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Small arterial homografts
Small
Arterial
Homografts
MARVIN GLICKLICH, M.D., Milwaukee, Wisconsin
METHOD
From the Diwision of Surgery, Marquette Uniaersity School of Medicine, and- the Allen-Bradley Medical Science Laboratorv. Milwaukee. Wisconsin. This work was subported in &t by a gran&-aid frown the Wisconsin He&t Association.
Segments of canine brachial and femoral arteries 2 to 4 mm. in external diameter of various lengths were obtained under sterile conditions from live donors, placed in normal saline solution in sealed tubes, and frozen slowly and stored in the freezer compartment of a household type refrigerator. Each graft was carefully measured before removal. All branches were ligated close to their origin with No. 5-O silk. Thus, a homograft bank was available for use as needed. The grafts were thawed using warm water just prior to use. Segments of twelve canine brachial and femoral host arteries were excised and replaced by homografts of closely equivalent diameter and slightly longer length. The host vessel size, that is, the external in situ diameter, was as follows: less than 2 mm., one; 2 to 2.5 mm., five; 2.6 to 3 mm., three; 3.1 to 3.5 mm., three. The host arteries were occluded and held with Potts ductus and coarctation clamps. With the aid of the Zeiss operating microscope, meticulous dissection of the adventitia from the distal 3 to 4 mm. of the host and graft vessels was accomplished to prevent inclusion in the suture line. End to end oblique anastomoses were used to minimize constriction and to permit adaptation of the constricted end of the donor artery to the more flaccid homograft end. No. 8-O monofilament nylon sutures* were used. Initial corner sutures were placed and continued as over and over sutures for one half of the oblique circumference. Moderate traction at the corners kept the anastomotic line straight and stabilized the
HE SYNTHETIC GRAFT has displaced the arhomograft for substitution of large arteries because of superior results. This has not proved to be the case in small arteries under 4 mm. in external diameter [1,2] where autologous artery and vein have repeatedly outperformed other available materials [3]. The search for a suitable small arterial prosthesis continues because autogenous artery or vein are not always available or feasible [1,4X]. As one examines the properties a suitable small arterial prosthesis must have, it becomes apparent that homologous artery has most of them except for the questions of immune response and deterioration of vessel wall strength. The artery is pliable, can bend and twist, and has low implantation porosity and high healing porosity 171. Homograft artery is easy to handle, has a smooth intimal surface, and is readily procurable. Many methods of sterilization are available. Thus, the arterial homograft as a small artery prosthesis deserves reconsideration. This study was performed to ascertain whether, with refinements in vascular anastomotic technics, dead arterial homografts can be utilized to replace short segments of small arteries 2 to 3.5 mm. in external diameter with successful long-term outcome. Because of the small size of the graft and host vessels, it was anticipated that persistence of the donor elastic tissue combined with gradual replacement of other elements of the graft by host collagen might yield an adequate long-term blood vessel without the serious complications which occur in large homografts.
T terial
vessels. (Fig. 1.) The Zeiss operating microscope provided magnification of 6 to 40 times although a magnification of 16 times was the usual working power. Such enlargement permitted meticulous suture placement within 0.5 mm. of the vessel edge with minimal trauma [8]. Photographs of the procedures and of the subsequent specimens were taken through the lens system * Experimental suture X 2317 with TE-11 needle was supplied through the courtesy of Davis and Geck Co., Danbury, Connecticut. 842
American
Journal
of Suvgevy
Small Arterial
of the microscol)c with apparatus developed in this laboratory and to be reported elsewhere. The degree of tension on the vessels was carefully controlled to aid in suturing but to avoid dehiscence and tearing. The vessels were irrigated and moistened at frequent intervals with normal saline sohtion to TIrevent drying. No anticoagulants were used. After completion of both proximal and distal anastomoses. a thin cuff of Surgicel@ was placed about each. Both occluding clamps were completely released almost simultaneously and the vessel was replaced in its bed. Nonocclusive finger pressure over both anastomoses for five to six minutes was applied to control bleeding from the suture holes. In most instances the Surgicel was subsequently removed. Procaine penicillin, 300.000 to 400,000 units, was given for three days postoperatively. Follow-up period ranged from five to eight and a half months at which time the homografts and host arteries were explored and excised. Photographs of the gross specimens were taken. The homografts with the attached host vessel were sectioned longitudinally and stained with hematoxylin and eosin, Verhoefi’s elastic tissue stain, and Masson trichrome stain RESULTS
Nine of the twelve homografts were patent (75 per cent). Three (25 per and functioning
cent) were thrombosed, atrophic, and obvious failures. Grossly, all functioning grafts pulsated in an expansile manner in situ and were difficult to distinguish from the adjacent host vessel. Results as listed in Table I are correlated with host vessel size, homograft diameter and length, homograft storage age, and duration of followup study.
