hypoplastic artery in brain(A1) of child with complex heart defects

My daughter has hypoplastic right heart syndrome(single ventricle) and she's had several open heart surgeries. She's now 5yrs old. She has been experiencing bad headaches for a year now and they did a brain/spinal MRI/MRA everything looked good except for a hypoplastic artery in right side of brain(A1). There were no blood clots around it. She continues to have headaches so they are adjusting pain medication to control it. After all of this we saw the cardiologist and he suggested that it may have been caused by the Blalock-Taussig shunt and stenting may be needed.

How common is this hypo artery in association to the BT? Do you know if they usually stent a hypo A1 artery or leave it alone? I read that a hypoplastic A1 increases your risk of stroke. Is there anything they can do to cut those risks? Does low cardiac output cause headaches? We already know she has low cardiac output which causes dilated capillaries in her face(the headaches started about the same time as the bright red face).

Any info would be helpful as we are not scheduled to see the card or neuro for a couple of months. Thanks

[Jeffrey R Boris, M.D.]

Dear HRHSmommy,

I am not familiar with B-T shunts specifically causing actual hypoplasia of an intracerebral artery.  This procedure has been performed for decades, and this has not been described in the medical literature.  Certainly, clotting in the shunt can extend up into the cerebral circulation, but you are not describing this.  In fact, the hypoplasia means that the vessel was probably formed that way.  We do know that patients with abnormal cardiac development can have abnormal vascular development in other locations.  As wel, there are certain syndromes that can do this, including DiGeorge syndrome (chromosome 22q11 deletion).

Overall, though, the good thing about the cerebral circulation is that it is typically redundant.  This means that, even though there may be hypoplasia of the artery on one side, there is arterial access from the other side through what is called the circle of WIllis.  Low cardiac output potentially may cause headaches, although the body usually compensates for this by varying blood pressure and blood vessel resistance to ensure that adequate blood flow reaches the brain.  Therefore, if the headaches are truly due to decreased cardiac output, I would expect many more systemic problems with your daughter, as well.  However, with single ventricle physiology, it is important to make sure that she doesn't have superior vena cava syndrome, in which the venous return from the head and neck is obstructed.  As well, it would be helpful to know if she is cyanotic, or not, and if her hematocrit is normal.  These are all things that can be discussed with your cardiologist and neurologist.