JOURNAL
OF SURGICAL
Experimental
RESEARCH
23, 14-18 (1977)
Cryoprobe
M. REICH, M.D.,
Production
F. OLUMIDE, M.D.,
of lntrahepatic
ERICJORGENSEN,
Portocaval
Shunt1
AND B. EISEMAN, M.D.2
Departments of Surgery, University of Colorado School of Medicine and Denver General Hospital, Denver, Colorado 80220 Submitted for publication
January 27, 1977
Emergency portocaval shunt for bleeding esophageal varices carries a hospital mortality of approximately 50% [4]. There is therefore an obvious clinical need for a technique that can decompress the hypertensive portal system but carries a lesser risk than the classic operative shunt. The objective of this experimental study was to determine the technical feasability of producing a large (5-9 mm in diam) shunt within the liver between a major branch of the portal vein and the intrahepatic vena cava using a cryoprobe passed through the portal vein.
vein. The latter was visualized and palpated with the fingers of the left hand placed over the right hepatic lobe, thus producing a target toward which the rigid probe was guided (Fig. 1). After the tip of the probe could be palpated above the liver within the hepatic vein, it was withdrawn until the tip was approximately 1 cm within the substance of the liver. The cryoprobe was then activated by a trigger mechanism achieving a tip temperature of -90” F. The initial transhepatic tunnel was resected in l-2 min. Care was taken not to apply cold when the EXPERIMENTAL STUDIES tip approached the extrahepatic portion of the hepatic vein. The tract was widened by a Twenty-five adult pigs were anesthetized and, under sterile conditions, the portal vein circular motion on withdrawal, controlling the probe with the left hand behind the liver. was surgically isolated. Occluding umbilical 9 mm in diameter, tapes were passed around both ends of the A tract, approximately vein and a 5-mm longitudinal incision made was the desired end point, but it was difbetween them. Retraction of the lips of the ficult to predict with accuracy the diameter venotomy was maintained with two 4-O of the tunnel or the uniformity of its caliber. After preliminary experiments familiarvascular sutures. The barrel of a 5-mm diamized us with the probe, the entire procedure eter Cryomedics Model RT-300 probe was from insertion to removal of the probe could inserted into the lumen of the portal vein be accomplished in 2 to 10 min. and passed through the temporarily loosThe cryoprobe was removed from the ened umbilical tape beneath the liver. vein, the venotomy was closed with a 5-O When the tip of the probe was beyond the vascular suture, and portal venous flow was tape, it was tightened, thus achieving hemoreestablished. In order to determine the exstasis. The probe was guided into the left istence of intrahepatic arterial shunts into main portal vein and thence pushed through 3-4 cm of the medial segment of the left the newly opened tract, samples were drawn from the hepatic venous effluent and meashepatic lobe toward the middle hepatic ured for PO,, both before and after cryo1 Supported by N.I.H. Grant No. AM17022. probe production of the shunt. 2 Address all correspondence to: B. Eiseman, M.D., Portograms were taken through a catheDepartment of Surgery, Denver General Hospital, terized branch of the portal vein, both beWest 8th Avenue and Cherokee Street, Denver, Colorado 80204. fore and after creation of the shunt. 14 Copyright All rights
0 1977 by Academic Press, Inc. of reproduction in any form reserved.
ISSN 0022404
REICH ET AL.:
INTRAHEPATIC
PORTOCAVAL
SHUNT
FIG. 1. Introduction of cryoprobe through portal vein. The probe ruptures the intrahepatic then enters the middle hepatic vein near its junction with the suprahepatic vena cava.
