The bidirectional cavopulmonary shunt

J

THoRAc CARDIOVASC SURG

1990;100:22-30

The bidirectional cavopulmonary shunt The bidirectional cavopulmonary shunt improves systemic arterial oxygen saturation without increasing ventricular work or pulmonary vascular resistance. Since 1983, 17 patients have undergone a cavopulmonary shunt procedure (five primary operations, 12 secondary operations). Diagnoses were single ventricle complex (n = 4), hypoplastic right heart syndrome (n = 10), and hypoplastic left ventricle (n = 3). Age at primary operation ranged from 31/ 2 to 30 months (median 6 months). Weight ranged from 3.5 to 9.7 kg. Age at secondary operation ranged from 10 months to 14 years (median 15 months), Seven cavopulmonary shunt operations were performed without cardiopulmonary bypass (six via thoracotomy and one via sternotomy) and 10, with cardiopulmonary bypass. AU patients in the bypass group had additional procedures: takedown of modified Blalock-Taussig shunt, seven patients; revision of right ventricular outflow tract, four patients; reconstruction of pulmonary arteries, four patients; tricuspid valvuloplasty, one patient; and Damus procedure, one patient. There was one (1/17) operative death (Damus procedure), One patient required early revision. Follow-up ranges from 1 to 53 months (median 23 months). Twelve of 16 had a good to excellent late result, with a rise in mean arterial oxygen saturation from 69% to 83%. Three patients died late (4 to 53 months) (pulmonary vascular disease, pulmonary arteriovenous malformatioffi, and pneumonia, one patient each). There was one late failure (converted to Glenn shunt). The cavopulmonary shunt is an excellent palliative procedure when right atrium-pulmonary artery connection (modified Fontan) must be deferred because of age, weight, or anatomic considerations. Five patients have undergone right atrium-pulmonary artery connection later. In addition, at the time of the modified Fontan operation, the cavopulmonary shunt approach may optimize the anatomic connection (eight additional patients).

John J. Lamberti, MD, Robert L. Spicer, MD (by invitation), J. Deane Waldman, MD (by invitation), Todd M. Grehl, MD (by invitation), Deborah Thomson, RN (by invitation), Lily George, MD (by invitation), Stanley E. Kirkpatrick, MD (by invitation), and James W. Mathewson, MD (by invitation), San Diego. Calif.

h e bidirectional cavopulmonary shunt may be defined as an operation that diverts the systemic venous return from the superior vena cava (SYC) or cavae to both lungs. This surgical connection can provide increased pulmonary blood flowin patients with cyanotic congenital heart disease and reduced pulmonary blood flow.The operation is based on experimental work described by Carlon, Mondini, and de Marchi I in 1951. They demonstrated the feasibility of diverting blood from the SYC to the right pulmonary artery (RPA) in dogs. The clinical use of an From the Divisions of Cardiology and Cardiac Surgery, Children's Hospital and Health Center, and Sharp Memorial Hospital, San Diego, Calif. Read at the Sixty-ninth Annual Meeting of The American Association fer Thoracic Surgery, Boston, Mass., May 8-10, 1989. Address for reprints: John J. Lamberti, MD, 8008 Frost St., Suite 400, San Diego, CA 92123.

12/6/20217

22

SYC-RPA shunt was subsequently demonstrated by Glenn 2, 3 and others." In 1966 Haller and co-workers' performed a bidirectional cavopulmonary shunt experimentally. Since then a number of reports have emphasized the utility of the bidirectional cavopulmonary shunt for palliation in cyanotic congenital heart disease.3,6,7 The cavopulmonary shunt usually consists of an endto-side anastomosis between the SYC and the undivided RPA. Variations include anastomosis of bilateral venae cavae to both pulmonary arteries and the total cavopulmonary shunt type of operation described by Kawashima's? and others. 10, II Each of these variations can provide excellent palliation and set the stage for diversion of the entire systemic venous return to the lungs, as described by Fontan and Bauder'? and later modified by others. 13-15 In our center, we prefer to wait until a child is 3 to 4 years of age before performing the Fontan operation or its modifications. We believe that the risk of a Fontan type connection will belowest if the ideal criteria

Volume 100 Number 1 July 1990

proposed by Fontan and others are carefully followed. Thus the cavopulmonary shunt offers an alternative to the modified Fontan procedure for patients considered to be at higher risk on the basis of age or other anatomic or physical characteristics. The present report details our experience with the cavopulmonary shunt in 17 infants and children since 1983. The indications, operative techniques, and long-term follow-up are presented.

Patient population Since 1983, 17 patients (Table I) have undergone application of the cavopulmonary shunt concept for the treatment of cyanotic congenital heart disease. For the entire group, the ages ranged from J112 months to 14 years (median age 13.0 months). Weights ranged from 4.8 to 28 kg (median weight 7.4 kg). Diagnoses were single ventricle (four patients), pulmonary atresia with intact ventricular septum and severe hypoplasia of the right. ventricle (five patients), tricuspid atresia (five patients), and hypoplastic left heart syndrome variant (three patients). In fivepatients (group I) the cavopulmonary shunt was a primary palliative procedure. In this subgroup, the ages ranged from 31/ 2 to 30 months (median age 6 months). The diagnoses were single ventricle (patients 2 and 5) and tricuspid atresia (patients 7, 13, and 16). All five patients were considered to be candidates for a modified Fontan procedure, but initial palliation with a cavopulmonary shunt was performed to allow for additional growth of the patient. In group I patients the cavopulmonary shunt was added to an existing (nonductal) source of pulmonary blood flow. All patients underwent preoperative catheterization with assessment of pulmonary artery pressure before surgical intervention. Twelve patients (group II) underwent cavopulmonary shunt as an additional palliative procedure or secondary operation. In each patient, anatomic or physical characteristics precluded the use of the modified Fontan operation. Group II patients had cyanosis as a result of reduced pulmonary blood flow; the cavopulmonary shunt was used to increase pulmonary blood flow and to provide a staging procedure for the ultimate use of the modified Fontan operation. Group II patients were older than group I patients and all had undergone at least one prior palliative procedure. Ages ranged from 10 months to 14 years (median age 15 months) and weights ranged from 6.6 to 28 kg (Table I). The diagnoses were tricuspid atresia and prior left modified Blalock-Taussig shunt (two patients), pulmonary atresia with intact ventricular septum and prior Blalock-Taussig shunt (five patients), and hypoplastic left heart syndrome variant (three patients).

