A Glossary of Heart Disease Terms
Leaflets: Thin pieces of tissue or flaps that make up a valve.
Left Ventricular Assist Device (LVAD): A mechanical device placed in people with end-stage heart disease whose hearts do not pump a sufficient amount of blood to keep the body healthy (heart failure). The device aids in the pumping function of the blood.
Lipid: Fat circulating in the blood.
Lipoprotein: A combination of fat and protein that transports lipids (fats) in the blood.
Loop Recorder (Event monitor): See Event monitor (above).
Low-Density Lipoprotein (LDL): A lipoprotein particle in the blood responsible for depositing cholesterol into the lining of the artery. Known as "bad" cholesterol, because high LDL is linked to coronary artery disease.
Magnetic Resonance Imaging
(MRI): A test that produces high-quality still and moving pictures of the heart and large blood vessels. MRI uses large magnets and radio-frequency waves to produce pictures of the body's internal structures. No X-ray exposure is involved. MRI acquires information about the heart as it is beating, creating moving images of the heart throughout its pumping cycle.
Mammary Artery (also called thoracic artery): Artery located in the chest wall and used for coronary artery bypass surgery. Most commonly kept intact at its origin, and sewn to the coronary artery beyond the site of blockage. If the surgeon removes the mammary artery from its origin to use as a bypass graft, it is then called a "free" mammary artery bypass graft.
Maze Procedure: A surgical treatment for chronic atrial fibrillation. The surgeon makes multiple incisions in the atrium to form a path or maze through which the impulse can travel to reach the atrioventricular node. After this is done, the atrium is sewn back together and a normal rhythm is more easily maintained.
Mechanical Valve: In people who require heart valve replacement surgery, it is sometimes desirable to implant a mechanical valve. A mechanical valve is made of artificial parts and functions similarly to a normal heart valve. People who have a mechanical valve implanted must take blood thinners lifelong to prevent blood clots from forming on the mechanical valve.
Metabolic Exercise Stress Test (also called metabolic stress test): A test used to measure the performance of the heart and lungs while they are under physical stress. The test involves walking on a treadmill or pedaling a stationary bike at increasing levels of difficulty, while being closely monitored.
Minimally Invasive Heart Surgery: Minimally invasive heart surgery is a technique developed to reduce the trauma associated with open heart surgery. The smaller incision that is used may allow the patient to heal more rapidly. It also helps to reduce the pain and discomfort associated with heart surgery.
Mitral Insufficiency (mitral regurgitation): A condition where blood in the left ventricle leaks back through the mitral valve into the left atrium and can back up into the lungs. The mitral valve normally opens to allow blood to flow into the left ventricle and then closes, preventing blood from backing up into the atrium during the ventricle's contraction.