| heart conduction system | An impulse-conducting system composed of modified cardiac muscle and having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart. (12 Dec 1998) |
|---|---|
| heart defects, congenital | Imperfections or malformations of the heart, existing at birth. (12 Dec 1998) |
| heart failure | A condition where there is ineffective pumping of the heart leading to an accumulation of fluid in the lungs. Typical symptoms include shortness of breath with exertion, difficulty breathing when lying flat and leg or ankle swelling. Causes include chronic hypertension, cardiomyopathy and myocardial infarction. (27 Sep 1997) |
| heart failure cells | Macrophages in the lung during left heart failure that often carry large amounts of haemosiderin. See: siderophore. (05 Mar 2000) |
| heart failure in kids | <radiology> Primary cardiomyopathy, aortic outflow obstruction, coarctation, supravalvular aortic stenosis, valvular aortic stenosis, noncardiac lesion, asphyxia, TTN (transient tachypnea of newborn), perinatal brain damage (IVH) see also: neonatal congestive heart failure (12 Dec 1998) |
| heart hormone | A substance present in extracts of cardiac tissue that augments cardiac contraction; possibly adenosine, a catecholamine, or some non-specific stimulant present generally in tissues. Synonym: cardiac hormone, heart hormone. (05 Mar 2000) |
| heart injuries | General or unspecified injuries to the heart. (12 Dec 1998) |
| heart massage | Rhythmic compression of the heart by pressure applied manually over the sternum (closed heart massage) or directly to the heart through an opening in the chest wall (open heart massage). It is done to reinstate and maintain circulation. (12 Dec 1998) |
| heart murmur | A finding on physical examination of the heart that can, in some cases, indicate the presence of cardiac disease. Murmurs result from vibrations set up in the bloodstream and the surrounding heart and great vessels as the result of turbulent flow. (27 Sep 1997) |
| heart murmurs | A sound generated by disturbed blood flow through the heart manifested as "turbulence". Turbulence is an irregular condition of motion caused by local vibrations of the wall of a vessel or heart chamber. Heart murmurs are usually detectable in ventricular outflow obstruction and in various types of heart valve disease and are differentiated from heart sounds, a physiological concept. (12 Dec 1998) |
| heart muscle | <anatomy> Tissue specialised for contraction. See twitch muscle, catch muscle: Cardiac muscle (heart muscle) is a striated but involuntary muscle responsible for the pumping activity of the vertebrate heart. The individual muscle cells are joined through a junctional complex known as the intercalated disc and are not fused together into multinucleate structures as they are in skeletal muscle. Skeletal muscle is a rather non-specific term usually applied to the striated muscle of vertebrates that is under voluntary control. The muscle fibres are syncytial and contain myofibrils, tandem arrays of sarcomeres. Smooth muscle is muscle tissue in vertebrates made up from long tapering cells that may be anything from 20-500m long. Smooth muscle is generally involuntary and differs from striated muscle in the much higher actin/myosin ratio, the absence of conspicuous sarcomeres and the ability to contract to a much smaller fraction of its resting length. Smooth muscle cells are found particularly in blood vessel walls, surrounding the intestine (especially the gizzard in birds) and in the uterus. The contractile system and its control resemble those of motile tissue cells (for example fibroblasts, leucocytes) and antibodies against smooth muscle myosin will cross react with myosin from tissue cells, whereas antibodies against skeletal muscle myosin will not. See: dense bodies. (18 Nov 1997) |
| heart position | A description of the heart's assumed electrical habitus based upon the form of the QRS complexes in leads aVL, aVF, V1, and V6. Sometimes loosely (and inaccurately) used to describe the frontal plane electric axis. Synonym: heart position. (05 Mar 2000) |
| heart rate | The number of beats per minute. Normal resting heart rates are variable with age, sex, size and overall cardiovascular condition. Heart rate can be determined by taking the pulse. Normal heart rate for an average sized adult is in the range of 60-85 beats/minute. (27 Sep 1997) |
