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Restrictive interatrial communication in total anomalous pulmonary venous connection
CONGENITAL HEART DISEASE
Restrictivelnteratrial Communicationin Total AnomalousPulmonaryVenousConnection KENT E. WARD, MD, CHARLES E. MULLINS, MD, JAMES C. HUHTA, MD, MICHAEL R. NIHILL, MD, DAN G. McNAMARA, MD, and DENTON A. COOLEY, MD
Restriction to systemic blood flow at the atrial level in total anomalous pulmonary venous connection (TAPVC) may play a role in the early development of congestive heart failure in some patients. Over a 4-year period, 21 patients with TAPVC without extracardiac obstruction presented from 1 day to 10 months of age (mean 2.6 months). of 21 patients, 17 (61% ) presented after 1 month of age with moderate to severe congestive heart failure. In the first week after birth 4 patients presented with minimal symptoms of congestive heart failure. A small patent foramen ovale (3 mm or less in diameter) was found in 19 of 21 patients (90%) by 2-dimensional echocardiography or angiography. Balloon or blade and balloon atrial septostomy was performed in these 19 patients and resulted in significant decreases in mean right to left atrial pressure gradient (from 2.6 to 0.25 mm Hg, p
monary to femoral artery pressure ratio (from 0.60 to 0.60, p
R
ecent advances in surgical technique and perioperative care of the neonate with congenital heart disease have decreased the morbidity and mortality associated with early total correction of many cardiac defects, including total anomalous pulmonary venous connection (TAPVC) without obstruction. Excluding patients with extracardiac obstruction, Turley et al,l Wammon et a12and Mazzucco et al3 reported a low operative mortality rate with early total correction in these patients. There are circumstances, however, where early -.-_____m___“-^ From the Lillie Frank Abercrombie Section of Cardiology, Department of Pediatrics, Baylor College of Medicine; Texas Children’s Hospital: and Texas Heart Institute, Houston, Texas. This study was supported in part by Grant RR-66188 from the General Clinical Research Branch, National Institutes of Health, Bethesda, Maryland. Manuscript received September 10,1985; revised manuscript received December 3, 1985, accepted December 6,1985. Address for reprints: Kent E. Ward, MD, Pediatric Cardiology, Oklahoma Children’s Memorial Hospital, P.O. Box 26307, Oklahoma City, Oklahoma 73126. 1131
palliation may be necessary or may enhance tbe success of a subsequent surgical repair: (1) Patients witb severe hemodynamic compromise because of a restrictive interatrial communication in whom the operative mortality is high. (2) Patients, often with the mixed typed of TAPVC, who lack a pulmonary venous confluence of adequate size for anastomosis to the left atrium. (3) Infants under treatment in a center in a part of the world in which surgery for congenital heart defects in infants younger than 6 months carries a high mortality risk.4-6 (4) Infants unable to undergo cardiopulmonary bypass, which requires the use of blood, because of parental religious convictions.7 Rashkind balloon atria1 septostomy has been shown to be effective in improving hemodynamics and allowing short-term palliation in some patients with TAPVC without obstructions-10 This procedure is intended for patients with a restrictive interatrial communication; however, the incidence of restriction at the atria1 level and the degree with which this restriction contributes to the altered hemodynamics in these patients are not known. The outcome of a large num-
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ed, including all 7 patients with return below the diaphragm and 4 patients with supracardiac TAPVC Included in this study were 21 patients without an extracardiac site of pulmonary venous obstruction. Patient data: Age and weight at presentation, presence or absence of cyanosis, tachypnea, hepatomegaly and cardiac murmur, and the results of the initial chest roentgenogram and 15-lead electrocardiogram were recorded. Follow-up data were obtained by clinic visits or phone contact with the patient’s family or the referring physician. Echocardiographic data: All patients had &dimensional echocardiograms performed at the time of initial presentation using a commercially available mechanical sector scanner (Advanced Technology Laboratories MK 500 or 600). Follow-up echocardiograms were performed in 20 of 21 patients after catheterization. Echocardiograms were reviewed and attention was directed to the atria1 septum, where characterization of the interatrial communication (whether a patent foramen ovale or a true atria1 septal defect) was recorded. The defect was measured in the subcostal &chamber view and a restrictive interatrial communication was defined as one that was 3 mm or less in diameter (Fig. 1). Catheterization data: All patients underwent cardiac catheterization and angiography within 2 months of diagnosis. Digitalis and diuretic drugs were withheld 12 hours before catheterization. Premeditation FIGURE 1. Echocardiographlc image of the atrial septum In an was administered in 13 patients and consisted of meinfant with total anomalous pulmonary venous connection. In posteperidine, 2 mg/kg, promethazine, 1 mg/kg, and chlorrior subcostal scans the atrial septum may appear intact (open promazine, 1 mg/kg. No premeditation was used in 8 white arrow, fop). More anterior scanning shows the interatrial patients. Ketamine, 0.5 to 1.0mg/kg intravenously, was communication (sma// white arrows, boffom). I = inferlor; L = lett; used as needed for sedation. LA = left atrium; LV = left ventricle; R = right; RA = rlght atrium; S After pressures and angiograms were recorded, = superior. balloon or blade and balloon atria1 septostomy was performed according to published techniques11J2in patients found to have a restrictive interatrial communication. A restrictive interatrial communication was ber of patients undergoing early atria1 septostomy with considered present if (1) the interatrial communication later surgical correction has not been published. During our investigation of the effects of septos- was 3 mm or less as measured by 2-dimensional echocardiography, (2) an 8-mm-diameter balloon could not tomy, our approach to management of patients with TAPVC has been to attempt palliation in the catheter- be pulled easily across the atria1 septum at the time of ization laboratory at the time of diagnosis to ensure an cardiac catheterization, or (3) right atria1 mean presadequate interatrial communication, aggressive anti- sure was greater