Similar Outcomes for Bidirectional Cavopulmonary Shunt and. Hemi-Fontan

ST. PETERSBURG, FLA. – Both the bidirectional cavopulmonary shunt and the hemi-Fontan procedure have been used in children with hypoplastic left heart syndrome. Is one better than the other?

Dr. Tom Karl, deputy director of pediatric cardiac surgery at Mater Children’s Hospital in South Brisbane, Queensland, sought to answer this question at the annual International Congenital Heart Disease Symposium.

One potential benefit of the bidirectional cavopulmonary shunt (also called the bidirectional Glenn shunt), he said, is decreased tricuspid insufficiency as the right ventricle’s geometry normalizes from volume unloading.

Other potential benefits include avoidance of later hypertrophy and subendocardial ischemic damage. General hemodynamic stability is promoted by improvement in effective systemic output – with reduced interstage mortality, better somatic growth, and the opportunity to correct associated abnormalities out of the neonatal period, he added.

But is the bidirectional cavopulmonary shunt better than the hemi-Fontan procedure when it is used as the second stage in the typical three-stage treatment sequence (between neonatal palliation, such as the Norwood procedure, and a Fontan operation) for the univentricular heart?

It does have some advantages: It is technically simpler; it can be performed on a beating heart at normothermia, and off pump in many cases; and it requires no prosthetic material. It also is a very good setup for an extracardiac variant of the Fontan operation.

"On the other hand, there is some potential for stenosis, and there is probably some asymmetry of flow in many cases," said Dr. Karl.

The hemi-Fontan doesn’t have asymmetry of flow; there is actually very good flow to the left lung, he said. Also, there is a long, favorable history of this type of anastomosis specifically in hypoplastic left heart syndrome, and the hemi-Fontan provides a good setup for a lateral tunnel Fontan completion. Stenosis risk is minimal.

However, the hemi-Fontan is technically more complex. It requires cardiopulmonary bypass, which some surgeons choose to do using deep hypothermic circulatory arrest, and it may pose greater risk to the sinoatrial node. The hemi-Fontan also requires a considerable load of prosthetic material, but this is not seen as a disadvantage if the procedure follows a Norwood procedure, Dr. Karl noted.

Sinus node dysfunction, which has been examined in detail by investigators at the Children’s Hospital of Philadelphia, is a common problem in the early postoperative period following a hemi-Fontan procedure (J. Thorac. Cardiovasc. Surg. 2001:121:582-3).

The investigators found that on postoperative day 1, sinus node dysfunction occurred in 9.8% of 51 patients undergoing bidirectional cavopulmonary shunt, compared with 36% of 79 hemi-Fontan patients.

"But these differences are amortized by the time the patient is discharged – 6% and 8%, respectively, had sinus node dysfunction at discharge – and in any case, most (81%) of the sinus nodes recover during the interstage period," Dr. Karl said.

Also, the incidence of sinus node dysfunction after a lateral tunnel and an extracardiac Fontan seems to be about the same, at 13% in each group, he noted.

"So what is the best anastomosis strategy for the cavopulmonary connection? Based on recent studies using computational flow modeling and MRI studies, it seems that the key factor ... relates mostly to the cross-sectional area of the anastomosis, and some of the other geometric factors don’t have as much effect as we had predicted earlier. So I think this comes down to surgeon’s choice or institutional choice, and both procedures work quite well," he said.

Dr. Karl declared he had no conflicts of interest.

ST. PETERSBURG, FLA. – Both the bidirectional cavopulmonary shunt and the hemi-Fontan procedure have been used in children with hypoplastic left heart syndrome. Is one better than the other?

Dr. Tom Karl, deputy director of pediatric cardiac surgery at Mater Children’s Hospital in South Brisbane, Queensland, sought to answer this question at the annual International Congenital Heart Disease Symposium.

One potential benefit of the bidirectional cavopulmonary shunt (also called the bidirectional Glenn shunt), he said, is decreased tricuspid insufficiency as the right ventricle’s geometry normalizes from volume unloading.

Other potential benefits include avoidance of later hypertrophy and subendocardial ischemic damage. General hemodynamic stability is promoted by improvement in effective systemic output – with reduced interstage mortality, better somatic growth, and the opportunity to correct associated abnormalities out of the neonatal period, he added.

But is the bidirectional cavopulmonary shunt better than the hemi-Fontan procedure when it is used as the second stage in the typical three-stage treatment sequence (between neonatal palliation, such as the Norwood procedure, and a Fontan operation) for the univentricular heart?

It does have some advantages: It is technically simpler; it can be performed on a beating heart at normothermia, and off pump in many cases; and it requires no prosthetic material. It also is a very good setup for an extracardiac variant of the Fontan operation.

"On the other hand, there is some potential for stenosis, and there is probably some asymmetry of flow in many cases," said Dr. Karl.

The hemi-Fontan doesn’t have asymmetry of flow; there is actually very good flow to the left lung, he said. Also, there is a long, favorable history of this type of anastomosis specifically in hypoplastic left heart syndrome, and the hemi-Fontan provides a good setup for a lateral tunnel Fontan completion. Stenosis risk is minimal.