Surgical technique In seven patients operation was accomplished without cardiopulmonary bypass (CPB). There were six right thoracotomies and one sternotomy. The sternotomy was used in a 4-month-old female infant (5.3 kg) born with asplenia syndrome. There were bilateral SVCs with no brachiocephalic connection. Pressure in the proximal SVC on each side was measured during clamping. Pressure did not rise above 28 mm Hg with the head slightly elevated. Accordingly, no intraoperative shunt was necessary for SVC decompression. Systemic heparinization (100 units/kg) was administered. The left SVC

Bidirectional cavopulmonary shunt 2 3

was divided at the cavoatrial junction and the cephalad end was anastomosed to the superior aspect of the left pulmonary artery with continuous absorbable suture. Four quadrant sutures were used to avoid the purse-string effect. After completion of the left cavopulmonary anastomosis, the arterial oxygen saturation immediately rose 14%. Then the right cavopulmonary connection was performed in similar fashion. After release of the right SVC clamp, the oxygen saturation rose an additionaIIO%. The six patients undergoing a right thoracotomy were operated on by means of a standard technique. In every patient an intraoperative shunt was used to prevent SVC hypertension during clamping. At operation the azygos vein was ligated and divided and the SVC was mobilized to the level of the innominate vein. The pericardium was entered anterior to the phrenic nerve and the pulmonary artery was completely dissected. After definition of the anatomy, systemic heparinization was administered. An SVC-right atrial temporary shunt was constructed with standard vena caval cannulas used for CPH. Special care was taken to avoid air embolism during shunting. Transient occlusion of the SVC with the temporary shunt clamped usually resulted in SVC pressure greater than 35 mm Hg. With the shunt functioning, SVC pressure tended to be approximately 20 mm Hg. Pressure measurements were performed by direct puncture. No SVC pressure monitoring lines were inserted before the operation. Upper compartment SVC monitoring cannulas should be avoided because they will interfere with the operative field and may be transected during division of the SVc. In addition, we believe that infants and small children should not have a foreign body in the SVC system after construction of the cavopulmonary shunt because stasis might predispose to thrombosis in situ. The SVC is divided a few millimeters above the right atrium with a Potts clamp to minimize tissue destruction. Great care is taken to avoid atrial tissue, because the sinoatrial node is very close to the cavoatrial junction and may be injured by the vascular clamp. The anastomosis must be performed carefully, because any kinking or twisting will interfere with flow in the venous system. We used absorbable 7-0 suture with four-quadrant stay sutures to prevent a purse-string effect. After completion of the anastomosis, the temporary shunt was removed and heparin was reversed only if oozing was noted in the tissues. A standard chest drainage system was used. No effort was made to close the pericardium. Routine postthoracotomy care was used. The head was maintained in a slightly elevated position during recovery. Early extubation was uniformly performed and fluid restriction was not used. In 10 patients the cavopulmonary shunt operation was performed with the aid of cardiopulmonary bypass (CPB). All had undergone previous palliative procedures and none was a candidate for the Fontan approach at the time of the cavopulmonary shunt operation. The ages of eight patients ranged from 10 to 21 months. In our institution, the Fontan procedure is not usually performed in patients under 30 months of age. Two older patients, aged 4 years and 14 years, underwent the cavopulmonary shunt as an additional palliative procedure. In patient I the diagnosis was asplenia with bilateral SVC and azygos continuation of the inferior vena cava. The pulmonary arteries were discontinuous. Operation consisted oftakedown of previous bilateral Blalock-Taussig shunts, restoration of pulmonary artery continuity, and end-to-side anastomosis of the left pulmonary artery and the left SVC; the RPA, which originated from the single ventricle, was divided at its origin and

2 4 Lambertiet aJ.

