THE APPLICATION OF THE Z-PLASTY TECHNIC TOHOLLOW CYLINDER ANASTOMOSIS

AN EXPERIMENTAL STUDY IN THE SURGERY OF BLOOD VESSELS*EMILE HOLMAN, M.D. AND RICHARD HAHN, M.D.

SAN FRANcisco, CALIFORNIA

THE RECENT REMARKABLE SURGE of inter-est in surgery of the vascular system hasproduced ingenious devices, highly com-plicated methods, and technical proceduresof unusual originality in this rapidly ex-panding field of surgical endeavor. Thenames of Graham, Cutler, Beck, Gross,Crafoord, Blalock, Potts, Gordon Murray,Brock, Gibbon, Harken, Bailey, Dennis,Varco and Dodrill, most of them on theroster of the members of this association,promptly come to mind. Shumacker's schol-arly review15 of the technics formerly andcurrently employed in the suturing of bloodvessels presents instructively the prevailingconcepts in this field, and the experimentalstudies of numerous resourceful investiga-tors (Brooks,3 Gross,5 Schmitz et al.,'4Johnson et al.,7, 8, 9, 10 Potts,12 Sako et al.,13Shumacker et al.,1 Swan et al.,20) havedemonstrated the fundamental issues in-volved. From experimental and clinical ex-periences, it soon became evident that con-tinuous nonabsorbable sutures were inad-visable if future growth in circumferencewere to be expected and if subsequentstenosis due to progressive contraction offibrous tissue deposited in circular manneraround the continuous suture were to beavoided. Potts,'2 on the basis of experi-

* Fron the Laboratory for Surgical Research,Stanford University School of Medicine.

This work was supported by a grant from theLife Insurance Medical Research Fund.

Presented before the American Surgical Asso-ciation, April 1, 1953.

mental observations following the anastomo-sis of the aorta to the pulmonary artery,advocated the use of a continuous silk su-ture for the express purpose of preventingthis progressive enlargement, since an in-creasing volume flow through a slowly en-larging anastomosis at this particular sitewould result in disastrous dilatation of theheart.

In end-to-end unions, as in re-establish-ing the divided aorta following resection ofa coarctation, it is customary to join thetwo ends by interrupted everting mattresssutures of silk, since these sutures permitgrowth at the anastomotic site and are com-paratively free of the complications ofthrombosis, stricture, dehiscence, or hemor-rhage. Certain features of the mattress su-ture demand caution in its use. More lengthof vessel wall is used up by this suture thanby the over-and-over continuous suture,and, contrary to appearances, increasingthe length of the everted cuff does not in-crease the strength of union if only theconventional type of mattress sutures areused. Also, gauging the amount of vesselwall to be included in the two arms of thesuture may be quite difficult when applyingsutures to structures in constant respiratoryor pulsatile motion. Neither too much nortoo little of the vessel wall included in thesuture is desirable (Fig. 1 A). Wide bitesproduce definite constriction of the lumen,whereas small bites introduce the potentialdanger of fatal separation due to the suture

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cutting through the small strands of in-

cluded tissue. The surprisingly powerfulelastic retraction of a large vessel, whentransected, is sufficient to separate the di-vided ends three to five centimeters. Fol-lowing reunion of such widely separatedends, there is considerable pull on the

the cut edge. Having doubly tied the twoends of the mattress suture, one thread isagain passed through the two edges as a

single plain suture, which is again doublytied (Fig. 1 B). This provides a broader andmore secure approximation of intimal sur-

faces and doubles the amount of vessel wall

d

FIG. 1

coaptation sutures. Hence, the need of in-cluding sufficient tissue to withstand thisdisruptive force. The reported deaths fromlate hemorrhage during the first few weeksafter an operation for ooarctation may wellhave been due to cutting through of suturesembracing too little of the vessel wall. Inthis connection, it is appropriate to recallHalsted's observation that tissue included ina suture dies, and that healing occurs

through fibrous substitution of this necrosedtissue.6 In the union of large vessels, there-fore, the interrupted mattress sutures shouldbe spaced about 1 to 1.5 mm. apart; shouldinclude 1 to 1.5 mm. of the vessel wall on

each side in the two arms of the suture, andshould be applied about 1 to 1.5 mm. from

FIG. 2. Principle of Z-plasty as applied to end-to-end union of blood vessels: parallel incisions a band c d are made, permitting approximation of aand c, b and d, with definite increase in circumfer-ence at site of anastomosis.

included in the suture, thereby effectivelystrengthening the line of union. By alternat-ing the mattress sutures with single plainstitches, the hazards of constriction and ofseparation may be further reduced (Fig.1 A). The amount of tissue included in thesutures may vary somewhat according tothe size of the vessels involved. For exam-

ple, in anastomoses involving large vessels,the cuff of everted tissue should be at least1 to 1.5 mm. wide and the sutures should bespaced about 1 mm. apart. In uniting ves-

sels only 3 millimeters in diameter, theover-and-over sutures may include only one-

half millimeter of tissue, but the bites mustbe closer together. In general, the nearer to

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the edge the suture is placed, the narrower

must be the interval between bites, andconversely, the wider the cuff of includedtissue, the wider may be the intervals be-tween loops.

