What might be the outcome of an abnormal RI or RAR?

An abnormal Resistance Index (RI) or Renal Artery Ratio (RAR) indicates a change in the hemodynamic status of the vascular structure in question. In particular, an elevated RI or RAR is often associated with increased distal vascular resistance. This is because these indices are used to assess how well blood is flowing through the vessels.

When the RI or RAR values are abnormal, it suggests that the resistance in the vascular bed has changed, likely increasing. Increased distal resistance can lead to issues such as reduced perfusion to downstream tissues, as the blood has more difficulty flowing through the narrowed or compromised pathways.

This situation is important clinically, as it could indicate significant vascular pathologies including stenosis or other obstructive processes. Thus, the outcome of an abnormal RI or RAR being an increase in distal resistance reflects the underlying hemodynamic changes that could adversely affect blood supply and tissue health.