Residual Right=to-Left Shunt Following Repair of Atrial Septal Defect

Transcription

1 Residual Right=to-Left Shunt Following Repair of Atrial Septal Defect Susan J. Desnick, Ph.D., M.D., William A. Neal, M.D., Demetre M. Nicoloff, M.D., and James H. Moller, M.D. ABSTRACT Information about 5 patients with residual right-to-left shunts following repair of an atrial septal defect is presented. In each patient the defect was located low in the atrial septum adjacent to the inferior vena cava. During operation, either the eustachian valve of the inferior vena cava had been mistaken for the lower margin of the defect or the lower portion of the defect was not closed; blood flow was then diverted from the inferior vena cava into the left atrium. To prevent this occurrence, the inferior margin of the atrial septal defect should be closed first. Operative closure of atrial septal defect is commonly undertaken between 4 and 10 years of age and is associated with both a low operative risk and few postoperative complications. Residual right-to-left cardiac shunting at the atrial level, an unusual complication of this operation, results from incomplete closure of the atrial septal defect or inadvertent diversion of the inferior vena caval blood flow into the left atrium. Right-to-left shunting of the blood commonly occurs in individuals with a low-lying or inferior vena caval type of atrial septal defect. Surgeons unfamiliar with defects in this area should be aware of the operative pitfalls. The purpose of this paper is to report and discuss our clinical and operative experience with 5 patients having atrial septal defects. Case Reports Patient 1 In this 27-year-old man a murmur had been noted at the age of 10 years. Physical examina- From the Departments of Pediatrics and Surgery, University of Minnesota Medical School, Minneapolis, MN. Supported by the Dwan Family Fund. Accepted for publication Sept 29, Address reprint requests to Dr. Moller, Box 447, University of Minnesota Hospitals, Minneapolis, MN tion revealed auscultatory findings of atrial septal defect. The thoracic roentgenogram and electrocardiogram were compatible with this diagnosis, although the latter showed a QRS axis of +240 degrees. Cardiac catheterization confirmed an atrial septal defect with a left-toright shunt. At operation a 3 cm atrial septal defect adjacent to the inferior vena cava was closed with a Teflon patch. Postoperative cardiac examination was normal, but the patient was cyanotic upon exercise. Cardiac catheterization one year following the operation revealed no left-to-right shunt, but the peripheral arterial oxygen saturation was 90% at rest and a 35% right-to-left shunt was calculated (Table). The right-sided cardiac pressures were normal. Angiograms showed that the superior vena cava drained normally, but the inferior vena cava drained exclusively into the left atrium. A second cardiac operation revealed that the patch had been placed so as to exclude the inferior vena cava from the right atrium. An incision was made in the patch, exposing the orifice of the inferior vena cava. A second Teflon patch was then constructed to surround the residual defect, permitting separate flow from the inferior vena cava into the right atrium. A graft was sutured into the inferior vena cava to enlarge its diameter and prevent constriction. Since this second operation, the patient has had no cardiac problems and is acyanotic. Patient 2 This 14-year-old boy was initially evaluated at age 5 years. Clinical and laboratory studies indicated an atrial septal defect, though the electrocardiogram was unusual for this diagnosis. Cardiac catheterization revealed a 55% left-toright shunt. Atrial pressures were equal and elevated (12 mm Hg). A right ventriculogram showed a normal-sized right ventricle. At operation an atrial septal defect was found adjacent to 291