Homografts
Results were considered good if the intima and anastomoses were intact and smooth and there was no evidence of constriction or dilatation (Fig. 2.) Five (41.2 per cent) homografts were classified as having good results. Fair results included patent functioning grafts with roughening or irregularity of the intima or suture line or dilatation of the graft. Four (33.3 per cent) grafts were classified as having fair results. Microscopic evaluation of the functioning homografts revealed the presence of a thickened and relatively cellular intima with elongated and flattened cells on the luminal surface. These cells seemed to be fibroblasts. (Fig. 3.) The thickness of the intima varied and was greater in those grafts noted to have grossly irregular intimas. The internal elastic lamina was present TABLE SUMYARY
Dog .. NO.
Host VlZSSCl Diam-
eter
(mm.) 1
2 3 4 5 6 7 8 9 10 11 12
2.5 1.5 3 3.0 3 2.8 2.8 2 2.0 35 22 2.2
5 2 R
I
OF RESULTS
r--Homograft----DiamLength (cm.)
ecer
rIuration of Age (mo.)
(mm.)
.(I
2.6 2.0 2.8 2.0
2 2.n 2.5 3
3 2 2.8 22 2.8 3 5 2.3 2
3 .o 35 3 3.0 7.0 4.5
35
3
0 B0 0
30
4 4 5 11 1 6 8 8 1 lwk. 2wk. 10
Follow-
Resr1lt
UP Study
ii 5 6 5 5 .i .i 5 b 8 8 3 8 R.T, i 7
3
Good Failure Good Pair Fair Failure Fair Fair Good Failure Good Good
Glicklich
FIG. 3. Photomicrograph of homograft implanted six and a half months, demonstrating somewhat thickened and cellular intima with flattened elongated cells on luminal surface.
FIG. 4. Elastic tissue stain demonstrating persistence of internal elastic lamina and condensed elastic fibers of the media in the homograft implanted for eight months.
in all functioning specimens with varying degrees of fracture. It is believed that some of the apparent disruption of this elastic layer might be artifact. The media was somewhat thinner and acellular with absence of smooth muscle. (Fig. 4.) The elastic tissue fibers were fairly abundant, interlacing, and condensed. Dense and quite acellular collagen layers lay between the internal elastic lamina and the medial elastic fibers and external to the medial elastic tissue. These features have been described by Vickery, McCombs, and Warren [9] and others [2,7,10]. An interesting feature noted herein and by Vickery, McCombs, and Warren is the absence of the round cell infiltrate of homograft rejection in all specimens.
series. Good pulses were present initially for three weeks but complete thrombosis occurred at seven months. There is strong suggestion that in smaller arterial grafts the length of the graft may have a critical relation to diameter which, if exceeded, may predispose to thrombosis [I 11. This relation has not been defined.
