Isolated reversal of flow in the vertebral artery - A missed entity.

Isolated reversal of flow in the vertebral artery is a rare phenomenon occurring in the general population and is due to intrinsic anatomical defects. The most common cause is subclavian stenosis; however, reversal of flow in the vertebral artery can occur regardless of any detection of anatomic deterioration. In this series, we report three asymptomatic cases where the extracranial Doppler scan preceding off-pump coronary arterial bypass grafting showed isolated reversal of flow in the vertebral artery. No signs of subclavian stenosis or steal syndrome were elicited. However, all patients subsequently suffered from a posterior circulation stroke following off-pump coronary arterial bypass grafting but recovered fully with medical management. We conclude that a detailed pre-operative neurological investigation can mitigate this risk and improve neurological outcomes following off-pump coronary arterial bypass grafting.