*
San Jose, Calif.
obstruction of the superior vena cava is associated with a rapid rise of the venous pressure of the upper half of the body. The signs and symp toms characteristic of the clinical picture are well known and these are related to the obstruction of the venous flow. If the obstruction is of gradual onset, or if the obstruction is above the level of the azygous vein, a collateral circulation will develop, permitting the blood to find its way back to the heart. In a previous paper by Allansmith and Richards, 1 the problem of superior vena cava obstruction as related primarily to benign lesions, was taken up in detail. The surgical approach to relief of the obstruction in 21 cases was de scribed. The cause of the obstruction, type of graft, and site of shunt to the heart was summarized. At this time, long-term follow-up studies are not avail able on all of these patients, but it is known that most of the grafts and prostheses eventually became obstructed. The initial relief of symptoms sometimes was lifesaving, however, and enough time was gained so that an efficient col lateral circulation could be developed. Intrathoracic malignant tumors are frequently associated with a rise in the venous pressure of the upper half of the body, both early and late in their course. A venous pattern on the chest wall is sometimes the first sign of an intrathoracic tumor, and may be found before the tumor is visible on the chest film. Partial obstruction of the superior vena cava may be the rule rather than the exception in the advanced stages of intrathoracic neoplasm. Although the neck veins may be prominent and the venous pressure somewhat elevated, the alarming symptoms associated with an acute obstruction of the vena cava are absent, and, if the patient is cyanotic or short of breath, the cause is probably related to invasion of the lung, rather than to the venous obstruction. On the other hand, acute obstruction of the superior vena cava may occur if an intrathoracic malignant tumor invades the vena cava causing a thrombosis of the lumen. The alarming rise of the venous pressure in the upper half of the body to 600 to 1,000 mm. of saline is associated with massive edema of the upper half of the body, acute shortness of breath, and somnolence. In order to save these patients, they must be propped upright and a phlebotomy of 500 to
A
CUTE
Received for publication Nov. 3, 1961. •Address: 606 Medico Dental Bldg-., San Jose, Calif. 258
Vol. 44, No. 2 August, 1962
SUPERIOR V E N A CAVA OBSTRUCTION
259 UK,U
1,000 c.c. must be carried out promptly. Administration of nasal oxygen par tially relieves the shortness of breath, and vigorous treatment with diuretics helps to overcome the cerebral edema. This type of vena cava obstruction may occur with a small tumor, which may not be detectable in the chest films because of the widening of the vena caval silhouette. While bronchoscopy may be performed with the patient in the upright position, the edema of the larynx and tracheobronchial tree may cause obstruc tion of the airway, and trauma to the mucosa, which is already engorged with blood, may cause bleeding which is difficult to control. A scalene node biopsy, or even a tracheotomy, in a patient whose venous pressure is above 600 mm. of saline, may be associated with a serious hemorrhage. CASE REPORT The following case report is t h a t of a 48-year-old crane operator, who had been in excellent general health. Six weeks prior to his admission to the hospital, a cough de veloped, productive of small amounts of bright red blood. At the same time, he began to notice swelling of his face and neck, so t h a t he was unable to button his shirt collar. The veins of his neck and chest wall became prominent, and he began to have episodes of somnolence. When the p a t i e n t was first seen in the hospital he had the typical facies of superior vena cava obstruction. The venous pressure was 600 mm. of saline, and he had to remain constantly in the upright position in order to breathe. A bronchoscopy was done with t h e patient in the upright position under a local anesthetic. Marked edema and engorgement of the mucosa were encountered, but there was no evidence of a tumor. A chest film revealed a widening of the superior mediastinal shadow, consistent with distention of the superior vena cava, and a minimal infiltration of the medial aspect of the upper lobe of the right lung was noted. The surgeon was very reluctant to perform a major operation on this poor risk patient if the cause of the obstruction was a malignant tumor. I n spite of t h e high venous pressure, a right scalene biopsy was performed. The venous bleeding and edema of the structures in the neck made the procedure difficult, but several enlarged lymph nodes were obtained. There was no evidence of tumor in any of these nodes. Since acute vena caval obstruction of this type had been reported due to conditions other than malignancy, the chest was opened through a sternum-splitting incision which was extended into the right fifth interspace. As is characteristic of operations performed under such circumstances, it is impossible to control (completely) the hemorrhage until the obstruction has been relieved. The veins bleed under a pressure t h a t would do credit to an artery, and even the veins of the bone marrow spurt blood. Enough of the bleed ing can be controlled using electrocoagulation, bone wax, and packs to make the operative field reasonably clean. An anaplastic carcinoma of the upper lobe of t h e right lung was found, and this was growing into the adjacent vena cava, causing complete obstruction. Mediastinal nodes were not found, and there was no other-evidence of tumor in the right hemithorax. A woven Teflon graft, supported by rigid Teflon rings, was sutured to the upper part of the vena cava at t h e junction of the innominate veins above, and to the antero-lateral wall of the right atrium below. As soon as the shunt was opened, the venous pressure dropped rapidly and it was possible to control all of the bleeding in the surgical wound. Immediately after the operation the venous pressure was normal, and the patient was able to lie in the recumbent position. There was a weight loss of seventeen pounds by diuresis. At the end of one week, radiotherapy with the linear accelerator was started. He received 5,000 rads to the tumor through opposing anterior and posterior ports. Therapy was continued over 31 days, during which time he was an outpatient.