than left atria1 mean pressure. After congestive medical therapy, and close follow-up. We the procedure, in 14 patients pressures were recorded report the incidence and hemodynamic consequences from both atria and in 12 measurements in the pulmoof a restrictive interatrial communication and the ef- nary and femoral artery were repeated. Blood oxygen saturation from the femoral artery was also measured fects of atria1 septostomy. in 10 patients. Methods Digitalis and diuretic drug therapy was restarted We reviewed the hospital records, catheterization within 24 hours and all patients were discharged from data and Z-dimensional echocardiographic studies for the hospital 1 day to 3 weeks after catheterization. all patients found to have isolated TAPVC during a Nineteen patients were followed in our clinic; 2 parecent 4-year period (April 1979 through April 1983). tients from outside the country were followed by their Patients with associated cardiac defects other than a referring cardiologists. Patients were referred for surgical correction at the patent ductus arteriosus were excluded. Of the 32 patients with isolated TAPVC diagnosed during the discretion of their attending cardiologist either bestudy period, 11 had hemodynamic or angiographic cause of persistent, uncontrolled congestiveheart failevidence of extracardiac obstruction and were exclud- ure or as an elective surgical procedure. Most patients
May I.1986
TABLE I
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Patient Data
-
Case
DX
wt. i&l)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 1% 19 20 21
Id Id 2d 5d Im 1.5m 1.5 m 2m 2m 2m 2.5 m 2.5 m 2.5 m 3m 3m 3m 3m 4m 4m 7m 10 m
3.2 4.0 2.9 3.0 3.7 2.5 3.5 3.8 4.5 3.2 4.4 4.3 4.5 4.1 5.4 4.4 4.7 4.7 5.5 6.9 6.4
Mean
2.6 m
4.3
Age at
1138
-.. of 5116
Clinical Exam __I___=~ .-.-
COlli%3CiiOii
c
T
H
CS (PDA) RA Mixed’ RA LVV cs LVV LVV (PDA) cs LVV LVV svc RA RA Mixed’ cs
-t -
-
-
+ -
-
-
+ + + -I+ + + -IT + -I+ + + + + +
+ -I” + + + + + + -I+ + + +
+ + + + + + + + + -I-
M
+ + + + + + + + + + + + + + + + + + +
CI?PS! Y-Ray NL NL NL A0 AB AB AB A0 AB AB AB AB AB AB AB AB AB AB AB AB A0
ECG NL NL RVH NL RAEIRVH RAEIRVH RAEIRVH RElRVH RAEIRVH RAEIRVH RAEIRVH RAEtRVH RAEIRVH RAEIRVH LAD RAEtRVH RAE/RVH RAEtRVH RAEIRVH RAE/RVH RAEIRVH
wt. at Surgery (kg)
Outcome
13 m 6.5 m 3.7 yr -
8.0 4.1 12.3 -
Alive Alive Alive -
20 m 5m 10 m 13 m 16 m 8M 4.5 m 8.0 m 10 m -
9.5 3.5 5.6 6.3 9.8 6.0 4.8 8.0 6.5 -
20 m 14 m 21 m 23 m 4m 16 m 3.8 yr
10.9 10.0 11.0 9.0 5.5 9.9 40.0
Alive Alive’ Alive Alive Alive Died7 Alive Alive Alive Alive Alive Died Alive Alive Alive Alive
15.8 m
8.0
Age at Surgery
* Pacemaker insertion for symptomatic sinus bradycardia. + Died 3 weeks postoperatively of hepatic failure. C = cyanosis; CS = coronary sinus; Dx = diagnosis; ECG = electrocardiogram; H = hepatomegaly; LAD = left-axis deviation: LVV = left vertical vein; M = murmur; Mixed’ = right pulmonary veins/left lower pulmonary vein to coronary sinus, left upper pulmonary vein to left vertical vein; Mixed* = right pulmonary veins to coronary sinus, left pulmonary veins to left vertical vein; PDA = patent ductus arteriosus; RA = right atrium; RAE = right atrial enlargement: RVH = right ventricular hypertrophy; SVC = superior vena cava; T = tachypnea.
who underwent surgery had normothermic cardiopulmonary bypass using cold potassium cardioplegia for myocardial preservation; 2 patients had profound hypothermia and circulatory arrest. The surgery was performed by one of us (DAC) and by Drs. Grady Hallman, George Reul and David Ott. Although the surgical approach was individualized, all patients underwent an operation in which techniques were used 13,14to effect an adequate anastomosis between the common pulmonary vein and the left atrium. Statistical methods: Statistical analysis of pre- and postseptostomy pressure and arterial blood oxygen saturation values was performed using the Student t test for paired observations. Patients: The types of TAPVC encountered included 9 supracardiac, 9 cardiac and 3 mixed. At presentation the patients were 1 day to 10 months old (mean 2.6 months) and weighed 2.5 to 6.9 kg (mean 4.3) (Table I). Presentation: Only 4 patients (19%) were younger than 1 month at the time of presentation and none had signs or symptoms suggestive of TAPVC (Table II). The other 17 patients presented after 1 month of age with growth failure and variable degrees of cyanosis and congestive symptoms, ranging from mild cardiomegaly and tachypnea to cardiovascular collapse requiring cardiopulmonary resuscitation (case 11). All had abnormal chest roentgenographic findings and all but 1 (case 15) had electrocardiographic evidence of right atria1 enlargement and right ventricular hypertrophy.
Results Echocardiographic diagnosis of a restrictive interatria1 communication: Before catheterization, 18 of 21 patients had technically adequate 2-dimensional echocardiograms. Fifteen of 18 patients (83%) had an interatrial communication less than 3 mm in diameter. A secundum atria1 septal defect was found in only 3 patients (nos. 1,8 and 15) and measured 4,5 and 9 mm, respectively (Table II). Catheterization and ~em~dy~arni~ results of atrial septostomy (Table II): Restriction at the atria1 level was present in 19 patients (90%). Balloon atria1 septostomy was performed in 6 patients and blade and balloon atria1 septostomy in 13. A significant decrease was noted in the mean right to left atria1 pressure gradient, decreasing from 2.8 to 0.25 mm Hg (n = 15, p
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TABLE II
PULMONARY
VENOUS
Echocardiographic
CONNECTION
and Catheterization
Data Catheterization
Data (mm Hg)
IAC by Echo
Case
Type
Diameter (mm)
1 2 3 4 5 8 7 8 9 10 11 12 13 14 15 18 17 18 19 20 21
ASD PFO PFO PFO PFO ASD PFO PFO PFO PFO PFO PFO ASD PFO PFO PFO PFO PFO
4 5 9 -
RAP/LAP
SFAP
SPAP
CPV/RA Grad (mean)
Pre
Post
Pre
Post
Pre
Post
10 0 7 0 12 8 3 8 8 8 1 3 0 8 3 3 7 2 11
0 1 0 0 0 5 2 0 1 3 4 2 3 1 0 8 4 1 1 2 4
0 0
50 42 55 40 80 70 55 80 50 85 90 80 70 75 32 70 90 75 65 55 84
50 40 55 80 50 85 70 80 80 55 70 80
80 70 85 90 85 70 02 95 70 90 88 100 80 75 90 105 90 95 90 00 98
60 95
0 0 0 1 0 0 0 0 0 0 1
95 95 95 105 95 105 100 90 105 105
ASD = atrial septal defect; CPV/RA Grad = mean pressure gradient between common pulmonary venous chamber and right atrium; IAC = interatrial communication; PFO = patent foramen ovale <3 mm dlameter; Post = post septostomy; Pre = pre septostomy; RAP/LAP = mean pressure gradlent between the right and left atrium; SFAP = systolic femoral artery pressure: SPAP = systolic pulmonary artery pressure.
