| arterial canal | Before birth, the blood headed from the heart (via the pulmonary artery) for the lungs is shunted away from the lungs and returned to the greatest of arteries (the aorta). The shunt is through a short vessel called the ductus arteriosus. When the shunt is open, it is said to be patent (pronounced pa'tent). The patent ductus arteriosus (PDA) usually closes at or shortly after birth and blood is permtted from that moment on to course freely to the lungs. If the ductus stays open (patent), flow reverses and blood from the aorta is shunted into the pulmonary artery and recirculated through the lungs. The PDA may close later spontaneously (on its own) or need to be ligated (tied off) surgically. (12 Dec 1998) |
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| arterial capillary | A capillary opening from an arteriole or metarteriole. (05 Mar 2000) |
| arterial circle of cerebrum | An anastomotic "circle" of arteries (roughly pentagonal in outline) at the base of the brain, formed, sequentially and in anterior to posterior direction, by the anterior communicating artery, the two anterior cerebral, the two internal carotid, the two posterior communicating, and the two posterior cerebral arteries. Synonym: circulus arteriosus cerebri, circle of Willis. (05 Mar 2000) |
| arterial cone | The left or anterosuperior, smooth-walled portion of the cavity of the right ventricle of the heart, which begins at the supraventricular crest and terminates in the pulmonary trunk. Synonym: arterial cone, pulmonary cone, pulmonary conus. (05 Mar 2000) |
| arterial duct | Before birth, the blood headed from the heart (via the pulmonary artery) for the lungs is shunted away from the lungs and returned to the greatest of arteries (the aorta). The shunt is through a short vessel called the ductus arteriosus. When the shunt is open, it is said to be patent (pronounced pa'tent). The patent ductus arteriosus (PDA) usually closes at or shortly after birth and blood is permtted from that moment on to course freely to the lungs. If the ductus stays open (patent), flow reverses and blood from the aorta is shunted into the pulmonary artery and recirculated through the lungs. The PDA may close later spontaneously (on its own) or need to be ligated (tied off) surgically. (12 Dec 1998) |
| arterial embolism | <cardiology, physiology> A sudden interruption in arterial blood flow to an organ or body part (extremity). The blockage is caused by a blot clot or atherosclerotic plaque that has moved through the arterial circulation from one position to another. The resulting mechanism is the same regardless of cause or location. Oxygen deprivation to the tissues distal to the occlusion become ischaemic and die (necrosis). Atrial fibrillation is a risk factor for arterial embolism due to the release of blood clots from the fibrillating heart. Blood vessel injury and increased levels of platelets can also be a risk for arterial embolism. Symptoms vary with location, but pain, coolness to an extremity and a absent or diminished pulse are common in the case of an extremity embolism. Treatment is often surgical or involves the use of blood clot dissolving medications (for example streptokinase) delivered selectively to the site of the blockage. (17 Oct 1997) |
| arterial flap | A flap that includes a direct specific artery within its longitudinal axis. Synonym: arterial flap. (05 Mar 2000) |
| arterial forceps | A locking forceps with sloping blades for grasping the end of a blood vessel until a ligature is applied. (05 Mar 2000) |
| arterial grooves | Branching grooves on the interior surface of the cranial vault in which the meningeal arteries course, the most prominent of which are related to branches of the middle meningeal artery. Synonym: sulci arteriosi. (05 Mar 2000) |
| arterial hyperaemia | active hyperaemia |
| arterial hypotension | See: hypotension. (05 Mar 2000) |
| arterial ligament | The remains of the ductus arteriosus. Synonym: arterial ligament, Botallo's ligament. (05 Mar 2000) |
| arterial line | An intra-arterial catheter. (05 Mar 2000) |
| arterial murmur | A murmur heard on auscultating an artery. (05 Mar 2000) |
| arterial nephrosclerosis | Patchy atrophic scarring of the kidney due to arteriosclerotic narrowing of the lumens of large branches of the renal artery, occurring in old or hypertensive persons and occasionally causing hypertension. Synonym: arterionephrosclerosis, senile nephrosclerosis. (05 Mar 2000) |