attached totherightsideoftheleftSYC.TheleftSYCwas then ligated at the junction withthe left atrium. After takedown of the right modified Blalock-Taussig shunt, the right SYC was divided below the insertion of the azygos vein and attached to the superior surface of the RPA. Thisoperation, first described by Kawashima and associatesf is known as a totalcavopulmonary shunt. Our casewasreported in 1986. 11 Patient 12 was born with double-outlet right ventricle, hypoplastic leftventricle, malposition of the greatarteries, and coarctation ofthe aorta. Her initial treatment (at another institution) consisted of bilateral pulmonary artery banding. Although the pulmonary artery bands were laterremoved, she developed severe bilateral pulmonary arterybranch stenosis. Six years before thecavopulmonary shuntoperation sheunderwent coarctation repairand division of a patentductus arteriosus at our institution. In September 1987, bilateral pulmonary artery reconstruction wasperformed withinsertion ofa 6 mmcentral aortopulmonary shunt. Onemonth latera cavopulmonary shunt was added to the 6 mmcentral aortopulmonary shunt. Thepulmonary arteries were considered toosmall to handle the entire systemic venous return. In eightotherpatients, CPB was necessary during construction of the cavopulmonary shunt. During the operation, additional procedures were performed inalleightpatients. Theconcomitant procedures arelisted inTableI. Infive patients, a right modified Blalock-Taussig was taken down and replaced by a cavopulmonary shunt. In patient 15, a rightmodified BlalockTaussig shunt was left in place and the cavopulmonary shunt was performed lateral to the insertion of the 4 mm shunt. In three patients with pulmonary atresiaand intact ventricular septum, a small hypertensive rightventricle was decompressed by pulmonary valvectomy and right ventricular outflow tract reconstruction during the same procedure. All three of these patients with hypoplastic rightheartsyndrome had myocardial sinusoids present at the timeof the cavopulmonary shuntoperation. Patient 10 underwent takedown of a central shunt and revision of a previously placed right ventricular outflow tract patch at the time of the cavopulmonary shunt operation. Pulmonary artery reconstruction was performed at the same time as the cavopulmonary shunt in three patients. Finally, patient 15underwent a second tricuspid annuloplasty procedure and the cavopulmonary shunt. In all patients undergoing operation with CPB,theSYCwas cannulated at itsjunction withthe innominate vein. Mobilizationof theSYCanddivision ofthe azygos vein, when appropriate,were performed forall patients undergoing operation. Care wastakento avoid injury to the sinoatrial node. In general, the SYCcan bedivided well above therightatrialtissue. Caremust be taken to avoid twisting the SYC during the anastomosis. Absorbable sutures were used and four quadrant sutures were placed toavoid a purse-string effect. Inthreepatients intheCPB group, the cavopulmonary shuntrepresented theonly source of pulmonary blood flow after the operation.

Results There was one operative death. A newborn infant with a variant of the hypoplastic left heart syndrome and a ventricular septal defect underwent division of patent ductus arteriosus, subclavian flap aortoplasty for repair of coarctation of the aorta, and pulmonary artery banding.

The Journal of Thoracic and Cardiovascular Surgery

The patient returned at 13 months of age with cyanosis and cardiomegaly. The ventricular septal defect was restrictive and the left ventricular cavity was moderately hypoplastic. Right ventricular pressure was 130/12 mm Hg and left ventricular pressure 75/8 mm Hg. There was a 100 mm Hg gradient across the pulmonary artery band. The patient underwent the Damus procedure" with debanding of the pulmonary artery and creation of a cavopulmonaryshunt. At the completionof the operation, the patient could not be weaned from CPB and appeared to have ventricular dysfunction aggravated by hypoxemia. Direct injection of tolazoline (Priscoline) into the pulmonary artery did not improve oxygenation. The patient could not be oxygenated and had a mean pulmonary artery pressure of 25 mm Hg. CPB was reinstituted, the cavopulmonary shunt was taken down, and a central systemic-pulmonary artery shunt was created. After creation of an ascending aorta-RPA shunt, he still could not be weaned from CPB. This infant was the only patient in the entire series with a preoperative mean pulmonary artery pressure greater than 20 mm Hg (20 to 24 mm Hg at catheterization). Autopsy confirmed a satisfactory Damus connection with a widely patent shunt. Microscopic examination of the pulmonary arterioles revealed mild peripheral extension of medial muscle. Intimal proliferation, plexiform lesions, and thromboembolization were not seen. There was mild focal interstitial fibrosis of the lungs. The clinical impressionwas that there was elevated pulmonary vascular tone aggravated by the operative procedure and not reversible under the conditions present during the operation. Sixteen (16/17) patients survived the cavopulmonary shunt operation (94%). All survivors had had mean pulmonary artery pressure or pulmonary venous wedge pressure measured at preoperative cardiac catheterization. Mean pulmonary artery pressure was never higher than 14 mm Hg in the survivors. The highest pulmonary venous wedge pressure was 17 mm Hg. Fifteen patients had immediate improvement in arterial oxygen saturation. (The average improvement in oxygensaturation was 15.6%.) Patient 3, aged 21 months and totally dependent on the cavopulmonary shunt, had a poor inital responseto operation. A Blalock-Taussigshunt had been excisedand replaced with a cavopulmonary shunt, which was the only source of pulmonary blood flow. When the saturation did not improve over 24 hours, angiography was performed. There was kinking at the anastomosis. The patient underwent revision of the anastomosis with an excellent long-term result. Angiography 28 months later (before a successful Fontan procedure) revealed a widely patent cavopulmonary shunt. The immediate postoperative response to the cavopul-

Volume 100 Number 1 July 1990

Bidirectional cavopulmonary shunt

25

Table I. Clinical data in 17 patients undergoing cavopu1monary shunt (CPS) operation Patient No.

