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Ann Thorac Surg 1995;59:342-347
© 1995 The Society of Thoracic Surgeons

Aortic to Right Ventricular Shunt for Pulmonary Atresia and Intact Ventricular Septum

Division of Cardiothoracic Surgery, Department of Surgery, University of California, Los Angeles, Medical Center, Los Angeles, California

Accepted for publication September 14, 1994.

	Abstract

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Acute or chronic myocardial ischemia may develop in patients with pulmonary atresia with intact ventricular septum and right ventricular-dependent coronary circulation. In such cases an aorta to right ventricle shunt may be used to reverse this ischemia. This report summarizes our experience with the placement of an aortic to right ventricular shunt in 5 patients. The shunts were made of Gore-Tex and ranged from 4 mm to 8 mm. Associated procedures were bidirectional Glenn (n = 2) and Fontan (n = 2). All 5 patients survived the procedure with documented early graft patency and no evidence of ischemia.

	Introduction

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Pulmonary atresia with intact ventricular septum (PA-IVS) constitutes a spectrum of pathology based on underdevelopment of the right ventricle and tricuspid valve. In those with the more severe form there is a 50% to 60% incidence of right ventricle to coronary artery connections [1]. These connections are frequently accompanied by the development of fibrous intimal hyperplasia, resulting in lumenal stenosis or complete obstruction of the native coronary circulation. The presence of high-grade lesions in the proximal coronary arterial system may produce a right ventricular-dependent coronary circulation [2]. Such patients are at high risk of myocardial ischemia, as desaturated blood from the right ventricle perfuses a significant portion of the myocardium. This situation may be worsened by reduced diastolic pressure from systemic to pulmonary artery shunts and by severe systemic desaturation. In such patients, decompression of the right ventricle by a right ventricular outflow patch, pulmonary valvotomy, or tricuspid valvotomy/valvectomy is poorly tolerated [3]. Thromboexclusion has been described for this lesion but may reduce flow to the coronary arteries dependent on a right ventricular source [4]. The preferred initial treatment in the neonatal period is a systemic to pulmonary artery shunt to provide a secure source of pulmonary blood flow, without decompression of the right ventricle. Subsequent palliation with a bidirectional Glenn shunt has the advantage of improving the arterial oxygen saturation without reducing diastolic pressure or imposing a volume load on the ventricle. Definitive therapy has been limited to the modified Fontan procedure with a lateral tunnel created so that oxygenated blood from the left atrium may fill the right ventricle and thus the coronary arteries. Orthotopic heart transplantation has been suggested as a treatment for this group of severely affected infants [5].

We have explored a new approach to this problem, which is to supply oxygenated blood at systemic pressure directly to the right ventricular cavity. This may be done by creating an aortic to right ventricular shunt. This shunt has been used successfully on 5 patients and is described in the report that follows. Freeman and associates [6] recently reported their experience with this approach in a patient undergoing a Fontan procedure.

	Case Reports

Top Footnotes Abstract Introduction Case Reports Comment References

 
Patient 1
This term baby boy was noted to be cyanotic a few hours after birth. Cardiac evaluation revealed PA-IVS, a severely hypoplastic right ventricle, and a right ventricular-dependent coronary circulation. On day 4 of life he underwent a modified left Blalock-Taussig shunt. He was then managed medically with digoxin, furosemide, and spironolactone. Over the next 6 months increasing cyanosis and respiratory distress on exercise developed. Repeat catheterization at age 2 years 8 months confirmed the diagnosis of PA-IVS with a patent shunt and mild left ventricular dysfunction. The right ventricle was severely hypoplastic and both the posterior descending and left anterior descending coronary arteries appeared to be arising from the right ventricle. Antegrade coronary angiography showed only the circumflex coronary artery to be arising from the aorta. In view of these findings we decided to proceed with a lateral tunnel Fontan procedure without decompressing the right ventricle.

