356
The Use of Mesh-tube-Constricted Dilated or Varicose Veins as Arterial Bypass Conduit A. Moritz, F. Raderer", H. Magometschnigg, W Trubel, R. Ullrich", G. Laufer, and M. S taudacher 2nd Surgical Department. * Department of Pathology. University of Vienna , Austria " Ludwig Boltzma nn Institute for Cardiosurgical Researc h, Vienna, Austria
In gene ra l, dilated an d var icose veins are not used as arte rial bypass grafts des pite their physiologica l endothelial lining. A unifor m sma ll diam eter may be ac hieved by inserti ng suc h veins into mes h tubes. To test the degree to which dilated veins can be constricted without forming folds, in-vitro an d experi mental investigations wer e per formed before such composites were used for clinical reconstr uctive surge ry. Ovine jug ular veins with a diam eter of 15 mm were inse rted into 6 mm tubes . After ca sting in paraffin wax none of the specime ns showed folds on the flow surface. In 12 shee p pai rs of mesh-constricted jugular veins and na tive fem oral veins were implan ted as fem oropopliteal bypass gra fts . Six anima ls we re killed at 6 months and 6 at one year. All bypasses re ma ined pa ten t an d none showe d signs of obstruc tion ca used by folds or a nasto moti c hyperplasia at a ngiographic con trol. Intimal hyperpl asia was significa ntly reduce d from 416 ± 1 4 3 ~m in the midportion of na tive vein grafts to 231 ± 7 6 ~ m (p =O.OOOl paired t-test) in constricted veins as well as at the anastomoses (358 ± 256 urn vs. 180 ± 73 pm : p = 0.00 8).
Par tially or tota lly mesh- tube-constri cted var icose veins were use d for infra inguina l reconstructions in 19 patie nts and for coron ary revas cularization in 3. All gra fts showe d an even calibra tion at contro l angiography. As constriction does not lead to interna l folds, vari cose or dilated veins may be used sucess fully as bypass grafts after inse rtion int o mesh tubes. The external reinforcement redu ces the intimal hyperplasia within the gra ft a nd als o reduces anastomo tic hyperp lasia . Key word s Vein grafts - Varicose veins - Intima l hyperplasia - Mesh-tu be constriction - Arte rial reconstru ction
Introducti on Autologous material is by far superior to all curre ntly availab le artificial grafts in arteri al reconstructions with r elatively low outflow such as infrapopliteal (11) and coronary revascularizat ions (7). Dilated or varicose veins have a natural, anti-th ro mbogenic endothelial lining but are generally not us ed for arterial bypa ss gra fting as unfavorable hemodynamic properties and late dilatation ar e anticipa ted. Ex-
Thorac. cardiovasc. Surgeon 40 (1992) 356-360 © Georg Thieme Verlag Stuttga rt New York
Netz umhtlllte dilatierte ode r va rlkdse Ven e n a ls arteri elle Bypasstranspla nta te Dilatierte oder varlkose Venen wer den , obwohl sie eine physiologische Endothelausk leidung haben , im a llgemeine n nicht als Bypasstr ansplantate verwend et. Durch Einziehen solche r Vene n in Schlauchmaterialien kann ein gleichfO rmiger Quer schnitt erz ielt werden. Urn festzustellen wie weit die Kaliberredu ktion moglich tst. ohne daB es zur Falten bildung der Wand kommt , wurd en In-vitro - und exper imentelle Untersuchungen du rchgeftihrt, bevor umhiillte Venen klinisch als Gefa bersat z verwe ndet wurden. Jugula rvenen von Schafen mit einem Durchmesser von 15 mm wurden in fi-mm- Netzschlau che eingezoge n . Nach dem AusgieBen mit Paraffi nwax zeigte keines der Praparate Falten an der innere n Oberflache. Netzumhtillte Ju gularvenen und na tive Fem oralvenen wurd en in Paar en bei 12 Schafen als femorop oplitealer Bypass implantiert. Sechs Tiere wurden nac h einem halb en Jahr und weiter e 6 nach 12 Monate n nachuntersu cht. Alle Bypasses wa ren durchga ngig un d frei von Stenose n. Die Intima hyperp lasie war bei den umhii llten Venen signifikant gegeniiber den nati v Implantlerte n Vene n reduzie rt (231 ± 76 urn vs 416 ± 143 urn: p = 0,0001 gepaarter t·Test). Ebens o war dies im Bereich der Anastomosen festzuste llen (180 ± 73 vs 358 ± 256 urn: p = 0,008).
Komplett oder teilweise net zverst arkte Venen worde n bel 19 Patient en fur periph er e und bei 3 fur a orto korona re Revaskularis ationen verwe ndet. Aile Grafts zeigten einen gleichmaBigen Querschnitt in der Kontrollan giogra phie. Da eine Kaliberr edu ktion dilatierter ode r vari koser Vene n durc h Einziehen in Netzschlauche nicht zu einer Faltenbildung fuhrt . konn en solche er folgreich als Bypasstra nsplantat verwendet werde n. Durch verstarkung von a uBen kommt es zu einer Hedu ktion der lntimadi cke im Graft un d an den Anastomosen.
ternal constriction has been used to ada pt th e graft diam eter to that of the host vessel (1) or to pr event graft compression (2). Experimenta l series ha ve shown a reduction of intimal hyperplasia by relieving th e stress of th e ar-
Presented in part at the 21st Annual Meeting of the German Society for Thoracic and Cardiovascular Surgery February 19- 22,1 992, Bonn
Received for Publication: J une 23. 1992
Downloaded by: University of British Columbia. Copyrighted material.
