The Blaylock/Taussing
Shunt (B/T Shunt)
Zachary's first open heart operation was the modified
Blalock-Taussig (B/T) Shunt. This procedure was performed by Dr. Edward
Bove at the University of Michigan Medical Center when Zachary was 6
days old. First I'll explain why this procedure was necessary and then
I'll tell you what the procedure actually involves. In the fetal
circulation there is an extra blood vessel called the ductus
arteriosus. It is a very short blood vessel extending from the
pulmonary artery to the aortic arch. Before the baby is born it
functions to shunt blood away from the lungs and into the main
arterial circulation. The ductus arteriosus closes within the first
few days after the baby is born and then the right ventricle pumps
blood only to the lungs. Zachary's problem was that his heart developed
with only one functional ventricle and it was pumping blood into his
aorta [he actually had a normal aorta and a stenotic(narrowed)
pulmonary artery coming off of the one ventricle]. Consequently, the
only way any blood could get to his lungs was from the aorta,
through the ductus arteriosus, into the right and left pulmonary
arteries and then into the lungs.
We knew about the condition of Zachary's heart before he was born and
decided he should be born at the University of Michigan so that he
could be close to his surgeon. Immediately after he was born he was
taken to another room and an i.v. was started. He was given a
special prostaglandin that told his body not to close the ductus
arteriosus. Zachary was able to get blood to his lungs and he
was able to maintain an oxygen saturation of ~75% (normal is >95%).
This was enough to survive but he couldn't stay on prostaglandin
forever.
The next step was to do the B/T shunt. The concept is really very
simple whereas the procedure itself is not. Basically, a replacement
for the ductus arteriosus had to be put in. The procedure involved
making an incision between the ribs on the back right side of Zachary's
chest to expose the right side of the heart and the right sided blood
vessels. Dr. Bove then sewed a 3.5 millimeter goretex tube between
the right subclavian artery (a branch off of the aorta) and the right
pulmonary artery (the right and left pulmonary arteries are connected).
This allowed direct blood flow to the lungs in virtually the same way
as the ductus arteriosus had. Zachary was able to maintain an oxygen
saturation of ~75% and could be taken off the prostaglandin. Luckily,
this surgery did not require the use of the heart-lung machine or the
stopping of the heart to be performed. The B/T shunt works to maintain
the O2 sats for ~4-6 months at which time Zachary would be ready for
his next procedure, the Hemi-Fontan.
Photos of Zachary in the Hospital