At operation, the right ventricle was severely hypoplastic. The pulmonary artery pressure was measured and found to be 8 mm Hg with a left atrial pressure of 3 mm Hg. The blood pressure was 80 mm Hg systolic with an arterial O₂ saturation of 74%. The patient was placed on cardiopulmonary bypass (CPB), and a modified Fontan procedure was performed with total cavopulmonary connection using a Gore-Tex (W.L. Gore, Naperville, IL) patch lateral tunnel in the right atrium and a snare-controlled adjustable atrial septal defect (ASD). The left subclavian to pulmonary artery Gore-Tex graft was taken down. Myocardial protection was achieved using cold blood cardioplegia given antegrade, retrograde through the coronary sinus, and directly into the right ventricular cavity. Warm blood cardioplegia was given antegrade and retrograde before release of the cross-clamp. The heart resumed normal sinus rhythm, and after rewarming the patient was weaned off CPB. Initial blood pressure was 85/60 mm Hg with a right atrial (RA) pressure of 16 mm Hg and a left atrial (LA) pressure of 8 mm Hg, with an O₂ saturation of 90% and the ASD partially open.

After 5 minutes off bypass and after protamine administration, a progressive deterioration in hemodynamics occurred with ST segment depression and a progressive increase in the LA pressure. The transesophageal echocardiogram showed poor ventricular function with severe hypokinesis anteriorly and laterally. These clinical parameters suggested inadequate coronary flow from the right ventricular collaterals. We therefore decided to revascularize the right ventricle using an aorta to right ventricular (Ao–RV) shunt. Heparin was readministered and CPB was reinstituted. A 5-mm Gore-Tex graft was placed from the aorta to the infundibulum of the right ventricle (Fig 1). Soon after the graft was opened, ventricular function, which was being monitored on transesophageal echocardiogram, dramatically improved. After rewarming, the patient was weaned from bypass without inotropic agents and with a blood pressure of 100/70 mm Hg, an RA pressure of 10 mm Hg, and an LA pressure of 3 mm Hg. The right ventricular (RV) pressure was suprasystemic and measured 130/25 mm Hg with the graft open and dropped to 15 mm Hg less than systemic with the graft closed.

View larger version (51K): [in this window] [in a new window]   Fig 1. . Aorta to right ventricle shunt in patient 1.

View larger version (168K): [in this window] [in a new window]   Fig 2. . Postoperative angiogram of patient 1 showing the patent aorta to right ventricle shunt.

Patient 2
This baby girl was noted to be cyanotic soon after birth and was started on a regimen of prostaglandin E. Cardiac catheterization demonstrated PA-IVS and a severely hypoplastic right ventricle. The right coronary artery had a connection to the right ventricle. The left anterior descending coronary artery arose from the infundibulum and the circumflex coronary arose from the apex of the right ventricular cavity (Fig 3). In view of these findings we decided to perform a systemic to pulmonary shunt without decompression of the right ventricle.

View larger version (80K): [in this window] [in a new window]   Fig 3. . Preoperative angiograms of patient 2 showing the right ventricle to coronary artery fistula.

During the ensuing weeks there were electrocardiographic changes suggesting ischemia with transient ST segment elevations. We therefore decided to proceed with an Ao–RV shunt to improve the coronary blood supply. At age 6 weeks the infant was taken to the operating room, where a severely hypoplastic right ventricle and dilated left ventricle were found. The patient was placed on CPB and systemically cooled. The right subclavian to pulmonary artery shunt was occluded. Cold blood cardioplegia was given antegrade into the aortic root and also directly into the RV cavity. A 4-mm Gore-Tex graft was placed from the aorta to the anterior right ventricle. After warm blood cardioplegia was given and the heart was deaired, the cross-clamp was released. The heart resumed a normal sinus rhythm but the patient could not be weaned from CPB because of what was believed to be a volume overload on the left ventricle due to the subclavian-to-pulmonary artery shunt. We therefore decided to takedown the subclavian-to-pulmonary artery shunt and replace it with a bidirectional Glenn shunt. The patient was easily weaned from bypass with an arterial O₂ saturation of 84%. The blood pressure was 80 mm Hg systolic and the RV pressure was only slightly less than systemic. Transesophageal echocardiogram demonstrated that ventricular function was now satisfactory.

