| HI | half-scan with interpolation; head injury; health insurance; hearing impaired; heart infusion; hemag... |
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| iPTH | immunoassay for parathyroid hormone; immunoreactive parathyroid hormone |
| LHRH, LH-RH | luteinizing hormone-releasing hormone |
| LHRHR | luteinizing hormone-releasing hormone receptor |
| LRH | luteinizing hormone-releasing hormone |
| cardiac pacemaker | An electrical device which delivers a small stimulant shock to the heart to effect cardiac contraction at a pre-determined rate. Many of today's pacemakers have two main components: the electrodes and the transducer (pulse generator). The electrodes are wires which are placed into the circulatory system and make physical contact with the heart muscle. A small electrical discharge from the pacemaker electrode stimulates the muscular wall of the heart to contract, thus pumping blood in an organised fashion. The transducer is a small device, usually implanted under the skin, that generates the electrical discharge at a pre-determined frequency. Transducers can monitor your heart's rate of contraction and deliver an electrical shock only when the heart is going too slow. (27 Sep 1997) |
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| cardiac pacing, artificial | Regulation of the rate of contraction of the heart muscles by an artificial pacemaker. (12 Dec 1998) |
| cardiac part of stomach | The area of the stomach close to the oesophageal opening (cardiac orifice or cardia) which contains the cardiac glands. Synonym: pars cardiaca gastris, pars cardiaca ventriculi, cardia, gastric cardia. (05 Mar 2000) |
| cardiac plexus | A wide-meshed network of anastomosing cardiopulmonary and splanchnic nerves arising from the afferent and autonomic nerve fibres (sympathetic) and vagus (parasympathetic) nerves, surrounding the arch of the aorta, the pulmonary artery, and continuing to the atria, ventricles, and coronary vessels. Synonym: plexus cardiacus. (05 Mar 2000) |
| cardiac polyp | Usually a rounded thrombus attached to the endocardium. (05 Mar 2000) |
| cardiac prominence | The conspicuous external bulge appearing on the ventral aspect of the human embryo as early as at the fourth week, indicative of the precocious development of the heart. (05 Mar 2000) |
| cardiac reserve | The heart's ability to respond to demands that exceed ordinary circumstances. (27 Sep 1997) |
| cardiac rhabdomyoma | <radiology> Associated with tuberous sclerosis (12 Dec 1998) |
| cardiac risk | A term to describe overall risk of developing heart disease (blockage of the coronary arteries). Typical risk factors include: diabetes, high blood pressure, prior heart attack, high cholesterol, obesity, smoking and a family history for heart attacks in parents or siblings. (27 Sep 1997) |
| cardiac segment | Cardiac segment; medial basal segment of inferior lobe of right and left lung; can only be seen from medial and inferior surfaces since it does not reach lateral surface of lung. Synonym: segmentum basale mediale, segmentum cardiacum, cardiac segment. (05 Mar 2000) |
| cardiac shock | A form of shock (inadequate delivery of oxygen to the tissues) that occurs secondary to the weakened pumping function of the heart. This condition may be precipitated by myocardial infarction or cardiomyopathy. Treatment includes fluid restriction, diuretics, vasopressors (dopamine) to support the blood pressure and the use of intravenous medications (dobutamine) which stimulate the heart to contract more forcefully. (27 Sep 1997) |
| cardiac skeleton | A complex framework of dense collagen forming four fibrous rings (annuli fibrosi), which surround the ostia of the valves, a right and left fibrous trigone, formed by connecting the rings, and the membranous portions of the interatrial and interventricular septa; it is found in association with the base of the ventricles, i.e., at the level of the coronary sulcus; its functions include: 1) contributing reinforcement of the valvular ostia while providing attachment for the leaflets and cusps of the valves; 2) providing origin and insertion for the myocardium; and 3) serving as a sort of electrical "insulator," separating the electrically conducted impulses of the atria and ventricles and providing passage for the common atrioventricular bundle of conductive tissue through the right fibrous trigone and membranous interventricular septum. Synonym: cardiac fibrous skeleton, cardiac skeleton, skeleton of heart. (05 Mar 2000) |
| cardiac souffle | A soft puffing heart murmur. (05 Mar 2000) |
| cardiac sound | The sounds heard over the cardiac region produced by the functioning of the heart. There are four distinct sounds: the first occurs at the beginning of systole and is heard as a "lubb" sound; the second is produced by the closing of the aortic and pulmonary valves and is heard as a "dupp" sound; the third is produced by vibrations of the ventricular walls when suddenly distended by the rush of blood from the atria; and the fourth is produced by atrial contraction and ventricular filling but is rarely audible in the normal heart. The physiological concept of heart sounds is differentiated from the pathological heart murmurs. (12 Dec 1998) |
| cardiac standstill | <cardiology> Cardiac standstill or arrest, absence of a heartbeat. Synonym: Beau's syndrome. (18 Nov 1997) |