.A

B

6mjmnm..

growth at the anastomotic site, and alsothat they will minimize the future stenosingeffect of the circular fibrosis accompanyinga continuous suture.

In the end-to-side anastomosis, the inci-sion in the recipient vessel is made at a rightangle to the longitudinal axis, since thenatural elasticity of the vessel will enlarge a

transverse slit but will tend to close a longi-tudinal slit (Fig. 1 D). Vessels may be cut

14mD'5

m=O

FIG. 3. Three types of end-to-end anastomosis ofblood vessels: A. Z-plasty resulting in an internalcircumference of 26 mm.; B. mattress everting su-tures producing an internal circumference of 14mm.; C. a continuous over-and-over suture pro-ducing an anastomosis 20 mm. in intemal circum-ference.

In end-to-side anastomosis, as in the Bla-lock procedure, or whenever one half ofthe circumference is somewhat inaccessible,the inaccessible half is united by a contin-uous everting mattress suture and the otherhalf by interrupted everting mattress su-

tures alternating with single plain sutures offine silk (Fig. 1 C). These interrupted su-

tures are employed in the expectation thatthey will provide adequately for necessary

FIG. 4. Aortogram to show the definite increasein internal diameter that occurs at Z, the site of anend-to-end union employing the double Z-plastytechnic.

across obliquely, thus producing oval open-

ings for anastomosis which are slightlylarger than the circular openings producedby transection of the vessel at a right angle.A larger opening may also be produced bytransecting the vessel at the site of theemergence of a large branch (Fig. 1 E).

Despite these efforts to provide an anasto-motic lumen which equals the lumen of thejoined ends, a degree of circular constriction

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EXPERIMENTAL STUDY IN SURGERY OF BLOOD VESSELS

by 1o da-gs Irmo. zV ato3M MCL.:a - _...._

FIG. 5. Flattened internal surfaces of thoracicaorta containing a double Z-plasty in animals killedafter (a) one day; (b) ten days; (c) one month;(d) two and one-half months; (e) three months.

almost inevitably occurs, particularly in theend-to-end union of vessels of small caliber.In a series of in vitro experiments, vesselswere approximated both by interruptedeverting mattress sutures, and by the con-

tinuous over-and-over suture. The averagedecrease in cross-sectional area was foundto be 15 and 8 per cent respectively.Ideally, the end-to-end or end-to-side anas-F.X0, ~~~~~~~~~~~~~~~~~~... ;.......... . .-.

... ..~~~~~.. ...........

FIG. 6. Section of aortic wall at junction of tipand angle, shoNving normal media covered bynormal intima.

tomoses should be free of any constriction,since it is the irregular and stenosed lumenwith its abnormal eddies in the flowingblood that invites the localization at thissite of inflammation, thrombosis, and theproduction of vegetations.

In an effort to secure an anastomoticlumen more nearly equal to that of thearteries involved, the principle of theZ-plasty for linear contractures was sub-jected to experimental study. Similar plastic

procedures have been applied experimnen-tally to the anastomosis of the intestine andcommon bile duct (Blocker et al.2 Singletonand Moore19). In cylindrical anastomosis, itis at once apparent that parallel incisionsa b and c d (Fig. 2) provide for a measur-

able increase in circumference when a isjoined to c, b to d, and the two arms andcross bar of the resulting Z are united. Forexample, when a divided thoracic aorta 15mm. in circumference was reunited by a

double Z-plasty, the circumference at the

FIG. 7

site of union measured 22 mm. Again whenthe thoracic aorta was subjected to threedifferent types of anastomosis (Fig. 3) util-izing A, the Z-plasty technic, B, interruptedmattress sutures, and C, a continuous over-

and-over suture, it was found that A ad-mitted a bougie 26 mm. in circumference, Ba 14 mm. bougie, and C a 20 mm. hougie.Obviously, the Z-plasty principle, when ap-plied to cylinder anastomosis, provides ad-ditional circumferential length.Two important questions concerning the

Z-plasty technic arose: would the hazards ofnecrosis and hemorrhage be increased be-cause of the creation of "critical angles,"and would the additional time and difficulty

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of performing the procedure nullify itspractical use?Experiment A. In nine mongrel dogs, 7

to 20 Kg. in weight, the thoracic aorta was

exposed through the left fifth intercostalspace. The aorta was mobilized by ligationand division of several intercostal arteries.A temporary by-pass to provide a contin-

urements were made at necropsy before sec-

tioning for histologic study.Results. In a preliminary experiment, the

abdominal aorta was transected and theends were reunited. This animal suffered a

fatal hemorrhage from disruption of thesuture line, which was attributed to tech-nical error incident to inexperience. In the

A.

l

d

JIl.