Postoperatively she had marked hypoxia with the arterial O₂ saturation in the 60% to 70% range for the first 2 days. Subsequently elevated pulmonary artery pressures developed with low cardiac output, requiring high-dose inotropic agents and pulmonary vasodilators. This gradually resolved. On postoperative day 11 a thrombus was detected in the superior vena cava. This was treated with a streptokinase infusion followed by heparin administration. On day 13 she required pericardiocentesis for a large pericardial effusion. On day 15 she had a seizure and ventricular fibrillatory arrest, from which she was successfully resuscitated. There were no further seizures with phenobarbitone treatment, and her computed tomographic scan and electroencephalogram were normal. On day 25 she was extubated and on day 30 she was discharged to a community hospital to establish feeding. Echocardiogram before discharge showed biphasic systolic and diastolic flow through the Ao–RV shunt. The O₂ saturation was 70% to 80% on 1.5 L O₂.

At the 1-year follow-up she was doing well and catheterization showed patency of the Ao–RV shunt.

Patient 3
This term baby girl presented with cyanosis. She was treated with prostaglandin E. Evaluation with echocardiography and cardiac catheterization confirmed the diagnosis of PA-IVS with severely hypoplastic right ventricle and multiple right ventricular to coronary artery communications. At age 2 days she underwent a right innominate artery to right pulmonary artery 3-mm Gore-Tex shunt. Repeat catheterization at 3 months confirmed the diagnosis of PA-IVS with a patent right Blalock-Taussig shunt. The right ventricle was severely hypoplastic. There was early filling of the right and left coronary arteries from the right ventricle. There were multiple right ventricle to coronary artery fistulas. The right coronary ostium was dilated and there was a severe stenosis in the proximal part of the artery. There was a tortuous fistula from the left coronary artery to the right ventricle. The O₂ saturation in the right ventricle was 43% with an arterial O₂ saturation of 83%. The pressure in the right ventricle was suprasystemic, 165/10 mm Hg, with a systemic pressure of 125/45 mm Hg. In view of these findings, we decided to proceed with a bidirectional Glenn shunt at age 6 months together with an Ao–RV shunt to ensure adequate coronary blood supply. The decision to add the Ao–RV shunt was based on the presence of the severe proximal stenosis in the right coronary artery and the presence of multiple RV-to-coronary artery fistulas.

At operation, the right ventricle and tricuspid valves were found to be severely hypoplastic and the left and right coronary arteries were dilated. On CPB an atrial septectomy was performed. The tricuspid valve measured 6 mm and was slightly regurgitant on testing. Therefore, a tricuspid annuloplasty was carried out. A 5-mm Gore-Tex graft was placed from the aorta to the right ventricle. A bidirectional Glenn shunt was created. After coming off bypass, the arterial diastolic pressure was found to be low at about 20 mm Hg with a systolic pressure of 80 mm Hg systolic. Occlusion of the Ao–RV shunt raised the blood pressure to 85/40 mm Hg. Echocardiography showed no significant tricuspid regurgitation. The coronary sinus was large, and we thought that coronary artery to coronary sinus fistulas possibly could account for the low diastolic pressure. Therefore, the Ao–RV shunt was partially snared to raise the diastolic pressure to 35 mm Hg. The arterial O₂ saturation with the Glenn and Blalock-Taussig shunts open was 93%.

Postoperatively, she did well except for persistent right upper lobe atelectasis, which resolved with chest physiotherapy.

