Alterations of coronary flow velocity during intervention for acute myocardial infarction: responses to complications of intracoronary thrombolysis and angioplasty.

Alterations, either an increase or decrease, in the distal flow velocity over time are associated with alterations in vessel diameter and/or unstable flow velocity. Unexplained unstable flow velocity patterns should act as early warning signs to prompt the interventionalist to assess continued coronary patency and need for renewed interventions.