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Herniorrhaphy
Herniorrhaphy is the surgical repair of a hernia by stitching the defect closed with the patient's own tissue, without mesh, now largely replaced by mesh hernioplasty.
Herniotomy
Herniotomy is a surgical operation in which the hernial sac is excised and ligated at its neck, and it is the standard curative procedure for inguinal hernia in children.
Heroin
Heroin (diacetylmorphine, diamorphine) is a semi-synthetic opioid first synthesized in 1874 by C.R. Wright and marketed by Bayer from 1898 as a cough medicine; now a Schedule I illicit drug, roughly 2-3 times more potent than morphine.
Herpangina
Herpangina is a contagious childhood viral illness caused by enteroviruses, mainly group A coxsackieviruses, producing fever, sore throat, and small posterior-mouth ulcers; it peaks in summer, resolves within a week, and is treated supportively.
Herpes simplex infections
Herpes simplex infections, caused by HSV-1 and HSV-2, are lifelong latent viral infections causing recurrent oral and genital lesions; treated with acyclovir, valacyclovir, or famciclovir but not curable, affecting billions worldwide.
Herpes simplex keratitis
Herpes simplex keratitis (HSK, herpetic keratitis) is HSV-1 corneal infection, a leading infectious cause of blindness. Dendritic epithelial disease heals with trifluridine or acyclovir; stromal disease needs steroids plus antivirals.
Herpes simplex labialis
Herpes simplex labialis (cold sores, fever blisters), recurrent lip lesions from latent HSV-1 reactivation; prodrome, 5-7 day course, triggers, and antiviral treatment evidence.
Herpes simplex meningitis
Herpes simplex meningitis, HSV-2 meningitis, Mollaret's recurrent lymphocytic meningitis: meningeal inflammation from HSV-1/2, mostly HSV-2 after genital herpes; self-limiting, diagnosed by CSF PCR, treated with IV acyclovir.
Herpes simplex virus
Herpes simplex virus (HSV-1, HSV-2) is a human virus causing oral and genital herpes, establishing lifelong latency in sensory neurons with periodic reactivation; no cure exists, but acyclovir, valacyclovir, and famciclovir control symptoms.
Herpes simplex virus encephalitis
Herpes simplex virus encephalitis (HSE, HSVE): rare HSV-1 brain infection of frontal and temporal lobes, diagnosed by CSF PCR, treated with IV acyclovir for 14–21 days; 70% mortality untreated, epilepsy and disability common in survivors.
Herpes simplex virus stromal keratitis
Herpes simplex virus stromal keratitis (HSK, herpes stromal keratitis) is immune-mediated corneal stromal inflammation after HSV-1 infection, causing scarring and vision loss; treated with tapered topical corticosteroids plus oral antivirals, as established by the HEDS trials.
Herpetiform pemphigus
Herpetiform pemphigus (pemphigus herpetiformis), named by Jablonska in 1975, is a rare pemphigus variant with itchy dermatitis herpetiformis-like grouped vesicles but pemphigus IgG autoantibodies to desmogleins or desmocollins, minimal acantholysis, and good dapsone response.
Hesitancy of micturition
Hesitancy of micturition, also called urinary hesitancy or urinary hesitation, is a delay or difficulty in starting urination, classified as a symptom rather than a disease.
Hetacillin
Hetacillin is a discontinued semisynthetic aminopenicillin prodrug, an acetone adduct of ampicillin (Versapen), with no antibacterial activity itself; it hydrolyzes in the body to ampicillin, its active form.
Heterochromia iridum
Heterochromia iridum, also called heterochromia iridis, is a difference in iris color between the two eyes or within one iris. Usually a harmless genetic trait, it can signal Horner syndrome, Waardenburg syndrome, neuroblastoma, injury, or latanoprost use.
