| 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) |
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| 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 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) |
| myocardial infarction in dumbbell form | Infarction involving the septum along with both inferior and anterior walls to make an H-or dumbbell-shaped configuration. Synonym: Roesler-Bressler infarct. (05 Mar 2000) |
| myocardial insufficiency | 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) |
| myocardial ischemia | A disorder of cardiac function caused by insufficient blood flow to the muscle tissue of the heart. The decreased blood flow may be due to narrowing of the coronary arteries (coronary arteriosclerosis), to obstruction by a thrombus (coronary thrombosis), or less commonly, to diffuse narrowing of arterioles and other small vessels within the heart. Severe interruption of the blood supply to the myocardial tissue may result in necrosis of cardiac muscle (myocardial infarction). (12 Dec 1998) |
| myocardial necrosis | Irreversible destruction of myocardial (heart muscle) cells. (27 Sep 1997) |
| myocardial reperfusion | Generally, restoration of blood supply to heart tissue which is ischemic due to decrease in normal blood supply. The decrease may result from any source including atherosclerotic obstruction, narrowing of the artery, or surgical clamping. Reperfusion can be induced to treat ischemia. Methods include chemical dissolution of an occluding thrombus, administration of vasodilator drugs, angioplasty, catheterization, and artery bypass graft surgery. However, it is thought that reperfusion can itself further damage the ischemic tissue, causing myocardial reperfusion injury. (12 Dec 1998) |
| myocardial reperfusion injury | Functional, metabolic, or structural changes in ischemic heart muscle thought to result from reperfusion to the ischemic areas. Changes can be fatal to muscle cells and may include oedema with explosive cell swelling and disintegration, sarcolemma disruption, fragmentation of mitochondria, contraction band necrosis, enzyme washout, and calcium overload. Other damage may include haemorrhage and ventricular arrhythmias. One possible mechanism of damage is thought to be oxygen free radicals. Treatment currently includes the introduction of scavengers of oxygen free radicals, and injury is thought to be prevented by warm blood cardioplegic infusion prior to reperfusion. (12 Dec 1998) |
| myocardial revascularization | The restoration of blood supply to the myocardium. (12 Dec 1998) |
| myocardial rigor mortis | Irreversible contraction of the left ventricle of the heart as a complication seen in the early period of cardiopulmonary bypass and now avoided by appropriate cardioplegic solutions. Synonym: myocardial rigor mortis, stone heart. (05 Mar 2000) |