Sunday, September 30, 2007

The Hybrid Procedure

Here is a bit of information about a new procedure that we may be elegible for. I'm currently weighting the pros and cons, but am leaning towards having this procedure first!

What are some of the more complex conditions requiring surgery?
The patients we're concerned with here are called "single ventricle patients," and that includes those with hypoplastic left heart syndrome (HLHS). Normally, you're born with two circulations: the right heart supplies the pulmonary circulation and the left heart supplies the systemic, or bodily, circulation. Some kids are born, unfortunately, with a deficient ventricle. In HLHS, it's that all-important left one. It can be so small that it's not even visible, and there's no evidence that it's there. Those are children who, 20 years ago, would have uniformly died.

Now, they often live because we perform palliative surgery on them. That may sound like a misnomer, but we call it palliation because it's not a cure. These babies live with their cardiac defect for the rest of their lives, in one way or another. Even under the best circumstances, they will need three surgeries very early on: one at birth (the Norwood), one at 6 months (the bi-directional Glenn Shunt) and one at 2 years of age (the Fontan). On the positive end of this spectrum, a patient can undergo these palliative surgeries and be asymptomatic. On the other end, there are those children who struggle with the one ventricle and who will need a heart transplant or, unfortunately, don't make it through the palliation.

Are there alternatives to the three-stage surgical approach for HLHS?
Yes, there's a hybrid procedure. The traditional way to treat HLHS begins with a Stage I Norwood Procedure, which is major reconstructive surgery laying out the connections in such a way that the right ventricle outflow of blood is directed into the body and pulmonary inflow is enabled passively. That's a lot of surgery and has to be done in the first two weeks of life.
By using the hybrid procedure, you basically establish a stable outflow by implanting a stent in the ductus arteriosus, which connects the pulmonary artery to the aorta. You then band the branch pulmonary artery to restrict some of the pulmonary blood flow. That can all be done without cardiopulmonary bypass. It typically takes between an hour and 90 minutes, as opposed to a six-hour, much more invasive Norwood. Most importantly, you're delaying the major reconstruction until the second stage. The reasoning behind this is that, at that point, the baby is older and stronger and has built up some immune defenses. A further advantage is reducing the number of "pump runs," those stretches of operating time involving the bypass machine, from three to two. Saving that pump run could result in a better outcome.

Why is it called a hybrid procedure?
It's called a hybrid because we're combining techniques that the interventional cardiologist typically uses in the cath lab, such as stenting, with surgical techniques. There are two operators—the interventional cardiologist and the cardiovascular surgeon—working together.

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