The animals were not heparinized nor was any attempt made to increase shunt patency by arterializing or otherwise increasing portal pressure or flow. Surviving animals were variously studied by follow-up portograms at laparotomy and sacrifice at periods up to 56 days following the transhepatic cryoprobe production of the portocaval shunt. After sacrifice, the tract through the liver was inspected for patency, and sections of the wall were examined microscopically. RESULTS
Of the 25 experimental animals, five died early in the experience during operation when the probe inadvertantly was passed too far into the hepatic vein beyond the hepatic confines. There were five other
15
portal vein and
early deaths postoperatively, variously attributed to prolonged interruption of the portal vein or to pulmonary embolism not due to fragments of frozen liver tissue. Five additional pigs were sacrificed within 24 hr of the operation to document the size and patency of the shunt. All were open. One of these animals was not sacrificed and subsequently was restudied a week later. There were 11 animals studied or sacrificed 5-56 days following the operation, as detailed in Fig. 2. In five animals the shunt was closed. In two of these in retrospect it was clear that immediate postoperative portograms had not shown a patent shunt. Perhaps the cryoprobe had not been passed into the hepatic vein. In another animal sacrificed on the 5th day the portal vein had clotted. The other two animals sacrificed at 42 and 56 days evidenced
16
JOURNAL
OF SURGICAL
RESEARCH:
thrombosis of the channel produced by the cryoprobe. The remaining six animals ranging from 9 to 42 days following operation all had patent shunts demonstrated both angiographically and by gross examination. Figures 3 and 4 are portograms of two such animals showing patent intrahepatic portocaval shunts 24 hr and 14 days following operation, respectively. The walls of the shunt were found to be irregular in the specimens examined up to a week following the operation. This reflected the uneven application of the cold probe and the damage to adjacent tissues. Specimens patent more than 9 days had smooth walls. It was impossible to determine whether or not the diameter of the shunt had appreciably decreased from the time of its original creation.
VOL. 23, NO. 1, JULY 1977 FIGURE 2 PATENCY
OF CRYOPROBE PORTOCAVAL
TRANSHEPATIC SHUNTS
Postoperative days when examined Shunt closed 5th 5th 5th 42nd 56th
Postoperative Postoperative Postoperative Postoperative Postoperative
Shunt open day” day” dayb day day
9th 14th 33rd 33rd 34th 42nd
Postoperative Postoperative Postoperative Postoperative Postoperative Postoperative
a In retrospect original postoperative failed to demonstrate a shunt. * Portal vein thrombosed.
day day day day day day
portogram
Histologic examination did not show a clear endothelialization of the shunt walls. Those that were patent thereafter showed well-aligned but nonendothelialized granu-
FIG. 3. Contrast material injected through shunt demonstrating large patent channel (I day after operation).
REICH ET AL .: INTRAHEPATIC
PORTOCAVAL
SHUNT
FIG. 4. Contrast material injected through shunt 14 days after operation showing smooth-walled and filling of vena cava.
17
channel
therefore, variously used spring coils and Teflon and silastic tubes to shore up the transhepatic tunnel. The current studies are based on a similar hypothesis but with two important differences: (1) that a tract is excised through the liver substance by a cryoprobe not merely by blunt dilation DISCUSSION and (2) that the procedure is performed via Rosch in 1971 first suggested creation of the portal vein. If the technique is peran intrahepatic portocaval shunt and re- fected so that the shunts remain open, the ported his experimental findings in dogs procedure could with less trauma to the pa[5]. Being a radiologist, he was primarily tient be performed under radiologic control interested in adapting the technique as a from the neck. varient of transjugular hepatic vein cathThe cryoprobe was chosen to create the tterization and cholangiography [2]. Since intrahepatic tunnel because of its proven Rosch’s original studies Lunderquist and ability to destroy surrounding tissue in a his colleagues have proven the relative controlled fashion, to seal off adjacent blood safety of placing stylets and catheters vessels, and because it is effected using percutaneously and via the jugular vein a small caliber, easily controlled and diacross the liver into the portal system rected tip [I]. [l-3]. Rosch used a series of dilating catheters passed over a guide wire to force SUMMARY a passage through the liver. He found that Experiments have been performed on 25 the path bluntly forced through the liver substances would not long remain patent. He, pigs creating a shunt through the liver
lation tissue lining. There were no arteriovenous shunts seen along the cold probe tract. Apparently the cryoprobe coagulated the arterioles along the shunt. Pigs surviving the operation appeared to be clinically unaffected.