2 3

4

5 6

7

8

9

10

Diagnosis Asplenia. SV. PS, bilateral SVC. PAs discont. SV, DILV, PS

L-BT, R-GOBT

Pulm Atr + IVS, hypoplastic RV, sinusoids Pulm Atr + IVS, hypoplastic RV, sinusoids SV, asplenia, bilateral SVC, PS Pulm Atr + IVS. hypoplastic RV, sinusoids Tr Atr, D-TGA, PS, VSD, small outlet chamber Pulm Atr + IVS, hypoplastic RV, sinusoids HLH variant. hypoplastic LV. MS, restrictive VSD, PAPVD, small ASD Pulm Atr + IVS, Ebstein's anomaly of TV. hypoplastic RV

R-GOBT, patch TV

Take down BT

R-GOBT

II

Tr Atr, small VSD

12

SV, MGA, DORV, coarctation. Mit Atr

13

15

Tr Atr, small VSD, WPW syndrome TGA, Pulm Atr, VSD, severe bilateral PA stenosis. "upstairsdownstairs" ventricles HLH variant

16 17

Tr Atr, VSD PS Tr Atr, Pulm Atr

14

Prior operation

Concomitant operation Take down BT, reconstruct PA

Age

Outcome/ Flu (mo)

14.5

82

88

Fontan 36 rna; died 53 rna, PAVM

9.7

68

86

21 rna

10.5

64

83

10 rna

6.6

60

80

0

Take down BT, reconstruct RVOT, Pulm valvectomy Bilateral CPS

Bjork 38 rna; A + W 39 rna CPS revised POD 3; Fontan 29 rna; A + W 32 rna A +W 31 rna

4mo

5.3

62

91

A + W 28 rna

13 rna

8.6

73

80

Fontan 25 rna; A + W 27 rna

0

Take down BT, reconstruct R VOT, Pulm valvectomy 0

14 rna

8.2

71

85

A + W 24 rna

II rna

7.0

74

82

A + W 23 rna

13 rna

7.4

76

Take down shunt, Pulm valvectomy + R VOT reconstruction repair RPA, + central Ao-Pulm narrow ASD, shunt revise RVOT L-GOBT 0

II rna

6.8

60

75

4 yr

17.6

73

90

Bilateral PAB; bilateral debanding; repair coarctation; bilateral PA repair + central Ao-pulrn shunt 0

Rerevision of LP A

14 yr

28

70

80

R-GOBT

Damus procedure; R-GOBT; TVplasty 0 L-GOBT

0

R-GOBT

L-GOBT

SFA. repair coarctation PAB

0

Take down BT, reconstruct R VOT Pulm valvectomy Damus procedure

4 yr

Preop. Postop. Weight 02 sat. O2 sat. (kg) (%) (%)

2'/2 yr

Operative death (sec text)

6 rna

6.7

67

92

Died 4 rna later after TV replacement (sec text) Died 17 rna later of tracheostomy complications not shunt related Initial good result; at 7 rna, LPA clotted; converted to Glenn shunt; A+W 19mo A + W 13 rna

Take down BT, bilateral PA reconstruction

15 rna

9.8

74

85

A+W 12mo

TVplasty (redo)

18 rna

8.4

69

84

A+W 12 rna

3.5 rna II rna

4.8 9.1

72 77

94 91

A + W 6 rna A+W I rna

0

0 0

Age. Age at CPS: 0, sal. was determined in room air before and after recovery from operation by transcutaneous technique: SV, single ventricle; PS. pulmonary stenosis:SVc. superior vena cava: PA, pulmonary artery: DILV. double-inlet left ventricle: Pulm Atr + IVS, pulmonary atresia plus intact ventricular septum: RV. right ventricle: Tr. Atr., tricuspid atresia: D-TGA. dextro-transposition of the great arteries; VSD, ventricular septal defect; HLH, hypoplastic left heart; LV. left ventricle; MS. mitral stenosis: VSD. ventricular septal defect; PAPVD, partial anornolous pulmonary venous drainage; ASD, atrial septal defect; TV, tricuspid valve; MGA. malposition of the great arteries: DORV, double-outlet right ventricle; Mit. Atr., mitral atresia; WPW, Wolff-Parkinson-White: L-BT, left classic BlalockTaussig shunt; GOBT, Great Ormond Street Blalaock-Taussig shunt; SFA, subclavian nap aortoplasty; PAB, pulmonary artery band; RVOT, right ventricular outflow tract; Ao, aorta; RPA, right pulmonary artery; LPA, left pulmonary artery; PAVM, pulmonary arteriovenous malformation; Bjork, Bjork procedure: A + W. alive and well.

2 6 Lamberti et al.

monary shunt in the other 15 patients was excellent. Patients not undergoing CPB were extubated on the day of operation. Table I details the preoperative and postoperative arterial oxygen saturations with the patients at rest and breathing room air. The early postoperative course was smooth in all patients and congestive heart failure was not encountered in any patient. Patient 16, the youngest patient in the series, had significant fluid retention for 6 weeks after the operation. Aggressive diuretic therapy was necessary because of bilateral pleural effusions. Two months after the operation the chest film was completely clear and her diuretic therapy was gradually withdrawn. Chylothorax occurred in the most recent operation, in patient 17. Five days after an uneventful cavopulmonary shunt performed through a right thoracotomy, chyle began to drain from the chest tube site. Two weeks of a fat-free diet did not resolve the pleural effusion and a 1week course of hyperalimentation with nothing by mouth was required for cure. Patient 17 had transient bouts of supraventricular tachycardia during the first 6 hours after the operation. No further arrhythmias occurred and no antiarrhythmic medication was required. No other patient had an arrhythmia attributable to manipulation of the cavoatrial junction. There were no neurologic complications. Follow-up ranges from 1 to 53 months; median followup is 23 months. Thirteen of the 16 operative survivors are alive and well. One patient had late failure of the cavopulmonary shunt as a result of fibrosis and kinking at the site of the SVC-RPA anastomosis. In this 14-year-old girl (patient 12), the preexisting severe RPA stenosis had been repaired with glutaraldehyde-preserved bovine pericardium. The early postoperative result was excellent. However, the patient returned in 5 months with evidence of SVC obstruction. Reoperation revealed obstruction of the SVC caused by fibrosis and wrinkling of the bovine pericardium. The cavopulmonary shunt was taken down and converted to a Glenn shunt. There were three late deaths. Patient 1, born with asplenia syndrome, died 53 months after bilateral cavopulmonary shunt (11) and 17 months after completion of total CPS (modified Fontan) by connecting hepatic vein blood flow to the left pulmonary artery with an intracardiac baffle. This youngster died of multiple pulmonary arteriovenous malformations causing severe cyanosis and a low output state.!" IS The pulmonary arteriovenous malformations were treated by multiple coil embolizations. Although initial improvement was noted after each embolization, progressive cyanosis developed. No biopsy specimens were obtained and no autopsy was permitted. Another late death occurred in an infant with Ebstein's