Before septostomy, pulmonary artery blood oxygen saturation was greater than femoral artery saturation in all but 1 patient, ranging from 1 to 11% [mean difference 4%). After septostomy, systemic arterial oxygen saturation decreased significantly, from 84% to 79% (n = 15, p
Of the 17 survivors, all are alive and well from 4 months to 4 years (mean 2.5 years) postoperatively. In 1 patient, pacemaker implantation 2 weeks after surgery was required for symptomatic sinus bradycardia. Five patients have had postoperative cardiac catheterization: all had normal pulmonary artery pressures and none have evidence of significant residual defects. Two patients did not have surgical correction of their defect: 1 had multiple anomalies and the other failed to return for surgery; at age 32 months (2 years after his last visit] pneumonia and respiratory failure developed and he died.
Discussion BurchelP5 was the first to suggest that the size of the interatrial communication in TAPVC may influence the circulatory dynamics. Burroughs and Edwards16 and Bonham-Carter et all7 found a strong association between the size of the interatrial communication and the length of survival in unoperated patients. Although some investigators report that restriction at the atria1 level is rare in TAPVC,18 others have found it more often. A patent foramen ovale was found in 68% of the patients reviewed by Burroughs and Edward@ in their natural history study of TAPVC and was believed to be restrictive in all but 1 patient. Whight et alI9 classified as “small or moderate” 70% of the interatrial communications in their group of 23 patients younger than 1 year of age who underwent surgical correction. Our echocardiographic studies support these findings, with a restrictive patent foramen ovale in 15 of 18 patients. Abolition of the atria1 pressure gradient, if
May I,1986
present, and a decrease in the pulmonary artery to femoral artery pressure ratio was observed in most of rlt0 those Obiihe patients. TLocn pllcI...v findincrc &AL .-___~- RI-P. -- _ similar served by Mullins et ale and Miller et aLg and likely reflect a decrease in pulmonary and an increase in systemic flow. Another finding that may, in part, reflect acute relief of restriction at the atria1 level after septostomy was the significant decrease in arterial oxygen saturation Before septostomy, we found, as have others,20 higher oxygen saturations in the pulmonary artery than in the femoral artery. This difference is due to the streaming effect of inferior vena caval blood through the foramen ovale, with pulmonary venous blood returning through either the superior vena cava, right atrium or coronary sinus, being preferentially directed across the tricuspid valve. Enlarging the foramen ovale enhances this streaming effect. This phenomenon, as well as the decrease in pulmonary blood flow, likely contributes to the observed decrease in systemic arterial saturation. We included in our study patients with gradual mean pressure gradients of as much as 12 mm Hg between the common pulmonary vein and right atrium. Most of these patients had TAPVC to the left vertical vein; none had hemodynamic or angiographic evidence of a discrete obstruction. This gradient is generated by torrential blood flow occurring through a long venous channel. Whether these patients are truly “obstructed” in an anatomic sense is open for debate. Burroughs and Edwardd6 found an indirect association between the length of the anomalous venous channel and the age at death in unoperated patients with TAPVC and suggested that length as well as diameter of the anomalous venous channel may be an important determinant of severity of obstruction to venous return. Thus, 2 of 4 patients in our study who had persistent, uncontrolled heart failure after septostomy (cases7 and 11) had TAPVC of this type and had mean pressure gradients of 12 and 8 mm Hg, respectively. However, 3 others with similar anatomy and hemodynamic findings were well palliated with septostomy (cases 5, 8 and 21). These patients may represent a subgroup less likely to achieve long-term benefit from a nonrestrictive interatrial communication. Because it is this group of patients where delay of surgery is desirable in order to minimize the incidence of late stenosis at the anastomosis, atria1 septostomy may be helpful. Complications of atria1 septostomy were rare in our experience. Puncture of the right atrium by the dilator occurred in 1 patient while the sheath-dilator set was being manipulated without a guidewire; this complication should be preventable. Other complications reported to occur during balloon or blade and balloon septostomy, l2 including perforation of the right ventricle and aorta, embohc episodes, arrhythmias and excessive blood loss, were not observed. Restriction of systemic blood flow at the atria1 level did not occur early in the newborn period. Only 4 of 21 patients were diagnosed before I month of age, none had signs or symptoms of pulmonary congestion or heart failure, and only 1 had abnorma1 electrocardio-
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POST 5
6
5
4
Hmgm3
2
1 I.3
1.0
PRE
POST
0.9 0.8
a 2 2 2
0.7 0.6
0.6
0.5 0.4 0.3
85
80 5 f/l 75 bQ 70 65 60
FIGURE 2. Top, tight atrial to left atrial before (n = 21) and after (n = 15) at pulmonary to femoral artery systolic pressure ratio (~A~/FA~) before (n = 21) and after (n = 12) atrial septostomy. ~offom, systemic arterial blood oxygen saturation (SAT) before and after (n = 15) atrial septostomy. IAC = interatrfal communication.
