Approaches To Esophageal Sutures

V CE

20TH ANNIVERSARY

Vol. 21, No. 5 May 1999

Refereed Peer Review

FOCAL POINT ★One-layer closure of esophageal incisions using the submucosa as the holding layer, avoiding penetration of the mucosa, and using absorbable suture material in an interrupted pattern permits normal esophageal healing following surgery.

KEY FACTS ■ The surface epithelium of the mucosa is stratified squamous with varying degrees of keratinization in different species. ■ The collateral vascular pathways in the wall of the esophagus are sufficient to maintain its viability and to ensure healing of an anastomosis when the entire thoracic blood supply to the esophagus is cut off. ■ One reason for the high rate of complications following esophageal surgery is that the esophagus is in constant motion from respiration and swallowing. ■ The submucosa is the functional holding layer of the esophageal wall.

Approaches to Esophageal Sutures The Hebrew University of Jerusalem Rehovot, Israel

San Juan, Puerto Rico

Carlos M. Mongil, DVM

Merav H. Shamir, DVM Ron Shahar, DVM, MSc Dudley E. Johnston, MVSc ABSTRACT: Suturing the esophagus after esophagotomy or esophageal resection and anastomosis can be problematic, and complications such as suture line breakdown, leakage, and stenosis are reported. This article discusses esophageal anatomy and physiology and complications associated with esophageal surgery; a history of suture methods used in esophageal surgery is also provided. A new suture technique is described and evaluated based on a retrospective study.

F

oreign bodies, tumors, and diverticula are some of the common reasons for performing an esophagotomy or esophageal resection and anastomosis. The method of closing esophageal incisions is controversial. Esophageal incisions have traditionally been closed in two layers using different suture patterns and materials, and the mucosa has historically been considered the strength layer of the esophageal wall. In 1988, Dallman1 revealed that the submucosa is the functional holding layer of the esophagus and that including the mucosa in the closure did not increase the strength of repair. This article presents a retrospective report of 21 clinical cases in which esophageal closure was performed using the submucosa as the holding layer, avoiding penetration of the mucosa, and using absorbable suture material in an interrupted pattern.

ESOPHAGEAL ANATOMY AND PHYSIOLOGY The esophagus is a simple muscular tube that has peristaltic activity and sphincters at both ends. The upper esophageal sphincter is a distinct anatomic structure comprised of muscle fibers of the cricopharyngeus muscle and circular muscle fibers of the proximal wall of the esophagus. The lower esophageal sphincter performs a physiologic function (i.e., it prevents food from indiscriminately entering the esophagus from the stomach, thus keeping the esophagus empty), but no distinct muscular structures have been identified.2,3 The lower sphincter also has a valvelike action to prevent acidic gastric reflux into the esophagus during inspiration when the intraluminal pressure of the esophagus is low. In dogs, the esophagus narrows at four places: near its origin, near its termination, at the thoracic inlet, and over the base of the heart. This explains why most obstructing foreign bodies are found at these sites. Also, the esophagus is fixed to

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surrounding structures at these four sites, and the short distances between these sites prevents mobilization of the esophagus. This must be taken into consideration when resection and anastomosis is planned.4