Summa ry
The Use ofMesh-tube-Constricted Dilated or Varicose Veins as Arte rial Bypass Conduit
Thom e. cardiovasc. Surgeon 40 (1992)
357
terialized venous wall (4). In an in-vitro series we evaluated to wh at extent veins can be cons tricted until redundant wall materi al forms folds at the flow surface. An experim ental se ries served to define the degree of anastomotic hyperp las ia caused by the compliance mismatch between reinforced vein and artery. In a clinical series we used varicose veins for infrai nguinal and coronary revascularizations.
Methods Jugular veins with an average outside diameter of 15.4 mm (12-1 8) were ha rvested at th e end of unre lat ed experime nts from 5 sh eep. The veins were filled with 1 : 2 diluted contrast media (Meglumin Iodamid. Uro miro" Gerot , Vienna. Austria) to a pressure of 100 mmHg and then photographed and radiographed. The reafter 5 em long segments were inse rted into tubes of inner diameter (10) 6 or 7 mm ma de of Dacron mesh fabri c (Meadox Lars" mesh , Oaklan d. NJ). These tu bes were sewn over a 6 or 7 mm mandril respectively usi ng 4/0 silk an d a locking stitch technique. A second radiogr aph. fixation with 9 % formaldehyd e. and casting with paraffin wax were done, again under 100 mmHg pressur e, The casts were cut transversely and ph otographed under a micr oscope in order to identify eventual irregularities or folds at the inner surface.
Animal experiments Under general anesth es ia the jugula r vein was dissected free in 12 sheep (50 - 70 kg). These veins were insert ed into a dacron mes h tube 6 mm ID and 12 em long and the composite wa s us ed as a femoropo pliteal bypass graft (Fig. 1). The mesh was included into the sutur e line at both anastomoses. The femor al artery and neighboring femoral vein we re ligated a nd clipped, On the contralateral side the femoral vein was harvested and implanted without reinforceme nt. For angiographic detennination of vascular dimensions. 5 mm stainless steel spheres were placed in
Nr.
Fig.l In 12 sheep native femoral veins (above)were compared to rnesbtube-constricted jugular veins as bypass grafts (below) in femorapopliteal posrtion.
the adjacent muscles. The animals received heparin only dur ing surgery (2 x 5000 IU) an d perioperative antibiotic prophy laxes for three days. amox icillin + clavulan acid 2.2 g t.i.d . (Augrnentin". Beecham. Belgium) and metronidazol 100 mg t.i.d. (Anaerobex'", Gerot, Austria). Ten days after surgery the animals were brought to a farm where they were kept out on the pastur e or in sta bles depending on the season. After 2 months and at termination of the experiment angiog ra phy of the grafts was perfo rmed . After perfusion fixation with gluta ra ldehyd e the midport ion of th e graft and the anastomoses were cut transversely and embedded in celloidin and the thickness of the intima was determined using an ocular micrometer. All animal experiments were endorsed by the Austrian Ministry of Scien ce and Education.
Sex
Age
Symptoms Wrap
Bypass
I
m
65
total
fem pop III
2
f f f
80 80 75
lib IV III III
partial partial partial
fern crur sequential popliteo-crural fern crur
m m m m f m m m m m m m m f m
54 70 61 76 56 72 54 82 76 70 71 70 72 67 70
lib IV III III lib IV III III III III III lib IV III III
partial total total total total partial partial total total total total total partial partial partial
fem pop I fem crur fem pop II fem pop III fem pop I fem pop III fem pop III fem pop III fem pop I fem crur fem crur fem pop III fem pop III fem crur fem crur
3 4 5 6 7 8 9 10
II 12 13 14 15 16 17 18 19
Remarks died 2 months pastop occluded 2 months postop
proximal stenosis after 16 months dilatation of peroneal artery
revision of end-to-end anast. occlusion of axbifern bypass
died 2 months postop
Patients who receivedpartially or totally mesh reinforced and constricted varicose veins as infrainguinal bypass grafts. Symptoms are listed as clinical stages. Femoropoplrteal Ifem pop) bypasses are differentiated by the popli·
teal segment (I, II, III)to wh ich the distalanastomoses wa s made. Femcrur indicates infrapopliteal bypass.
Table 1 Patient description
of clinical series
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In-vitro studies
A. Moritz et ai.
Thome. card/ Dvase . Surgeon 40 (199 2)
Fig. 2 Dissected varicose vein before insertion into mesh tube. This vein was used for the femoropopliteal bypass shown in Fig. 4.
Fig.3 Paraffin cast ofovine jugular vein constricted from 15 to 6 mm diameter.
Fig. 4 Mesh-tube-constricted varicose vein used as femoropopliteal
Clinical expe rience
Three patients underwent coronary revascularization with varicose veins . All patients had at least tw o arterial grafts used and one vein graft was made suitable by inse rtion into a mesh tube, a 6 mm tube was used in the first case and 5 mm tubes the re after. All three unde rwe nt control angiography.
Partially or totally mes h-constricted veins have been used for 19 infrain guinal reconstructions (Table I) includ ing 11 femoropopliteal and 8 infrapopliteal bypasses. Veins were dissected atrau matically (Fig. 2) an d flushed and sto red in a solution conta ining he parin. papaverin, and albumin (5). Dilated seg ments or. if appropriate, the whole vein were inserted into 6 mm 10 mesh tubes . As the material is provided only in sh eets 15 by 15 em large. segments had to be anas tomosed with 5/0 silk stitches when longer tub es we re necessary. Sma ll side bran ches of the vein wer e ligated with 4/0 Vicryl@(Ethlcon, Hamburg. FBGJ. la rger branches wer e cut flush a nd the opening was oversewn with 7/0 Prolen e'" (Eth icun, Hamburg. FBG) suture. All pat ients underwent intraoperative angiography and either intravenous or intraart er ial DSA contro l before hospital discharge.
bypass graft.