The Journal of Thoracic and Cardiovascular Surgery

anomaly of the tricuspid valve, pulmonary atresia, and intact ventricular septum (patient 10). As a neonate the infant underwent immediate right ventricular outflow tract reconstruction and a central shunt. At 11 months of age the central shunt was excised, the outflow tract enlarged, and a cavopulmonary shunt performed. Right pulmonary artery stenosis was reconstructed with bovine pericardium. Two weeks later angiography revealed good function of the cavopulmonary shunt and severe tricuspid regurgitation. Four months later the child was severely limited by tricuspid regurgitation. In addition, the cavopulmonary shunt anastomosis had narrowed as a result of constriction and fibrosis of the bovine pericardium. The child died after takedown of the cavopulmonary shunt, reconstruction of the SVC, closure of the atrial septal defect, and tricuspid valve replacement. Patient 11 died 17 months after a cavopulmonary shunt performed for palliation of tricuspid and pulmonary atresia. The patient initially had a left modified BlalockTaussig shunt. The patient enjoyed excellent palliation and his death was not shunt related. He had multiple congenital anomalies, a tracheostomy, and a severe neurologic deficit since birth and died of a tracheostomy-related incident. The 13 long-term survivors have had excellent palliation. As the children have grown older and larger, their arterial oxygen saturation has gradually decreased and their exercise tolerance has become more limited. We have not documented any decline in late saturation as a result of venous collateral formation between the SVC and the inferior vena cava. Five patients have undergone completion of the modified Fontan connection without difficulty. In one patient the Bjork modification'? was used. One patient undergoing direct right atrium-pulmonary artery anastomosis had a sick sinus syndrome for 3 weeks after his modified Fontan procedure. He underwent an atrial pacing study and an exercise test before discharge. No abnormality of sinoatrial node function was detected at the time of discharge. Nine patients underwent follow-up angiography. In two patients (described earlier), the angiogram showed stenosis of the anastomosis caused by fibrosis and shriveling of a bovine pericardial patch used to reconstruct a stenotic RPA. In patients in whom direct anastomosis of the SCV to the RPA was possible, excellent growth of the anastomosis was noted. Fig. 1 depicts the 3-year result in patient 2. This study was performed before a Bjork procedure for completion of his repair. Fig. 1 reveals wide patency of the anastomosis. This patient underwent the Bjork procedure 38 months after the cavopulmonary shunt operation. In patient 14, early postoperative angiog-

Volume 100 Number 1 July 1990

Fig. 1. Angiogram reveals wide patency ofthe cavopulmonary anastomosis in patient 2. The angiogram was performed 3 years after the cavopulmonary shunt operation. Bidirectional pulmonary blood flow is noted. The patient still had some pulmonary blood flowthrough the main pulmonary artery at the time of this angiogram.

raphy and technetium perfusion studies confirmed excellent bilateral pulmonary blood flow and wide patency of the anastomosis.

Discussion This report details our experience with the cavopulmonary shunt to augment pulmonary blood flow in selected children with cyanotic congenital heart disease. Followup studies after the Fontan approach have shown that important risk factors include (1) ventricular function, especiallycompliance, (2) pulmonary vascular resistance, and (3) pulmonary arterial anatomy-often distorted by prior shunt procedures.P''? In contrast to a systemicpulmonary shunt, the cavopulmonary shunt does not increase ventricular work (thereby avoiding further ventricular hypertrophy and decreased compliance), does not put the pulmonary vascular resistance at risk, and does not distort the pulmonary arteries. In comparison with the Glenn shunt, the cavopulmonary shunt provides bilateral pulmonary blood flow and thereby avoids the mismatch that may occur between the volume of SVC flow and the cross-sectional area of the entire right lung. Whereas previous reports on the Glenn shunt or the Fontan procedure discuss the importance of normal pulmonary vascular resistance,3.2o-22 we believe that low pulmonary artery pressure, in addition to normal pulmo-

