The Hybrid Procedure

Until the 1980’s, most forms of Hypoplastic Left Heart Syndrome (HLHS) were fatal. That group of defects involve the left side of the heart, the side that pumps blood to the body, and surgeons had no procedure that could offer any hope. More often than not, all Pediatric Cardiologists could do was to offer Compassionate Care. This country has put men on the moon, many doctors would ask themselves. So why in the hell can’t we save these kids?

That changed with the development of the Norwood Procedure (a three operation sequence developed in 1981) and the first Neonatal Heart Transplant in the United States (1986) . But even though it was an answer, the Norwood Stage I is a difficult procedure.  It is a six-hour operation, a major re-plumbing of the heart and surrounding blood vessels performed when the child is less than one week old. Imagine, if you can, operating on a damaged heart the size of a walnut. And the delicate part isn’t the repair, it is balancing the blood flow correctly. Everything flows through the Tricuspid Valve, and you can increase the flow rate (which increases the pressure on the valve) some, but not a lot. Get the pressure too high and you damage the Tricuspid Valve, and we can’t have that. For a HLHS patient, the Norwood Stage I is the most important, the most difficult, and the most dangerous operation of the three.

What if it were possible for the Stage I to be an easier operation? Or better yet, what if you were able to eliminate it completely?

Well you can’t just disregard the Stage I – major HLHS requires some type of surgical intervention – but it can be an easier operation. Doctors in major heart hospitals around the US are refining what is known as the “Hybrid approach” and the early results are promising.

The Hybrid was developed at Nemours Cardiac Center in Orlando, Florida in 1999 and takes place not in the Operating Room, but in the Catheterization Lab. The chest is opened and both Pulmonary arteries are banded to restrict blood flow. Next, a stent is implanted in the Ductus Arteriosus to keep it open (creating a Patent Ductus Arteriosus, or PDA). And while the stent is placed via Catheter, it is not inserted through the groin. The Catheter is inserted directly into the Pulmonary Artery via the incision in the chest. At times, an Atrial Septal Defect (ASD) will also need to be created.

Once the stent is in place, the operation is over. Total time: 60 to 90 minutes, and the Heart/Lung bypass machine was not used. After the Hybrid, the rest of the Norwood is carried out as before. But the Hybrid Procedure allows the major surgery to be delayed, until the child is older and stronger.

A 2008 study showed that the results of this new operation were favorable. The University of Chicago started using the Hybrid for their high risk HLHS patients, but found that the results were so good that it is offered to all Norwood Procedure candidates. (Observant readers will notice that the “60 to 90 minutes” link and the “results were so good” link quote the same doctor, who worked at Chicago but later moved to Boston.)

Very few hospitals perform the Hybrid Procedure for HLHS; so if you get a prenatal diagnosis of Hypoplastic Left Heart Syndrome, be sure to ask about all treatment options – including (and especially) the Hybrid.

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One Response to “The Hybrid Procedure”

  1. heather Says:

    asher had the hybrid at SickKids in Toronto in December 2006. he got the PDA stent and PA bands, but he also got a modified BT-shunt, which went from his MPA to the proximal innominate, just above the arch. asher was the 17th hybrid his surgeon had ever performed. he was VERY high risk b/c he was not diagnosed prenatally, only at 8 days when he nearly died. he was extremely weak, and given the severity of his HLHS (including a pinhole ASD, mitral atresia and an almost non-existant aorta), this was the best option for us. there is no way he would have survived the Norwood. the second stage is rough, since it’s the Norwood AND Glenn at the same time, so it’s massive. but thanks to the hybrid, he actually survived to the Norwood/Glenn and is now post-Fontan/pacemaker.

    the one thing i would add to your description of the surgery is that, even when the ASD doesn’t need to be created, it often needs to be enlarged by ballooning it. asher’s was ballooned during the surgery, but it still closed on its own 4 weeks later, so it had to be stented. this lead to some unforeseen complications, however, since the stent became embedded in the atrial wall, and once it was encased in scar tissue it blocked his RPVs and needed to be removed. asher now has some residual stent material in his AV node.

    but still, going with the hybrid instead of the Norwood was definitely one of the best decisions i have ever made! 🙂

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