A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


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LOW DENSITY LIPOPROTEINS (LDL) Low Density Lipoprotein (LDL) is a type of cholesterol carrier which deposits cholesterol on the walls of blood vessels. (See also High Density Lipoprotein.)

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MARFAN'S SYNDROME Marfan’s syndrome is an inherited disease characterized by aneurysms in the aorta, excessive height, abnormally long fingers and toes, and problems with the eyes. (For more information on Marfan's Syndrome, please see http://www.marfan.org/; http://www.crtelco.com/~ckbryant/marfan.html; or http://www.aorn.org/JOURNAL/1296/HOMESTUD/article.htm)

MINIMALLY INVASIVE DIRECT CORONARY ARTERY BYPASS SURGERY (MIDCAB) Minimally invasive direct coronary artery bypass, MIDCAB, surgery refers to open heart bypass surgery performed through a small incision in the chest wall. The purpose of the smaller incision is to reduce pain and recovery time. MIDCAB surgery follows the same basic premise as traditional coronary artery bypass graft, CABG surgery. The blocked section of artery is bypassed surgically through the attachment of a healthy section of artery, usually an internal mammary artery. In a MIDCAB procedure the surgeon operates through a 12 cm incision. (A full sternotomy used in a conventional CABG requires, on average, a 30 cm incision.) The heart is not stopped or placed on cardiopulmonary bypass (the heart-lung machine) for a MIDCAB operation. New heart stabilizers limit motion in the operation field to within 1 millimeter, permitting the surgeon to operate while the heart continues to beat. Because the patient is not placed on the heart-lung machine and because of the smaller incision size, the average post-operative length of stay for MIDCAB patients is only 2-3 days -- versus an average of 5 days for conventional CABG patients.

MINIMALLY INVASIVE SURGERY Minimally invasive surgery, also known as beating heart surgery, refers to the last advancement in open heart surgery. Minimally invasive procedures are performed through a small incision in the chest wall to reduce pain and recovery time. (In conventional open heart surgery a full sternotomy is performed -- the full length of the breast bone, 30 cm long on average, is opened. The average length of a minimally invasive incision ranges from 9-12 cm long.) There are three major types of minimally invasive procedures: (1) minimally invasive direct coronary artery bypass, MIDCAB; (2) minimally invasive valve repair and replacement; and (3) minimally invasive port-access. Originally developed in the early 1960s by a Russian surgeon, minimally invasive techniques have been perfected in the last few years with the development of new medical technologies.

MITRAL INCOMPETENCE Mitral incompetence is a problem with the mitral valve that connects the left atrium to the left ventricle. The valve does not create a complete seal when closed, permitting some blood to flow back into the left atrium when the ventricle contracts -- normally all blood flows out through the aorta. The damage to the valve can be congenital, a result of scarring from an infection, or caused by a myocardial infarction (death of some heart muscle). Symptoms and signs of mitral incompetence include breathlessness, atrial fibrillation (rapid, irregular, ineffective heartbeats), embolisms, enlargement of the left ventricle, and a murmur (systolic). In severe cases the valve should either be repaired or replaced surgically.

MITRAL STENOSIS A stenotic mitral valve has a narrowed valve opening. Mitral stenosis is often caused by rheumatic fever. Symptoms are the same as for mitral incompetence (except that the heart murmur is diastolic instead of systolic). In severe cases the valve should either be repaired or replaced surgically.

MITRAL VALVE The mitral valve connects left atrium to the left ventricle. It has two cusps that, when open, lets blood flow in one direction, from the left atrium into the left ventricle.

MONOUNSATURATED FAT Monounsaturated fat helps to lower blood cholesterol when used in place of saturated fat in the diet. (See also Saturated Fat; Polyunsaturated Fat; and Omega-3 Fatty Acids.)

MRI/MAGNETIC RESONANCE IMAGING MRI/Magnetic Resonance Imaging uses magnets and computer technology to take detailed pictures inside the body.

MUGA SCAN A MUGA scan uses low dose radioactive material given intravenously to visualize the heart’s pumping action (ejection fraction).

MURMUR A murmur is a abnormal sound made by blood that is flowing irregularly, or turbulently in the heart or arteries. It may be caused by a narrowed vessel or valve, a leaking valve, or too much blood flow through a normal vessel. The presence of a murmur may not mean a significant heart problems, but usually requires further evaluation. Systolic murmurs occur when the heart is contracting. Diastolic murmurs occur when the heart is relaxing. Continuous murmurs usually indicate abnormal communications between arteries and veins or between the aorta and other parts of the heart.

MYOCARDIAL INFARCTION Myocardial infarction is the death of a section of heart muscle caused by a loss of blood flow from a coronary artery. Most myocardial infarctions occur in the left ventricle and cause sharp pain in the chest, which can spread to the arms and throat. Other complications include ventricular fibrillation, heart failure, embolisms, mitral incompetence, and shock.

MYOCARDITIS Myocarditis is any inflammation of the heart muscle.

MYOCARDIUM The myocardium is the muscular middle layer of the heart, responsible for making the heart contract.

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NUCLEAR STRESS TESTING Nuclear stress testing is a test done in order to find areas of decreased blood flow to the heart at times when the heart is stressed. A radioactive isotope is injected into the blood stream prior to having a patient exercise. Once the patient has reached his/her target heart rate, a nuclear scan is performed which looks at the concentration of the isotope in various parts of the heart. Areas which appear light in color on the scan do not receive enough blood flow during exercise are likely to be served by a stenotic vessel. Testing is repeated after several hours while the patient is at rest, to determine extent of disease. This test is also known as a stress thalium test.