MHA is the form of intravascular hemolysis
These disorders is characterized by the presence of vascular lesions that predispose the circulating RBCs to mechanical injury.
RBCs may be disrupted by physical trauma in a following circumstances:
1) Patients with valve replacement – Trauma to the RBC due to sheer forces from the prosthetic valve.
2) Disseminated intravascular coagulation DIC - widespread deposition of fibrin in the small vessels leads to mechanical damage to the RBCs as they squeeze through abnormally narrowed vessels.
3) Malignant hypertension
4) thrombotic thrombocytopenic purpura
5) hemolytic-uremic syndrome
Peripheral Smear – shows injured RBCs – schistocytes i.e. red cell fragments also called as "burr cells," "helmet cells," and "triangle cells" due to different shapes.