Layers in the Esophageal Wall The esophageal wall has four layers: mucosa, submucosa, inner circular and outer longitudinal muscularis, and adventitia.2 The serosa in the rest of the gastrointestinal (GI) tract (except the caudal half of the rectum) represents the visceral layer of the peritoneum that reflects on and around the abdominal viscera. It is composed mainly of mesothelial cells in a loose connective tissue. The esophagus is surrounded by adventitia only, except in the thorax where it is partially covered ventrally by mediastinal pleura. Although this attachment is loose, the pleura can be a source of mesothelial cells and fibrin to help seal the esophageal incision after suturing.4 The surface epithelium of the mucosa is stratified squamous with varying degrees of keratinization in different species. The lamina propria of the mucosa is strong and thick and is comprised of loose connective tissue of collagenous, elastic, and reticular fibers.5 The mucosal layer is thicker in the esophagus than in other parts of the tubular digestive tract, primarily because it has a thicker lamina propria. However, most of the connective tissue in the wall of the esophagus is in the submucosa.1 Segmental Blood Supply The esophageal blood supply has traditionally been described as segmental. The bronchoesophageal artery supplies blood to the cervical and cranial portions of the thoracic esophagus. The caudal part of the thoracic esophagus is supplied by the left gastric artery that crosses the diaphragm. Other segments of the thoracic esophagus are supplied by direct segmental branches from the thoracic aorta.2 In addition, a collateral blood supply in the wall of the esophagus has been shown to exist. In a classic experiment, Macmanus and colleagues6 devascularized large portions of the canine esophagus (thoracic esophagus, cervical esophagus, or both) by ligating the segmental blood supply. The esophagus was then divided, and a reanastomosis was performed immediately. On postmortem examinations, no necrosis of the esophagus was observed. These results confirmed that the collateral vascular pathways in the wall of the esophagus are sufficient to maintain its viability and to ensure healing of an anastomosis when the entire thoracic blood supply to the esophagus is cut off. The capacity of this intrinsic blood vessel network does have a limit.

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Necrosis and perforation can occur (always at the level of the second thoracic vertebra) when both the cervical and thoracic segmental blood supplies to the esophagus are ligated. This study suggests that the transition zone between the cervical and thoracic esophagus has the poorest blood supply of any part of the structure.6

COMPLICATIONS OF ESOPHAGEAL SURGERY Complications reported after esophageal surgery include suture line breakdown, leakage, and stenosis.7,8 Several explanations for the high complication rate have been suggested. The absence of the serosal layer that exists in most of the GI tract is one potential reason for postoperative complications. The serosa is believed to exude a fibrin clot that creates an early seal of the incision and to provide alignment of apposed tissue layers after suturing. It is now known that the former role is performed by the mediastinal pleura; to replace the missing latter role, a more accurate apposition of layers after esophageal surgery is required.9,10 Tissue rest is one of the basic requirements of wound healing; however, the esophagus is in constant motion because of swallowing and diaphragmatic movement. Diaphragmatic contractions cause the line of an anastomosis to move up and down as much as 3 cm. Such movements would obviously interfere with the important sealing process that is desirable in the early postoperative period.11,12 The esophageal wall poorly tolerates longitudinal stretching and tension. When a portion of the esophagus is resected, tension is created in the suture line because of lack of mobility in the esophagus. This tension increases considerably during diaphragmatic contractions.3,12 A mortality rate of 33% was reported in dogs with esophageal anastomosis after resection of a third of the thoracic esophagus.13 In another experiment, a positive correlation was found between the extent of resection and the mortality rate from anastomotic breakdown.14 The segmental blood supply was thought to influence esophageal healing after suturing. However, as discussed, a rich plexus of intramural vessels exists in the submucosa. These vessels can support segments of the esophagus that have had their segmental blood supply compromised. This suggests that a successful anastomosis can be expected in cases of considerable segmental vascular compromise as long as there is no disruption of the intramural blood supply.4,6,11,14 Another important reason for the greater vulnerability of the esophagus is the lack of omentum. The omentum serves an important role in supporting GI anastomoses, and omental wrapping is the most valuable

MEDIASTINAL PLEURA ■ COLLATERAL BLOOD SUPPLY ■ DIAPHRAGMATIC CONTRACTIONS

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adjunct procedure for protecting such anastomoses. The omentum adds a supplementary layer that provides a seal after adhering to the outer layer of an anastomosis, and new blood vessels arising from the omental vessels may provide additional blood supply. In addition, phagocytic and other immune functions of the omentum may allow local containment of anastomotic leakage.15 Lack of serosa, movement associated with respiration and swallowing, and a meager blood supply compared with the remainder of the alimentary tract all contribute to potential problems that may be encountered during and after surgery of the esophagus.3 Thus esophageal surgery requires even more exacting techniques than does surgery on other portions of the alimentary tract.