FIG. 8. Flattened segments of carotid, (a andb) iliac, (c) and femoral (d) vessels of small diam-eter in which single Z-plasties produced definitewidening at site of end-to-end union. Femoralanastomosis d was thrombosed.

uous flow of blood to the lower body dur-ing the operation was effected by a lengthof polythene tubing inserted and ligated inposition in the proximal and distal aorta.The aorta was transected, and reapproxi-mated by a double Z-plasty applied to boththe anterior and posterior halves of the cir-cumference. The incisions forming the arms

of the Z traversed an entire quadrant, andwere made to create a 45-degree angle withthe transected edge of the aorta. The anas-

tomosis was effected by applying continuousover-and-over sutures to the two arms andcrossbar of the Z, interrupted at the angles.No attempt was made to reinforce the crit-ical angles. Following the anastomosis, theby-pass tubing was removed and the inci-sions in the aorta were closed. No anticoag-ulants were administered. Aortograms (Fig.4) were made immediately after surgery,and again prior to necropsy. Careful meas-

FIG. 9. The Z-plasty technic may be usefullyapplied to the end-to-end union of grafts, A; to theend-to-side anastomosis, B; and to the occasionalcase of coarctation of the aorta; C.

remaining nine animals, no immediate or

late hemorrhage occurred. At necropsy,

measurements were made exactly at thesuture line and 1 cm. immediately proximaland distal to it. The mean value of the lattertwo was interpreted as equalling approxi-mately the original diameter at the site ofdivision. All nine animals showed an in-crease in the cross-sectional area at the siteof anastomosis. These increases ranged from16 to 20 per cent. The gross appearance ofthe specimens after fixation in formalin, andthe increase in diameter at the suture lineare readily seen in Figure 5. Histologicalstudy of the specimens showed the intimalregeneration to be complete at time of sac-

rifice in each instance. No degeneration of348

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Volume 139 EXPERIMENTAL STUDY IN SURGERY OF BLOOD VESSELSNumber 3

the "critical angle" was observed in anyspecimen (Fig. 6).

Experiments B. Twenty-one additionalanastomoses, utilizing the single Z-plasty ononly one-half the circumference, were per-formed on the divided femoral, carotid andoccasionally the iliac arteries in animalsweighing 9, 11, 12, 12 and 17 kilograms re-pectively. The single Z-plasty provides ananastomotic lumen equal to that of the ves-sel involved, whereas the double Z-plastyinsures a lumen greater at the site of unionthan proximal or distal to it. The femoralvessels measured about 3 mm. in diameter,the iliac vessels 5 mm. in diameter and thecarotids 3 to 4 mm. in diameter. In joiningvessels of such small bore, it was found de-sirable to employ the following successivesteps (Fig. 7): (a) two single plain sutureswere applied at opposite poles; (b) the pos-terior halves were united by a continuousover-and-over suture; (c) parallel hockey-stick-like incisions were then made in theanterior half of the two ends with sharp finescissors; (d) the broadened blunt tips wereunited to the opposite angles with singleplain sutures; and (f) the two arms andcrossbar of the resulting Z were approxi-mated with continuous over-and-over su-tures interrupted at each angle. The initialbrisk bleeding from the site of anastomosisusually ceased after a five minute impatientwait. Occasionally one or two reinforcingsutures were necessary.

After a few initial difficulties, it was foundthat the principle of Z-plasty could be ap-plied to small vessels 3 or more millimetersin diameter with comparative facility (Fig.8). In the 21 anastomoses of these small ves-sels, thrombosis occurred five times, threetimes in femoral anastomoses located only afew centimeters beyond iliac anastomoseson the same side. There was no dehiscenceor hemorrhage in a single instance.

SUMMARY

From these studies it is evident that theZ-plasty type of anastomosis of blood vessels

produces a desirable increase in cross-sec-tional area at the site of union. The in-creased time and the greater technical diffi-culties encountered in performing the oper-ation are distinct disadvantages, and the lat-ter can, in inexperienced hands, providesuch additional hazards as to preclude itsuse. However, an increasing facility ob-tained only by repeated operations upon theexperimental animal reduces these hazards,and should make available an additionaltechnic in the rapidly expanding field ofoperative procedures requiring the anasto-mosis of blood vessels.The principle may be applied, for exam-

ple, in the free grafting of arterial or venoussegments resulting in anastomotic cross sec-tions more nearly equal to the caliber of thejoined vessels (Fig. 9 A). In the end-to-sideanastomosis of small blood vessels, the prin-ciple may be applied to secure a larger anas-tomotic opening (Fig. 9 B). In the occa-sional case of coarctation of the aorta, theZ-plasty may provide an anastomosis equalto the diameter of the aorta on either side,without loss of aortic wall (Fig. 9 C). Asimilar technic may be employed in theend-to-end reunion of divided ureters orcommon ducts. Primarily, however, theprinciple is offered as a means of avoidingundesirable constriction at the site of theend-to-end union of blood vessels of smallbore.

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HOLMAN AND HAHN Annals of SurgeryHOLMANANDHAHN ~~~~~~~~~~~September, 1953

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