| heart arrest | Sudden and usually momentary cessation of cardiac function. This sudden cessation may, but not usually, lead to death, sudden, cardiac. (12 Dec 1998) |
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| heart arrest, induced | Arrest of the contraction of the myocardium by the use of cardioplegic chemical compounds (cardioplegic solutions) or of cold during heart surgery. (12 Dec 1998) |
| heart, artificial | A pumping mechanism that duplicates the output, rate, and blood pressure of the natural heart. It may replace the function of the entire heart or a portion of it, and may be an intracorporeal, extracorporeal, or paracorporeal heart. (12 Dec 1998) |
| heart-assist devices | Small pumps, often implantable, designed for temporarily assisting the heart, usually the left ventricle, to pump blood; they consist of a pumping chamber and a power source, which may be partially or totally external to the body and activated by electromagnetic motors; the devices are used after myocardial infarction or to wean the repaired heart from the heart-lung machine after open-heart surgery. (12 Dec 1998) |
| heart atrium | The upper right and left chambers of the heart. (12 Dec 1998) |
| heart attack | This refers to that damage that occurs to the heart when one of the coronary arteries becomes occluded. Common symptoms include crushing, substernal chest pain that may radiate to the jaw or the left arm, accompanied by nausea, sweating and shortness of breath. Fainting is a more uncommon presentation. (27 Sep 1997) |
| heart auscultation | Act of listening for sounds within the heart. (12 Dec 1998) |
| heart beat | A complete cardiac cycle, including spread of the electrical impulse and the consequent mechanical contraction. Synonym: ictus cordis. (05 Mar 2000) |
| heart biopsy | <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) |
| heart block | <cardiology, physiology> A conduction disturbance that results in the inappropriate delay (or complete inability) of a electrical impulse, generated in the atria, to reach the ventricles (via the atrioventricular node). Clinical types are divided into first (nonserious), second and third degree (most serious) AV blocks. Some drugs may precipitate an AV block (for example clonidine, methyldopa, verapamil). A permanent pacemaker may be required for a third degree (complete) heart block. (07 Apr 1998) |
| heart bypass, left | Diversion of the flow of blood from the pulmonary veins directly to the aorta, avoiding the left atrium and the left ventricle. This is a temporary procedure usually performed to assist other surgical procedures. (12 Dec 1998) |
| heart bypass, right | Diversion of the flow of blood from the entrance to the right atrium directly to the pulmonary arteries, avoiding the right atrium and right ventricle. This a permanent procedure often performed to bypass a congenitally deformed right atrium or right ventricle. (12 Dec 1998) |
| heart catheterization | Procedure which includes placement of catheter, recording of intracardiac and intravascular pressure, obtaining blood samples for chemical analysis, and cardiac output measurement, etc. Specific angiographic injection techniques are also involved. (12 Dec 1998) |
| 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) |