Fetal Heart Surgery - Which conditions are curable ?

Dateline: 05/03/98

With the explosion of technology in cardiac surgery, it is difficult to point to one development and say "This is it, THIS is the most innovative advance in recent times". However, the concept of treating diseases of the heart even when the "child" is in the womb - fetal intervention - is perhaps the nearest to "IT".

In previous articles, we have discussed the concept of minimally invasive heart surgery, and the use of this novel technique in treating coronary artery disease , heart valve disease and birth defects of the heart. For more information on minimally invasive surgery, visit the MICAS website. After this, in a few articles, I focussed on some aspects of fetal heart surgery. This week, I'll continue where I left off, and take a look at which kind of conditions might be correctable by fetal heart surgery.

Fetal Heart Surgery is an idea which has totally captured my imagination. It has strong detractors as well. So I thought of starting a forum to discuss this contentious issue. Many, many issues are involved. I will discuss some of them here. It would be nice if you could suggest others as well. You can post your comments on the Bulletin Board.

This week, the issue is ....

WHICH CONDITIONS MIGHT BE CURED BY FETAL SURGERY ?

Fetal cardiac surgery is neither the "Holy Grail of Cardiac Surgery", nor a "Panacea of all heart ailments" .... not by a long way. In fact, surprisingly, there are not too many conditions which have been identified as "treatable" by fetal surgery.

The aim of fetal intervention should be to provide fetuses with heart defects, who had hitherto been "condemned-to-die", a meaningful chance of survival. Preserving heart muscle function, preventing progression of already existing changes (like a condition called FIBROELASTOSIS), and restoring a near-normal pattern of growth to the heart chambers and blood vessels are the targets of fetal surgery.

If this is achieved, then any future operations after the child is born could be fully reconstructive ones, done at a single stage and with reasonable chance of restoring a normal heart, and a normal life-span to the survivor. Contrast this with the present situation, where corrective operations for complex heart defects need to be done in multiple stages, each with its own risks and complications, and ultimately resulting in a life expectancy and a life-style considerably different from normal persons. That such ideals can be achieved is suggested by the encouraging results of animal experiments.

When should fetal surgery be performed ?

Timing of surgery is another controversial issue. The aim must be to identify fetuses with disease that is neither too mild to need intervention, nor too advanced to allow meaningful correction. Performing fetal surgery beyond 30 weeks of gestation may be difficult to justify in view of the higher risk to the mother. Also, even after surgery, significant growth or other beneficial changes in the fetal heart may not be expected so late in the pregnancy. If at all intervention is needed at this stage, it may be safer to electively deliver the infant, and treat the condition by neonatal surgery or catheter intervention.

And what conditions can we expect to cure ?

There seems to be a universal acceptance that fetal surgery will help in treating hypoplastic left and right heart syndromes, and valvar atresias or stenoses. Being extremely rare, of far smaller surgical significance are lesions like primary obstruction of the foramen ovale, ductus arteriosus, tetralogy of Fallot with absent pulmonary valve or complete heart block

But then, all this so far is armchair-reasoning. Historically, when heart and lung bypass (called "Cardio-Pulmonary Bypass" or CPB) became clinically applicable, there was a virtual explosion of new operations, treating conditions that no one had even dreamed were correctable just a few years before that.

I predict that when fetal cardiac surgical techniques become equally advanced and safe, (which won't be long), innovative cardiac surgeons will surely expand the indications for the procedure to cover the entire spectrum of congenital heart disease.

And that would be the end of birth defects of the heart, as we know them today. This sure is a great time to be a cardiac surgeon !

Next week : The Mother's Point of View