Dictionary

thorax The area of the body that is located between the abdomen and the neck. Within the thorax are the lungs, the heart, and the first section of the aorta. Also known as chest.

thrive, failure to See failure to thrive.

thrombectomy A procedure to remove a clot (thrombus).

thrombi Plural of thrombus.

thrombin An enzyme that presides over the conversion of a substance called fibrinogen to fibrin, which promotes blood clotting.

Right ventricular hypertrophy (RVH) Thickening and enlargement of the muscle of the right ventricle.

Overriding aorta A case in which the aorta overrides or straddles the wall (the septum) between the ventricles, permitting oxygen-poor blood to flow through the VSD into the aorta. Open-heart surgery is done on patients with tetralogy of Fallot in infancy or early childhood. Untreated tetralogy of Fallot is usually fatal before age 20. With…

tetraphocomelia–thrombocytopenia syndrome See TAR syndrome.

tetraploid Having four full sets of chromosomes: 4 copies of each autosomal chromosome plus 4 sex chromosomes. In humans, tetraploid is equal to 92 chromosomes.

T-4 cell A T cell that expresses the CD4 transmembrane glycoprotein (CD4+ T cell). T-4 cells are active in the body’s immune response, helping to turn on this system when it is challenged by an infection or by foreign matter in the body. HIV attacks T-4 cells, knocking out the body’s ability to defend itself…

T-4 count A test that counts the number of T-4 cells in the blood, for example, to assess the immune status of a patient with HIV. Of the various ways to read a T-4 count test, the best indicator of health may be the absolute T-4 count, the actual number of T-cells per unit volume…

thalamotomy A procedure that is performed via stereotactic surgery and is designed to destroy part of the thalamus in order to relieve intractable pain, seizures, or involuntary movements, as in Parkinson’s disease.