| heart rate, foetal | The heart rate of the foetus. The normal range at term is between 120 and 160 beats per minute. (12 Dec 1998) |
| heart rupture | Laceration or tearing of the walls of the heart, of the interatrial or interventricular septum, of the papillary muscles or chordae tendineae, or of any of the valves of the heart. Rupture may be due to a variety of pathological entities, however, the majority are secondary to myocardial infarction (heart rupture, post-infarction). (12 Dec 1998) |
| beer heart | <cardiology, pathology> A weakness of the cardiac muscle which is seen in some chronic alcoholics, may be related to a thiamin deficiency or occur for unknown reasons. Origin: Gr. Pathos = disease (27 Sep 1997) |
|---|---|
| beriberi heart | Heart disease due to thiamine deficiency that may be epidemic or sporadic as characterised by cardiac metabolic damage and myocardial failure, often of the "high output" type, with oedema (except in "dry" beri) and polyneuritis. The term is derived from Singhalese, "I am unable." (05 Mar 2000) |
| biopsy, heart | <investigation, procedure, surgery> A procedure which involves the removal of a small specimen of cardiac muscle tissue for microscopic analysis. This is generally performed at the same time as a cardiac catheterisation or as a very similar, yet separate, procedure. A small piece of heart tissue is taken via a small forceps inserted into the cardiac catheter site (usually threaded through a vein in the neck). This test may reveal the cause of a cardiomyopathy, myocarditis, amyloidosis or a heart transplant rejection. (21 Mar 1998) |
| bony heart | The presence of extensive calcareous patches in the pericardium and walls of the heart, some of which chronically develop bony changes. (05 Mar 2000) |
| box-like heart | <radiology> Ebstein's anomaly, massive cardiomegaly, primarily RA enlargement (12 Dec 1998) |
| brain-heart infusion agar | A medium used for the isolation of fastidious microorganisms, especially fungi. (05 Mar 2000) |
| carcinoid heart disease | Cardiac manifestation of malignant carcinoid syndrome. It is a unique form of fibrosis involving the endocardium, primarily of the right heart. The fibrous deposits tend to cause constriction of the tricuspid and pulmonary valves. (12 Dec 1998) |
| machine, heart-lung | A machine that does the work both of the heart (pump blood) and the lungs (oxygenate the blood). Used, for example, in open heart surgery. Blood returning to the heart is diverted through the machine before returning it to the arterial circulation. Also called a pump-oxygenator. (12 Dec 1998) |
| valvular heart disease | A general term that applies to any abnormality of one of the heart valves, tricuspid, mitral, aortic or pulmonic valves. (27 Sep 1997) |
| rate, heart | Number of heart beats per minute. The normal resting adult heart beats regularly at an average rate of 60 times per minute. (young children's hearts beat faster). The speed of the heartbeat (heart rate) is governed by the speed of electrical signals from the pacemaker of the heart, the sa node, located in the right atrium (upper chamber of the heart). The electrical signals from the sa node travel across the atria and cause these two upper heart chambers to contract, delivering blood into the lower heart chambers, the ventricles. The electrical signals then pass through the av node to reach the ventricles. Electrical signals reaching the ventricles cause these chambers to contract, pumping blood to the rest of the body, generating the pulse. During rest, the speed of electrical signals originating from the sa node is slow, so the heart beats slowly. During exercise or excitement, the speed of signals from the sa node increases, and the heartbeat quickens. (12 Dec 1998) |
| venous heart | <anatomy> The right side, including both the atrium and ventricle, of the heart. (05 Mar 2000) |
| ventricles of heart | One of the two lower chambers of the heart. Synonym: ventriculus cordis. (05 Mar 2000) |
| parchment heart | A congenital or acquired condition in which there is thinning of the right ventricular myocardium. Synonym: right ventricular hypoplasia. (05 Mar 2000) |
| vertical heart | Loosely descriptive of the heart's electrical axis when this is directed at approximately +90 |
| partial heart block | Impulses penetrate the atrioventricular junction in some relation to the ventricular rate. Synonym: incomplete atrioventricular block. (05 Mar 2000) |