Patient 4
This infant girl was born with PA-IVS. She underwent a classic right Blalock-Taussig shunt in the newborn period. She subsequently had a left Blalock-Taussig Gore-Tex shunt placed at 2 years of age for increasing cyanosis. Cardiac catheterization at this time showed right ventricular to right coronary artery sinusoids. She was lost to follow-up until 7 years of age, when repeat catheterization showed the same with a mean pulmonary artery pressure of 20 mm Hg. Further catheterization at 13 years demonstrated a markedly hypoplastic right ventricle with extensive communications to the right coronary artery system. The RV pressure was suprasystemic. Selective injections into the right coronary artery showed areas of severe stenosis in the proximal portion of this artery. The left coronary system was small. The pressure in the left pulmonary artery was 16 mm Hg and in the right pulmonary artery it was 10 mm Hg with a stenosis at their confluence. Left ventricular function was satisfactory, with an ejection fraction of 0.53. Her symptoms were those of fatigue and exercise intolerance. We thought that she was a good candidate for a bidirectional Glenn shunt combined with an Ao–RV shunt.

The left Blalock-Taussig shunt was taken down, a bidirectional Glenn shunt was created, the stenosis at the confluence of the branch pulmonary arteries was patched, and an 8-mm Gore-Tex shunt was inserted from the aorta to the RV. After weaning from CPB the blood pressure was 100/80 mm Hg. The RV pressure was 95/75 mm Hg with the shunt open and 60/2 mm Hg with the shunt closed. Transesophageal echocardiography showed a trivial tricuspid regurgitant jet and excellent ventricular function.

Her postoperative course was unremarkable and she was discharged home after 5 days.

Patient 5
This boy was born full-term; severe cyanosis developed on his second day of life. Echocardiogram revealed PA-IVS. He was placed on a regimen of prostaglandin E and underwent cardiac catheterization, during which an atrial septotomy was performed. A right Blalock-Taussig shunt was performed on day of life 4. At age 8 months, he underwent a bidirectional Glenn shunt with patch augmentation of proximal left pulmonary artery stenosis. At age 21 months, he had chest pain with diaphoresis accompanied by electrocardiographic changes. Cardiac catheterization revealed PA-IVS and RV-dependent coronary circulation with large fistulous connections to the right coronary artery and circumflex coronary artery. The anterior descending artery was not well seen either antegrade or from the right ventricle. The left atrial pressure was 3 mm Hg, the mean pulmonary artery pressure was 10 mm Hg, and left ventricular function was slightly reduced. A positron emission tomographic scan showed evidence of apical and inferior ischemia.

The child then underwent takedown of the Blalock-Taussig shunt, a lateral tunnel unidirectional Fontan with snare adjustable ASD, and Ao–RV 6-mm Gore-Tex shunt. After weaning from CPB, systemic and RV pressures were equal with the shunt open. Intraoperative echocardiography showed good ventricular function with RV to aortic flow with systole and aortic to RV flow during diastole. The child's ASD was snared on postoperative day 1 and he was extubated on day 2. He had an uneventful recovery with resolving electrocardiographic changes and was discharged home on postoperative day 7. He was discharged on a regimen of low-dose warfarin and aspirin.

	Comment

Top Footnotes Abstract Introduction Case Reports Comment References

 
Patients with PA-IVS currently are stratified into three groups based on the morphology of the right ventricle and tricuspid valve [7, 8]. In those with mild or moderate RV hypoplasia, treatment options include decompression of the RV in the hope that this will stimulate its growth and eventually allow for a biventricular repair. Decompression can be accomplished by valvotomy or RV outflow tract patching, usually combined with a systemic to pulmonary artery shunt. Patients with a severely hypoplastic RV are treated as neonates with a shunt only. If they do not have an RV-dependent coronary circulation, they undergo a procedure on bypass at 2 to 3 months of age with enlargement of the RV by myectomy, insertion of a transannular patch, a bidirectional Glenn shunt, and an adjustable ASD.