Besults
In-vitro tests Jugular veins of sheep with an average outside diameter of 15.4 mm (12-1 8) could eas ily be insert ed into 6 an d 7 mm mesh tubes. On radio graphs only irregular ities caused by the longitudinal sutur e line could be observe d. The re have been no signs of longitudin al folds or wri nkles. The sam e could be found at examination of the cross sections of the paraffin casts. which showed no irregularities at the inside of the constricted veins (Fig. 3).
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358
The Use ofMesh-tube-Constricted Dilat ed or Varicose Veins as Art erial Bypa ss Conduit
Thom c. cardiovasc. Surgeon 40(1 992)
Fig.5 Meskor>
Animal studies
Clinical implantation diam eter appea red still too large for the host vessel. The two veins implanted thereafter were inserted into 5 mm tubes which resulted in a smooth caliber transition to the host vess el (Fig. 5). Discussion
Grafts lined with auto logous endo thelium show significan tly better performance in arterial reconstructions with limited outflow. such as infrap opliteal (11) or coronary revascularizations (7). Many gra ft alternatives have been looked for when the saphenous vein or arteria l grafts for coronary cases are not available or suitable. Arm veins show a reasonab le long-term patency in peripheral reconstructions but tend to dilate in the long run (3). Use d for coronary revascularization the intermediate patency is less tha n optimal (10). Deep femoral veins may be used but have to be tape red at both ends to achieve a relatively sm ooth tran sition to the grafted vessel (8). Varicose veins usu ally are not considere d for bypass grafting as the irregular inner diameter may cause zones of blood stagnation with subsequent thromboses . or aneurysmal dilatation of the weakened wall segments may occur. As all these grafts are lined with antithro mbogenic en dothe lium they shou ld perform as well as the sa pheno us vein. once the caliber is reduced and smoothe ned and the wall is reinforced. Insertion into constricting mesh tubes appears to be a means to solve this problem . This was don e to adap t th e graft diameter to that of coronary arteries in a clinical series reported by Barra (1) . A major concern however was the gen eration of folds by the redundant vein wa ll material after constriction. In our in-vitro tests we found that constri ction of thin-walled jugular veins from 15 to 6 mm did not create any folding of wall structures or cause stenoses . Human varicose veins with irregular wall thickness could be constr icted safely by 51 % from 13 to 6.3 mm (6). In our animal model again jugular veins of 15 mm diameter we re inserte d into 6 mm mesh tub es and used as bypass grafts. All grafts. the na tively implanted femoral veins as well as the control gra fts. remained patent. Intimal hyperplasia caused by the arterialization of graft veins was sign ificantiy reduced by the redu ction of th e wa ll stress. This findin gs are corroborated by earlier investigations of Karayannakos
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stricted varicose vein used as aortocoronary bypass graft to a marginal branch of the circumflex artery.
All 12 fem oropopliteal bypasses wer e pat ent 6 months after implantation. Constricted jugular veins had a uniform caliber as opposed to the na tively implan ted femoral veins. whi ch dilat ed to 8 to 10 mm at th e distal anas tomose s. No a ngiogra phic sign s of a nastomotic hyperpla sia or stenoses. whi ch might be caused by any inversion of th e dacron mesh into the vascular lumen , were observed at the distal anastomoses. None.of the grafts showed folds at inspection of the cross-sections on explantati on in 6 animals after 6 month s. In the constricted veins intima l hyperplasia was significantly re duce d at the midporti on of the grafts (231 ± 76 urn) as com pa red to the na tively implanted femo ra l veins (416 ± 143 ~m ; p=O.OOOI pai red t-testl , The same was found at cross se ctions of the center of the anastomoses where the stiffer, reinforced veins had an intimal thick ness of 180± 7 3~ m and the natively imp lante d veins of 358 ± 257 urn (p = 0.0008).
At cont rol a ngiography pri or to discharge all grafts showed sati sfactory ca libration with out signs of longitudinal folds (Fig. 4). In two veins which were only partially supported. the diameter of the remaining vein was underestimated and thes e segm ents appeare d relative ly wide. In some of the early ca ses thicker side bra nches that had merely been ligat ed caused indentatio ns into the gra ft lumen. At angiographic restudy of these pa tients the degree of nar rowing was clea rly redu ced. pro bab ly by atrophy of ab un dant wa ll material and resorption of the ligatures. One poplitea l-pedal re construction occluded 2 months after surgery. This graft was placed as a secondary procedure after a pr eviously failed reconstruction . A jump graft to the dorsal pedal artery had failed primarily. At angiography prior to discharge the anstom oses to the severely disea sed posterior tibial artery showed a 50 % stenosis. In addition some appositional thrombus was found at the offspring of the occlude d jump segment. Amputation below the knee became necessary 4 months after surgery. A 80-year-old patient with a composit e sequential reconstr uction for acute limb ische mia died 2 months after su rgery from heart failur e and a 70-year-old ma n died 2 months after surgery of cer eb ra l stro ke. Four grafts needed revisions. In one femoroperoneal graft the tibial artery developed a stenosis distal to the anastomoses, which was dilated successfully. One partially constricted graft becam e sten otic and finally occluded in the pro ximal. non-reinforced segment. The pati ent could not undergo revision before her hyperthyroid crisis was managed medi cally. A PTFE interposition graft was placed betw een the fem oral arte ry an d the gr aft above the knee joint. One graft had to be revised at the site of an end-toend anastomosis in a thin unsupported segment of the graft. In a patient with graft extension of an axiUo-bifemoral graft th e right limb had to be thrombectomized two times. Finally a PTFE graft was interposed between the right limb . the deep femoral artery. and th e dis tal meshconstricted vein graft. The remaining reconstructions were pat ent 13 (2 to 42) months after surgery. All three mesh- constricted aortocoronary vein grafts were pa tent at con tro l angiogra phy. The first graft had been inser ted into a 6 mm tube and the resulting inner
359
A. Moritz
Thorae. eardio vasc . Surgeon 40(992)
ez at.