SUTURE METHODS The classic two-layer inverting esophageal suture developed for humans in the 1920s was first described in the veterinary literature in 1965.16 At that time, the mucosa was considered to have the greatest sutureholding capabilities of all the esophageal layers and the submucosa was not mentioned. Mucosa was sutured in one layer, and the muscularis (with serosa if possible) was sutured in the other.16 It was also believed that the closure must be leak-proof because rapid sealing with fibrin does not occur in the esophagus as it does in the rest of the intestinal tract.10 The method of using an inverting suture pattern to create serosal apposition is no longer considered necessary in surgery of the intestine or esophagus.9 Some authors still recommend everting the muscular layer, especially if tension at the suture line is anticipated, whereas others claim that one layer of everting suture pattern is sufficient.4,16 In 1949, Swenson described a method in which one row of 4-0 braided silk interrupted sutures was placed in the mucosa and the knots were tied within the lumen. The second layer of interrupted 4-0 silk included the full thickness of the muscular coat and some of the submucosa. Sutures were placed 2 to 3 mm apart.12 The practice of using nonabsorbable suture material in the mucosa and keeping the knots within the lumen is very much accepted today, except that polypropylene is used more commonly than is silk.4,7,17 There appears to be some movement away from the use of traditional nonabsorbable suture material for esophageal suturing; however, the literature continues to stress the necessity of suturing the mucosa. The most widely recommended suture pattern today is a two-layer closure in which the first layer incorporates the mucosa and submucosa and the second layer apposes the muscularis.3–5,7,18 Rosin stated that adher-

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ence to meticulous technique in suturing the esophagus is more important than is the type of suture used.3 He suggested that preference should be given to one of two techniques: (1) an inner mucosal–submucosal layer of continuous absorbable suture and an outer muscular layer of interrupted nonabsorbable suture, or (2) an inner layer of interrupted nonabsorbable sutures with the knots tied in the lumen and an outer layer of interrupted nonabsorbable sutures. Sutures should be placed approximately 2 to 3 mm apart and 2 mm from the cut edge and should be tied with sufficient tension so that a tight seal forms without interfering with the blood supply.3 To enhance esophageal dilation during bolus passage, some authors do not recommend a continuous pattern when suturing anastomoses.4 In an experimental study in 1993, three suture methods (i.e., double-layer appositional closure, single-layer simple interrupted closure, and single-layer continuous closure) were compared, all of which used absorbable sutures of polydioxanone sulfate through all layers of the esophageal wall.19 All methods were basically successful; however, based on measurement of bursting strength and operating time, the authors recommended either the double-layer appositional closure or the single-layer interrupted closure.

REINFORCING THE SUTURE LINE Circumferential myotomy and omental flap are two of the most commonly used techniques for reinforcing esophageal anastomoses. They are especially indicated when tension is anticipated. A circumferential myotomy is recommended to reduce tension from the anastomosis site.4 Complete circular myotomy was found to interrupt the deep longitudinal vessels in the submucosal vascular plexus, which tends to adhere to the circular muscle layer and is destroyed or damaged by complete myotomy. Partial circular myotomy, in which only the longitudinal muscle layer is transected, preserves this submucosal vascular network and yet is as effective as complete myotomy in reducing tension.14 The omental flap is used successfully to reinforce esophageal anastomoses. In a controlled study of anastomoses of the thoracic esophagus, a 25% defect was left in the suture line and then wrapped with omentum. Only 1 of 12 dogs died following leakage from the suture line.20 Omental grafts are used in humans to support esophageal perforation repairs and to provide blood supply to the mediastinal area when infection is present.15 SUBMUCOSA IN THE GASTROINTESTINAL TRACT The submucosa in the GI tract (other than the esophagus) is the strong, fibroelastic connective tissue

SUTURE MATERIAL ■ SUTURE PATTERNS ■ CIRCUMFERENTIAL MYOTOMY ■ OMENTAL FLAP

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that provides the strength needed for suturing the intestinal wall. In 1887, Halsted was the first to show that the submucosa was the strong layer of the small intestine; all suture methods for closing intestinal incisions and anastomoses that have been developed since then have incorporated the submucosa in the closure.4,5,7

