REPERFUSION

Reperfusion is the restoration of blood flow to tissue that has experienced ischemia. It is a central objective in the treatment of acute myocardial infarction, ischemic stroke, acute limb ischemia, and during organ transplantation. While restoring circulation can salvage endangered tissue and improve survival, the sudden return of blood can also cause injury, known as reperfusion injury, through mechanisms such as reactive oxygen species generation, calcium overload, inflammatory responses, endothelial dysfunction, and microvascular obstruction.

Reperfusion injury can contribute to edema, hemorrhagic transformation in the brain, and the no-reflow phenomenon where blood flow fails to adequately resume at the tissue level despite restored arterial patency. The severity and occurrence of injury depend on factors including duration of ischemia, the extent of collateral circulation, and the rapidity and method of reperfusion.

Clinically, reperfusion is achieved by pharmacologic or mechanical means. Pharmacologic options include thrombolytic therapy with agents such as tissue plasminogen activator. Mechanical approaches include percutaneous coronary intervention with angioplasty and stenting, mechanical thrombectomy for large-vessel occlusions, and surgical revascularization. In transplantation and certain surgical settings, controlled reperfusion and techniques to minimize injury are also important considerations. Timing is critical; earlier reperfusion generally improves outcomes, though therapies carry risks such as bleeding with thrombolytics and contrast-associated complications.

Research continues to explore strategies to mitigate reperfusion injury, including pharmacologic adjuncts, controlled reperfusion, and conditioning techniques. Reperfusion remains a balance between restoring function and limiting additional tissue damage.