Acknowledge me nts This study was supported by the Fonds zur Forderung der Wisse nschaftliche n Forschung Grant #756 9-me d and the Ludwig Boltzmann Institute for Cardiosurgical Researc h
Referen ces I
2
Barra. 1. A . A Volant. 1. P. Leroy et a l.: Constrictive perivenous mesh prosthesis for preservation of vein integrity. J . Thora e. Cardiovasc . Surg. 92 (1986) 330-336 Deriu. G. P. . E. Boiiotta. L. Bonavina ct al.: Great saphenous vein protection in arterial reconstructive surgery. Eur. J. Vase.
Surg. 3 (1 989) 253-260 3
lIarris. R. W . G. Andros. L. B. Dulawa. R. W ouaa:S. X. Sal les-Cunha. and R. Apyan: Successful long-term limb salvage using cephalic vein bypass grafts. Ann. Surg. 200 (1984) 785 -
792 4
Karayanna cos. P. E.. 1. R. Hostetler; M. G. Bond ot a l.: Late failure in vein grafts : Mediating factors in sube ndot helia l fibro-
5
LoGerfo. F. W . C. C. lIaudenschild. and W C. Quist: A clinical technique for preservation of spasm a nd preservation of endo thelium in sa phenous vein grafts . Arch. Surg. 119 (1984) 1212
muscular hyperplasia. Ann. Surg. 187 (1 978) 183- 188
- 1214 Fig.6 Factor VIII staining of cross sections of a proximal natively mplanted {Bl and a more distal dacron-mesh-constricted vein segment {Al after occlusion of an axillobifemoral bypass limb. Notice the increased number of vasa vasorum in the reinforced vein (d).
(4). In his study he foun d the porosity of the wrap material to be crucial: afte r wrapping with non poro us material isch emia with consec utive thickening of the wa ll will r esult. The disad vantage of exte rnal reinforcement however is reduced elasticity. Compliance mism atch was found to play a significant r ole in the development of anas tomotic hyperplasia and subseque nt failure of nonautogenous arte rial gra fts (9, 12). In our exper imental mod el the positive effect of wall stress relief outweighed the potential disadvantage of wa ll stiffening by th e mesh tubes. and anastomotic hyperplasia was re duced compared to native vein grafts . The clinical speci mens re trieved at revisi ons of partially reinfor ced gra fts showed a clear increa se in the density of vasa vasorum und er the mesh . A significant reduction of intimal hyperp lasia was not obvious in the two pairs of specimen . However qu antifi cation is difficult in cross sections tha t have not been perfu sion fixed (Fig. 6). In all in-vitro. experimental, and clinical sa mp les the oversized veins have been redu ced by the external mesh to a un iform an d ade qua te bypass dia meter without creation of significant stenoses or folds. Vein gra fts may be redu ced by at least 50 % in diam eter after inserti on into constric ting mesh tubes witho ut any negative effects. As indicated by our expe rime ntal series intimal and anas tomotic hyperplasia is r edu ced by this tech nique .
6
7
Moritz. A.. F. Grabenuioqet; F. Raderer et al.: Mesh tube constricted var icose veins used as bypass grafts for infra inguinal a rteria l reconstruc tion. Arch. Surg . 127 (992) 416 - 420 Sapsford. R. N.. G. D. Oakley. and S. Talbot: Early patency of expanded polytetra fluoroeth ylene vascular grafts in aorto-coronary bypass . J. Thorac. Cardiovasc. Surg . 81 ( 981) 860 -
864 s Schulman. M. 1... M. R. Badhey. A. Yateo. end G. Pillari: A sapheno us alternative: Prefer ential use of supe rficial femoral and popliteal vein as femoro popliteal bypass grafts. Am. J. Surg .
152 (1986) 231 -237 9
10
Scottiurai. V 5. . 1. S. T. Yao. W R. Flinn. and R. C. Batson: Intimal hyperplasia a nd neointi ma: An ultrastru ctural analysis of thrombosed grafts in huma ns. Surgery 93 (1983 ) 809-8 17 Stoney. W 5.. W C. Alford. G. R. Burrus . D. M. Glassford. M. R. Petracec, and C. 5. Thomas : The fate of a rm veins used for aorto-coronary bypass grafts . J. Thorac. Cardiovasc. Surg. 88
(1984) 522-526 11
12
Veit h. F. J.. S. K. Gupta. E. Ascer et al.: Six yea r prospective multicenter randomized compar ison of auto logous saphenous vein a nd expanded polytetra fluoroethy lene grafts in infrainguinal arterial reconstr uctions . J. Vase. Surg. 3 (1986) 104 -11 4 Walden. R.. G. 1. t.ttalten. 1. Megerman. and W M. Abbott: Matched elastic properties and successful arterial gra fting.
