A Hypotensive transfusion reaction or HTR is a rare condition that presents with

low blood pressure Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the dia ...

associated with administration of

blood product A blood product is any therapeutic substance prepared from human blood. This includes whole blood; blood components; and plasma derivatives. Whole blood is not commonly used in transfusion medicine. Blood components include: red blood cell concen ...

s. The low blood pressure quickly resolves when the transfusion is stopped. HTRs are caused by the production of

bradykinin Bradykinin (BK) (Greek brady-, slow; -kinin, kīn(eîn) to move) is a peptide that promotes inflammation. It causes arterioles to dilate (enlarge) via the release of prostacyclin, nitric oxide, and endothelium-derived hyperpolarizing factor and ...

produced through

Factor XII Coagulation factor XII, also known as Hageman factor, is a plasma protein. It is the zymogen form of factor XIIa, an enzyme () of the serine protease (or serine endopeptidase) class. In humans, factor XII is encoded by the ''F12'' gene. Struct ...

activation by negatively charged surfaces such as filters. When mechanisms for the degradation of bradykinin are impaired, the

peptide Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. A ...

builds up and causes hypotension.

Angiotensin converting enzyme Angiotensin-converting enzyme (), or ACE, is a central component of the renin–angiotensin system (RAS), which controls blood pressure by regulating the volume of fluids in the body. It converts the hormone angiotensin I to the active vasoconstr ...

(ACE) is primarily responsible for its degradation (75%) but can be inhibited by administration of

blood pressure Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" r ...

medications called

ACE inhibitor Angiotensin-converting-enzyme inhibitors (ACE inhibitors) are a class of medication used primarily for the treatment of hypertension, high blood pressure and heart failure. They work by causing relaxation of blood vessels as well as a decrease i ...

s. Polymorphisms in ACE or aminopeptidase P (APP), another enzyme responsible for bradykinin degradation (20%) may also contribute to HTRs.

References

{{reflist Hypotension