1136
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graphic or chest roentgenographic findings. Seventeen patients presented with varying degrees of congestive heart failure after 1 month (mean 2.6 months) and restrictive interatrial communication apparently developed in the interim. All had pulmonary artery to femoral artery pressure ratios greater than 0.50. This development of restriction at the atria1 level can best be explained on the basis of intrauterine hemodynamic conditions and the changes that occur early after birth. Experimental work in fetal lambs shows that only 7 to 8% of the combined ventricular output in utero traverses the pulmonary circuit and returns through the pulmonary veins.2* Thus, blood flow across the fossa ovalis in the fetus with TAPVC would be increased by, at most, 8%. The stimuli for development of a large interatrial communication, as would be present in patients with right-heart obstructive lesions (tricuspid atresia, pulmonary atresia with intact ventricular septum], would not be present with TAPVC in utero. Soon after birth, systemic cardiac output would be maintained across a patent foramen ovale of “normal” size. However, as pulmonary vascular resistance drops, pulmonary blood flow is augmented at the expense of systemic flow. With rapid growth in the first few weeks and months, demands for systemic output increase greatly and flow across a restrictive interatrial communication becomes limited. Creation of a nonrestrictive interatrial communication at this time should decrease symptoms of pulmonary overcirculation and decreased systemic perfusion. The operative mortality rate of 5% in our review compares favorably with the recent reports of early total correction with operative mortality rates of 0 to 12% in patients with nonobstructed TAPVC.1-3 Whether surgery in the second year after birth will decrease the incidence of late postoperative pulmonary venous obstruction is not known. Whightlg and Dickinsonz2 and their co-workers found a high incidence of late obstruction in patients who underwent surgery in the first year of life. None of our patients studied postoperatively has evidence of significant pulmonary venous obstruction; however, long-term follow-up is needed. Postmortem examination of the lungs of the patient who died revealed no evidence of advanced pulmonary vascular disease. This finding, as well as the absence of elevated pulmonary artery pressures in patients who underwent catheterization postoperatively, is consistent with another reportzl that irreversible pulmonary vascular obstructive disease is rare in this anomaly.
Acknowledgmentz We gratefully acknowledge the secretarial assistance of Nancy Mitchell and Sherri McSpadden.
References 1. Turley K, Tucker WY, Ullyot DJ, Ebert PA. Total anomalous pulmonary venous connection in infancy: influence of age and type of lesion. Am r cardiol fs8o;kwz-97. 2. Hammon JW, Bender HW, Graham TP, Boucek RJ, Smith CW, Erath HG. Total anomalous pulmonary venous connection in infancy. 1 Thorac Cardiovast Surg 1980;80:544-551. 3. Mazzucco A, Rizzoli G, Fracasso A, Stellin G, Valfre C, Pellegrino P, Bortolotti U, Gallucci V. Experience with operation for TAPVC in infancy. 1 Thorac Cardiovasc Sure 1983:85:886-690. 4. Jacobsen JR, Boesen ?, Wennevold A. Congenital heart disease before the age of two. Dan Med Bull 1982;29:32-41. 5. Naito Y, Fujita T, Tomino T, Yoshihara K, Isobe F, Nayashi K. Kito Y, Manabe H, Kamiya T. Surgical treatment for severe congknital heart diseases. Inn Circ J 1983:47:1137-3146. 6. Oku’H, Shirot&i H, Okanoto F. Yokota Y, Yokoyama T, Kawai I, Makino S, Satsuie N, Ando F, Nishioka T, Noritake S, Shinohara T, Nakamura Y, Oka H, Saga T, Wakaki N. Surgical results and factors affecting operative mortality in TAPVC. lpn Circ 1 1982;46:675-683. 7. Henlinn CE, Carmichael Ml, Keats AS, Coolev DA. Cardiac operation for congenital heart disease in children of [ehovah’sWitnesses. 1 Th&ac Cardiovast Surg 1985;89:914-920. 8. Mullins CE, El-Said G, Neches WH. Williams R, Vargo T, Nihill M, McNamara D. Balloon atrial septostomy for total anomalous pulmonary venous return. Br Heart J 1973;35:752-757. 9. Miller WW, Rashkind WI, Miller RA, Hastreiter AR, Green EW, Golinko RJ, Young D. Total anomaJ&s pulmonary venous return: effective palliation of critically ill infants by balloon atrial septostomy (abstr). Circulation 1967;36:suppJII:II-189. 10. Serratto M, Bucheleres G, Bicoff P, Miller RA, Hastreiter AR. Palliative balloon atrial septostomy for total anomalous pulmonary venous connection in infancy. [ Pediatr 1968;73:734-739. 11. Rashkind WJ, Miller WW. Creation of an atria1 septal defect without thoracotomy: palliative approach to complete transposition of the great arteries. TAMA 19fi6:196:991-994. 12. Park SC, Neches WH, Mullins CE, Girod DA, Olley PM, Falkowski G, Garibian VA, Mathews RA, Fricker F], Beerman LB, Lenox CC, Zuherbuhler JR. Blade atrial septostomy: collaborative study. Circulation 1982;66:258-266. 13. Reardon MJ, Cooley DA, Kubrusly L, Ott DA, Johnson W, Kay GL, Sweeney MS. Total anomalous pulmonary venous return: report of 201 patients treated surgically. Texas Heart Institute Journal 1985;12:131-141. 14. Kirklin JW. Surgical treatment of total anomalous pulmonary venous connection in infancy. In: Baratt-Boyes BG, Neutze /M, Harris EA, eds. Heart Disease in Infancy: Diagnosis and Surgical Treatment. London: Churchill Livingstone, 1973:89. 15. Burchell HB. Total anomalous pulmonary venous drainage: clinical and physiologic patterns. Mayo CJin Proc 1956;31:161-167. 16. Burroughs JT, Edwards JE. Total anomalous pulmonary venous connection. Am Heart r 1960;59:913-931, 17. Bonham-Carter RE, Capriles M, Noe Y. Total anomaJous puJmonary venous drainage; a clinical and anatomical study of 75 children. Br Heart 1 1969;31:45-51. 18. Nadas AS, Fyler DC. Pediatn’c Cardiology. 3rd ed. New York: W.B. Saunders, 1972:640-652. 19. Whight CM, Barratt-Boyes BG, Caider AL, Neutze JM, Bandt PW. Total anomalous pulmonary venous connection. Long term results following repair in infancy. r Thorac Cardiovasc Surg 1978;75:52-63. 20. Moller JH. Neal WA. Heart Disease in Infancy. New York: AppletonCentury Crofts, 1981:347-359. 21. Peterson RC, Edwards WD. Pulmonary vascular disease in 57 necropsy cases of TAPVC. Histooatholoev 1983:7:487-496. 22. Diikinson DF, Pari&eIazhlian KG, Tweedle MC, West CR, Piccoli GP, Musumeci F, Hamilton DI. TAPVC: repair using deep hypothermia and circulatory arrest in 44 consecutive infants. Br Heart [ 1982;48:249-254.