Bidirectional cavopulmonary shunt 27

nary resistance, is a critical success factor. Pulmonary vascular resistance could be normal when there is pulmonary venous hypertension caused by systemic atrioventricular valve abnormalities or elevated ventricular enddiastolic pressure. In these circumstances, the pulmonary artery pressure would be elevated and a cavopulmonary shunt would not function properly. The need to minimize pulmonary artery pressure and resistance is a major consideration when palliating infants destined for a Fontantype repair. In general, we believe it is better to use a smaller systemic-pulmonary artery shunt or to place an early pulmonary artery band in these infants. Recent reports advocate the early use of the Damus connection with or without a cavopulmonary shunt for patients ultimately destined for the Fontan connection.P 24 Because the pulmonary artery pressure is critical in determining outcome after the cavopulmonary shunt, we recommend aggressive attempts at direct (through systemic-pulmonary shunts with 4F catheters if necessary) or indirect measurement (using the pulmonary venous wedge pressure-'). Intraoperative pressure measurements may also be helpful in decision making when other methods of obtaining the pulmonary artery pressure have not been fruitful. Traditional thinking has indicated that the Glenn shunt should be avoided in infants less than 6 months of age." Our data suggest that the cavopulmonary shunt can be done at any age after the pulmonary vascular resistance has reached it nadir. Seven of our patients were younger than 1 year of age and each received excellent palliation. The cavopulmonary shunt operation can be performed with or without CPB depending on the preoperative source of pulmonary blood flow. In our experience." a 4 mm modified Blalock-Taussig shunt performed in the neonate will provide adequate palliation for about 1 year. In infants of 12 to 18 months of age the cavopulmonary shunt appears to be an excellent addition to a previous left-sided Blalock-Taussig shunt. Because the cavopulmonary shunt places neither the pulmonary vasculature nor ventricular function at risk, it is our preferred "bridge" to the Fontan procedure. An important aspect of preoperative evaluation is the precise definition of the systemic venous connections: (1) Are there two SVCs? (2) Is there a brachiocephalic anastomosis? (3) Is there azygos continuation of the inferior vena cava? When two SVCs are present, both need to be joined to the appropriate pulmonary artery. If this were to be done at two different procedures, a sizeable brachiocephalic anastomosis might allow flow intended for the pulmonary artery to be diverted to the lower-resistance atrium. However, if both SVCs are anastomosed

The Journal of Thoracic and Cardiovascular

2 8 Lambertiet aJ.

at a single operation, the large brachiocephalic connection can act as a bridge to allow equilibration of right and left pulmonary blood flow.When there is azygos continuation of the inferior vena cava, the SVC receiving the azygos vein will be carrying over 60% of all systemic venous return. This factor must be considered when this vessel is being connected to the pulmonary arteries, especially if pulmonary hypoplasia or stenosis is present. An additional advantage of the cavopulmonary shunt is the possibility that balloon dilatation of peripheral branch pulmonary artery stenosis can be performed after the shunt is in place and functioning. The development of pulmonary arteriovenous fistulas in patient I is of interest because pulmonary flow maldistribution 28, 29 and systemic venous collaterals-? have been reported in other patients undergoing a type of cavopulmonary shunt procedure. The pulmonary fistulas in our patient became apparent within 2 years of the cavopulmonary shunt operation. Because others in our series have been followed up longer without evidence of such fistulas, we do not believe that a direct causal relationship exists between the cavopulmonary shunt and pulmonary arteriovenous fistulas. In conclusion, the cavopulmonary shunt providesexcellent palliation for selected patients with cyanotic congenital heart disease. The cavopulmonary shunt approach is a useful adjunct to completion of Fontan-type repairs. Pulmonary artery pressure must be low for optimal function of the cavopulmonary shunt. Finally, bovine pericardium augmentation of the pulmonary arteriesin conjunction with a cavopulmonary shunt should be avoided. REFERENCES I. Carlon CA, Mondini PG, de Marchi RD. Surgical treatment of some cardiovascular diseases (a new vascular anastomosis). J Int Coli Surg 1951;16:1-11. 2. Glenn WWL. Circulatory bypass of the right side of the heart. IV. Shunt between superior vena cava and distal right pulmonary artery-report of clinical application. N Engl J Med 1958;259:117-20. 3. Glenn WWL. Superior vena cava-pulmonary artery shunt. Ann Thorac Surg 1989;47:62-4. 4. Bakulev AN, Kolesnikov SA. Anastomosis of superior vena cava and pulmonary artery in the surgical treatment of certain congenital defects of the heart. J THORAC SURG 1959;37:693-702. 5. Haller JA, Adkins JC, Worthington M, Ravenhorst J. Experimental studies on permanent bypass of the right heart. Surgery 1966;59:1128-32. 6. Hopkins RA, Armstrong BE, Serwer GA, Peterson RJ, Oldham HN. Physiological rationale for a bidirectional • cavopulmonary shunt: a versatile complement to the Fon-

Surgery

7.

8.

9.

10.

II.

12. 13. 14.

15.

16. 17.

18.

19.

20.

21.

22.