Arch. Surg. 115 (1980) 11 66- 1169
Doz. Dr. A. Moritz II. Chir. Univ.-Klinik Spitalgasse 23
A·1090 Wien Austria
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360
The Use of Mesh-tube-Constricted Dilated or Varicose Veins as Arterial Bypass Conduit A. Moritz, F. Raderer", H. Magometschnigg, W Trubel, R. Ullrich", G. Laufer, and M. S taudacher 2nd Surgical Department. * Department of Pathology. University of Vienna , Austria " Ludwig Boltzma nn Institute for Cardiosurgical Researc h, Vienna, Austria
In gene ra l, dilated an d var icose veins are not used as arte rial bypass grafts des pite their physiologica l endothelial lining. A unifor m sma ll diam eter may be ac hieved by inserti ng suc h veins into mes h tubes. To test the degree to which dilated veins can be constricted without forming folds, in-vitro an d experi mental investigations wer e per formed before such composites were used for clinical reconstr uctive surge ry. Ovine jug ular veins with a diam eter of 15 mm were inse rted into 6 mm tubes . After ca sting in paraffin wax none of the specime ns showed folds on the flow surface. In 12 shee p pai rs of mesh-constricted jugular veins and na tive fem oral veins were implan ted as fem oropopliteal bypass gra fts . Six anima ls we re killed at 6 months and 6 at one year. All bypasses re ma ined pa ten t an d none showe d signs of obstruc tion ca used by folds or a nasto moti c hyperplasia at a ngiographic con trol. Intimal hyperpl asia was significa ntly reduce d from 416 ± 1 4 3 ~m in the midportion of na tive vein grafts to 231 ± 7 6 ~ m (p =O.OOOl paired t-test) in constricted veins as well as at the anastomoses (358 ± 256 urn vs. 180 ± 73 pm : p = 0.00 8).
Par tially or tota lly mesh- tube-constri cted var icose veins were use d for infra inguina l reconstructions in 19 patie nts and for coron ary revas cularization in 3. All gra fts showe d an even calibra tion at contro l angiography. As constriction does not lead to interna l folds, vari cose or dilated veins may be used sucess fully as bypass grafts after inse rtion int o mesh tubes. The external reinforcement redu ces the intimal hyperplasia within the gra ft a nd als o reduces anastomo tic hyperp lasia . Key word s Vein grafts - Varicose veins - Intima l hyperplasia - Mesh-tu be constriction - Arte rial reconstru ction
Introducti on Autologous material is by far superior to all curre ntly availab le artificial grafts in arteri al reconstructions with r elatively low outflow such as infrapopliteal (11) and coronary revascularizat ions (7). Dilated or varicose veins have a natural, anti-th ro mbogenic endothelial lining but are generally not us ed for arterial bypa ss gra fting as unfavorable hemodynamic properties and late dilatation ar e anticipa ted. Ex-
Thorac. cardiovasc. Surgeon 40 (1992) 356-360 © Georg Thieme Verlag Stuttga rt New York
Netz umhtlllte dilatierte ode r va rlkdse Ven e n a ls arteri elle Bypasstranspla nta te Dilatierte oder varlkose Venen wer den , obwohl sie eine physiologische Endothelausk leidung haben , im a llgemeine n nicht als Bypasstr ansplantate verwend et. Durch Einziehen solche r Vene n in Schlauchmaterialien kann ein gleichfO rmiger Quer schnitt erz ielt werden. Urn festzustellen wie weit die Kaliberredu ktion moglich tst. ohne daB es zur Falten bildung der Wand kommt , wurd en In-vitro - und exper imentelle Untersuchungen du rchgeftihrt, bevor umhiillte Venen klinisch als Gefa bersat z verwe ndet wurden. Jugula rvenen von Schafen mit einem Durchmesser von 15 mm wurden in fi-mm- Netzschlau che eingezoge n . Nach dem AusgieBen mit Paraffi nwax zeigte keines der Praparate Falten an der innere n Oberflache. Netzumhtillte Ju gularvenen und na tive Fem oralvenen wurd en in Paar en bei 12 Schafen als femorop oplitealer Bypass implantiert. Sechs Tiere wurden nac h einem halb en Jahr und weiter e 6 nach 12 Monate n nachuntersu cht. Alle Bypasses wa ren durchga ngig un d frei von Stenose n. Die Intima hyperp lasie war bei den umhii llten Venen signifikant gegeniiber den nati v Implantlerte n Vene n reduzie rt (231 ± 76 urn vs 416 ± 143 urn: p = 0,0001 gepaarter t·Test). Ebens o war dies im Bereich der Anastomosen festzuste llen (180 ± 73 vs 358 ± 256 urn: p = 0,008).
Komplett oder teilweise net zverst arkte Venen worde n bel 19 Patient en fur periph er e und bei 3 fur a orto korona re Revaskularis ationen verwe ndet. Aile Grafts zeigten einen gleichmaBigen Querschnitt in der Kontrollan giogra phie. Da eine Kaliberr edu ktion dilatierter ode r vari koser Vene n durc h Einziehen in Netzschlauche nicht zu einer Faltenbildung fuhrt . konn en solche er folgreich als Bypasstra nsplantat verwendet werde n. Durch verstarkung von a uBen kommt es zu einer Hedu ktion der lntimadi cke im Graft un d an den Anastomosen.
ternal constriction has been used to ada pt th e graft diam eter to that of the host vessel (1) or to pr event graft compression (2). Experimenta l series ha ve shown a reduction of intimal hyperplasia by relieving th e stress of th e ar-
Presented in part at the 21st Annual Meeting of the German Society for Thoracic and Cardiovascular Surgery February 19- 22,1 992, Bonn
Received for Publication: J une 23. 1992
Downloaded by: University of British Columbia. Copyrighted material.
