Abstract
Congenital cardiac surgeons love to be creative, to be innovators, and to be early adopters. Ten years ago we eagerly pursued the promises of robotic surgery. Today, million dollar robots bought for congenital cardiac programs are being used in the urology operating room (OR) or collecting dust in storerooms. But it wasn’t just us—an army of salespersons, commercial exhibitors, and our hospital public relations teams looking for the competitive edge to make our hospital special also played a role in the game. By the time we congenital surgeons realized that there were so few operations that could be accomplished with a robot, so many ongoing expenses, and so few advantages, many robots had been sold, sales commissions had been distributed, the glossy brochures had been mailed, and the local TV news spots had been broadcast.
Let’s wind the clock on 10 years and talk about hybrid ORs for congenital heart surgery. Rather than talking about $1 million outlays we are now talking $5 million to $10 million. The principal driver in this latest health care industrial/surgical collaboration is the hybrid Norwood. What value are we going to see for our $5 million to $10 million?
The hybrid Norwood is a means of maintaining the fetal circulation for the baby with hypoplastic left heart syndrome (HLHS) and in addition restricting pulmonary blood flow with bilateral pulmonary artery bands. The ductus is stented, and at some stage the atrial septum is opened with a catheter-based procedure. It is unclear whether there is any advantage in doing the stenting procedure at the same time and in the same room (“hybrid OR”) as the banding procedure. The procedure has the advantage of avoiding cardiopulmonary bypass in the newborn, although with the continuing evolution of bypass hardware for neonates, avoidance of cardiopulmonary bypass is becoming an ever-lessening advantage (witness the <2% mortality for many neonatal operations such as the arterial switch and repair of tetralogy for >20 years). 1
The fundamental question is whether the fetal HLHS circulation is better for the child’s survival, stability, and development than the Norwood/Sano. Although there are no trials to date to answer this question definitively, the answer to this question is likely to be a resounding no.
Here’s why. Considerable new evidence has accumulated over the last 5 years regarding the cerebral circulation of the fetus with aortic atresia prenatally. 2 Because blood must flow retrograde across a hypoplastic isthmus to get to the cerebral circulation and because the brain is competing with the coronary circulation for that restricted flow, it is not surprising that both echo Doppler and magnetic resonance imaging fetal blood flow studies have documented reduced cerebral blood flow in the fetus with aortic atresia. 3 Stenting the duct does not improve this situation and can in fact exacerbate it through kinking or compression of the isthmus. Ductal tissue can fibrose and further limit retrograde flow to the brain and coronaries after the neonatal period. This problem has even led some groups to suggest that a reverse shunt, that is, from the main pulmonary artery to the innominate artery, should be a part of the hybrid procedure to guarantee adequate cerebral and coronary blood flow. 4
In contrast to the hybrid procedure, the Norwood procedure reestablishes the natural location of the coronary arteries as the first branch of the aorta. The second and third branches with a surgical Norwood are the innominate and carotid arteries supplying the brain.
Another problem: the baby with either a Blalock shunt or banded branch pulmonary arteries has a steal from the coronary circulation during diastole. Avoiding this problem is the fundamental advantage of the Sano shunt and the reason why all centers where the Sano shunt is performed report a higher diastolic pressure and greater early postoperative stability than with a Blalock shunt. 5 It’s easy to be fooled and think that the bands of a hybrid operation confer the same stability that the usual pulmonary artery band provides with no diastolic runoff but that is not true, because the stented ductus exposes the branch pulmonary arteries to aortic diastolic flow.
One of the fundamental principles of the single-ventricle track is to avoid pulmonary artery distortion to achieve an optimal Fontan candidate. Banding of the branch pulmonary arteries is not a good way to avoid scarring and distortion of both branch pulmonary arteries. Furthermore, we know what happens when the main pulmonary artery is exposed to systemic pressure from the Ross experience. A significant percentage of patients develop considerable dilation of the supravalvar main pulmonary artery. 6 This has also been a problem with the hybrid operation. 7
What happens to a stent that is positioned in the wall of the descending aorta and arch? Although occasionally it is not embedded, this is not usually the case. Attempts to remove a stent can result in shredding of the vessel and a need for major reconstruction. The “comprehensive stage 2 operation” is indeed comprehensive, requiring a more difficult reconstruction of the aortic arch and proximal descending aorta than in the undisturbed aorta of the neonate. 7
The results of the hybrid Norwood have not been superior to the Norwood/Sano when the latter is performed at experienced, high-volume centers. 8 Present case selection for the hybrid procedure, which excludes babies with more severe forms of HLHS (smaller arch, isthmus, or ascending aorta), suggests that if it were applied across the board, results would be worse than the Norwood/Sano. So if there is no role for the hybrid OR for HLHS, can the expense be justified?
The midmuscular ventricular septal defect (VSD) is no longer unmanageable by surgery and no longer requires a ventriculotomy. 9 For many years surgeons have described use of the moderator band folded into the standard midmuscular VSD, which almost always lies at the septal end of the moderator band. There is the occasional apical VSD that is better managed by device closure, but these are not being approached with a hybrid procedure. What about adult cardiac surgeons who are doing more transapical catheter–based aortic valve replacements and aortic aneurysm device placement—is that relevant in a children’s hospital where aortic valve replacement and aneurysm surgery are uncommon operations?
Letting the crowd know that the emperor is wearing no clothes depending on your perspective requires the innocence of a child, considerable courage, or political naïveté. A hybrid OR can be a stealth maneuver for talking the hospital administration into a new catheterization lab that might be able to double as a spare OR. But it’s more likely that it will be used primarily as a standard catheterization lab. Surgeons who suggest that a hybrid OR may not be worth a $5 million to $10 million investment will be viewed by some cardiologists as stealing resources from their partners and perhaps giving them to a noncardiac program or, even worse, to the surgical arm of the program. And the public relations people have already produced those beautiful glossy brochures and won’t be able to distribute them, the local TV reporters have lost a great medical advances story, and some salespeople have lost the commission on $5 million to $10 million sale. Perhaps that’s why we haven’t seen many (or any) papers reporting what we are all doing with those million dollar doorstop robots in the OR storeroom.