ANALYSIS
OF
HOMOGRAFT
FAILURES
Of the three homografts which thrombosed, technical or judgment failures are deemed responsible for two. In two instances large branches proximal to the homograft, siphoning blood away from the surgical site, were incriminated. In animal number two, the host artery was a 1.5 mm. small branch of the main femoral artery. The main artery diverted blood flow from the graft. A similar circumstance occurred in number six in which a 2.8 mm. brachial artery had a functioning large branch just above the proximal anastomosis. In addition, the anastomoses themselves were considered poor at the time because of excessive motion of the dog under too light an anesthetic. Graft number ten was the longest in the
COMMENTS
Great emphasis is placed on the attention to technical details in performing anastomoses of these small arteries and homografts. Errors that predispose to clotting are magnified in significance the smaller the diameter of the artery. Use of the operating microscope helps to recognize and avoid these insults. The advantages of a tiny smooth monofilament suture in minimizing the intraluminal foreign body surface at the suture line are obvious. It is possible that poor patency resulting in other series [12,13] may be due to the large braided and twisted multistrand sutures used. For the duration of this study it is believed that the preservation of the homograft elastic tissue combined with ingrowth of host collagen resulted in excellent vessels in a reasonable percentage of homografts. Whether this would persist over longer term follow-up study is a legitimate question that will have to be answered in further studies. Whether the encouraging results of this small study can be reproduced in larger numbers and transposed to small arterial homografts in human subjects remain to be ascertained. Americas
Journal of Surgevy
Small Arterial Homografts
I. Refinements of technic of anastomosis of small arteries, including the use of the Zeiss operating microscope and No. 8-O monofilament nylon sutures, were applied to frozen canine wall arterial homografts as substitutes for canine arteries 2 to 3.5 mm. in external diameter. 2. Over a five to eight and a half month followup period, nine of twelve (75 per cent) homografts remained patent and functioning. 3. Five (41.2 per cent) homografts were good and four (Xi.3 per cent) were fair. 4. For the period of this study the successful homografts resulted in satisfactory blood vessel replacements. 5. The encouraging results warrant further work in evaluating the homograft as a small artery prosthesis.
REFERENCES 1. MASSELL, T. B., HERINGMON, E. C., and GREENSI-ONE, S. M. Woven dacron and woven Teflon prostheses: use for small artery replacement. .lirh. Surg., 84: 91, 1962. 1. DEBAKEY, M. E., JORDA?;, G., BEALL, A. C., JR., O’~‘EAL, R. M., ABBOTT, J. P., and HALPERT, B. Basic biologic reactions to vascular grafts and prostheses. S. C&z. North America, 45: 477, 1965. 3. CONNOLLY, J. E. and HARRIS, E. J, Autogenous in bitu saphenous win bypass for femoral popliteal
Vol. 111, June 1966
S-L-,
5. WESoL0TvSKI. S. .I.. FRIES, c. c.. L~1ilG. w. J,, SATVYER, I’. !i,, and DETERLING, Ii. ;1 , JR. ‘The synthetic vascular graft: nc’w ccmccpt., new techniques. .-I&. Suig., 84: i-1, 19&l. 6. KRIPPAEHIE, W. W., DESHPANDE. I’. J.. JACKSON, D. S.. and DUNPHY, J. E. Reaction of connrctive tissue to collagen-dacron prosthwes ,.I we. J. Swg., 110: 186, 1965. i. WESoLowSKI, S. A. The healing of vascular prosthcws. Suryeuy, 5i: 319, 1965. 8. JACORSOS, J. H. and SUAREZ, E. C. Microsurgery in anastomosis of small vessels. S. Fr~ium, 1 1: 243, 1960. 9. VICKERY, C. M., MCCOMBS, H. C., and WARREN, R. Experimental small artery grafts in dogs treated with immunosuppressive drugs. :Vw England J. dletz.. 2i2 : 325, 1965. 10. BESCITI. h. and BELLINAZZO, I’. Experimental studies of the fate of arterial homografts. dn& ology, 4: 483, 1953. 11. ANGOLA, J., I’ALMER, T. H., and WELCH, C. S. Long femoral and ileofcmoral grafts. S. f~0~w, 3: 243, 1932. 12. BROWN, R. B., HUGGINS, C. E., and KOTH, D. R. An experimental reevaluation of the problem of small vessel replacement. Surgery, 43: 63, 1958. 13. MOORE, T. C., RIBERI, A., and KAJIKURI, H. Freeze-dried and alcohol-preserved homografts for replacement of small arteries. S/fr~. (;?m~. & Obst., 103: 165, t956.
