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Cardiopulmonary exercise testing
Cardiopulmonary exercise testing (CPET, also written CPX) is a non-invasive test that measures breath by breath how the cardiovascular, ventilatory, and gas-exchange systems respond to exercise.
Cardiothoracic surgery
Cardiothoracic surgery, also called thoracic and cardiovascular surgery, operates on the heart, great vessels, lungs, esophagus, and thymus. Divided into adult cardiac, thoracic, and congenital surgery; defined by cardiopulmonary bypass, CABG, and TAVR-era practice.
Cardiovascular Diagnostic Techniques
Cardiovascular diagnostic techniques (cardiac diagnostic tests): ECG, echocardiography, cardiac CT/MRI, nuclear imaging, stress testing, and catheterization used to diagnose heart and vessel disease, from Einthoven's 1902 electrocardiograph to CCTA and AI-based analysis.
Cardiovascular drift
Cardiovascular drift, or cardiac drift, is the progressive rise in heart rate and fall in stroke volume during prolonged constant-rate exercise, amplified by heat and dehydration, reduced in trained athletes, and relevant to heart-rate-based training zones.
Cardiovascular physiology
Cardiovascular physiology: how the heart and circulation move blood. Covers cardiac output (HR × SV), preload, afterload, contractility, pressure-volume loops, Frank–Starling law, coronary flow autoregulation, and modern multiomics and arterial stiffness research.
Cardiovascular response to exercise
The cardiovascular response to exercise is the coordinated adjustment of the heart and circulation that raises oxygen delivery to working muscle, lifting cardiac output from about 5 L/min at rest to 20–40 L/min.
Cardioversion
Cardioversion, also called synchronized cardioversion or electrical cardioversion, restores normal sinus rhythm in arrhythmias such as atrial fibrillation using a synchronized electric shock or antiarrhythmic drugs; pioneered by Bernard Lown in 1962.
Carotid artery
The carotid arteries, also known as the arteria carotis, are paired neck arteries supplying the brain, face, and neck; their narrowing from plaque is a major cause of stroke.
Carotid artery dissection
Carotid artery dissection, a tear of the carotid artery wall forming a false lumen, part of cervical artery dissection; a leading cause of stroke in young adults (incidence 2.6–2.9/100,000), treated with antiplatelets or anticoagulation, with low recurrent stroke risk.
Carotid endarterectomy
Carotid endarterectomy (CEA) is surgical removal of plaque from the carotid bifurcation to prevent stroke. Introduced 1954; proven for symptomatic ≥70% stenosis by NASCET and ECST in 1991.
Carotid sinus
The carotid sinus, or carotid bulb, is a dilation at the bifurcation of the common carotid artery that houses baroreceptors regulating blood pressure and heart rate.
Carotid stenting
Carotid artery stenting (CAS), an endovascular alternative to carotid endarterectomy introduced in 1994, places a self-expanding stent in a narrowed carotid artery; CREST showed similar 4-year outcomes with more stroke after CAS and more MI after CEA.
Carpal bones
Carpal bones (carpus): the eight wrist bones in two rows, proximal scaphoid, lunate, triquetrum, pisiform and distal trapezium, trapezoid, capitate, hamate, linking forearm to metacarpals and forming the carpal tunnel.
Carpal tunnel
Carpal tunnel, also called carpal tunnel syndrome or median nerve entrapment, is an osteofibrous wrist canal carrying the median nerve and nine flexor tendons; nerve compression there causes numbness, first described by Paget in 1854 and treated by ligament release.
Carpal tunnel surgery
Carpal tunnel surgery (carpal tunnel release) divides the transverse carpal ligament to decompress the median nerve. Open, mini-open, and endoscopic techniques show similar long-term outcomes; endoscopic release returns patients to work about 7 to 9 days earlier.
Carpal tunnel syndrome
Carpal tunnel syndrome (median nerve entrapment) is compression of the median nerve at the wrist causing thumb, index, and middle finger numbness; diagnosed with CTS-6, treated with splinting, steroid injection, or carpal tunnel release.
Cartilage
Cartilage: non-vascular connective tissue of chondrocytes in a collagen and chondroitin sulfate matrix; hyaline, fibrocartilage, and elastic types; cushions joints, heals poorly, repaired by microfracture, ACI, MACI.
Castleman disease
Castleman disease (angiofollicular lymph node hyperplasia) is a rare lymphoproliferative disorder with unicentric and multicentric forms, driven partly by IL-6 and HHV-8, treated by surgery or siltuximab.
Cataract
Cataract: clouding of the eye's lens, mainly age-related; leading cause of curable blindness (94 million affected). Treated only by surgery, phacoemulsification or manual small incision cataract surgery, with comparable outcomes.
Cataract surgery
Cataract surgery removes the eye's clouded lens and implants an intraocular lens; standard technique is Kelman's 1967 phacoemulsification through sub-3 mm incisions, evolved from couching and Daviel's 1750 extraction.
Cauda equina
Cauda equina, "horse's tail" in Latin, is the bundle of lumbar, sacral, and coccygeal nerve roots descending from the conus medullaris (spinal cord ends L1-L2) to the coccyx; compression causes cauda equina syndrome, a surgical emergency.
Cauda equina syndrome
Cauda equina syndrome (CES): surgical emergency from compression of lumbosacral nerve roots, defined by bladder, bowel, or sexual dysfunction with back and leg pain; diagnosed by urgent MRI, treated by decompression, ideally within 48 hours.
Caul
Caul: amniotic membrane remaining on a newborn's head or face at birth; en caul birth is delivery inside an intact amniotic sac. Rare (about 1.5% in a Swedish cohort), used deliberately in preterm cesarean delivery, and long sold as a drowning-preventing talisman.
Cauliflower ear
Cauliflower ear, also known as wrestler's ear, is a lumpy, shriveled deformity of the external ear caused by blunt trauma that cuts off the cartilage's blood supply.
Causes of autism
Causes of autism: ASD arises from combined genetic and environmental factors; heritability about 80-86%, rare de novo variants plus common-variant load, prenatal risks, and no vaccine link per WHO.
Cavernous sinus
Cavernous sinus: paired dural venous sinus beside the sella turcica containing the internal carotid artery and cranial nerves III, IV, V1, V2, VI; drains ophthalmic and cerebral veins to the petrosal sinuses.
Cavernous sinus thrombosis
Cavernous sinus thrombosis (CST), septic or aseptic clot in the cavernous sinus at the skull base; usually a complication of facial or sinus infection, often Staphylococcus aureus, treated with IV antibiotics, heparin, steroids, and surgery.
Cecum
Cecum (caecum): blind pouch starting the large intestine in the right iliac fossa, joined by the ileum at the ileocecal valve, giving attachment to the appendix; midgut-derived, supplied by the ileocolic artery.
Celiac artery
Celiac artery (celiac trunk, celiac axis): short T12-level branch of the abdominal aorta supplying the foregut via left gastric, splenic, and common hepatic arteries; variants occur in about 10% of people.
Celiac plexus
Celiac plexus (solar plexus), the largest autonomic nerve plexus, lies anterior to the aorta around the celiac trunk at T12–L2, innervating upper abdominal organs and serving as the target of neurolytic blocks for pancreatic and upper abdominal cancer pain.