2 292 The Annals of Thoracic Surgery Vol 21 No 4 April 1976 Oxygen Saturation Data following Repair of Atrial Septa1 Defect Systemic Arterial Oxygen Right- to-left Saturation (oh) Shunt (O/O) Patient No. Rest Exercise Rest Exercise 1 90 Not done Not done the entrance of the inferior vena cava. The defect was closed by suturing an Ivalon sponge patch over the defect, proceeding superiorly to inferiorly. At 13 years of age the patient developed fatigue and cyanosis. Findings on clinical and laboratory examination were similar to those at the preoperative evaluation except for the presence of mild cyanosis. Cardiac catheterization revealed no evidence of a left-to-right shunt, but with exercise the aortic oxygen saturation fell to 82% (see the Table). Angiography from the inferior vena cava revealed contrast medium entering both atria. A second cardiac operation showed the lower edge of the Ivalon patch moving freely within the right atrium, creating a baffle across the orifice of the inferior vena cava. A residual atrial septal defect 2 cm in diameter was present inferiorly. The lower edge of the patch was divided over half of its length, and the excess patch material was resected. Sutures were placed through the inferior edge of the atrial septal defect and the lower portion of the Ivalon patch. Postoperatively the patient has been acyanotic and without cardiac symptoms. Patient 3 This 13-year-old girl had been found at 5 years of age to have clinical, electrocardiographic, and roentgenographic findings of an atrial septal defect, and cardiac catheterization confirmed the diagnosis. At operation a large atrial septal defect was repaired with interrupted sutures tied over an Ivalon sponge. Following this operation the patient remained asymptomatic for three years. When she was 8 years old, routine postoperative cardiac catheterization at rest revealed normal right-sided cardiac pressures and oxygen saturations. With supine bicycle exercise, however, the peripheral arterial oxygen saturation decreased to 87% and a 22% right-to-left atrial shunt was calculated (see the Table). A second operation disclosed a residual defect in the inferior portion of the atrial septum. The Ivalon patch was opened for half its length, and mattress sutures were placed around the inferior margin of the defect. A 1.5 cm Teflon-felt patch was used to close the defect entirely, the upper half of the patch sutured to the edges of the Ivalon sponge and the lower half sewn to the inferior margin of the defect. Postoperatively the patient has remained without cardiac abnormalities. Patient 4 In this 10-year-old girl a cardiac murmur had been heard at birth. Evaluation at age 5 years showed findings of patent ductus arteriosus. Cardiac catheterization revealed a small patent ductus arteriosus and a small bidirectional shunt at the atrial level. Six months after division and ligation of the ductus the patient underwent repair of the atrial septal defect. The defect, which extended from the entrance of the superior vena cava to that of the inferior vena cava, was closed by direct suture proceeding superiorly to inferiorly. There was difficulty in placing the most inferior sutures. Postoperatively the patient was asymptomatic, although she described circumoral cyanosis. Clinical examination was normal. Cardiac catheterization revealed an aortic saturation of 93% at rest and 83% with exercise. A right-toleft shunt was calculated at 20% with exercise (see the Table). Angiography was also used to demonstrate the shunt from the inferior vena cava into the left atrium (Fig 1). At reoperation observation revealed that the inferior border of the defect was not included in the closure stitches, so that an opening from the inferior vena cava had been created into the left atrium. This residual defect was closed with a three-corner stitch. The first suture was placed at

3 293 Desnicketal: Right-to-Left Shunt after ASDRepair A B Fig 1. (Patierit 4.) (A) Antevoposteviov and (B) /ntrr.nl irrferior zieiii7 cnz~ogri7rri. Folloziiing irijectiori ofcoritrnst riint~rial irito the irifpriorziena cazia, koth the riglit arid left atria are opacified. the inferior border of the defect and the middle portion of the stitch below the inferior border. A strip of 1.6 mm Teflon felt was then placed beneath the sutures to act as a buttress, and the sutures were tied over this material. The patient had an uneventful postoperative course and has subsequently been without cardiac symptoms. Patient 5 In this 4-year-old boy symptoms of congestive cardiac failure had appeared in infancy. Clinical and laboratory examination revealed a tentative diagnosis of total anomalous pulmonary venous connection. When he was 5 months old cardiac catheterization and angiography showed total anomalous pulmonary venous connection to the left superior vena cava. Since the child s response to medical management was poor, a corrective operation was performed. At Operation an atrial septal defect was observed in continuity with the inferior vena cava. Due to the proximity of the defect and the cava and the presence of a cannula in this vessel, the defect was not completely closed at its most inferior point. The left superior vena cava was ligated, and a side-to-side anastomosis was created between the left atrium and the common pulmonary vein. The patient was acyanotic for the next two years but then developed cyanosis and exercise intolerance. Cardiac catheterization revealed a peripheral arterial oxygen saturation of 90% (see the Table). Injection of contrast material into the inferior vena cava produced opacification of the left atrium. The patient underwent a second operation. A flap of tissue was identified that had been sewn across the inferior vena cava during the initial repair for the atrial septal defect, precluding drainage into the right atrium. This tissue was incised and the residual defect was closed transversely by direct suture. The child had an uneventful postoperative course and has remained acyanotic with normal exercise tolerance. Comment Diversion of the inferior vena cava into the left atrium during operative repair of secundumtype atrial septal defects was reported in 1957 by