Arterial
Homografts
MARVIN GLICKLICH, M.D., Milwaukee, Wisconsin
METHOD
From the Diwision of Surgery, Marquette Uniaersity School of Medicine, and- the Allen-Bradley Medical Science Laboratorv. Milwaukee. Wisconsin. This work was subported in &t by a gran&-aid frown the Wisconsin He&t Association.
Segments of canine brachial and femoral arteries 2 to 4 mm. in external diameter of various lengths were obtained under sterile conditions from live donors, placed in normal saline solution in sealed tubes, and frozen slowly and stored in the freezer compartment of a household type refrigerator. Each graft was carefully measured before removal. All branches were ligated close to their origin with No. 5-O silk. Thus, a homograft bank was available for use as needed. The grafts were thawed using warm water just prior to use. Segments of twelve canine brachial and femoral host arteries were excised and replaced by homografts of closely equivalent diameter and slightly longer length. The host vessel size, that is, the external in situ diameter, was as follows: less than 2 mm., one; 2 to 2.5 mm., five; 2.6 to 3 mm., three; 3.1 to 3.5 mm., three. The host arteries were occluded and held with Potts ductus and coarctation clamps. With the aid of the Zeiss operating microscope, meticulous dissection of the adventitia from the distal 3 to 4 mm. of the host and graft vessels was accomplished to prevent inclusion in the suture line. End to end oblique anastomoses were used to minimize constriction and to permit adaptation of the constricted end of the donor artery to the more flaccid homograft end. No. 8-O monofilament nylon sutures* were used. Initial corner sutures were placed and continued as over and over sutures for one half of the oblique circumference. Moderate traction at the corners kept the anastomotic line straight and stabilized the
HE SYNTHETIC GRAFT has displaced the arhomograft for substitution of large arteries because of superior results. This has not proved to be the case in small arteries under 4 mm. in external diameter [1,2] where autologous artery and vein have repeatedly outperformed other available materials [3]. The search for a suitable small arterial prosthesis continues because autogenous artery or vein are not always available or feasible [1,4X]. As one examines the properties a suitable small arterial prosthesis must have, it becomes apparent that homologous artery has most of them except for the questions of immune response and deterioration of vessel wall strength. The artery is pliable, can bend and twist, and has low implantation porosity and high healing porosity 171. Homograft artery is easy to handle, has a smooth intimal surface, and is readily procurable. Many methods of sterilization are available. Thus, the arterial homograft as a small artery prosthesis deserves reconsideration. This study was performed to ascertain whether, with refinements in vascular anastomotic technics, dead arterial homografts can be utilized to replace short segments of small arteries 2 to 3.5 mm. in external diameter with successful long-term outcome. Because of the small size of the graft and host vessels, it was anticipated that persistence of the donor elastic tissue combined with gradual replacement of other elements of the graft by host collagen might yield an adequate long-term blood vessel without the serious complications which occur in large homografts.
T terial
vessels. (Fig. 1.) The Zeiss operating microscope provided magnification of 6 to 40 times although a magnification of 16 times was the usual working power. Such enlargement permitted meticulous suture placement within 0.5 mm. of the vessel edge with minimal trauma [8]. Photographs of the procedures and of the subsequent specimens were taken through the lens system * Experimental suture X 2317 with TE-11 needle was supplied through the courtesy of Davis and Geck Co., Danbury, Connecticut. 842
American
Journal
of Suvgevy
Small Arterial
of the microscol)c with apparatus developed in this laboratory and to be reported elsewhere. The degree of tension on the vessels was carefully controlled to aid in suturing but to avoid dehiscence and tearing. The vessels were irrigated and moistened at frequent intervals with normal saline sohtion to TIrevent drying. No anticoagulants were used. After completion of both proximal and distal anastomoses. a thin cuff of Surgicel@ was placed about each. Both occluding clamps were completely released almost simultaneously and the vessel was replaced in its bed. Nonocclusive finger pressure over both anastomoses for five to six minutes was applied to control bleeding from the suture holes. In most instances the Surgicel was subsequently removed. Procaine penicillin, 300.000 to 400,000 units, was given for three days postoperatively. Follow-up period ranged from five to eight and a half months at which time the homografts and host arteries were explored and excised. Photographs of the gross specimens were taken. The homografts with the attached host vessel were sectioned longitudinally and stained with hematoxylin and eosin, Verhoefi’s elastic tissue stain, and Masson trichrome stain RESULTS
Nine of the twelve homografts were patent (75 per cent). Three (25 per and functioning
cent) were thrombosed, atrophic, and obvious failures. Grossly, all functioning grafts pulsated in an expansile manner in situ and were difficult to distinguish from the adjacent host vessel. Results as listed in Table I are correlated with host vessel size, homograft diameter and length, homograft storage age, and duration of followup study.