ALLANSMITH
260
J. Thoracic and Cardiovas. Surg.
The only complication of t h e operation and radiotherapy was a deep stitch abscess in the central p a r t of the midline sternal wound. This was treated conservatively over a period of weeks, and eventually healed. Four months postoperatively he continued to do well and a bronchoscopy revealed no evidence of tumor. At t h a t time a chest film showed only a small density or scar adjacent to the mediastinum on the right. The venous pressure continued to be normal. A superior vena cavagram revealed the graft to be well preserved and free from any obstruction or irregularity. There was some evidence of reoanalization of the superior vena cava.
Fig. 1.—Four months postoperatively the vena cavagram revealed a well functioning graft. There is also some evidence of reoanalization of the superior vena cava which had been completely obstructed by tumor at the time of operation. Six months postoperatively he was again admitted to the hospital following a con vulsive seizure. Seven months postoperatively he died from complications secondary to a large cerebral metastasis. Autopsy revealed an entirely p a t e n t Teflon graft, well lined, with a smooth endothelial surface. There was no evidence of narrowing at either end, although there was dense scarring in the mediastinum incident to the irradiation therapy. The vena cava showed some evidence of reoanalization, having a lumen approximately the size of a pencil. There was no evidence of tumor or infection in the thoracic cavity, although the irradiation change was extensive. There was no evidence of tumor in the primary or secondary bronchi of t h e upper lobe of t h e right lung. A large cerebral metastasis and an adrenal metastasis were the only evidences of residual tumor. DISCUSSION
This case illustrates the use of a bypass graft as a lifesaving procedure in the presence of a superior vena cava obstruction due to a malignant tumor. It
Vol. 44, No. 2 August, 1962
SUPERIOR VENA CAVA OBSTRUCTION
261
has been the experience of the author that the cause of the acute complete vena cava obstruction is related to the growth of the tumor through the vena cava wall obliterating the lumen, rather than to external pressure on the vena cava from the tumor. In this instance, the vena cava was completely blocked by tumor and a positive biopsy was obtained by opening the vena cava. Irradiation to tolerance with the linear accelerator had not caused any narrowing or throm bosis in the Teflon graft. In spite of dense scarring and post-irradiation change in all of the surrounding structures, the Teflon graft, supported with rings of rigid plastic, resisted the encroachment of the scar tissue.
Fig- 2.—Reinforced Teflon graft. Note the rigid plastic rings sutured to the woven Teflon graft in order to preserve the lumen when the graft is inserted into the vena cava, a low pressure system.
Description of the Graft.—A graft of woven Teflon, % inch in diameter and 7 inches long, was reinforced by sliding rigid plastic rings over the outside of the graft and suturing them with 5-0 black silk sutures, so that they sup ported the graft wall. The rings measured y2 inch in internal diameter, 2 mm. in thickness, and 2 mm. in width. These were sutured at intervals of 1 cm. along the graft. One ring at each end was immediately adjacent to the anas tomosis to the superior vena cava above, and to the heart below. The replacement or bypass of vital veins of the body presents a problem which has not been successfully solved. The surgical failures attributed to thrombosis and stricture formation are related to the slow flow and low pressure in the veins. In 1955, Deterling and Bohnslay 2 reported the use of vessel grafts and plastic prostheses for relief of superior vena cava obstruction. After initial good results, all of the grafts and prostheses became obstructed. Blum, Medl, and Keefer 3 used aortic homografts in the postrenal inferior vena cava in 1956. Their results were disappointing. Homografts and silicone rubber tubes were used experimentally by Ohara and Sakai* in 1957. Their efforts to find a suit able vein replacement met with little success, and thrombosis and stenosis oc curred in all cases. In the experimental work of Deterling and Bohnslay, 2 aortic homografts were found superior to autologous jugular veins, Ivalon, woven nylon, and Dacron. There was a 40 per cent narrowing of the lumen due to constriction in those few which remained patent. In 1955, Sauvage and Wesolowski 5 studied anastomoses and grafts in the venous system with