4 294 The Annals of Thoracic Surgery Vol 21 No 4 April 1976 Bedford and associates [2]. They described 3 patients in whom the eustachian valve of the inferior vena cava was mistaken for the lower edge of the atrial septal defect and was included in the suture line during repair of the defect. Subsequently, cyanosis, decreased peripheral arterial oxygen saturation, or both were observed due to shunting of inferior vena caval blood into the left atrium. Several case reports have appeared since, and similar operative complications have been described [l, Our 5 patients were found to have residual right-to-left atrial shunts as late as eight years after the initial repair of their atrial septal defect. While 3 patients (Nos. 1, 2, and 5) developed cardiac symptoms postoperatively, the other 2 (Nos. 3 and 4) were detected solely because of cardiac catheterization routinely performed at Fig 2. Operative technique for closure of inferior vena caua type of atrial septal defect. Insets show incorrect method of closure. (SVC = superior vena caua; ASD = atrial septal defect; CS = coronary sinus; TV = tricuspid valzw; IVC = inferior uena cnua.) our institution as part of the postoperative follow-up. Decreased peripheral oxygen saturation in these 2 patients was demonstrated only with exercise. One of the common findings in our patients was a low-lying atrial septal defect proximal to the inferior vena cava, as has been typically described in patients reported by others [l-91. This type of defect represents an operative pitfall to the surgeon who is unaware of the possibility of creating a shunt by mistaking the eustachian valve of the inferior vena cava for the lower rim of the atrial septal defect (Fig 2). This possibility occurs particularly when the repair sutures are placed superiorly to inferiorly, as they were in 3 of our patients. In other patients, the inferior aspect of the defect may not be closed. If a small opening exists, the relationship between the residual defect and the atrial septum causes blood to be shunted from the inferior vena cava into the left atrium. No one has reported any typical clinical features that distinguish patients with atrial septal defects in this unusual location; some preopera- Incompletely closed ASD eustachian

5 295 Desnicketal: Right-to-Left Shunt after ASDRopair tive clue would be helpful to the surgeon. Reviewing the electrocardiograms of our patients, only 1 showed the typical findings of the usual atrial septal defect. In another (Patient 4), the electrocardiogram was normal. The remaining 3 patients had electrocardiograms that were atypical for atrial septal defect. Whether or not these differences are significant is difficult to determine, since a much larger sample of patients must be compared electrocardiographically. Because there is no definitive method of identifying persons with inferior vena cava type atrial septal defects, it is the surgeon s responsibility to make that determination at operation. The initial sutures at the inferior end of the defect should be placed so that they include both edges of the defect plus the posterior wall of the left atrium. This process will ensure that blood coming from the inferior vena cava enters only the right atrium. We think it is important, in spite of the surgeon s precautions, to perform postoperative cardiac catheterization studies in all patients with low-lying atrial septal defects; catheterization should include measurements made during exercise. An alternative for centers not wishing to perform postoperative cardiac catheterization is to determine systemic arterial oxygen saturation at rest and during exercise. Individuals with right-to-left atrial shunts can be identified by systemic arterial desaturation. Detection of all patients with right-to-left atrial shunts, ideally before they manifest cardiac symptoms, is necessary, and successful surgical repair of residual defects can be carried out. References 1. Arnfred E: A clinical and hemodynamic evaluation of the results of surgical correction of atrial septal defect. J Cardiovasc Surg (Torino) 8:93, Bedford DE, Sellors TH, Somerville W, et al: Atrial septal defect and its surgical treatment. Lancet 1:1255, Bjork VO, Johansson L, Jonsson B, et al: The operation and management of a case after diversion of the inferior vena cava into the left atrium after the open repair of an atrial septal defect. Thorax 13:261, Clause HC, Sanger PW, Taylor FH, et al: Unusual complications in open heart surgery. Coll Works Cardiopulm Dis 5-6:305, Mustard WT, Firor WB, Kidd L: Diversion of the venae cavae into the left atrium during closure of atrial septal defects. J Thorac Cardiovasc Surg 47:317, Ross JK, Johnson DC: Complications following closure of atrial septal defect of the inferior vena caval type. Thorax 27:754, Sellors TH: Atrial seytal defects. Proc R SOC Med 54:781, Staple TW, Ferguson TB, Parker BM: Diversion of the inferior vena cava into the left atrium following atrial septal defect closure. Am J Roentgenol Radium Ther Nucl Med 98:851, Weldon CS, Hartmann AF Jr: Management of iatrogenic inferior vena caval-left atrial communications (abstract). Circulation 42:(Suppl 3):205, 1970