Homografts
Results were considered good if the intima and anastomoses were intact and smooth and there was no evidence of constriction or dilatation (Fig. 2.) Five (41.2 per cent) homografts were classified as having good results. Fair results included patent functioning grafts with roughening or irregularity of the intima or suture line or dilatation of the graft. Four (33.3 per cent) grafts were classified as having fair results. Microscopic evaluation of the functioning homografts revealed the presence of a thickened and relatively cellular intima with elongated and flattened cells on the luminal surface. These cells seemed to be fibroblasts. (Fig. 3.) The thickness of the intima varied and was greater in those grafts noted to have grossly irregular intimas. The internal elastic lamina was present TABLE SUMYARY
Dog .. NO.
Host VlZSSCl Diam-
eter
(mm.) 1
2 3 4 5 6 7 8 9 10 11 12
2.5 1.5 3 3.0 3 2.8 2.8 2 2.0 35 22 2.2
5 2 R
I
OF RESULTS
r--Homograft----DiamLength (cm.)
ecer
rIuration of Age (mo.)
(mm.)
.(I
2.6 2.0 2.8 2.0
2 2.n 2.5 3
3 2 2.8 22 2.8 3 5 2.3 2
3 .o 35 3 3.0 7.0 4.5
35
3
0 B0 0
30
4 4 5 11 1 6 8 8 1 lwk. 2wk. 10
Follow-
Resr1lt
UP Study
ii 5 6 5 5 .i .i 5 b 8 8 3 8 R.T, i 7
3
Good Failure Good Pair Fair Failure Fair Fair Good Failure Good Good
Glicklich
FIG. 3. Photomicrograph of homograft implanted six and a half months, demonstrating somewhat thickened and cellular intima with flattened elongated cells on luminal surface.
FIG. 4. Elastic tissue stain demonstrating persistence of internal elastic lamina and condensed elastic fibers of the media in the homograft implanted for eight months.
in all functioning specimens with varying degrees of fracture. It is believed that some of the apparent disruption of this elastic layer might be artifact. The media was somewhat thinner and acellular with absence of smooth muscle. (Fig. 4.) The elastic tissue fibers were fairly abundant, interlacing, and condensed. Dense and quite acellular collagen layers lay between the internal elastic lamina and the medial elastic fibers and external to the medial elastic tissue. These features have been described by Vickery, McCombs, and Warren [9] and others [2,7,10]. An interesting feature noted herein and by Vickery, McCombs, and Warren is the absence of the round cell infiltrate of homograft rejection in all specimens.
series. Good pulses were present initially for three weeks but complete thrombosis occurred at seven months. There is strong suggestion that in smaller arterial grafts the length of the graft may have a critical relation to diameter which, if exceeded, may predispose to thrombosis [I 11. This relation has not been defined.