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Materials and Methods Case Selection The surgical records of patients that underwent esophageal surgery at the University of Pennsylvania School of Veterinary Medicine and The Hebrew University of Jerusalem’s Koret School of Veterinary Medicine between 1989 and 1994 were evaluated. Criteria for inclusion in this study included a complete surgery report, an Figure 1A adequately documented clinical record, and a postoperative survival of at least 24 hours. The review of surgical cases yielded 21 patients that met the criteria for this study. Group 1 included 15 patients that underwent esophagotomy to remove a foreign body; group 2 consisted of six patients that underwent esophageal resection and anastomosis, five for strictures and one for a large diverticuFigure 1B Figure 1—One-layer closure of an esophageal incision using lum. All procedures were inthe submucosa as the strength layer. (A) The muscular and trathoracic and required insubmucosal layers were incorporated in the closure; the nee- tercostal thoracotomy.

DALLMAN’S WORK The mucosal layer is thicker in the esophagus than in other parts of the digestive tract (because of the thicker lamina propria) and is more difficult to separate from the submucosa. Therefore the mucosa was believed to be the strong holding layer of the esophageal wall.3,10 In 1988, Dallman1 compared the ability of each layer of the esophageal wall to hold sutures against tension. No significant difference was demonstrated between the suture-holding ability of submucosa alone and that of the submucosa and mu- dle emerged as close as possible to the edge of the mucosa, cosa together. The muscu- and penetration into the lumen was avoided. (B) The edges Suture Technique laris had the least ability to of all three layers were apposed. Care was taken to avoid Group 1 hold sutures against tension. compression of tissue within the suture. Esophagotomies (n = 15) The conclusion of this were made longitudinally. A study was that the submucosa is the functional holding simple interrupted suture pattern was used, and the muslayer of the esophageal wall and that including the mucular and submucosal layers were incorporated in the clocosa in the closure did not increase the strength of resure; penetration into the lumen was avoided (Figure 1A). pair.1 Thus Dallman demonstrated that the sutureThe edges of the mucosa were apposed because the deep holding ability of the esophagus is similar to that of the layer of the mucosa was penetrated so that the needle rest of the GI tract, rendering the assumption that the emerged as close as possible to the cut edge of the mucosa. mucosa is the strong layer incorrect. Care was taken to avoid compression of tissue within the suture (Figure 1B). Sutures were placed 3 mm apart and 3 A NEW SUTURE METHOD FOR THE ESOPHAGUS mm from the cut edge of the esophagus. 3-0 PolydioxBased on Dallman’s experimental studies, a new apanone sulfate (PDS) suture was used to close the incision proach to esophageal suturing was proposed. This method in 7 dogs, 4-0 PDS in 4 dogs, 3-0 chromic gut in 3 dogs, uses the submucosa as the holding layer, avoids penetration and 3-0 polyglactin in 1 dog (Table I). of the mucosa, and uses one layer of absorbable suture material in an interrupted pattern.21 The following discussion Group 2 reports on 21 cases of esophageal surgery in which DallThe resections and anastomoses in group 2 (n = 6) man’s experimental findings were implemented. were performed using the same suture pattern as deSUBMUCOSA ■ ONE-LAYER CLOSURE TECHNIQUE ■ INCLUSION CRITERIA

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scribed for group 1. 3-0 PDS was used in two dogs, 4-0 PDS in one dog and one cat, 2-0 chromic gut in one dog, and 3-0 chromic gut in one cat (Table II).

Postoperative Treatment In all cases, nothing was given by mouth for the first 24 hours; then soft food and water were given for the first 2 weeks. Antibiotics were administered before surgery and for the first 10 days following surgery. Follow-up Evaluation Short-term evaluation (days 1 to 10) was obtained from the patient’s medical records. Long-term evaluation (16 animals) was conducted by telephone interview with owners and was based on information regarding the consistency of the food being fed and the patient’s ability to swallow and retain food. Postoperative positive-contrast esophagograms using fluoroscopy (9 patients) and radiography (3 patients) were obtained in 12 arbitrarily selected patients.