Restrictivelnteratrial Communicationin Total AnomalousPulmonaryVenousConnection KENT E. WARD, MD, CHARLES E. MULLINS, MD, JAMES C. HUHTA, MD, MICHAEL R. NIHILL, MD, DAN G. McNAMARA, MD, and DENTON A. COOLEY, MD
Restriction to systemic blood flow at the atrial level in total anomalous pulmonary venous connection (TAPVC) may play a role in the early development of congestive heart failure in some patients. Over a 4-year period, 21 patients with TAPVC without extracardiac obstruction presented from 1 day to 10 months of age (mean 2.6 months). of 21 patients, 17 (61% ) presented after 1 month of age with moderate to severe congestive heart failure. In the first week after birth 4 patients presented with minimal symptoms of congestive heart failure. A small patent foramen ovale (3 mm or less in diameter) was found in 19 of 21 patients (90%) by 2-dimensional echocardiography or angiography. Balloon or blade and balloon atrial septostomy was performed in these 19 patients and resulted in significant decreases in mean right to left atrial pressure gradient (from 2.6 to 0.25 mm Hg, p
monary to femoral artery pressure ratio (from 0.60 to 0.60, p
R
ecent advances in surgical technique and perioperative care of the neonate with congenital heart disease have decreased the morbidity and mortality associated with early total correction of many cardiac defects, including total anomalous pulmonary venous connection (TAPVC) without obstruction. Excluding patients with extracardiac obstruction, Turley et al,l Wammon et a12and Mazzucco et al3 reported a low operative mortality rate with early total correction in these patients. There are circumstances, however, where early -.-_____m___“-^ From the Lillie Frank Abercrombie Section of Cardiology, Department of Pediatrics, Baylor College of Medicine; Texas Children’s Hospital: and Texas Heart Institute, Houston, Texas. This study was supported in part by Grant RR-66188 from the General Clinical Research Branch, National Institutes of Health, Bethesda, Maryland. Manuscript received September 10,1985; revised manuscript received December 3, 1985, accepted December 6,1985. Address for reprints: Kent E. Ward, MD, Pediatric Cardiology, Oklahoma Children’s Memorial Hospital, P.O. Box 26307, Oklahoma City, Oklahoma 73126. 1131
palliation may be necessary or may enhance tbe success of a subsequent surgical repair: (1) Patients witb severe hemodynamic compromise because of a restrictive interatrial communication in whom the operative mortality is high. (2) Patients, often with the mixed typed of TAPVC, who lack a pulmonary venous confluence of adequate size for anastomosis to the left atrium. (3) Infants under treatment in a center in a part of the world in which surgery for congenital heart defects in infants younger than 6 months carries a high mortality risk.4-6 (4) Infants unable to undergo cardiopulmonary bypass, which requires the use of blood, because of parental religious convictions.7 Rashkind balloon atria1 septostomy has been shown to be effective in improving hemodynamics and allowing short-term palliation in some patients with TAPVC without obstructions-10 This procedure is intended for patients with a restrictive interatrial communication; however, the incidence of restriction at the atria1 level and the degree with which this restriction contributes to the altered hemodynamics in these patients are not known. The outcome of a large num-
1132
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VENOUS
CONNECTION
ed, including all 7 patients with return below the diaphragm and 4 patients with supracardiac TAPVC Included in this study were 21 patients without an extracardiac site of pulmonary venous obstruction. Patient data: Age and weight at presentation, presence or absence of cyanosis, tachypnea, hepatomegaly and cardiac murmur, and the results of the initial chest roentgenogram and 15-lead electrocardiogram were recorded. Follow-up data were obtained by clinic visits or phone contact with the patient’s family or the referring physician. Echocardiographic data: All patients had &dimensional echocardiograms performed at the time of initial presentation using a commercially available mechanical sector scanner (Advanced Technology Laboratories MK 500 or 600). Follow-up echocardiograms were performed in 20 of 21 patients after catheterization. Echocardiograms were reviewed and attention was directed to the atria1 septum, where characterization of the interatrial communication (whether a patent foramen ovale or a true atria1 septal defect) was recorded. The defect was measured in the subcostal &chamber view and a restrictive interatrial communication was defined as one that was 3 mm or less in diameter (Fig. 1). Catheterization data: All patients underwent cardiac catheterization and angiography within 2 months of diagnosis. Digitalis and diuretic drugs were withheld 12 hours before catheterization. Premeditation FIGURE 1. Echocardiographlc image of the atrial septum In an was administered in 13 patients and consisted of meinfant with total anomalous pulmonary venous connection. In posteperidine, 2 mg/kg, promethazine, 1 mg/kg, and chlorrior subcostal scans the atrial septum may appear intact (open promazine, 1 mg/kg. No premeditation was used in 8 white arrow, fop). More anterior scanning shows the interatrial patients. Ketamine, 0.5 to 1.0mg/kg intravenously, was communication (sma// white arrows, boffom). I = inferlor; L = lett; used as needed for sedation. LA = left atrium; LV = left ventricle; R = right; RA = rlght atrium; S After pressures and angiograms were recorded, = superior. balloon or blade and balloon atria1 septostomy was performed according to published techniques11J2in patients found to have a restrictive interatrial communication. A restrictive interatrial communication was ber of patients undergoing early atria1 septostomy with considered present if (1) the interatrial communication later surgical correction has not been published. During our investigation of the effects of septos- was 3 mm or less as measured by 2-dimensional echocardiography, (2) an 8-mm-diameter balloon could not tomy, our approach to management of patients with TAPVC has been to attempt palliation in the catheter- be pulled easily across the atria1 septum at the time of ization laboratory at the time of diagnosis to ensure an cardiac catheterization, or (3) right atria1 mean presadequate interatrial communication, aggressive anti- sure was greater than left atria1 mean pressure. After congestive medical therapy, and close