ANALYSIS
OF
HOMOGRAFT
FAILURES
Of the three homografts which thrombosed, technical or judgment failures are deemed responsible for two. In two instances large branches proximal to the homograft, siphoning blood away from the surgical site, were incriminated. In animal number two, the host artery was a 1.5 mm. small branch of the main femoral artery. The main artery diverted blood flow from the graft. A similar circumstance occurred in number six in which a 2.8 mm. brachial artery had a functioning large branch just above the proximal anastomosis. In addition, the anastomoses themselves were considered poor at the time because of excessive motion of the dog under too light an anesthetic. Graft number ten was the longest in the
COMMENTS
Great emphasis is placed on the attention to technical details in performing anastomoses of these small arteries and homografts. Errors that predispose to clotting are magnified in significance the smaller the diameter of the artery. Use of the operating microscope helps to recognize and avoid these insults. The advantages of a tiny smooth monofilament suture in minimizing the intraluminal foreign body surface at the suture line are obvious. It is possible that poor patency resulting in other series [12,13] may be due to the large braided and twisted multistrand sutures used. For the duration of this study it is believed that the preservation of the homograft elastic tissue combined with ingrowth of host collagen resulted in excellent vessels in a reasonable percentage of homografts. Whether this would persist over longer term follow-up study is a legitimate question that will have to be answered in further studies. Whether the encouraging results of this small study can be reproduced in larger numbers and transposed to small arterial homografts in human subjects remain to be ascertained. Americas
Journal of Surgevy
Small Arterial Homografts
I. Refinements of technic of anastomosis of small arteries, including the use of the Zeiss operating microscope and No. 8-O monofilament nylon sutures, were applied to frozen canine wall arterial homografts as substitutes for canine arteries 2 to 3.5 mm. in external diameter. 2. Over a five to eight and a half month followup period, nine of twelve (75 per cent) homografts remained patent and functioning. 3. Five (41.2 per cent) homografts were good and four (Xi.3 per cent) were fair. 4. For the period of this study the successful homografts resulted in satisfactory blood vessel replacements. 5. The encouraging results warrant further work in evaluating the homograft as a small artery prosthesis.
REFERENCES 1. MASSELL, T. B., HERINGMON, E. C., and GREENSI-ONE, S. M. Woven dacron and woven Teflon prostheses: use for small artery replacement. .lirh. Surg., 84: 91, 1962. 1. DEBAKEY, M. E., JORDA?;, G., BEALL, A. C., JR., O’~‘EAL, R. M., ABBOTT, J. P., and HALPERT, B. Basic biologic reactions to vascular grafts and prostheses. S. C&z. North America, 45: 477, 1965. 3. CONNOLLY, J. E. and HARRIS, E. J, Autogenous in bitu saphenous win bypass for femoral popliteal
Vol. 111, June 1966
S-L-,
5. WESoL0TvSKI. S. .I.. FRIES, c. c.. L~1ilG. w. J,, SATVYER, I’. !i,, and DETERLING, Ii. ;1 , JR. ‘The synthetic vascular graft: nc’w ccmccpt., new techniques. .-I&. Suig., 84: i-1, 19&l. 6. KRIPPAEHIE, W. W., DESHPANDE. I’. J.. JACKSON, D. S.. and DUNPHY, J. E. Reaction of connrctive tissue to collagen-dacron prosthwes ,.I we. J. Swg., 110: 186, 1965. i. WESoLowSKI, S. A. The healing of vascular prosthcws. Suryeuy, 5i: 319, 1965. 8. JACORSOS, J. H. and SUAREZ, E. C. Microsurgery in anastomosis of small vessels. S. Fr~ium, 1 1: 243, 1960. 9. VICKERY, C. M., MCCOMBS, H. C., and WARREN, R. Experimental small artery grafts in dogs treated with immunosuppressive drugs. :Vw England J. dletz.. 2i2 : 325, 1965. 10. BESCITI. h. and BELLINAZZO, I’. Experimental studies of the fate of arterial homografts. dn& ology, 4: 483, 1953. 11. ANGOLA, J., I’ALMER, T. H., and WELCH, C. S. Long femoral and ileofcmoral grafts. S. f~0~w, 3: 243, 1932. 12. BROWN, R. B., HUGGINS, C. E., and KOTH, D. R. An experimental reevaluation of the problem of small vessel replacement. Surgery, 43: 63, 1958. 13. MOORE, T. C., RIBERI, A., and KAJIKURI, H. Freeze-dried and alcohol-preserved homografts for replacement of small arteries. S/fr~. (;?m~. & Obst., 103: 165, t956.