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TABLE I Esophagotomy in 15 Dogs

Dog No.

Esophagogram Long-Term after Clinical Suture Surgery Esophagogram Evaluation Material (days) Findings (days) a

1 2 3

3-0 PDS 4-0 PDS 4-0 PDS

4 5 6 7 8 9 10 11 12 13 14 15

21 397 5

3-0 PDS 3 3-0 PDS 425 3-0 PDS 73 4-0 PDS — 4-0 PDS — 3-0 PDS — 3-0 Chromic 1248 gut 3-0 Chromic 992 gut 3-0 PDS — 3-0 PDS — 3-0 Polyglactin — 3-0 Chromic 90 gut

Normal Normal Slight narrowing Normal Normal Normal — — — Normal

21 397 913 — 425 73 31 — 1095 1248

Normal

992

— — — Normal

— 485 500 90

a

All dogs were clinically normal at these times. PDS = polydioxanone sulfate; — = esophagograms were not performed and/or no information regarding long-term clinical evaluation was in the files.

TABLE II Esophageal Resection in 4 dogs and 2 cats Esophagogram after Suture Surgery Esophagogram Material (days) Findings

days. Two dogs (cases 3 and 4) had an esophagogram on days 3 and 5 after surgery, and no leakage was noticed. A mild radiographic narrowing at the surgical site was reported in 1 of these dogs (case 3), but there was no clinical evidence of an esophageal problem. All dogs were reexamined 10 to 14 days after surgery (i.e., at the time of suture removal) and found to be clinically normal. Long-term follow-up (range, 21 days to 3 years or more) either by telephone or reexamination was available for 12 of the 15 dogs. All dogs were in good clinical condition and were eating regular commercial food, and there were no reports of dysphagia, regurgitation, or vomiting. Long-term esophagograms (available for 7 dogs; 21 to 1248 days after surgery) revealed uniform esophageal diameters.

Long-term Clinical Evaluation (yrs)

Group 2 Contrast radiographs were required for diagnosis in all six animals (four 16 4-0 PDS — — Died dogs and two cats) in (8 days) 17 2-0 Chromic 2 and 35 Normal 6a Results group 2. Resections and gut Group 1 anastomoses were per— — 6a The mean age of the 15 18 3-0 Chromic formed to correct esophgut a dogs (9 males, 6 females) 19 ageal strictures in five ani4-0 PDS 30 Normal 1 in group 1 was 4 years. Ra- 20 mals (cases 16 through 20). 3-0 PDS — — Died diography was performed 21 One cat (case 16) died 3-0 PDS 210 Small in all cases to establish the of unrelated causes 8 days diverticulum 1.5a diagnosis. Preoperative a after surgery. The cat was Clinically normal at these times. positive-contrast esopha- PDS = polydioxanone sulfate; — = esophagograms not performed icteric and anorectic prior gograms were obtained in in these cases. to the esophageal surgery. cases in which survey raA jejunostomy tube was diographs failed to confirm the diagnosis. placed; the cat was fed through the tube for the first 6 During surgery, evidence of perforation of the esophdays after surgery, at which point leakage around the agus by a foreign body was found in 11 of the 15 patube was noted. The cat died of severe peritonitis due tients. Length of hospitalization ranged from 2 to 10 to the leakage. No leakage or stricture formation was Case No.

POSTOPERATIVE ESOPHAGOGRAMS ■ FOREIGN BODY ■ LONG-TERM FOLLOW-UP

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S
M’