Heterophoria
Heterophoria (phoria, latent strabismus), ICD-10 H50.5, is a latent eye misalignment visible only when fusion is broken; about 80% of people have some degree, symptomatic only when vergence compensation fails.
Heterosynaptic plasticity
Heterosynaptic plasticity: lasting synaptic strength changes at synapses not active during induction, also called modulatory input-dependent plasticity. It counteracts Hebbian runaway dynamics, stabilizes synaptic weights, and supports long-term memory maintenance.
Heterotopic sebaceous glands
Heterotopic sebaceous glands, also called ectopic sebaceous glands or Fordyce spots, are hair-follicle-free oil glands at mucosal sites such as the lips, buccal mucosa, and genitals; benign, present in about 80% of adults, ICD-11 ED91.0.
Heterotopic transplantation
Heterotopic transplantation is a surgical approach that implants an organ graft at a non-anatomical site while leaving the native organ in place, as in the piggyback heart transplant.
Hexafluorenium
Hexafluorenium (Mylaxen), C36H42N2, a bis-quaternary fluorene nondepolarizing neuromuscular blocker and reversible non-competitive plasma cholinesterase inhibitor used to prolong succinylcholine; US NDA withdrawn 1994.
Hexamidine
Hexamidine is an aromatic diamidine antiseptic (C20H26N4O2), used as its diisethionate salt for skin infections, amoebic keratitis, and as a preservative, limited to 0.1% in cosmetics.
HEXASIIL
HEXASIIL (SIIHEXA) is a WHO-prequalified, fully liquid hexavalent DTwP-HepB-IPV-Hib infant vaccine by Serum Institute of India, given at 6, 10, 14 weeks plus a 12-24 month booster.
Hexasodium phytate
Hexasodium phytate (SNF472, hexasodium fytate), intravenous hexasodium salt of phytate (IP6) that binds hydroxyapatite to inhibit vascular calcification and calciphylaxis; tested through phase 3 in hemodialysis patients.
Hexaxim
Hexaxim (also Hexyon, Hexacima) is Sanofi Pasteur's fully liquid 6-in-1 hexavalent infant vaccine against diphtheria, tetanus, acellular pertussis, polio, hepatitis B, and Hib; WHO-prequalified since December 2014, first licensed 2012, sold in over 100 countries.
Hexestrol
Hexestrol (hexoestrol, CAS 84-16-2) is a synthetic non-steroidal estrogen, a hydrogenated diethylstilbestrol derivative used as a hormonal antineoplastic agent, carcinogenic in hamsters and a Lassa virus entry inhibitor.
Hexetidine
Hexetidine (Oraldene, Hexoral) is a cationic pyrimidine-derivative antiseptic mouthwash for gingivitis, ulcers, sore throat, and thrush; less effective than chlorhexidine, with limited oral retention.
Hexobarbital
Hexobarbital, also called hexobarbitone and marketed as Evipan or Evipal, is a short-acting barbiturate anesthetic introduced in 1932 by Bayer chemists, used in over 10 million operations before being replaced by thiopental.
Hexocyclium
Hexocyclium (Tral) is a discontinued quaternary amine muscarinic acetylcholine receptor antagonist, methylsulfate salt, ATC A03AB10, formerly used for gastric ulcers and diarrhea, with about 5-fold ileal over cardiac receptor selectivity.
Hexosaminidase (β-N-acetylhexosaminidase)
β-N-acetylhexosaminidase (Hex A αβ, Hex B ββ, Hex S αα; HEXA/HEXB) is a lysosomal GH20 enzyme; only Hex A with GM2 activator degrades GM2 ganglioside, and its deficiency causes Tay-Sachs and Sandhoff diseases.
Hexylcaine
Hexylcaine (cyclaine, osmocaine; CAS 532-77-4) is a short-acting ester local anesthetic, 1-(cyclohexylamino)propan-2-yl benzoate, acting on voltage-gated sodium channels; synthesized 1944, used topically from 1952, now discontinued in the US.