18
JOURNAL
OF SURGICAL
RESEARCH:
substance between the portal vein and the vena cava. The technique involves passage of a small caliber (5 mm) probe via an incision in the portal vein to a major branch of the left hepatic vein. Directed toward a finger on the middle hepatic vein, a 9-mm diameter tunnel is created through 3 cm of liver tissue to the hepatic venous outflow tract. A rigid cryoprobe (-70°C) created a 9-mm diameter tunnel between the portal and hepatic veins through the substance of the liver. Six of 11 animals sacrificed between 5 and 56 days postoperatively had patent shunts; these unheparinized animals had normal portal pressures. The technique is designed ultimately to provide a relatively atraumatic method for
VOL. 23, NO. 1, JULY 1977
creating an emergency portocaval shunt in patients with bleeding esophageal varices. REFERENCES
1. Gothlin, J., Lunderquist, 2. 3.
4.
5.
A., and Tylen, U.: Selective phlebography of the pancreas. Acta Radiol. 15: 474, 1976. Hanafee, W., and Weiner, M. Transjugular percutaneous cholangiography. Radiology 8: 35, 1%7. Lunderquist, A., and Vang, J. Transhepatic catheterization and obliteration of the coronary vein in patients with portal hypertension and esophageal varices. N. Engl. J. Med. 291: 646,1974. Orloff, M. J., Chandler, J. G., Charter, A. C., Condon, J. K., Grambort, D. E. Modafferi, T. R., and Levin, S. E. Emergency portocaval shunt treatment for bleeding esophageal varices. Arch. Surg. 10s: 293, 1974. Rosch, J.. Hanafee, W., Snow, H., Basenfus, M., and Gray, R. Transjugular intrahepatic portocaval shunt. Amer. J. Surg. 121: 588, 1971.
OF SURGICAL
Experimental
RESEARCH
23, 14-18 (1977)
Cryoprobe
M. REICH, M.D.,
Production
F. OLUMIDE, M.D.,
of lntrahepatic
ERICJORGENSEN,
Portocaval
Shunt1
AND B. EISEMAN, M.D.2
Departments of Surgery, University of Colorado School of Medicine and Denver General Hospital, Denver, Colorado 80220 Submitted for publication
January 27, 1977
Emergency portocaval shunt for bleeding esophageal varices carries a hospital mortality of approximately 50% [4]. There is therefore an obvious clinical need for a technique that can decompress the hypertensive portal system but carries a lesser risk than the classic operative shunt. The objective of this experimental study was to determine the technical feasability of producing a large (5-9 mm in diam) shunt within the liver between a major branch of the portal vein and the intrahepatic vena cava using a cryoprobe passed through the portal vein.
