| irritability | 1. The state or quality of being irritable; quick excitability; petulance; fretfulness; as, irritability of temper. 2. <physiology> A natural susceptibility, characteristic of all living organisms, tissues, and cells, to the influence of certain stimuli, response being manifested in a variety of ways, as that quality in plants by which they exhibit motion under suitable stimulation; especially, the property which living muscle processes, of responding either to a direct stimulus of its substance, or to the stimulating influence of its nerve fibres, the response being indicated by a change of form, or contraction; contractility. 3. <medicine> A condition of morbid excitability of an organ or part of the body; undue susceptibility to the influence of stimuli. See Irritation. Origin: L. Irritabilitas: cf. F. Irritabilite. Source: Websters Dictionary (01 Mar 1998) |
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| anterior myocardial infarction | Infarction involving the anterior wall of the heart, and producing indicative electrocardiographic changes in the anterior chest leads and often in limb lead I. (05 Mar 2000) |
| anteroinferior myocardial infarction | Infarction involving both anterior and inferior walls of the heart simultaneously. (05 Mar 2000) |
| anterolateral myocardial infarction | Extensive anterior infarction producing indicative changes across the precordium as well as in leads I and aVL. (05 Mar 2000) |
| anteroseptal myocardial infarction | An anterior infarction in which indicative electrocardiographic changes are confined to the medial chest leads (V1-V4). (05 Mar 2000) |
| biopsy, myocardial | <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) |
| myocardial | Refers to the heart's muscle mass. (09 Oct 1997) |
| myocardial biopsy | <procedure> 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. (27 Sep 1997) |
| myocardial bridge | A bridge of cardiac muscle fibres extending over the epicardial aspect of a coronary artery; this finding, in cases of sudden unexpected death, has led to speculation that cardiac contraction during exertion could constrict the coronary artery. (05 Mar 2000) |
| myocardial contraction | Contractile activity of the heart. (12 Dec 1998) |
| myocardial contusion | A bruise to the heart muscle, usually caused by a blunt force applied to the anterior thorax (motor vehicle accident). Commonly seen in association with a rib or sternum fracture. Complications include cardiac arrhythmias and death. (27 Sep 1997) |
| myocardial depressant factor | A low molecular weight peptide of about 800-1000 having a negative inotropic effect. It is released into the circulation during experimental haemorrhagic pancreatitis, severe ischemia, and postoligaemic shock. (12 Dec 1998) |
| myocardial diseases | Diseases of the myocardium. (12 Dec 1998) |
| myocardial infarct imaging | <radiology> Tc-99m pyrophosphate (PYP) 20 mCi, peak abnormality 2-3 days, often falsely negative before 2 days, abnormal for 7-10 days, mechanism: calcium influx into ischemic cells, PYP incorporated into crystalline structure, analogous to hydroxyapatite see: nuclear cardiology (12 Dec 1998) |
| myocardial infarction | A term used to describe irreversible injury to heart muscle. Synonym: heart attack. See: infarction. Common symptoms include substernal, crushing chest pain that may radiate to the jaw or arms. Chest pains may be associated with nausea, sweating and shortness of breath. Acronym: MI (27 Sep 1997) |