Summa ry
The Use ofMesh-tube-Constricted Dilated or Varicose Veins as Arte rial Bypass Conduit
Thom e. cardiovasc. Surgeon 40 (1992)
357
terialized venous wall (4). In an in-vitro series we evaluated to wh at extent veins can be cons tricted until redundant wall materi al forms folds at the flow surface. An experim ental se ries served to define the degree of anastomotic hyperp las ia caused by the compliance mismatch between reinforced vein and artery. In a clinical series we used varicose veins for infrai nguinal and coronary revascularizations.
Methods Jugular veins with an average outside diameter of 15.4 mm (12-1 8) were ha rvested at th e end of unre lat ed experime nts from 5 sh eep. The veins were filled with 1 : 2 diluted contrast media (Meglumin Iodamid. Uro miro" Gerot , Vienna. Austria) to a pressure of 100 mmHg and then photographed and radiographed. The reafter 5 em long segments were inse rted into tubes of inner diameter (10) 6 or 7 mm ma de of Dacron mesh fabri c (Meadox Lars" mesh , Oaklan d. NJ). These tu bes were sewn over a 6 or 7 mm mandril respectively usi ng 4/0 silk an d a locking stitch technique. A second radiogr aph. fixation with 9 % formaldehyd e. and casting with paraffin wax were done, again under 100 mmHg pressur e, The casts were cut transversely and ph otographed under a micr oscope in order to identify eventual irregularities or folds at the inner surface.
Animal experiments Under general anesth es ia the jugula r vein was dissected free in 12 sheep (50 - 70 kg). These veins were insert ed into a dacron mes h tube 6 mm ID and 12 em long and the composite wa s us ed as a femoropo pliteal bypass graft (Fig. 1). The mesh was included into the sutur e line at both anastomoses. The femor al artery and neighboring femoral vein we re ligated a nd clipped, On the contralateral side the femoral vein was harvested and implanted without reinforceme nt. For angiographic detennination of vascular dimensions. 5 mm stainless steel spheres were placed in
Nr.
Fig.l In 12 sheep native femoral veins (above)were compared to rnesbtube-constricted jugular veins as bypass grafts (below) in femorapopliteal posrtion.
the adjacent muscles. The animals received heparin only dur ing surgery (2 x 5000 IU) an d perioperative antibiotic prophy laxes for three days. amox icillin + clavulan acid 2.2 g t.i.d . (Augrnentin". Beecham. Belgium) and metronidazol 100 mg t.i.d. (Anaerobex'", Gerot, Austria). Ten days after surgery the animals were brought to a farm where they were kept out on the pastur e or in sta bles depending on the season. After 2 months and at termination of the experiment angiog ra phy of the grafts was perfo rmed . After perfusion fixation with gluta ra ldehyd e the midport ion of th e graft and the anastomoses were cut transversely and embedded in celloidin and the thickness of the intima was determined using an ocular micrometer. All animal experiments were endorsed by the Austrian Ministry of Scien ce and Education.
Sex
Age
Symptoms Wrap
Bypass
I
m
65
total
fem pop III
2
f f f
80 80 75
lib IV III III
partial partial partial
fern crur sequential popliteo-crural fern crur
m m m m f m m m m m m m m f m
54 70 61 76 56 72 54 82 76 70 71 70 72 67 70
lib IV III III lib IV III III III III III lib IV III III
partial total total total total partial partial total total total total total partial partial partial
fem pop I fem crur fem pop II fem pop III fem pop I fem pop III fem pop III fem pop III fem pop I fem crur fem crur fem pop III fem pop III fem crur fem crur
3 4 5 6 7 8 9 10
II 12 13 14 15 16 17 18 19
Remarks died 2 months pastop occluded 2 months postop
proximal stenosis after 16 months dilatation of peroneal artery
revision of end-to-end anast. occlusion of axbifern bypass
died 2 months postop
Patients who receivedpartially or totally mesh reinforced and constricted varicose veins as infrainguinal bypass grafts. Symptoms are listed as clinical stages. Femoropoplrteal Ifem pop) bypasses are differentiated by the popli·
teal segment (I, II, III)to wh ich the distalanastomoses wa s made. Femcrur indicates infrapopliteal bypass.
Table 1 Patient description
of clinical series
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In-vitro studies
A. Moritz et ai.
Thome. card/ Dvase . Surgeon 40 (199 2)
Fig. 2 Dissected varicose vein before insertion into mesh tube. This vein was used for the femoropopliteal bypass shown in Fig. 4.
Fig.3 Paraffin cast ofovine jugular vein constricted from 15 to 6 mm diameter.
Fig. 4 Mesh-tube-constricted varicose vein used as femoropopliteal
Clinical expe rience
Three patients underwent coronary revascularization with varicose veins . All patients had at least tw o arterial grafts used and one vein graft was made suitable by inse rtion into a mesh tube, a 6 mm tube was used in the first case and 5 mm tubes the re after. All three unde rwe nt control angiography.
Partially or totally mes h-constricted veins have been used for 19 infrain guinal reconstructions (Table I) includ ing 11 femoropopliteal and 8 infrapopliteal bypasses. Veins were dissected atrau matically (Fig. 2) an d flushed and sto red in a solution conta ining he parin. papaverin, and albumin (5). Dilated seg ments or. if appropriate, the whole vein were inserted into 6 mm 10 mesh tubes . As the material is provided only in sh eets 15 by 15 em large. segments had to be anas tomosed with 5/0 silk stitches when longer tub es we re necessary. Sma ll side bran ches of the vein wer e ligated with 4/0 Vicryl@(Ethlcon, Hamburg. FBGJ. la rger branches wer e cut flush a nd the opening was oversewn with 7/0 Prolen e'" (Eth icun, Hamburg. FBG) suture. All pat ients underwent intraoperative angiography and either intravenous or intraart er ial DSA contro l before hospital discharge.
bypass graft.
