Overview
Elizabeth H. Stephens, M.D., Ph.D., a pediatric and congenital cardiac surgeon at Mayo Clinic in Rochester, Minnesota, discusses the anatomy, physiology and surgical management of tetralogy of Fallot.
Tetralogy of Fallot findings include a ventricular septal defect and often a narrowed pathway to the lungs that can cause babies to turn blue. Although the first surgical repair is performed in infancy, these patients frequently require re-operation on the pulmonary valve as teenagers or adults.
ELIZABETH STEPHENS: My name is Elizabeth Stephens. I'm a pediatric and congenital cardiac surgeon at Mayo Clinic. Today I'll be discussing tetralogy of fallot. One of the things that I love about tetralogy of fallot is that it's central to the history of cardiac surgery.
The blue babies who were seemingly miraculously cured by the truly pioneering work of Dr. Blalock, Vivien Thomas, and Dr. Helen Taussig were tetralogy babies. And from there, the field of cardiac surgery grew.
Tetralogy of fallot is due to the position of the muscle below the aorta called the infundibular septum not being aligned properly. That leads to the major characteristics of tetralogy, the VSD, or hole between the ventricles, the narrowed area of the right ventricular outflow tract, or area below the pulmonary valve, and narrowing of the pulmonary valve. Shown in this diagram is the pulmonary valve. The blue star indicates the infundibular septum, which doesn't line up with the rest of the septum below, creating the VSD shown here, and also results in the narrowing of the pulmonary valve area. This narrowing is also shown in B and is what causes patients to be blue, because not enough blood flow is reaching the lungs. In C, the repair's shown, with the VSD patch. And in this example, the transannular patch, which opens up the pathway to the lungs.
The physiology of each baby depends on how much flow is getting to the lungs. In blue tetralogy, there is less flow to the lungs and their oxygen saturation is lower. While in pink tetralogy, their physiology is more like a straightforward VSD, where the lungs receive too much blood flow. And their saturations are fine, but they may have trouble eating and gaining weight.
In terms of management, some babies will show symptoms, such as spells of low saturations relatively early, while others will not. Those who do have symptoms can frequently be managed for a while with medications. But some will need early repair. In general, we aim for elective repair at three to six months.
The goals of the repair are to close the hole in the heart, which is done with a patch and improve flow out to the lungs. In some babies, their own pulmonary valve can be used. This is called valve sparing. And we widen the areas above and below the valve.
In other cases, the valve and area around the valve, called the annulus, is too small. And this area will need to be patched. This is called a transannular patch repair, which is shown here. There are also usually muscle bundles under the pulmonary valve that are resected.
These babies have a good prognosis. And this is an operation that we commonly perform. They usually stay in the hospital around five days or so, and then are discharged with follow up appointments with our cardiologists.
We at Mayo Clinic, in particular, see a lot of teenage and adult patients who had a tetralogy repair as a baby. Frequently over time, these patients will need the pulmonary valve to be readdressed. Some of these patients can be managed with a transcatheter pulmonary valve replacement, done in the Cath lab without open heart surgery. While others, depending on various factors, may need open surgical valve replacement.
Thankfully, once we put in that open surgical valve in these patients, and this is a tissue valve that does not need anticoagulation long term, when that valve breaks down, that valve can usually be replaced in the Cath lab with a transcatheter technique. I hope you have found this video helpful. And be sure to check out our other educational videos on the Mayo Clinic YouTube channel, as well as our website.