However, the hemi-Fontan is technically more complex. It requires cardiopulmonary bypass, which some surgeons choose to do using deep hypothermic circulatory arrest, and it may pose greater risk to the sinoatrial node. The hemi-Fontan also requires a considerable load of prosthetic material, but this is not seen as a disadvantage if the procedure follows a Norwood procedure, Dr. Karl noted.

Sinus node dysfunction, which has been examined in detail by investigators at the Children’s Hospital of Philadelphia, is a common problem in the early postoperative period following a hemi-Fontan procedure (J. Thorac. Cardiovasc. Surg. 2001:121:582-3).

The investigators found that on postoperative day 1, sinus node dysfunction occurred in 9.8% of 51 patients undergoing bidirectional cavopulmonary shunt, compared with 36% of 79 hemi-Fontan patients.

"But these differences are amortized by the time the patient is discharged – 6% and 8%, respectively, had sinus node dysfunction at discharge – and in any case, most (81%) of the sinus nodes recover during the interstage period," Dr. Karl said.

Also, the incidence of sinus node dysfunction after a lateral tunnel and an extracardiac Fontan seems to be about the same, at 13% in each group, he noted.

"So what is the best anastomosis strategy for the cavopulmonary connection? Based on recent studies using computational flow modeling and MRI studies, it seems that the key factor ... relates mostly to the cross-sectional area of the anastomosis, and some of the other geometric factors don’t have as much effect as we had predicted earlier. So I think this comes down to surgeon’s choice or institutional choice, and both procedures work quite well," he said.

Dr. Karl declared he had no conflicts of interest.

ST. PETERSBURG, FLA. – Both the bidirectional cavopulmonary shunt and the hemi-Fontan procedure have been used in children with hypoplastic left heart syndrome. Is one better than the other?

Dr. Tom Karl, deputy director of pediatric cardiac surgery at Mater Children’s Hospital in South Brisbane, Queensland, sought to answer this question at the annual International Congenital Heart Disease Symposium.

One potential benefit of the bidirectional cavopulmonary shunt (also called the bidirectional Glenn shunt), he said, is decreased tricuspid insufficiency as the right ventricle’s geometry normalizes from volume unloading.

Other potential benefits include avoidance of later hypertrophy and subendocardial ischemic damage. General hemodynamic stability is promoted by improvement in effective systemic output – with reduced interstage mortality, better somatic growth, and the opportunity to correct associated abnormalities out of the neonatal period, he added.

But is the bidirectional cavopulmonary shunt better than the hemi-Fontan procedure when it is used as the second stage in the typical three-stage treatment sequence (between neonatal palliation, such as the Norwood procedure, and a Fontan operation) for the univentricular heart?

It does have some advantages: It is technically simpler; it can be performed on a beating heart at normothermia, and off pump in many cases; and it requires no prosthetic material. It also is a very good setup for an extracardiac variant of the Fontan operation.

"On the other hand, there is some potential for stenosis, and there is probably some asymmetry of flow in many cases," said Dr. Karl.

The hemi-Fontan doesn’t have asymmetry of flow; there is actually very good flow to the left lung, he said. Also, there is a long, favorable history of this type of anastomosis specifically in hypoplastic left heart syndrome, and the hemi-Fontan provides a good setup for a lateral tunnel Fontan completion. Stenosis risk is minimal.

However, the hemi-Fontan is technically more complex. It requires cardiopulmonary bypass, which some surgeons choose to do using deep hypothermic circulatory arrest, and it may pose greater risk to the sinoatrial node. The hemi-Fontan also requires a considerable load of prosthetic material, but this is not seen as a disadvantage if the procedure follows a Norwood procedure, Dr. Karl noted.

Sinus node dysfunction, which has been examined in detail by investigators at the Children’s Hospital of Philadelphia, is a common problem in the early postoperative period following a hemi-Fontan procedure (J. Thorac. Cardiovasc. Surg. 2001:121:582-3).

The investigators found that on postoperative day 1, sinus node dysfunction occurred in 9.8% of 51 patients undergoing bidirectional cavopulmonary shunt, compared with 36% of 79 hemi-Fontan patients.

"But these differences are amortized by the time the patient is discharged – 6% and 8%, respectively, had sinus node dysfunction at discharge – and in any case, most (81%) of the sinus nodes recover during the interstage period," Dr. Karl said.

Also, the incidence of sinus node dysfunction after a lateral tunnel and an extracardiac Fontan seems to be about the same, at 13% in each group, he noted.

"So what is the best anastomosis strategy for the cavopulmonary connection? Based on recent studies using computational flow modeling and MRI studies, it seems that the key factor ... relates mostly to the cross-sectional area of the anastomosis, and some of the other geometric factors don’t have as much effect as we had predicted earlier. So I think this comes down to surgeon’s choice or institutional choice, and both procedures work quite well," he said.

Dr. Karl declared he had no conflicts of interest.