Besults
In-vitro tests Jugular veins of sheep with an average outside diameter of 15.4 mm (12-1 8) could eas ily be insert ed into 6 an d 7 mm mesh tubes. On radio graphs only irregular ities caused by the longitudinal sutur e line could be observe d. The re have been no signs of longitudin al folds or wri nkles. The sam e could be found at examination of the cross sections of the paraffin casts. which showed no irregularities at the inside of the constricted veins (Fig. 3).
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358
The Use ofMesh-tube-Constricted Dilat ed or Varicose Veins as Art erial Bypa ss Conduit
Thom c. cardiovasc. Surgeon 40(1 992)
Fig.5 Meskor>
Animal studies
Clinical implantation diam eter appea red still too large for the host vessel. The two veins implanted thereafter were inserted into 5 mm tubes which resulted in a smooth caliber transition to the host vess el (Fig. 5). Discussion
Grafts lined with auto logous endo thelium show significan tly better performance in arterial reconstructions with limited outflow. such as infrap opliteal (11) or coronary revascularizations (7). Many gra ft alternatives have been looked for when the saphenous vein or arteria l grafts for coronary cases are not available or suitable. Arm veins show a reasonab le long-term patency in peripheral reconstructions but tend to dilate in the long run (3). Use d for coronary revascularization the intermediate patency is less tha n optimal (10). Deep femoral veins may be used but have to be tape red at both ends to achieve a relatively sm ooth tran sition to the grafted vessel (8). Varicose veins usu ally are not considere d for bypass grafting as the irregular inner diameter may cause zones of blood stagnation with subsequent thromboses . or aneurysmal dilatation of the weakened wall segments may occur. As all these grafts are lined with antithro mbogenic en dothe lium they shou ld perform as well as the sa pheno us vein. once the caliber is reduced and smoothe ned and the wall is reinforced. Insertion into constricting mesh tubes appears to be a means to solve this problem . This was don e to adap t th e graft diameter to that of coronary arteries in a clinical series reported by Barra (1) . A major concern however was the gen eration of folds by the redundant vein wa ll material after constriction. In our in-vitro tests we found that constri ction of thin-walled jugular veins from 15 to 6 mm did not create any folding of wall structures or cause stenoses . Human varicose veins with irregular wall thickness could be constr icted safely by 51 % from 13 to 6.3 mm (6). In our animal model again jugular veins of 15 mm diameter we re inserte d into 6 mm mesh tub es and used as bypass grafts. All grafts. the na tively implanted femoral veins as well as the control gra fts. remained patent. Intimal hyperplasia caused by the arterialization of graft veins was sign ificantiy reduced by the redu ction of th e wa ll stress. This findin gs are corroborated by earlier investigations of Karayannakos
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stricted varicose vein used as aortocoronary bypass graft to a marginal branch of the circumflex artery.
All 12 fem oropopliteal bypasses wer e pat ent 6 months after implantation. Constricted jugular veins had a uniform caliber as opposed to the na tively implan ted femoral veins. whi ch dilat ed to 8 to 10 mm at th e distal anas tomose s. No a ngiogra phic sign s of a nastomotic hyperpla sia or stenoses. whi ch might be caused by any inversion of th e dacron mesh into the vascular lumen , were observed at the distal anastomoses. None.of the grafts showed folds at inspection of the cross-sections on explantati on in 6 animals after 6 month s. In the constricted veins intima l hyperplasia was significantly re duce d at the midporti on of the grafts (231 ± 76 urn) as com pa red to the na tively implanted femo ra l veins (416 ± 143 ~m ; p=O.OOOI pai red t-testl , The same was found at cross se ctions of the center of the anastomoses where the stiffer, reinforced veins had an intimal thick ness of 180± 7 3~ m and the natively imp lante d veins of 358 ± 257 urn (p = 0.0008).
At cont rol a ngiography pri or to discharge all grafts showed sati sfactory ca libration with out signs of longitudinal folds (Fig. 4). In two veins which were only partially supported. the diameter of the remaining vein was underestimated and thes e segm ents appeare d relative ly wide. In some of the early ca ses thicker side bra nches that had merely been ligat ed caused indentatio ns into the gra ft lumen. At angiographic restudy of these pa tients the degree of nar rowing was clea rly redu ced. pro bab ly by atrophy of ab un dant wa ll material and resorption of the ligatures. One poplitea l-pedal re construction occluded 2 months after surgery. This graft was placed as a secondary procedure after a pr eviously failed reconstruction . A jump graft to the dorsal pedal artery had failed primarily. At angiography prior to discharge the anstom oses to the severely disea sed posterior tibial artery showed a 50 % stenosis. In addition some appositional thrombus was found at the offspring of the occlude d jump segment. Amputation below the knee became necessary 4 months after surgery. A 80-year-old patient with a composit e sequential reconstr uction for acute limb ische mia died 2 months after su rgery from heart failur e and a 70-year-old ma n died 2 months after surgery of cer eb ra l stro ke. Four grafts needed revisions. In one femoroperoneal graft the tibial artery developed a stenosis distal to the anastomoses, which was dilated successfully. One partially constricted graft becam e sten otic and finally occluded in the pro ximal. non-reinforced segment. The pati ent could not undergo revision before her hyperthyroid crisis was managed medi cally. A PTFE interposition graft was placed betw een the fem oral arte ry an d the gr aft above the knee joint. One graft had to be revised at the site of an end-toend anastomosis in a thin unsupported segment of the graft. In a patient with graft extension of an axiUo-bifemoral graft th e right limb had to be thrombectomized two times. Finally a PTFE graft was interposed between the right limb . the deep femoral artery. and th e dis tal meshconstricted vein graft. The remaining reconstructions were pat ent 13 (2 to 42) months after surgery. All three mesh- constricted aortocoronary vein grafts were pa tent at con tro l angiogra phy. The first graft had been inser ted into a 6 mm tube and the resulting inner
359
A. Moritz
Thorae. eardio vasc . Surgeon 40(992)
ez at.