vein. The latter was visualized and palpated with the fingers of the left hand placed over the right hepatic lobe, thus producing a target toward which the rigid probe was guided (Fig. 1). After the tip of the probe could be palpated above the liver within the hepatic vein, it was withdrawn until the tip was approximately 1 cm within the substance of the liver. The cryoprobe was then activated by a trigger mechanism achieving a tip temperature of -90” F. The initial transhepatic tunnel was resected in l-2 min. Care was taken not to apply cold when the EXPERIMENTAL STUDIES tip approached the extrahepatic portion of the hepatic vein. The tract was widened by a Twenty-five adult pigs were anesthetized and, under sterile conditions, the portal vein circular motion on withdrawal, controlling the probe with the left hand behind the liver. was surgically isolated. Occluding umbilical 9 mm in diameter, tapes were passed around both ends of the A tract, approximately vein and a 5-mm longitudinal incision made was the desired end point, but it was difbetween them. Retraction of the lips of the ficult to predict with accuracy the diameter venotomy was maintained with two 4-O of the tunnel or the uniformity of its caliber. After preliminary experiments familiarvascular sutures. The barrel of a 5-mm diamized us with the probe, the entire procedure eter Cryomedics Model RT-300 probe was from insertion to removal of the probe could inserted into the lumen of the portal vein be accomplished in 2 to 10 min. and passed through the temporarily loosThe cryoprobe was removed from the ened umbilical tape beneath the liver. vein, the venotomy was closed with a 5-O When the tip of the probe was beyond the vascular suture, and portal venous flow was tape, it was tightened, thus achieving hemoreestablished. In order to determine the exstasis. The probe was guided into the left istence of intrahepatic arterial shunts into main portal vein and thence pushed through 3-4 cm of the medial segment of the left the newly opened tract, samples were drawn from the hepatic venous effluent and meashepatic lobe toward the middle hepatic ured for PO,, both before and after cryo1 Supported by N.I.H. Grant No. AM17022. probe production of the shunt. 2 Address all correspondence to: B. Eiseman, M.D., Portograms were taken through a catheDepartment of Surgery, Denver General Hospital, terized branch of the portal vein, both beWest 8th Avenue and Cherokee Street, Denver, Colorado 80204. fore and after creation of the shunt. 14 Copyright All rights
0 1977 by Academic Press, Inc. of reproduction in any form reserved.
ISSN 0022404
REICH ET AL.:
INTRAHEPATIC
PORTOCAVAL
SHUNT
FIG. 1. Introduction of cryoprobe through portal vein. The probe ruptures the intrahepatic then enters the middle hepatic vein near its junction with the suprahepatic vena cava.
The animals were not heparinized nor was any attempt made to increase shunt patency by arterializing or otherwise increasing portal pressure or flow. Surviving animals were variously studied by follow-up portograms at laparotomy and sacrifice at periods up to 56 days following the transhepatic cryoprobe production of the portocaval shunt. After sacrifice, the tract through the liver was inspected for patency, and sections of the wall were examined microscopically. RESULTS
Of the 25 experimental animals, five died early in the experience during operation when the probe inadvertantly was passed too far into the hepatic vein beyond the hepatic confines. There were five other
15
portal vein and
early deaths postoperatively, variously attributed to prolonged interruption of the portal vein or to pulmonary embolism not due to fragments of frozen liver tissue. Five additional pigs were sacrificed within 24 hr of the operation to document the size and patency of the shunt. All were open. One of these animals was not sacrificed and subsequently was restudied a week later. There were 11 animals studied or sacrificed 5-56 days following the operation, as detailed in Fig. 2. In five animals the shunt was closed. In two of these in retrospect it was clear that immediate postoperative portograms had not shown a patent shunt. Perhaps the cryoprobe had not been passed into the hepatic vein. In another animal sacrificed on the 5th day the portal vein had clotted. The other two animals sacrificed at 42 and 56 days evidenced
16
JOURNAL
OF SURGICAL
RESEARCH:
thrombosis of the channel produced by the cryoprobe. The remaining six animals ranging from 9 to 42 days following operation all had patent shunts demonstrated both angiographically and by gross examination. Figures 3 and 4 are portograms of two such animals showing patent intrahepatic portocaval shunts 24 hr and 14 days following operation, respectively. The walls of the shunt were found to be irregular in the specimens examined up to a week following the operation. This reflected the uneven application of the cold probe and the damage to adjacent tissues. Specimens patent more than 9 days had smooth walls. It was impossible to determine whether or not the diameter of the shunt had appreciably decreased from the time of its original creation.
VOL. 23, NO. 1, JULY 1977 FIGURE 2 PATENCY
OF CRYOPROBE PORTOCAVAL
TRANSHEPATIC SHUNTS
Postoperative days when examined Shunt closed 5th 5th 5th 42nd 56th
Postoperative Postoperative Postoperative Postoperative Postoperative
Shunt open day” day” dayb day day
9th 14th 33rd 33rd 34th 42nd
Postoperative Postoperative Postoperative Postoperative Postoperative Postoperative
a In retrospect original postoperative failed to demonstrate a shunt. * Portal vein thrombosed.
day day day day day day
portogram
Histologic examination did not show a clear endothelialization of the shunt walls. Those that were patent thereafter showed well-aligned but nonendothelialized granu-
FIG. 3. Contrast material injected through shunt demonstrating large patent channel (I day after operation).
