heart septum The dividing wall between the right and left sides of the heart. That portion of the septum that separates the right and left atria of the heart is termed the atrial, or interatrial, septum, whereas the portion of the septum that lies between the right and left ventricles of the heart is called…
heart transplant An operation in which a diseased or malfunctioning heart is replaced with a healthy donor heart taken from a deceased person. See also transplant.
heart valve One of the four heart valves. All four heart valves are one-way valves, permitting forward and avoiding backward flow of blood. Blood entering the heart first passes through the tricuspid valve, and then the pulmonary valve. After returning from the lungs, the blood passes through the mitral (bicuspid) valve and leaves the heart…
heart ventricle One of the two lower chambers of the heart. The right ventricle receives blood from the right atrium and pumps it into the lungs via the pulmonary artery, and the left ventricle receives blood from the left atrium and pumps it into the circulation system via the aorta.
heartburn An uncomfortable feeling of burning and warmth that occurs in waves, rising up behind the breastbone (sternum) and moving toward the neck. Heartburn has nothing to do with the heart. It is usually due to gastroesophageal reflux, the return of stomach acid into the esophagus. See also gastroesophageal reflux disease.
heart-lung machine A machine that does the work both of the heart and of the lungs: pumping and oxygenating blood. Blood returning to the heart is diverted through a heart-lung machine before being returned to arterial circulation. Such machines may be used during open-heart surgery. Also known as pump-oxygenator or cardiopulmonary bypass machine.
Hypertrophic Cardiomyopathy (HCM) is a genetic heart condition characterized by abnormal thickening (hypertrophy) of the heart muscle, particularly the walls of the left ventricle. This thickening can make it harder for the heart to pump blood effectively and can affect the heart’s electrical system, leading to arrhythmias (irregular heartbeats). Key Features of HCM: If you…
Hct Hematocrit.
HCV Hepatitis C virus. See hepatitis C.
HDL High density lipoprotein. See HDL cholesterol.
HDL cholesterol High density lipoprotein cholesterol. Lipoproteins, which are combinations of fats (lipids) and proteins, are the form in which lipids are transported in the blood. HDLs transport cholesterol from the tissues of the body to the liver, so the cholesterol can be eliminated in the bile. HDL cholesterol is therefore considered the “good” cholesterol:…
HDV Hepatitis D virus. See hepatitis D.