No reflow phenomenon
No reflow phenomenon is the failure of blood to reperfuse an ischemic area after the physical obstruction has been removed or bypassed. The underlying mechanism is related to arterial microvasculature damage. It is primarily seen during percutaneous coronary intervention (PCI) in the setting of acute myocardial infarction (AMI), but has also been observed in other organs, including the brain and kidneys. Coronary no-reflow phenomenon is specifically related to reduced antegrade coronary blood flow despite proximal coronary artery patentcy. It is an independent predictor of worse clinical outcomes including heart failure, fatal arrhythmias, myocardial infarction, and increased  mortality rates. Pathophysiology. The underlying mechanism of no reflow phenomenon is centered around the damage caused by microvascular obstruction (MVO). There have been two proposed underlying causes of no reflow phenomenon: In both types of no reflow phenomenon, the extent of damage to the microvasculature is directly proportional to the length of time the tissue is ischemic, with longer periods of ischemia related to greater damage to the arterial microvasculature.