found at the anastomosis site on gross postmortem examination. Histologic evaluation of the affected segment of the esophagus revealed adequate tissue healing. One dog (case 20), which had a large portion of its thoracic esophagus resected, died from complications caused by leakage from the anastomosis site. The remaining two dogs and one cat that underwent resections and anastomoses to correct esophageal strictures (cases 17 through 19) recovered from surgery and were discharged within 5 days. Short- (range, 1 to 14 days) and long-term (range, 1 to 6 years) evaluation was available for these three animals. All returned to a ENDIU MP normal diet and showed no clinical signs of esophageal disease. EsophagoANNIVERSARY grams were performed 30 and 35 days after surgery in cases 17 and 19. Esophageal diameter and motiliAlmost any textbook discussion ty were normal. of esophageal surgery comments Resection and anastomoon the difficulty of and sis was performed in one complications associated with dog to remove a large diverticulum (case 21). Eighthe procedure. Various theories teen months after surgery, have been purported to explain the patient was eating a these phenomena. We believe commercial diet and was that the basic principles of clinically normal. Seven esophageal suturing that have months after surgery, an evolved over the past 70 years esophagogram revealed should change based on persistence of a small diDallman’s finding in 1988 verticulum.
CO

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(i.e., that the mucosa is the strength layer in the wall of the esophagus, as it is elsewhere in the gastrointestinal tract). The single-layer closure recommended in this article brings esophageal surgery into the same realm as surgery of the small and large intestine and the urinary bladder, in which single-layer appositional closures are commonly accepted as the preferred technique today.

Discussion The use of absorbable suture material and one layer of sutures, utilization of the submucosa as the holding layer of the esophagus, and avoidance of the mucosa represent a new approach to esophageal closure. Based on a controlled study conducted to compare three esophageal suture patterns in which the sutures penetrated all layers of the esophagus, it was concluded that the esophageal closure was more likely to fail at suture holes than at the space be-

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Figure 2—Injury to the esophageal wall by pressure necrosis

from a foreign body (right), and resected segment of the esophagus showing several areas of necrosis (left). Some esophageal wall damage can be seen at the line of resection, which was left untouched to avoid resection of an excessive length of esophagus.

tween sutures; furthermore, all methods were found to be adequate for proper healing of a healthy esophagus.19 It was also reported that closing the incision with one layer of sutures took half the time required for closing it in two layers.19 The surface epithelium of the esophagus is generally stratified squamous with varying degrees of keratinization.2 This epithelium and the strong, thick lamina propria produce a mucosa that resembles skin. It is well known that suppuration occurs around nonabsorbable sutures left in the skin and that scar tissue forms until the sutures are removed. It is likely that the same thing happens in the esophagus and that nonabsorbable sutures left in place indefinitely can be a factor in excessive scar tissue formation and stenosis. The report of a 50% mortality rate in a study in which a double layer of nonabsorbable sutures (with the knots tied within the lumen) was used13 supports this hypothesis. In 1965, it was reported that peritoneal and serosal defects sutured with fine silk in rats and rabbits yielded a higher percentage of adhesions than occurred when such defects were left unsutured.9 It can be assumed that a two-layer closure is stronger and provides a tighter seal than does a one-layer closure; however, a two-layer closure can interfere with the blood supply to the healing edges, and the large volume of suture material can cause irritation.22 Procedures such as pericardial and transdiaphragmatic omental patching have been used to decrease the chance of leakage from an esophageal incision. It has been reported that contiguous mediastinal structures become adherent to the area of anastomosis, which is as

SURFACE EPITHELIUM ■ SKINLIKE MUCOSA ■ PERITONEAL AND SEROSAL DEFECTS

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effective a sealing barrier as the omentum in the abdomen.4 In our study of esophageal surgery in 21 animals, only one dog died as a result of leakage from the suture site after resection of a large portion of the thoracic esophagus. In many cases, the sutured edges of the esophagotomy or anastomosis were compromised by pressure from the foreign body (Figure 2). Long-term clinical evaluation and esophagograms showed no problems.