Abnormalities of the coronary circulation occurs in 60% of patients with a severely hypoplastic right ventricle [1]. These abnormalities fall into three broad groups. The mildest form consists of tortuous sinusoidal connections between the right ventricle and the coronary circulation and the native coronary circulation is unobstructed and normal in distribution. These patients are considered to have a nonindependent coronary circulation. In these patients it has been shown that decompression of the RV is usually well-tolerated and will result in resolution of the fistulous connection. One approach to these patients is a subclavian to pulmonary artery Gore-Tex shunt in the neonatal period without decompression of the RV. At 2 to 3 months, a repeat catheterization is performed. If this demonstrates a non–RV-dependent coronary circulation, the RV is decompressed with a transannular patch if growth of the RV is considered possible. If RV growth is thought to be unlikely, the patient is treated by tricuspid valve excision and a bidirectional Glenn shunt is performed.

The RV-dependent coronary anomalies include those with broad, short fistulous connections to the RV, even if the native circulation is unobstructed. Decompression in this situation will result in a steal into the RV cavity and myocardial ischemia. The more severe forms of RV-dependent coronary circulation include those with stenoses or discontinuity of the native coronary circulation with origin of the coronary arteries from the RV cavity. The initial palliation for these patients consists of a subclavian to pulmonary artery Gore-Tex shunt without RV decompression.

These patients may then have a bidirectional Glenn shunt as a second stage, or if they have acceptable hemodynamics they may proceed directly to a lateral tunnel Fontan procedure. The lateral tunnel Fontan exposes the tricuspid valve to oxygenated blood which may enter the RV to supply the coronary circulation. We have had 6 patients with an RV-dependent coronary circulation [9] who have had a successful Fontan procedure without evidence of ischemia. In all cases, the RV cavity was not decompressed. There have been no late deaths in this group.

Thromboexclusion of the RV has been reported as a means of dealing with the RV-dependent coronary circulation [4]. This has had mixed results. It would be expected to be effective only in those cases with an intact native coronary circulation. A potential drawback to the technique is that thrombi may retrograde enter the coronary circulation by large fistulas and produce ischemia.

The concept of an Ao–RV shunt was first described by Freeman and associates [6]. This shunt would theoretically reduce the RV systolic pressure to systemic levels while the elevated diastolic pressure would supply the coronary circulation with oxygenated blood. The actual hemodynamics obtained in our 5 patients were variable. In 1 patient, the RV systolic pressure was suprasystemic with the shunt open and the diastolic pressure remained low. In other patients the RV systolic and aortic pressures equalized. We therefore hypothesize that in some patients the shunt may be restrictive (either due to shunt diameter or dynamic infundibular obstruction) whereas in others it is not. In 1 patient the arterial diastolic pressure was significantly lowered by opening the Ao–RV shunt. In the absence of tricuspid regurgitation confirmed by transesophageal echocardiography, this suggested excessive coronary runoff, perhaps as a result of fistulas between the RV and the coronary veins. Tricuspid regurgitation would also result in a steal from aorta-to-RV-to-right artery and therefore must be repaired, as was done in patient 3. One should be keenly aware of an excessive reduction in diastolic pressure and either repair tricuspid regurgitation or reduce the shunt size if encountered.

Flow through the shunt appears to be bidirectional and biphasic. Intraoperative echocardiography of patient 5 demonstrated RV to aortic flow with systole and aorta to RV flow with diastole. These echocardiographic findings are consistent with the majority of hemodynamic findings. As such, we suspect the shunt provides oxygenated aortic root blood for perfusion of the RV sinusoids during diastole. To date, we have not seen any evidence of RV dilatation as a result of the Ao–RV shunt.