Acknowledge me nts This study was supported by the Fonds zur Forderung der Wisse nschaftliche n Forschung Grant #756 9-me d and the Ludwig Boltzmann Institute for Cardiosurgical Researc h
Referen ces I
2
Barra. 1. A . A Volant. 1. P. Leroy et a l.: Constrictive perivenous mesh prosthesis for preservation of vein integrity. J . Thora e. Cardiovasc . Surg. 92 (1986) 330-336 Deriu. G. P. . E. Boiiotta. L. Bonavina ct al.: Great saphenous vein protection in arterial reconstructive surgery. Eur. J. Vase.
Surg. 3 (1 989) 253-260 3
lIarris. R. W . G. Andros. L. B. Dulawa. R. W ouaa:S. X. Sal les-Cunha. and R. Apyan: Successful long-term limb salvage using cephalic vein bypass grafts. Ann. Surg. 200 (1984) 785 -
792 4
Karayanna cos. P. E.. 1. R. Hostetler; M. G. Bond ot a l.: Late failure in vein grafts : Mediating factors in sube ndot helia l fibro-
5
LoGerfo. F. W . C. C. lIaudenschild. and W C. Quist: A clinical technique for preservation of spasm a nd preservation of endo thelium in sa phenous vein grafts . Arch. Surg. 119 (1984) 1212
muscular hyperplasia. Ann. Surg. 187 (1 978) 183- 188
- 1214 Fig.6 Factor VIII staining of cross sections of a proximal natively mplanted {Bl and a more distal dacron-mesh-constricted vein segment {Al after occlusion of an axillobifemoral bypass limb. Notice the increased number of vasa vasorum in the reinforced vein (d).
(4). In his study he foun d the porosity of the wrap material to be crucial: afte r wrapping with non poro us material isch emia with consec utive thickening of the wa ll will r esult. The disad vantage of exte rnal reinforcement however is reduced elasticity. Compliance mism atch was found to play a significant r ole in the development of anas tomotic hyperplasia and subseque nt failure of nonautogenous arte rial gra fts (9, 12). In our exper imental mod el the positive effect of wall stress relief outweighed the potential disadvantage of wa ll stiffening by th e mesh tubes. and anastomotic hyperplasia was re duced compared to native vein grafts . The clinical speci mens re trieved at revisi ons of partially reinfor ced gra fts showed a clear increa se in the density of vasa vasorum und er the mesh . A significant reduction of intimal hyperp lasia was not obvious in the two pairs of specimen . However qu antifi cation is difficult in cross sections tha t have not been perfu sion fixed (Fig. 6). In all in-vitro. experimental, and clinical sa mp les the oversized veins have been redu ced by the external mesh to a un iform an d ade qua te bypass dia meter without creation of significant stenoses or folds. Vein gra fts may be redu ced by at least 50 % in diam eter after inserti on into constric ting mesh tubes witho ut any negative effects. As indicated by our expe rime ntal series intimal and anas tomotic hyperplasia is r edu ced by this tech nique .
6
7
Moritz. A.. F. Grabenuioqet; F. Raderer et al.: Mesh tube constricted var icose veins used as bypass grafts for infra inguinal a rteria l reconstruc tion. Arch. Surg . 127 (992) 416 - 420 Sapsford. R. N.. G. D. Oakley. and S. Talbot: Early patency of expanded polytetra fluoroeth ylene vascular grafts in aorto-coronary bypass . J. Thorac. Cardiovasc. Surg . 81 ( 981) 860 -
864 s Schulman. M. 1... M. R. Badhey. A. Yateo. end G. Pillari: A sapheno us alternative: Prefer ential use of supe rficial femoral and popliteal vein as femoro popliteal bypass grafts. Am. J. Surg .
152 (1986) 231 -237 9
10
Scottiurai. V 5. . 1. S. T. Yao. W R. Flinn. and R. C. Batson: Intimal hyperplasia a nd neointi ma: An ultrastru ctural analysis of thrombosed grafts in huma ns. Surgery 93 (1983 ) 809-8 17 Stoney. W 5.. W C. Alford. G. R. Burrus . D. M. Glassford. M. R. Petracec, and C. 5. Thomas : The fate of a rm veins used for aorto-coronary bypass grafts . J. Thorac. Cardiovasc. Surg. 88
(1984) 522-526 11
12
Veit h. F. J.. S. K. Gupta. E. Ascer et al.: Six yea r prospective multicenter randomized compar ison of auto logous saphenous vein a nd expanded polytetra fluoroethy lene grafts in infrainguinal arterial reconstr uctions . J. Vase. Surg. 3 (1986) 104 -11 4 Walden. R.. G. 1. t.ttalten. 1. Megerman. and W M. Abbott: Matched elastic properties and successful arterial gra fting.
Arch. Surg. 115 (1980) 11 66- 1169
Doz. Dr. A. Moritz II. Chir. Univ.-Klinik Spitalgasse 23
A·1090 Wien Austria
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