REICH ET AL .: INTRAHEPATIC
PORTOCAVAL
SHUNT
FIG. 4. Contrast material injected through shunt 14 days after operation showing smooth-walled and filling of vena cava.
17
channel
therefore, variously used spring coils and Teflon and silastic tubes to shore up the transhepatic tunnel. The current studies are based on a similar hypothesis but with two important differences: (1) that a tract is excised through the liver substance by a cryoprobe not merely by blunt dilation DISCUSSION and (2) that the procedure is performed via Rosch in 1971 first suggested creation of the portal vein. If the technique is peran intrahepatic portocaval shunt and re- fected so that the shunts remain open, the ported his experimental findings in dogs procedure could with less trauma to the pa[5]. Being a radiologist, he was primarily tient be performed under radiologic control interested in adapting the technique as a from the neck. varient of transjugular hepatic vein cathThe cryoprobe was chosen to create the tterization and cholangiography [2]. Since intrahepatic tunnel because of its proven Rosch’s original studies Lunderquist and ability to destroy surrounding tissue in a his colleagues have proven the relative controlled fashion, to seal off adjacent blood safety of placing stylets and catheters vessels, and because it is effected using percutaneously and via the jugular vein a small caliber, easily controlled and diacross the liver into the portal system rected tip [I]. [l-3]. Rosch used a series of dilating catheters passed over a guide wire to force SUMMARY a passage through the liver. He found that Experiments have been performed on 25 the path bluntly forced through the liver substances would not long remain patent. He, pigs creating a shunt through the liver
lation tissue lining. There were no arteriovenous shunts seen along the cold probe tract. Apparently the cryoprobe coagulated the arterioles along the shunt. Pigs surviving the operation appeared to be clinically unaffected.
18
JOURNAL
OF SURGICAL
RESEARCH:
substance between the portal vein and the vena cava. The technique involves passage of a small caliber (5 mm) probe via an incision in the portal vein to a major branch of the left hepatic vein. Directed toward a finger on the middle hepatic vein, a 9-mm diameter tunnel is created through 3 cm of liver tissue to the hepatic venous outflow tract. A rigid cryoprobe (-70°C) created a 9-mm diameter tunnel between the portal and hepatic veins through the substance of the liver. Six of 11 animals sacrificed between 5 and 56 days postoperatively had patent shunts; these unheparinized animals had normal portal pressures. The technique is designed ultimately to provide a relatively atraumatic method for
VOL. 23, NO. 1, JULY 1977
creating an emergency portocaval shunt in patients with bleeding esophageal varices. REFERENCES
1. Gothlin, J., Lunderquist, 2. 3.
4.
5.
A., and Tylen, U.: Selective phlebography of the pancreas. Acta Radiol. 15: 474, 1976. Hanafee, W., and Weiner, M. Transjugular percutaneous cholangiography. Radiology 8: 35, 1%7. Lunderquist, A., and Vang, J. Transhepatic catheterization and obliteration of the coronary vein in patients with portal hypertension and esophageal varices. N. Engl. J. Med. 291: 646,1974. Orloff, M. J., Chandler, J. G., Charter, A. C., Condon, J. K., Grambort, D. E. Modafferi, T. R., and Levin, S. E. Emergency portocaval shunt treatment for bleeding esophageal varices. Arch. Surg. 10s: 293, 1974. Rosch, J.. Hanafee, W., Snow, H., Basenfus, M., and Gray, R. Transjugular intrahepatic portocaval shunt. Amer. J. Surg. 121: 588, 1971.