tan principle. J THORAC CARDIOVASC SURG 1985;90: 391-8. Mazzera E, Como A, Picardo S, et al. Bidirectional cavopulmonary shunts: clinical applications as staged or definitive palliation. Ann Thorac Surg 1989;47:415-20. Kawashima Y, Kitamura S, Matsuda H, Shimazaki Y, Nakano S, Hirose H. Total cavopulmonary shunt operation in complex cardiac anomalies. J THORAC CARDIOVASC SURG 1984;87:74-81. Kawauchi M, Asano K, Shindo G, Miyairi T. Total cavopulmonary shunt with replacement of common atrioventricular valve for an infant with single atrium and single ventricle. Ann Thorac Surg 1985;40:192-4. Kreitmann P, Bourlon F, Jourdan J, Dor V. Surgical treatment of primitive ventricle and complex congenital heart malformation with total exclusion of the right heart: report of a case. J THORAC CARDIOVASC SURG 1982;84:150. Waldman JD, Lamberti JJ. Anastomosis of systemic veins to pulmonary arteries for physiologic repair of asplenia syndrome. Pediatr Cardiol 1986;6:327-30. Fontan F, Baudet E. Surgical repair of tricuspid atresia. Thorax 1971;26:240-8. Kreutzer EA. Atriopulmonary anastomosis. J THORAC CARDIOVASC SURG 1982;83:427-36. Jonas RA, Castaneda AR. Modified Fontan procedure: atrial baffle and systemic venous to pulmonary artery anastomatic techniques. J Cardiac Surg 1988;3:91-6. de Leval M, Kilner P, Gewillig M, Bull C. Total cavopulmonary connection: a logical alternative to atriopulmonary connection for complex Fontan operations. J THoRAc CARDIOVASC SURG 1988;96:682-95. Waldman JD, Lamberti JJ, George L, et al, Experience with Damus procedure. Circulation 1988;78(Pt 2):III32-9. Matsuda H, Kawashima Y, Hirose H, Nakano S, Kishimoto H, Sano T. Evaluation of total cavopulmonary shunt operation for single ventricle with common atrioventricular valve and left isomerism. Am J Cardiol 1986;58:180-2. Gomes AS, Benson L, George B, Laks H. Management of pulmonary arteriovenous fistulas after superior vena cavaright pulmonary artery (Glenn) anastomosis. J THORAC CARDIOVASC SURG 1984;87:636-9. Bjork VO, Olin CL, Bjarke BB, Thoren CA. Right atrialright ventricular anastomosis for correction of tricuspid atresia. J THORAC CARDIOVASC SURG 1979;77: 452-8. Kirklin JK, Blackstone EH, Kirklin JW, Pacifico AD, Bargeron LM. The Fontan operation: ventricular hypertrophy, age, and date of operation as risk factors. J THORAC CARDIOVASC SURG 1986;92:1049-64. Fontan F, Deville C, Quaegebeur J, et al. Repair of tricuspid atresia in 100 patients. J THORAC CARDIOVASC SURG 1983;85:647-60. Choussat A, Fontan F, Beese P, Vallot F, Chaune A, Bricaud A. Selection criteria for Fontan's procedure. In: Anderson RA, Shinebourne EA, eds. Paediatric cardiology 1977, Edinburgh: Churchill Livingstone, 1978:559-61.

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23. Freedom RM. The dinosaur and banding of the main pulmonary trunk in the heart with functionally one ventricle and transposition of the great arteries: a saga of evolution and caution. J Am Coli Cardiol 1987;10:427-9. 24. DiDonato R, DiCarlo 0, Giannico S, Marcelletti C. Palliation of complex cardiac anomalies with subaortic obstruction: new operative approach. J Am Coil Cardiol 1989; 13:406-12. 25. Waldman JD, LaCorte MA, Dick M, Miettinen 0, John SA, LaFarge CG. The pulmonary venous wedge pressure in pulmonary artery hypertension. Cathet Cardiovasc Diagn 1977;3:231-9. 26. Karp RB, Bargeron LM. Late results of superior vena cava-right pulmonary artery anastomosis for tricuspid atresia. In: Kirklin JW, ed. Advances in cardiovascular surgery. New York: Grune and Stratton, 1973:37-44. 27. Lamberti JJ, Carlisle JR, Lodge FA, et al. Systemicpulmonary shunts in infants and children: early and late results ..J THORAC CARDIOVASC SURG 1984;88:76-81. 28. Boruchow IB, Swenson EW, Elliott LP, Wheat MW. Study of the mechanisma of shunt failure after superior vena cava-right pulmonary artery anastomosis. J THoRAc CARDIOVASC SURG 1970;60:531-9. 29. Laks H, Mudd G, Standeven JW, Fagan L, Willman VL. Long-term effect of the superior vena cava-pulmonary artery .anastornosis on pulmonary blood flow. J THORAC CARDIOVASC SURG 1977;74:253-60. 30. Willman VL, Barner HB, Mudd JG, Fagan LF, Kaiser GC. Superior vena cava-pulmonary artery anastomosis. J THORAC CARDIOVASC SURG 1974;67:380-6.

Discussion Dr. Richard J. Peterson (Durham. NiC}. At Duke University we have also used the bidirectional cavopulmonary shunt in a number of patients. It is our impression that a bidirectional shunt may improve postoperative recovery in selected patients with complex anatomy. We have found first-pass radionuclide angiocardiography to be a useful adjunct in evaluation of the relative right and left pulmonary blood flow in these patients. [Slide) This first-pass radionuclide study demonstrates bidirectional flow to the right and left lungs and subsequent return to the systemic ventricle. Time activity histograms confirm relative quantitation of flow to the right and left lungs with preferential right lung flow (62%) in this particular study performed in January of 1983. A similar study performed in the same patient in June of 1983 demonstrated a dynamic equilibration of flow, with nearly equal flow to the right and left lungs. I commend Dr. Lamberti and his colleagues for their series of bidirectional cavopulmonary shunts. They have confirmed the efficacy and relative safety of the procedure. We also support the concept of the bidirectional shunt as a bridge to a Fontan procedure, especially in younger patients with complex physiology. An interesting facet in their study is the use of bidirectional cavopulmonary shunts in seven patients less than I year of age. I would like to ask Dr. Lamberti to further define the specific

