heparin
[hep´ah-rin]1. an acid mucopolysaccharide present in many tissues, especially the liver and lungs, and having potent anticoagulant properties. It also has lipotrophic properties, promoting transfer of fat from blood to the fat depots by activation of the enzyme lipoprotein lipase.
2. a mixture of active principles capable of prolonging blood clotting time, obtained from domestic animals; used in the prophylaxis and treatment of clotting disorders, such as thrombophlebitis, pulmonary embolism, disseminated intravascular coagulation, acute myocardial infarction, or stroke syndrome, and to prevent clotting during extracorporeal circulation, blood transfusion, and blood sampling.
heparin lock a type of intermittent intravenous device for the administration of heparin. It does not require a continuous flow of fluids; the intravenous fluid flow can be disconnected and the heparin lock filled with a heparin solution that maintains patency of the needle. 
Two types of heparin or saline lock sets. From Lammon et al., 1995.
lock
[lok]1. a place, often airtight, where something is sealed in.
2. a device such as a clamp for holding something firmly in place.
heparin lock see heparin lock.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
heparin lock
Intensive care A cylindrical multiport device with a rubberized access port which is incorporated into a venous access catheter and designed to facilitate IV administration of medications. See Access device, Heparin. Cf Saline lock.McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.
hep·a·rin lock
(hep'ăr-in lok)An indwelling venous catheter used when intravenous infusions or withdrawal of venous blood for testing must be performed repeatedly over an extended period; between uses it is filled with the anticoagulant heparin.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012