follow-up. We the procedure, in 14 patients pressures were recorded report the incidence and hemodynamic consequences from both atria and in 12 measurements in the pulmoof a restrictive interatrial communication and the ef- nary and femoral artery were repeated. Blood oxygen saturation from the femoral artery was also measured fects of atria1 septostomy. in 10 patients. Methods Digitalis and diuretic drug therapy was restarted We reviewed the hospital records, catheterization within 24 hours and all patients were discharged from data and Z-dimensional echocardiographic studies for the hospital 1 day to 3 weeks after catheterization. all patients found to have isolated TAPVC during a Nineteen patients were followed in our clinic; 2 parecent 4-year period (April 1979 through April 1983). tients from outside the country were followed by their Patients with associated cardiac defects other than a referring cardiologists. Patients were referred for surgical correction at the patent ductus arteriosus were excluded. Of the 32 patients with isolated TAPVC diagnosed during the discretion of their attending cardiologist either bestudy period, 11 had hemodynamic or angiographic cause of persistent, uncontrolled congestiveheart failevidence of extracardiac obstruction and were exclud- ure or as an elective surgical procedure. Most patients
May I.1986
TABLE I
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Patient Data
-
Case
DX
wt. i&l)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 1% 19 20 21
Id Id 2d 5d Im 1.5m 1.5 m 2m 2m 2m 2.5 m 2.5 m 2.5 m 3m 3m 3m 3m 4m 4m 7m 10 m
3.2 4.0 2.9 3.0 3.7 2.5 3.5 3.8 4.5 3.2 4.4 4.3 4.5 4.1 5.4 4.4 4.7 4.7 5.5 6.9 6.4
Mean
2.6 m
4.3
Age at
1138
-.. of 5116
Clinical Exam __I___=~ .-.-
COlli%3CiiOii
c
T
H
CS (PDA) RA Mixed’ RA LVV cs LVV LVV (PDA) cs LVV LVV svc RA RA Mixed’ cs
-t -
-
-
+ -
-
-
+ + + -I+ + + -IT + -I+ + + + + +
+ -I” + + + + + + -I+ + + +
+ + + + + + + + + -I-
M
+ + + + + + + + + + + + + + + + + + +
CI?PS! Y-Ray NL NL NL A0 AB AB AB A0 AB AB AB AB AB AB AB AB AB AB AB AB A0
ECG NL NL RVH NL RAEIRVH RAEIRVH RAEIRVH RElRVH RAEIRVH RAEIRVH RAEIRVH RAEtRVH RAEIRVH RAEIRVH LAD RAEtRVH RAE/RVH RAEtRVH RAEIRVH RAE/RVH RAEIRVH
wt. at Surgery (kg)
Outcome
13 m 6.5 m 3.7 yr -
8.0 4.1 12.3 -
Alive Alive Alive -
20 m 5m 10 m 13 m 16 m 8M 4.5 m 8.0 m 10 m -
9.5 3.5 5.6 6.3 9.8 6.0 4.8 8.0 6.5 -
20 m 14 m 21 m 23 m 4m 16 m 3.8 yr
10.9 10.0 11.0 9.0 5.5 9.9 40.0
Alive Alive’ Alive Alive Alive Died7 Alive Alive Alive Alive Alive Died Alive Alive Alive Alive
15.8 m
8.0
Age at Surgery
* Pacemaker insertion for symptomatic sinus bradycardia. + Died 3 weeks postoperatively of hepatic failure. C = cyanosis; CS = coronary sinus; Dx = diagnosis; ECG = electrocardiogram; H = hepatomegaly; LAD = left-axis deviation: LVV = left vertical vein; M = murmur; Mixed’ = right pulmonary veins/left lower pulmonary vein to coronary sinus, left upper pulmonary vein to left vertical vein; Mixed* = right pulmonary veins to coronary sinus, left pulmonary veins to left vertical vein; PDA = patent ductus arteriosus; RA = right atrium; RAE = right atrial enlargement: RVH = right ventricular hypertrophy; SVC = superior vena cava; T = tachypnea.
who underwent surgery had normothermic cardiopulmonary bypass using cold potassium cardioplegia for myocardial preservation; 2 patients had profound hypothermia and circulatory arrest. The surgery was performed by one of us (DAC) and by Drs. Grady Hallman, George Reul and David Ott. Although the surgical approach was individualized, all patients underwent an operation in which techniques were used 13,14to effect an adequate anastomosis between the common pulmonary vein and the left atrium. Statistical methods: Statistical analysis of pre- and postseptostomy pressure and arterial blood oxygen saturation values was performed using the Student t test for paired observations. Patients: The types of TAPVC encountered included 9 supracardiac, 9 cardiac and 3 mixed. At presentation the patients were 1 day to 10 months old (mean 2.6 months) and weighed 2.5 to 6.9 kg (mean 4.3) (Table I). Presentation: Only 4 patients (19%) were younger than 1 month at the time of presentation and none had signs or symptoms suggestive of TAPVC (Table II). The other 17 patients presented after 1 month of age with growth failure and variable degrees of cyanosis and congestive symptoms, ranging from mild cardiomegaly and tachypnea to cardiovascular collapse requiring cardiopulmonary resuscitation (case 11). All had abnormal chest roentgenographic findings and all but 1 (case 15) had electrocardiographic evidence of right atria1 enlargement and right ventricular hypertrophy.
Results Echocardiographic diagnosis of a restrictive interatria1 communication: Before catheterization, 18 of 21 patients had technically adequate 2-dimensional echocardiograms. Fifteen of 18 patients (83%) had an interatrial communication less than 3 mm in diameter. A secundum atria1 septal defect was found in only 3 patients (nos. 1,8 and 15) and measured 4,5 and 9 mm, respectively (Table II). Catheterization and ~em~dy~arni~ results of atrial septostomy (Table II): Restriction at the atria1 level was present in 19 patients (90%). Balloon atria1 septostomy was performed in 6 patients and blade and balloon atria1 septostomy in 13. A significant decrease was noted in the mean right to left atria1 pressure gradient, decreasing from 2.8 to 0.25 mm Hg (n = 15, p
1134
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TABLE II
PULMONARY
VENOUS
Echocardiographic
CONNECTION
and Catheterization
Data Catheterization
Data (mm Hg)
IAC by Echo
Case
Type
Diameter (mm)
1 2 3 4 5 8 7 8 9 10 11 12 13 14 15 18 17 18 19 20 21
ASD PFO PFO PFO PFO ASD PFO PFO PFO PFO PFO PFO ASD PFO PFO PFO PFO PFO
4 5 9 -
RAP/LAP
SFAP
SPAP
CPV/RA Grad (mean)
Pre
Post
Pre
Post
Pre
Post
10 0 7 0 12 8 3 8 8 8 1 3 0 8 3 3 7 2 11
0 1 0 0 0 5 2 0 1 3 4 2 3 1 0 8 4 1 1 2 4
0 0
50 42 55 40 80 70 55 80 50 85 90 80 70 75 32 70 90 75 65 55 84
50 40 55 80 50 85 70 80 80 55 70 80
80 70 85 90 85 70 02 95 70 90 88 100 80 75 90 105 90 95 90 00 98
60 95
0 0 0 1 0 0 0 0 0 0 1
95 95 95 105 95 105 100 90 105 105
ASD = atrial septal defect; CPV/RA Grad = mean pressure gradient between common pulmonary venous chamber and right atrium; IAC = interatrial communication; PFO = patent foramen ovale <3 mm dlameter; Post = post septostomy; Pre = pre septostomy; RAP/LAP = mean pressure gradlent between the right and left atrium; SFAP = systolic femoral artery pressure: SPAP = systolic pulmonary artery pressure.