The indications for the Ao–RV shunt are not yet defined. Our experience certainly suggests that in the presence of ischemia either preoperatively or intraoperatively, the Ao–RV shunt reverses the ischemia and in patient 1 resulted in markedly improved ventricular function. In patients with the most severe form of RV-dependent coronary circulation, the Ao–RV shunt could be used electively at the time of a bidirectional Glenn shunt. If this is well tolerated with good left ventricular function, the Fontan procedure could be performed as a subsequent stage.

The long-term patency of the Ao–RV shunt may be questioned, and in patient 1 it was found to be closed at 1 year. As flow is more phasic than a systemic to PA shunt, a higher occlusion rate could be expected. In the 3 other patients the shunt remained patent at 1 year. Patency may be improved by using as large a shunt as possible (which is our current policy) and the potential use of low-dose anticoagulation. Our current technique consists of an epicardial suture line in the RV infundibulum. A circumferential endocardial myectomy may be added as necessary to ensure good inflow to the RV cavity.

This experience with a relatively new procedure suggests that it may be useful to reverse left ventricular ischemia associated with RV-dependent coronary circulation. This limited experience also demonstrates that the shunt is well-tolerated and there were no cases of late sudden death. Whether it should be used electively on all cases with the more severe form of RV-dependent coronary circulation will be determined by further clinical experience.

	Footnotes

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Address reprint requests to Dr Laks, Division of Cardiothoracic Surgery, UCLA Medical Center, 10833 Le Conte Ave, Rm 62-182, Los Angeles, CA 90024-1741.

	References

Top Footnotes Abstract Introduction Case Reports Comment References

 

1. Calder AL, Co EE, Sage MD. Coronary arterial abnormalities in pulmonary atresia with intact ventricular septum. Am J Cardiol 1987;59:436–42.[Medline]
2. Gittenberg-deGroot AC, Sauer U, Bindl L, Babic R, Essed CE, Buhlmeyer K. Competition of coronary arteries and ventriculo-coronary arterial communications in pulmonary atresia with intact ventricular septum. Int J Cardiol 1988;18:243–8.[Medline]
3. O'Connor WN, Cottrill CM, Johnson GL, Noonan JA, Todd EP. Pulmonary atresia with intact ventricular septum and ventriculo-coronary communication: surgical significance. Circulation 1982;65:805–9.[Abstract/Free Full Text]
4. Coles JG, Freedom RM, Lightfoot NE, et al. Long-term result in neonates with pulmonary atresia and intact ventricular septum. Ann Thorac Surg 1989;47:213–7.[Abstract]
5. Hawkins JA, Thorne JK, Boucek MM, et al. Early and late results in pulmonary atresia with intact ventricular septum. J Thorac Cardiovasc Surg 1990;100:492–7.[Abstract]
6. Freeman JE, DeLeon SY, Lai S, Fisher EA, Ow EP, Pifarre R. Right ventricle-to-aorta conduit in pulmonary atresia with intact ventricular septum and coronary sinusoids. Ann Thorac Surg 1993;56:1393–4.[Abstract]
7. Billingsley AM, Laks H, Boyce SW, George B, Santulli T, Williams RG. Definitive repair in patients with pulmonary atresia and intact ventricular septum. J Thorac Cardiovasc Surg 1989;97:746–54.[Abstract]
8. De Leval M, Bull C, Stark J, Anderson RH, Taylor JFN, Macartney FJ. Pulmonary atresia and intact ventricular septum: surgical management based on a revised classification. Circulation 1982;66:272–80.[Abstract/Free Full Text]
9. Pearl JM, Laks H, Stein DG, Drinkwater DC, George BL, Williams RG. Total cavopulmonary anastomosis versus conventional modified Fontan procedure. Ann Thorac Surg 1991;52:189–96.[Abstract]

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This Article Abstract Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Hillel Laks Richard N. Gates Peter W. Grant Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Laks, H. Articles by Harake, B. Search for Related Content PubMed PubMed Citation Articles by Laks, H. Articles by Harake, B.