CONCLUSION The analysis of clinical cases in this report is sufficient and accurate to demonstrate the efficacy and safety of the new suture method. No animals were excluded from this study because of complications related to the suture method. We conclude that the technique of a one-layer closure of esophageal incisions using the submucosa as the strength layer, not penetrating into the lumen, and using absorbable suture material is adequate for proper esophageal healing. This technique is safe and does not appear to predispose animals to postoperative complications such as leakage or stenosis. Although both PDS and chromic surgical gut suture material were used in this study, we strongly recommend the use of a synthetic absorbable monofilament material such as PDS. REFERENCES 1. Dallman MJ: Functional suture-holding layer of the esophagus in the dog. JAVMA 192:638, 1988. 2. Dyce KM, Sack WO, Wensing CJG: Textbook of Veterinary Anatomy. Philadelphia, WB Saunders Co, 1987, pp 116– 117. 3. Rosin E: Surgery of the esophagus. Vet Clin North Am 5: 557–564, 1975. 4. Fingeroth JM: Surgical techniques for esophageal disease, in Slatter D (ed): Textbook of Small Animal Surgery. Philadelphia, WB Saunders Co, 1993, pp 549–561. 5. Gourley IM, Vasseur PB: General Small Animal Surgery. Philadelphia, JB Lippincott Co, 1985, pp 233–299. 6. Macmanus JE, Dameron JT, Paine JR: The extent to which one may interfere with the blood supply of the esophagus and obtain healing on anastomosis. Surgery 28:11–23, 1950. 7. Schunk CM: Removal of esophageal foreign bodies, in Bojrab MJ (ed):Current Techniques in Small Animal Surgery, ed 3. Philadelphia, Lea & Febiger, 1990, pp 201–207. 8. Knight GC: Transthoracic esophagotomy in dogs: A survey of 75 operations. Vet Rec 75:264–266, 1963. 9. Glucksman DL: Serosal integrity and intestinal adhesions. Surgery 60:1009–1011, 1966.

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10. Gideon L: Esophageal anastomosis in two foals. JAVMA 184:1146–1148, 1984. 11. Pavletic MM: Reconstractive esophageal surgery in the dog: A literature review and case report. JAAHA 17:435–442, 1981. 12. Swenson O, Clatworthy HW: Partial esophagectomy with end-to-end anastomosis in the posterior mediastinum. Surgery 25:839–848, 1949. 13. Parker NR, Walter PA, Gay J: Diagnosis and surgical management of esophageal perforation. JAAHA 25:587–594, 1989. 14. Muangsombut J, Hankins JR, Mason GR: The use of circular myotomy to facilitate resection and end–to-end anastomosis of the esophagus. J Thorac Cardiovasc Surg 68:522– 529, 1974. 15. Hosgood G: The Omentum—The forgotten organ: Physiology and potential surgical applications in dogs and cats. Compend Contin Educ Pract Vet 12(1):45–51, 1990. 16. Pass MA: Surgical repair of esophageal defects. JAVMA 59:1453–1456, 1971. 17. Waldron DR: Cervical and thoracic esophageal resection and anastomosis, in Bojrab MJ (ed): Current Techniques in Small Animal Surgery, ed 2. Philadelphia, Lea & Febiger, 1983, pp 133–142. 18. Lipowitz AJ, Caywood DD: Atlas of General Small Animal Surgery. St. Louis, Mosby, 1989, pp 46–50. 19. Oakes MG, Hosgood G, Snider TG, et al: Esophagotomy closure in the dog. A comparison of a double-layer appositional and two single-layer appositional techniques. Vet Surg 22:451–456, 1993. 20. Goldsmith HS, Kiely AA, Randall HT: Protection of intrathoracic esophageal anastomoses by omentum. Surgery 63:464–466, 1968. 21. Johnston DE: Reflections on suturing. Compend Contin Educ Pract Vet 11(1):56, 1989. 22. Hermreck AS, Crawford DG: The esophageal anastomotic leak. Am J Surg 132:794–798, 1976.

About the Authors Drs. Shamir, Shahar, and Johnston are affiliated with the Department of Surgery, Veterinary Teaching Hospital, Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel. Dr. Mongil operates a surgery referral practice out of the Dr. Diaz Umpierre Veterinary Hospital in San Juan, Puerto Rico. Dr. Shahar is a Diplomate of the European College of Veterinary Surgeons and the American Board of Veterinary Practitioners, Dr. Johnston is a Diplomate of the American College of Veterinary Surgeons and the European College of Veterinary Surgeons, and Dr. Mongil is a Diplomate of the American College of Veterinary Surgeons.

SUTURE SITE COMPROMISE ■ PDS SUTURE