ALLANSMITH
262
J. Thoracic and Cardiovas. Surg.
special reference to growth changes. The intrathoracie venae cavae were grafted with Orion cloth or aortic homografts, but all of the grafts became constricted or totally obliterated. Ashburn, Sewell, and Huggins, 6 in 1956, used homologous arteries in the vena cava, but all of their grafts showed stenosis of the distal anastomosis within 5 months. In 1956, Egdahl and Hume 7 reported experimental work, including nonsuture blood vessel anas tomoses, using polyethylene tubing as the prosthetic material. The results with the polyethylene were unsatisfactory. Using perforated polyethylene tubing, there was short-term success when the tubes were lined with a venous homograft. The superiority of the perforated polyethylene tubing over the solid tubing wa's due to external vascularization, through the perforations of the tubes. The above review indicates that, clinically and experimentally, a completely satisfactory graft replacement for the vital veins has not been developed. In 1957, MacLean and co-workers,8 used an Ivalon-Lucite prosthesis to replace the intrathoracie inferior vena cava. They presented a follow-up study of early work done with molded Ivalon in their laboratory and stated that stenosis or complete obstruction developed within 10 months in all cases. They also reported the unsuccessful attempt to use fresh aortic homografts to re place 2 to 4 cm. segments of intrathoracie inferior vena cava. The Ivalon-Lucite prosthesis was made by wrapping a thin layer of Ivalon over a glass rod, approximately the size of the inferior vena cava. Lucite rings, 2 mm. in width and 2 mm. thick, were slipped over the Ivalon and spaced at intervals of 0.5 cm. A second layer of Ivalon was then wrapped over the Lucite rings and a prosthesis was completed by compressing with a gauze bandage and boiling. As long as one of the Lucite rings was included in the anastomosis at either end of the prosthesis, the grafts remained patent and were successful in resisting collapse due to fibrous constriction of the sur rounding tissues. Follow-up studies with veno grams revealed that, if stenosis or obstruction occurred, it took place early in the postoperative course. There was very little change after the first 4 months. SUMMARY
Replacement of the vital veins in the body in the past has been unsuccess ful clinically and in the laboratory. The use of a woven Teflon graft supported by rigid plastic rings has over come this problem. At the end of 7 months, when the patient died from a cerebral metastasis, the graft showed no evidence of constriction or thrombus formation at autopsy. It may be noted that the graft survived irradiation to tolerance with the linear accelerator, even though there was marked irradiation fibrosis of all of the surrounding tissues. REFERENCES 1. Allansmith, E., and Bichards, V.: 353-359, 1958.
Superior Vena Caval Obstruction, Am. J. Surg. 96:
Vol. 44, No. 2 August. 1962
SUPERIOR V E N A CAVA OBSTRUCTION
263 ^
u o
2. Deterling, R., and Bohnslay, S.: Use of Vessel Grafts and Plastic Prostheses for Relief of Superior Vena Cava Obstruction, Surgery 38: 1008, 1955. 3. Blum, L., Medl, W., and Keefer, E. B. C : Aortic Homograft Substitution for the Postrenal Inferior Vena Cava, A. M. A. Arch. Surg. 72: 567, 1956. 4. Ohara, I., and Sakai, T.: Transplantation of the Large Venous System W i t h Various Blood Vessel Substitutes, Surgery 42: 929, 1957. 5. Sauvage, L., and Wesolowski, S.: Anastomosis and Grafts in the Venous System With Special Reference to Growth Changes, Surgery 37: 714, 1955. 6. Ashburn, E., Sewell, W., and Huggins, C : Experimental Replacement of the Superior Vena Cava W i t h Homologous Arteries, and Report of a Case of Malignant Ob struction Replaced W i t h a Heterologous Artery, J . THORACIC SURG. 3 1 : 618, 1956. 7. Egdahl, R., and Hume, D.: Nonsuture Blood Vessel Anastomosis—An Experimental Study Using Polyethylene as the Prosthetic Material, A. M. A. Arch. Surg. 72: 232, 1956. 8. MacLean, L., Phibbs, C , Flom, R., and Brainard, J.: Replacement of Vital Veins, A. M. A. Arch. Surg. 149: 549, 1959.