Before septostomy, pulmonary artery blood oxygen saturation was greater than femoral artery saturation in all but 1 patient, ranging from 1 to 11% [mean difference 4%). After septostomy, systemic arterial oxygen saturation decreased significantly, from 84% to 79% (n = 15, p
Of the 17 survivors, all are alive and well from 4 months to 4 years (mean 2.5 years) postoperatively. In 1 patient, pacemaker implantation 2 weeks after surgery was required for symptomatic sinus bradycardia. Five patients have had postoperative cardiac catheterization: all had normal pulmonary artery pressures and none have evidence of significant residual defects. Two patients did not have surgical correction of their defect: 1 had multiple anomalies and the other failed to return for surgery; at age 32 months (2 years after his last visit] pneumonia and respiratory failure developed and he died.
Discussion BurchelP5 was the first to suggest that the size of the interatrial communication in TAPVC may influence the circulatory dynamics. Burroughs and Edwards16 and Bonham-Carter et all7 found a strong association between the size of the interatrial communication and the length of survival in unoperated patients. Although some investigators report that restriction at the atria1 level is rare in TAPVC,18 others have found it more often. A patent foramen ovale was found in 68% of the patients reviewed by Burroughs and Edward@ in their natural history study of TAPVC and was believed to be restrictive in all but 1 patient. Whight et alI9 classified as “small or moderate” 70% of the interatrial communications in their group of 23 patients younger than 1 year of age who underwent surgical correction. Our echocardiographic studies support these findings, with a restrictive patent foramen ovale in 15 of 18 patients. Abolition of the atria1 pressure gradient, if
May I,1986
present, and a decrease in the pulmonary artery to femoral artery pressure ratio was observed in most of rlt0 those Obiihe patients. TLocn pllcI...v findincrc &AL .-___~- RI-P. -- _ similar served by Mullins et ale and Miller et aLg and likely reflect a decrease in pulmonary and an increase in systemic flow. Another finding that may, in part, reflect acute relief of restriction at the atria1 level after septostomy was the significant decrease in arterial oxygen saturation Before septostomy, we found, as have others,20 higher oxygen saturations in the pulmonary artery than in the femoral artery. This difference is due to the streaming effect of inferior vena caval blood through the foramen ovale, with pulmonary venous blood returning through either the superior vena cava, right atrium or coronary sinus, being preferentially directed across the tricuspid valve. Enlarging the foramen ovale enhances this streaming effect. This phenomenon, as well as the decrease in pulmonary blood flow, likely contributes to the observed decrease in systemic arterial saturation. We included in our study patients with gradual mean pressure gradients of as much as 12 mm Hg between the common pulmonary vein and right atrium. Most of these patients had TAPVC to the left vertical vein; none had hemodynamic or angiographic evidence of a discrete obstruction. This gradient is generated by torrential blood flow occurring through a long venous channel. Whether these patients are truly “obstructed” in an anatomic sense is open for debate. Burroughs and Edwardd6 found an indirect association between the length of the anomalous venous channel and the age at death in unoperated patients with TAPVC and suggested that length as well as diameter of the anomalous venous channel may be an important determinant of severity of obstruction to venous return. Thus, 2 of 4 patients in our study who had persistent, uncontrolled heart failure after septostomy (cases7 and 11) had TAPVC of this type and had mean pressure gradients of 12 and 8 mm Hg, respectively. However, 3 others with similar anatomy and hemodynamic findings were well palliated with septostomy (cases 5, 8 and 21). These patients may represent a subgroup less likely to achieve long-term benefit from a nonrestrictive interatrial communication. Because it is this group of patients where delay of surgery is desirable in order to minimize the incidence of late stenosis at the anastomosis, atria1 septostomy may be helpful. Complications of atria1 septostomy were rare in our experience. Puncture of the right atrium by the dilator occurred in 1 patient while the sheath-dilator set was being manipulated without a guidewire; this complication should be preventable. Other complications reported to occur during balloon or blade and balloon septostomy, l2 including perforation of the right ventricle and aorta, embohc episodes, arrhythmias and excessive blood loss, were not observed. Restriction of systemic blood flow at the atria1 level did not occur early in the newborn period. Only 4 of 21 patients were diagnosed before I month of age, none had signs or symptoms of pulmonary congestion or heart failure, and only 1 had abnorma1 electrocardio-
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POST 5
6
5
4
Hmgm3
2
1 I.3
1.0
PRE
POST
0.9 0.8
a 2 2 2
0.7 0.6
0.6
0.5 0.4 0.3
85
80 5 f/l 75 bQ 70 65 60
FIGURE 2. Top, tight atrial to left atrial before (n = 21) and after (n = 15) at pulmonary to femoral artery systolic pressure ratio (~A~/FA~) before (n = 21) and after (n = 12) atrial septostomy. ~offom, systemic arterial blood oxygen saturation (SAT) before and after (n = 15) atrial septostomy. IAC = interatrfal communication.