Bidirectional cavopulmonary shunt 2 9

criteria for performance of this shunt relative to pulmonary vascular resistance. Dr. Lamberti. We think the pulmonary artery pressure is more important than resistance. Elevated end-diastolic pressure in the ventricle or atrioventricular valve regurgitation may be a relative contraindication to this type of shunt unless something else is being done that would improve ventricular performance. We would perform the shunt in an appropriate patient if the pulmonary artery pressure was less than 20 mm Hg and the resistance was presumably normal. Dr. Peterson. What is your concept of the influence of the bidirectional cavopulmonary shunt in young patients in terms of pulmonary artery growth, perhaps relative to systemic pulmonary shunts? Dr. Lamberti. I think we have restudied six patients, and it appears that the pulmonary arteries grow. We have not attempted to measure the pulmonary arteries in a systematic fashion. However, the angiogram at 3 years' follow-up suggests that the vena cava, the anastomosis, and the arteries have all grown. Dr. Richard A. Jonas (Boston, Mass.). I strongly endorse Dr. Lamberti's presentation. In the past we were faced with the dilemma of how to deal with patients with complex forms of single ventricle who had a number of risk factors for the Fontan procedure, particularly patients after first-stage palliation of hypoplastic left heart syndrome. With Dr. Lamberti's encouragement, we began a program of placing a bidirectional cavopulmonary shunt for such patients about a year ago. Since then we have performed 30 of these operations at Boston Children's Hospital with no deaths, either early or late. One patient required takedown a few days postoperatively because of persistent cyanosis. Probably the most remarkable thing about this group of patients has been the complete absence of persistent pleural effusions, even though these were particularly high-risk Fontan patients. Had these patients had Fontan operations, a large percentage of them undoubtedly would have had persistent pleural effusions for 2 to 3 weeks. The mean oxygen saturation postoperatively in room air, as in Dr. Lamberti's group, was quite satisfactory, at 83%. Dr. Lamberti, do you have any evidence that this operation does in fact reduce the risk of a subsequent Fontan procedure, which is our hope? If so, is it by improving the standard risk factors like ventricular function or pulmonary resistance, or do you think there may be some physiologic adaptation to higher venous pressure that might improve the subsequent suitability for a Fontan procedure? Dr. Lamberti. I think it might be a preparatory operation. We have completed the connection in only four patients. One of the patients had mildly troublesome pleural effusions after the Bjork modification, even though he had no pleural effusions after the cavopulmonary shunt. We encountered pleural effusions in the 3Y2-month-old baby who had a cavopulmonary shunt, so we have seen pleural effusions after this shunt. Finally, to do the connection, one must mobilize the right atrium. The sick sinus syndrome was present for about 2 weeks after a Fontan procedure in one of our patients. In summary, I can't definitely say that this approach prepares the patients for the Fontan operation other than that the cavopulmonary shunt makes them older so that they may be at lower risk for a Fontan connection.

3 0 Lamberti et al.

Dr. Yasunaru Kawashima (Osaka. Japan). I quite agree with Dr. Lamberti that the bidirectional cavopulmonary shunt is an excellent palliative procedure for complex cardiac anomaties. In addition, this can be a definitive palliation in a certain type of anomaly. In patients without an inferior vena cava and with azygos or hemiazygos continuation, this bidirectional shunt, together with ligation of the pulmonary arterial trunk, provides definitive palliation though the arterial oxygen saturation remains a little low because of hepatic venous flow. We performed the total cavopulmonary shunt operation for the first time in 1968, and since then 39 such operations have been performed in Japan. The result of this operation was not satisfactory when performed together with atrioventricular valve replacement, but a reasonable result was obtained when performed before atrioventricular valve regurgitation developed. Pulmonary arteriovenous fistula formation is a great concern in this operation, but so far the later result is also satisfactory in most of the patients. Dr. John L. Myers (Hershey, Pa.). The bidirectional cavopulmonary shunt offers a nice alternative to the standard systemic artery-pulmonary artery shunt in those infants who need more pulmonary blood flow and who have anatomy that commits them to a Fontan procedure, but who are not yet ready for total cavopulmonary connection. However, we proceed with the Fontan operation any time after 1 year of age if the physiology is good. Infants with hypoplastic left heart syndrome or single ventricle with pulmonary atresia receive a systemic artery-pulmonary artery shunt in the newborn period. Despite small 4 mm Impra shunts (Impra, Inc., Tempe, Ariz.), these infants frequently have some degree of excessive pulmonary blood flow and congestive heart failure until they grow into the shunt. Application of the bidirectional cavopulmonary shunt in

The Journal of Thoracic and Cardiovascular Surgery

these newborn infants would be highly advantageous if the pulmonary vascular resistance could be kept low either by postoperative hyperventilation and/or infusion of prostaglandin E J or by maintaining the neonate on prostaglandin E, for several weeks until the pulmonary vascular resistance drops. This shunt would certainly avoid the chronic volume overload on these single ventricles, which are often of a right ventricular morphology. I have two questions for the authors: Your youngest patient was 3Y2 months old. Did you encounter any problems postoperatively related to reactive pulmonary vascular resistance and what levelof central venous pressure did you have postoperatively? Dr. Lamberti. We did not encounter any problems related to pulmonary resistance in that patient. I would do the shunt in any patient in whom the pulmonary artery pressure was known to be under 20 mm Hg. I do not routinely insert catheters in the superior compartment after this operation. We measure the pressure in the operating room and check for a gradient across the anastomosis. Typically, the pressures are in the 12 to 14 or 16 mm Hg range. Then, because the management postoperatively is somewhat different than for a systemicpulmonary shunt, we try to extubate the baby early and avoid fluid restriction. Other than that, we have not systematically measured pressure in the superior compartment. Dr. Myers. Have you considered using this bidirectional cavopulmonary shunt in either neonates or infants younger than 3 months? Dr. Lamberti. I would be very cautious about using the shunt in a newborn infant, but I would use it in a I-month-old child if I had the right patient, if the pressure was low. I am sure that there are I-rnonth-old babies who could tolerate this shunt.