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Ledderhose disease
Ledderhose disease, or plantar fibromatosis, is a rare benign fibroproliferative disorder of the plantar fascia causing painful nodules; treated conservatively, with radiotherapy or fasciectomy, though surgical recurrence is common.
Ledipasvir
Ledipasvir (GS-5885) is a Gilead HCV NS5A inhibitor, marketed in the fixed-dose combination Harvoni (ledipasvir 90 mg/sofosbuvir 400 mg), FDA-approved in 2014 for chronic hepatitis C genotype 1 and later for ages 3 and up, genotypes 1, 4, 5, 6.
Leech therapy
Leech therapy, or hirudotherapy, attaches live medicinal leeches to the skin to draw blood, relieving venous congestion in flaps, grafts, and replanted parts; FDA-cleared since 2004.
Leeza Mangaldas
Leeza Mangaldas, Indian sex educator, Columbia '11 graduate, author of The Sex Book (HarperCollins, 2022), and co-founder of Leezu's; creates Hindi and English sex-ed content with over 100 million YouTube views.
Lefamulin
Lefamulin (Xenleta, formerly BC-3781) is a first-in-class semisynthetic pleuromutilin antibiotic, approved IV and oral for adults with community-acquired bacterial pneumonia, noninferior to moxifloxacin in the LEAP 1 and LEAP 2 phase 3 trials.
LEFFTDS study
LEFFTDS (Longitudinal Evaluation of Familial Frontotemporal Dementia Subjects) was an NIH-funded North American natural history study following 300-plus members of families with MAPT, GRN, or C9orf72 mutations; it merged with ARTFL into ALLFTD in 2019.
Leflunomide
Leflunomide (Arava) is an oral DMARD for rheumatoid arthritis, approved by the FDA in 1998. A prodrug of teriflunomide, it inhibits DHODH; boxed warnings cover pregnancy contraindication and hepatotoxicity, with cholestyramine washout available.
Left anterior descending artery
Left anterior descending artery (LAD), anterior interventricular branch of the left coronary artery; supplies 50-60% of the left ventricle; its occlusion causes anterior STEMI, the highest-risk coronary occlusion.
Left anterior fascicular block
Left anterior fascicular block (LAFB, left anterior hemiblock) is a conduction delay in the anterior fascicle of the left bundle branch, causing marked left axis deviation on ECG; common in the elderly and a marker of cardiac risk.
Left atrial appendage closure
Left atrial appendage closure (LAAC) is a catheter-based or surgical procedure that seals the left atrial appendage to prevent stroke in atrial fibrillation patients unable to take anticoagulants.
Left atrial appendage occlusion
Left atrial appendage occlusion (LAAO), also called left atrial appendage closure, seals the left atrial appendage to prevent stroke in atrial fibrillation; Watchman and Amulet devices show noninferiority to anticoagulation with less non-procedural bleeding.
Left atrial enlargement
Left atrial enlargement (LAE), also called left atrial dilatation, is atrial remodeling from chronic pressure or volume overload due to hypertension, diastolic dysfunction, or mitral valve disease; defined by indexed LA volume >34 mL/m², it predicts atrial fibrillation, stroke, and heart failure.
Left axis deviation
Left axis deviation (LAD): ECG finding with QRS frontal axis between -30 and -90 degrees, positive lead I and negative leads II/aVF. Causes include left anterior fascicular block, LVH, inferior MI; borderline finding in athlete screening.
Left bundle branch block
Left bundle branch block (LBBB) is a ventricular conduction disorder with QRS ≥120 ms on ECG, common after age 50, linked to heart disease and TAVR, and a key CRT selection criterion.
Left colectomy
Left colectomy is an operation that removes the left portion of the colon, typically for cancer or diverticular disease, with splenic flexure mobilization as its key challenge.
Left Heart Bypass
Left heart bypass (LHB, distal aortic perfusion) drains oxygenated blood from the left atrium and returns it to the distal aorta or femoral artery during thoracoabdominal aneurysm repair, reducing spinal cord ischemia; used since the 1950s.
Left heart catheterization
Left heart catheterization (LHC) is an invasive procedure in which a catheter is advanced into the left ventricle to measure pressures and image the coronary arteries.
Left posterior fascicular block
Left posterior fascicular block (LPFB), or left posterior hemiblock, is a rare conduction block in the posterior fascicle of the left bundle branch, causing right axis deviation on ECG and usually reflecting coronary or other structural heart disease.
Left sided ulcerative colitis
Left-sided ulcerative colitis (Montreal E2) is UC limited to the colon distal to the splenic flexure, about 40% of cases at diagnosis, treated first with combined rectal and oral 5-aminosalicylates.
Left superior caval vein
Left superior caval vein (persistent left superior vena cava, PLSVC): the most common thoracic venous anomaly, a left-sided SVC draining via the coronary sinus, present in about 0.6% of people and up to 10% of congenital heart disease patients.
Left ventricular failure
Left ventricular failure (ICD-11 BD11), also called left-sided heart failure, is abnormal left ventricular function causing pulmonary congestion and fluid retention; classified by ejection fraction (reduced, mid-range, preserved, improved), AHA/ACC stages A–D, and NYHA classes I–IV.
Left ventricular hypertrophy
Left ventricular hypertrophy (LVH) is thickening of the left ventricle wall, usually from hypertension or aortic stenosis; diagnosed by ECG and echocardiography, treated by controlling the underlying cause.
Leg press
Leg press: machine-based lower-body exercise pushing a weighted platform, targeting quadriceps, glutes, hamstrings, and calves. Seated, sled, 45-degree, and vertical variants; stop short of knee lockout; strength gains are modality-specific versus squats.
Legal Abortion
Legal abortion is pregnancy termination performed under a jurisdiction's law. Also called legalized or lawful abortion. Distinguished by safety evidence (0.7 vs 8.8 deaths per 100,000 vs childbirth), global liberalization trends, and post-Dobbs US travel and telehealth access.
Legal medicine
Legal medicine, also called forensic medicine or medical jurisprudence, applies medical knowledge to questions of law, spanning forensic pathology, toxicology, psychiatry, and clinical forensic medicine, with death investigation as its central activity.
Legg–Calvé–Perthes disease
Legg–Calvé–Perthes disease (LCPD, Perthes disease) is idiopathic avascular necrosis of the femoral head in children aged about 4–8, male-to-female 4:1, described by Legg, Calvé, and Perthes around 1910, healing over 2–4 years.
Legionnaires' disease
Legionnaires' disease, also called legionellosis, is severe pneumonia caused by Legionella bacteria inhaled from contaminated water aerosols. Named after the 1976 American Legion convention outbreak in Philadelphia; incubation 2–10 days, mortality 5–10%, no vaccine.
Leiden University Medical Center
Leiden University Medical Center (LUMC, Leids Universitair Medisch Centrum) is a Dutch university medical center formed in 1996 from Academic Hospital Leiden and Leiden University's Faculty of Medicine, known for rare-disease care, ten research themes, and the Leiden Bio Science Park.
Leif I. Solberg
Leif I. Solberg is an American family physician and health services researcher at HealthPartners Institute in Minneapolis, elected to the National Academy of Medicine in 2017.
Leighton E. Cluff
Leighton E. Cluff was an American infectious-diseases physician and immunologist who chaired medicine at the University of Florida and served as president of the Robert Wood Johnson Foundation.