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Aortic stenosis
Aortic stenosis (AS), narrowing of the aortic valve limiting blood flow from the left ventricle, usually from age-related calcification or a bicuspid valve; severe AS (velocity ≥4 m/s, AVA ≤1.0 cm²) is treated by surgical or transcatheter valve replacement.
Aortic valve
Aortic valve: the three-cusp semilunar valve between the left ventricle and aorta. Covers anatomy, embryology, bicuspid valve, stenosis and regurgitation criteria, and SAVR, TAVI, and repair options.
Aortic valve area calculation
Aortic valve area calculation estimates aortic valve opening (cm²) via the invasive Gorlin formula (1951), the Doppler continuity equation, or planimetry by TEE, CMR, or CT; AVA <1.0 cm² defines severe aortic stenosis.
Aortic valve repair
Aortic valve repair: surgical restoration or preservation of the native aortic valve without a prosthesis, using cusp repair, remodeling (Yacoub), or reimplantation (David); low early mortality, ~10% bicuspid reoperation risk.
Aortic valve replacement
Aortic valve replacement (AVR) replaces a diseased aortic valve, via open-heart SAVR or catheter-based TAVR/TAVI, using mechanical valves needing lifelong warfarin or tissue valves; ESC 2025 prefers SAVR under 70, TAVI at 70+.
Aortic valvuloplasty
Aortic valvuloplasty, also known as balloon aortic valvuloplasty (BAV), is a catheter-based procedure that dilates a narrowed aortic valve with an inflated balloon, relieving aortic stenosis without open surgery.
Aortitis
Aortitis is inflammation of the aortic wall, divided into infectious aortitis (Salmonella, Staphylococcus, streptococci) and noninfectious aortitis (giant cell arteritis, Takayasu arteritis, idiopathic), differing in presentation, imaging, treatment, and mortality.
Aorto-ventricular tunnel
Aorto-ventricular tunnel (aortico-left ventricular tunnel, ALVT): rare congenital extracardiac channel from the ascending aorta above the sinotubular junction to the left (>90%) or right ventricle, treated by surgical patch closure.
Aortobifemoral bypass
Aortobifemoral bypass is an open vascular operation joining the abdominal aorta to both femoral arteries with a Y-shaped graft, used since the 1950s for aortoiliac occlusive disease.
Aortoenteric fistula
Aortoenteric fistula (AEF): abnormal communication between the aorta and GI tract, usually the duodenum; primary (aneurysm erosion) or secondary (graft erosion after aortic surgery). Causes massive GI bleeding or sepsis; treated by open or endovascular repair with high mortality.
Aortography
Aortography is an X-ray imaging technique in which contrast dye injected into the aorta shows blood flow through the aorta and its branches, used to diagnose aortic disease.
Aortoiliac occlusive disease
Aortoiliac occlusive disease (AIOD, Leriche syndrome) is atherosclerotic narrowing or blockage of the distal aorta and iliac arteries, causing claudication, erectile dysfunction, and absent femoral pulses; treated endovascular-first with stenting or aortobifemoral bypass.
Aortopulmonary space
Aortopulmonary space (aortopulmonary window): a mediastinal compartment between aortic arch and left pulmonary artery, and a rare congenital hole between aorta and pulmonary artery requiring patch repair.
Aortopulmonary window
Congenital aortopulmonary window (APW, aortopulmonary septal defect) is a rare defect, 0.1-0.6% of congenital heart disease, with an opening between the ascending aorta and pulmonary artery above separate semilunar valves, causing left-to-right shunt, heart failure, and requiring early patch surgical repair.
AP306
AP306 (EOS-789) is an oral first-in-class pan phosphate transporter inhibitor blocking NaPi-IIb, PiT-1, and PiT-2, developed by R1 Therapeutics and Alebund for hyperphosphatemia in dialysis patients, now in a global Phase 2b trial.
Apabetalone
Apabetalone (RVX-208, RVX-000222) is Resverlogix's investigational BD2-selective BET protein inhibitor for atherosclerosis and diabetes; its phase 3 BETonMACE trial missed the primary MACE endpoint but reduced heart failure hospitalization.
APACE study
APACE study (Advantageous Predictors of Acute Coronary Syndromes Evaluation, NCT00470587): prospective multicenter cohort by University Hospital Basel testing history, ECG, and biomarkers for rapid AMI diagnosis in chest pain.
Apadamtase alfa
Apadamtase alfa (Adzynma, rADAMTS13, BAX 930) is Takeda's recombinant human ADAMTS13 enzyme replacement therapy for congenital thrombotic thrombocytopenic purpura, first FDA-approved November 9, 2023, with a 2026 boxed warning for neutralizing antibodies.
Apadenoson
Apadenoson (BMS068645, ATL146e, Stedivaze) is a selective adenosine A2A receptor agonist developed as a pharmacologic stress agent for myocardial perfusion imaging; its Phase 3 program was terminated for business reasons and it was never approved.
Apalutamide
Apalutamide (ARN-509, Erleada) is Janssen's oral androgen receptor inhibitor for prostate cancer; FDA approved February 2018 for nmCRPC after SPARTAN doubled metastasis-free survival, expanded 2019 to mCSPC after TITAN.
Apamarga Ksara
Apamarga Ksara (Apāmārga Kṣāra) is the official Ayurvedic alkaline preparation of Achyranthes aspera ash, pH 10-11, applied as a caustic for hemorrhoids and fistula and taken internally at 125-500 mg.
Apamarga Ksara Taila
Apamarga Ksara Taila (Apamarga Kshara Taila) is an Ayurvedic medicated oil of Achyranthes aspera alkali in sesame oil, used for tinnitus and deafness via karna purana, and studied in Uttarabasti for urethral stricture and tubal blockage infertility.
Apathy in dementia
Apathy in dementia (ICD-11 6D86.3) is a sustained reduction in goal-directed behavior in neurocognitive disorders, affecting roughly 21-90% of patients; methylphenidate and non-pharmacological approaches are the main treatments.
Apaziquone
Apaziquone (EO9, Qapzola, EOquin) is a mitomycin C analog bioreductive prodrug for intravesical treatment of non-muscle invasive bladder cancer; not FDA approved after 2016 phase III failure.
Apex beat
Apex beat (apical impulse, point of maximal impulse): the palpable left ventricular impulse, normally in the fifth left intercostal space at the midclavicular line; palpable in about 50% of adults and used to assess cardiomegaly and ventricular character.
APEX trial (NCT01583218)
APEX (NCT01583218) was Portola's phase 3 trial of extended betrixaban versus enoxaparin prophylaxis in 7,513 acutely ill medical patients; cohort 1 missed its primary endpoint, but the FDA approved betrixaban in 2017 while the EMA refused.
Apexification
Apexification is an endodontic treatment that induces a calcified apical barrier at the open apex of an immature, nonvital permanent tooth, using calcium hydroxide or an MTA plug.
APG-2449
APG-2449 (CAS 2196186-84-0) is Ascentage Pharma's orally active FAK/ALK/ROS1 triple tyrosine kinase inhibitor, a third-generation ALK TKI with phase 1 ORR 78.6% in TKI-naive ALK+ NSCLC and two China CDE-cleared Phase III studies.
Apgar score
Apgar score: rapid 0-10 newborn assessment devised by Virginia Apgar in 1952, scoring color, heart rate, reflexes, tone, and respiration at 1 and 5 minutes; not a predictor of individual outcome or asphyxia diagnosis.
Aphakia
Aphakia is the absence of the crystalline lens in the eye. This condition severely blurs vision and loses accommodation, requiring correction with an IOL or spectacles.