| Abdomen | The area of the body between the bottom of the ribs and the top of the thighs. |
| Abdominal aorta | The portion of the aorta in the abdomen. |
| Ablation | Elimination or removal. |
| ACE (angiotensin-converting enzyme) inhibitor | A drug that lowers blood pressure by interfering with the breakdown of a protein-like substance involved in blood pressure regulation. |
| AICD (Automatic Implantable Cardioverter Defibrillator) | Surgically implanted device that monitors the heartbeat and delivers electrical impulses to correct an abnormal rhythm and restore a regular heart beat. |
| Aldactone | |
| Amiodarone | A kind of medicine (called an antiarrhythmic), which is used to treat irregular heart rhythms such as atrial fibrillation and ventricular tachycardia. It works by regulating nerve impulses in your heart. Amiodarone is mainly given to patients who have not responded to other antiarrhythmic medicines. |
| Aneurysm | A sac-like protrusion from a blood vessel or the heart, resulting from a weakening of the vessel wall or heart muscle. |
| Angina or angina pectoris | Chest discomfort, pain, tightness or pressure that occurs when diseased blood vessels restrict blood flow to the heart. May also have associated pain in neck, jaw, back, or arm. May include profuse sweating, nausea, or shortness of breath. Angina may be a single symptom or a combination of these symptoms. |
| Angiography | An x-ray technique that makes use of a dye injected into the coronary arteries to study blood circulation through the vessels. The test allows physicians to measure the degrees of obstruction to blood flow. Circulation through an artery is not seriously reduced until the inside diameter of the vessel is more than 75% obstructed. |
| Angioplasty | A nonsurgical technique for treating diseased arteries by temporarily inflating a tiny balloon inside an artery. The balloon is inflated several times to attempt to stretch the cholesterol block so that it no longer causes a significant obstruction. Also known as percutaneous transluminal coronary angioplasty (PTCA). |
| Annulus | The ring around a heart valve where the valve leaflet merges with the heart muscle. |
| Antiarrhythmics | Medicines that are used to treat patients who have irregular heart rhythms. |
| Anticoagulant | Any drug that slows or prevents the blood from clotting; a blood thinner. |
| Antihypertensive | Any drug or other therapy that lowers blood pressure. |
| Antiplatelet | A medicine that reduces the clumping of platelets in the blood. An antiplatelet medicine helps thin the blood to prevent clot formation. |
| Aorta | The largest artery in the body and the initial blood-supply vessel from the heart. |
| Aortic Stenosis | A narrowing or stiffening of the aortic valve due to aging, disease (such as rheumatic fever), or birth defects. |
| Aortic valve | The valve that regulates blood flow from the heart into the aorta. |
| Apex | Pointed part of the heart's left lower chamber (ventricle). |
| Arrhythmia (or dysrhythmia) | An abnormal heartbeat. |
| Arterial bypass graft | A femoro-popliteal bypass procedure is done when the main artery in the leg, the femoral artery is blocked. The surgeon either uses one of your veins or an artificial vein to bypass the blockage and thus provide a blood supply to the lower leg again. Bypass can interest other arteries too (the aorta and the iliac arteries, the popliteal arteries and the calf arteries…). |
| Arteries | They are the blood vessels that bring oxygen and nutrients from the heart to the organ and cells in the body. The largest artery in the body is called the aorta, and runs from the heart to the abdomen. Some of the arteries may be referred to more often: the iliac artery (in the lower abdomen), the femoral artery (in the thigh), the radial artery (in the forearm), and the carotid arteries (in the neck). |
| Arterioles | Small, muscular branches of arteries. When they contract, they increase resistance to blood flow, and blood pressure in the arteries increases. |
| Arteriosclerosis | A disease process, commonly called hardening of the arteries, which includes a variety of conditions that cause artery walls to thicken and lose elasticity. |
| Artery | A vessel that carries oxygen-rich blood to the body. |
| Ascending aorta | The first portion of the aorta, emerging from the heart's left ventricle. |
| Atherectomy | A non-surgical technique for treating diseased arteries with a rotating device that cuts or shaves away obstructing material inside the artery. |
| Atherosclerosis | A disease process in which fatty substances, such as cholesterol, are deposited on the inner lining of blood vessels. |
| Atria | The two upper chambers of the heart. |
| Atrial Fibrillation | Rapid uncoordinated contraction of individual heart muscle fibres of the atrial wall. The atria involved can't contract and so pumps blood ineffectively, if at all. |
| Atrial flutter | A type of arrhythmia where the upper chambers of the heart (the atria) beat very fast, causing the walls of the lower chambers (the ventricles) to beat inefficiently as well. |
| Atrial septal defect | See septal defect. |
| Atrial tachycardia | A type of arrhythmia that begins in the heart's upper chambers (the atria) and causes a very fast heart rate of 160 to 200 beats a minute. A resting heart rate is normally 60 to 100 beats a minute. |
| Atrioventricular (AV) node | A group of cells located between the atria (upper two chambers) and the ventricles (lower two chambers) that regulates the electrical current (heart rhythm) that passes through it to the ventricles. |
| Atrioventricular block | An interruption or disturbance of the electrical signal between the heart's atria (upper two chambers) and the ventricles (lower two chambers). |
| Atrium | Either one of the heart's two upper chambers. |
| Autoregulation | When blood flow to an organ stays the same although pressure changes in the artery that delivers blood to that organ may have changed. |