1136
TOTAL ANOMALOUS
PULMONARY
VENOUS
CONNECTION
graphic or chest roentgenographic findings. Seventeen patients presented with varying degrees of congestive heart failure after 1 month (mean 2.6 months) and restrictive interatrial communication apparently developed in the interim. All had pulmonary artery to femoral artery pressure ratios greater than 0.50. This development of restriction at the atria1 level can best be explained on the basis of intrauterine hemodynamic conditions and the changes that occur early after birth. Experimental work in fetal lambs shows that only 7 to 8% of the combined ventricular output in utero traverses the pulmonary circuit and returns through the pulmonary veins.2* Thus, blood flow across the fossa ovalis in the fetus with TAPVC would be increased by, at most, 8%. The stimuli for development of a large interatrial communication, as would be present in patients with right-heart obstructive lesions (tricuspid atresia, pulmonary atresia with intact ventricular septum], would not be present with TAPVC in utero. Soon after birth, systemic cardiac output would be maintained across a patent foramen ovale of “normal” size. However, as pulmonary vascular resistance drops, pulmonary blood flow is augmented at the expense of systemic flow. With rapid growth in the first few weeks and months, demands for systemic output increase greatly and flow across a restrictive interatrial communication becomes limited. Creation of a nonrestrictive interatrial communication at this time should decrease symptoms of pulmonary overcirculation and decreased systemic perfusion. The operative mortality rate of 5% in our review compares favorably with the recent reports of early total correction with operative mortality rates of 0 to 12% in patients with nonobstructed TAPVC.1-3 Whether surgery in the second year after birth will decrease the incidence of late postoperative pulmonary venous obstruction is not known. Whightlg and Dickinsonz2 and their co-workers found a high incidence of late obstruction in patients who underwent surgery in the first year of life. None of our patients studied postoperatively has evidence of significant pulmonary venous obstruction; however, long-term follow-up is needed. Postmortem examination of the lungs of the patient who died revealed no evidence of advanced pulmonary vascular disease. This finding, as well as the absence of elevated pulmonary artery pressures in patients who underwent catheterization postoperatively, is consistent with another reportzl that irreversible pulmonary vascular obstructive disease is rare in this anomaly.
Acknowledgmentz We gratefully acknowledge the secretarial assistance of Nancy Mitchell and Sherri McSpadden.
References 1. Turley K, Tucker WY, Ullyot DJ, Ebert PA. Total anomalous pulmonary venous connection in infancy: influence of age and type of lesion. Am r cardiol fs8o;kwz-97. 2. Hammon JW, Bender HW, Graham TP, Boucek RJ, Smith CW, Erath HG. Total anomalous pulmonary venous connection in infancy. 1 Thorac Cardiovast Surg 1980;80:544-551. 3. Mazzucco A, Rizzoli G, Fracasso A, Stellin G, Valfre C, Pellegrino P, Bortolotti U, Gallucci V. Experience with operation for TAPVC in infancy. 1 Thorac Cardiovasc Sure 1983:85:886-690. 4. Jacobsen JR, Boesen ?, Wennevold A. Congenital heart disease before the age of two. Dan Med Bull 1982;29:32-41. 5. Naito Y, Fujita T, Tomino T, Yoshihara K, Isobe F, Nayashi K. Kito Y, Manabe H, Kamiya T. Surgical treatment for severe congknital heart diseases. Inn Circ J 1983:47:1137-3146. 6. Oku’H, Shirot&i H, Okanoto F. Yokota Y, Yokoyama T, Kawai I, Makino S, Satsuie N, Ando F, Nishioka T, Noritake S, Shinohara T, Nakamura Y, Oka H, Saga T, Wakaki N. Surgical results and factors affecting operative mortality in TAPVC. lpn Circ 1 1982;46:675-683. 7. Henlinn CE, Carmichael Ml, Keats AS, Coolev DA. Cardiac operation for congenital heart disease in children of [ehovah’sWitnesses. 1 Th&ac Cardiovast Surg 1985;89:914-920. 8. Mullins CE, El-Said G, Neches WH. Williams R, Vargo T, Nihill M, McNamara D. Balloon atrial septostomy for total anomalous pulmonary venous return. Br Heart J 1973;35:752-757. 9. Miller WW, Rashkind WI, Miller RA, Hastreiter AR, Green EW, Golinko RJ, Young D. Total anomaJ&s pulmonary venous return: effective palliation of critically ill infants by balloon atrial septostomy (abstr). Circulation 1967;36:suppJII:II-189. 10. Serratto M, Bucheleres G, Bicoff P, Miller RA, Hastreiter AR. Palliative balloon atrial septostomy for total anomalous pulmonary venous connection in infancy. [ Pediatr 1968;73:734-739. 11. Rashkind WJ, Miller WW. Creation of an atria1 septal defect without thoracotomy: palliative approach to complete transposition of the great arteries. TAMA 19fi6:196:991-994. 12. Park SC, Neches WH, Mullins CE, Girod DA, Olley PM, Falkowski G, Garibian VA, Mathews RA, Fricker F], Beerman LB, Lenox CC, Zuherbuhler JR. Blade atrial septostomy: collaborative study. Circulation 1982;66:258-266. 13. Reardon MJ, Cooley DA, Kubrusly L, Ott DA, Johnson W, Kay GL, Sweeney MS. Total anomalous pulmonary venous return: report of 201 patients treated surgically. Texas Heart Institute Journal 1985;12:131-141. 14. Kirklin JW. Surgical treatment of total anomalous pulmonary venous connection in infancy. In: Baratt-Boyes BG, Neutze /M, Harris EA, eds. Heart Disease in Infancy: Diagnosis and Surgical Treatment. London: Churchill Livingstone, 1973:89. 15. Burchell HB. Total anomalous pulmonary venous drainage: clinical and physiologic patterns. Mayo CJin Proc 1956;31:161-167. 16. Burroughs JT, Edwards JE. Total anomalous pulmonary venous connection. Am Heart r 1960;59:913-931, 17. Bonham-Carter RE, Capriles M, Noe Y. Total anomaJous puJmonary venous drainage; a clinical and anatomical study of 75 children. Br Heart 1 1969;31:45-51. 18. Nadas AS, Fyler DC. Pediatn’c Cardiology. 3rd ed. New York: W.B. Saunders, 1972:640-652. 19. Whight CM, Barratt-Boyes BG, Caider AL, Neutze JM, Bandt PW. Total anomalous pulmonary venous connection. Long term results following repair in infancy. r Thorac Cardiovasc Surg 1978;75:52-63. 20. Moller JH. Neal WA. Heart Disease in Infancy. New York: AppletonCentury Crofts, 1981:347-359. 21. Peterson RC, Edwards WD. Pulmonary vascular disease in 57 necropsy cases of TAPVC. Histooatholoev 1983:7:487-496. 22. Diikinson DF, Pari&eIazhlian KG, Tweedle MC, West CR, Piccoli GP, Musumeci F, Hamilton DI. TAPVC: repair using deep hypothermia and circulatory arrest in 44 consecutive infants. Br Heart [ 1982;48:249-254.