823 articles
Cardiac excitation-contraction coupling
Cardiac excitation-contraction coupling (EC coupling) links cardiomyocyte depolarization to contraction via calcium-induced calcium release: L-type Ca²⁺ entry triggers RyR2 SR release at dyads, then SERCA2a and NCX remove Ca²⁺ for relaxation.
Cardiac imaging and diagnostics
Cardiac imaging and diagnostics is the set of tests that produce pictures or functional measurements of the heart, including echocardiography, cardiac MRI, nuclear perfusion imaging, and coronary CT angiography.
Cardiac marker
Cardiac marker (cardiac biomarker): blood substance released when the heart is damaged, measured by immunoassay. Cardiac troponin I/T is the preferred marker for myocardial infarction; high-sensitivity troponin assays enable 1–2 hour rule-out, replacing AST, LDH, CK, and CK-MB.
Cardiac output
Cardiac output (CO) is the blood volume the heart pumps per minute, CO = heart rate × stroke volume. Measured by Fick principle, thermodilution via pulmonary artery catheter, and Doppler, pulse contour, and bioimpedance monitors judged against a ±30% percentage error criterion.
Cardiac pacemaker
Cardiac pacemaker: the sinoatrial node, the heart's natural pacemaker in the right atrium firing at 60–100 bpm, and implanted artificial pacemakers treating bradycardia, including leadless versus transvenous devices.
Cardiac PET
Cardiac PET: positron emission tomography of the heart using tracers such as rubidium-82, nitrogen-13 ammonia, and 15O-water for myocardial perfusion imaging, blood flow quantification, viability, and inflammation, preferred over SPECT for diagnostic accuracy.
Cardiac physiology
Cardiac physiology is the study of how the heart generates and regulates blood flow, spanning electrical and calcium signals, cardiac muscle mechanics, and measurement of cardiac output.
Cardiac plexus
Cardiac plexus: autonomic nerve network at the heart's base where sympathetic cardiac nerves and vagal branches converge into superficial and deep portions, first described by Falloppia in 1561, distributing innervation to atria, ventricles, and intrinsic cardiac ganglia.
Cardiac skeleton
The cardiac skeleton, or fibrous skeleton of the heart, is a framework of dense connective tissue between the atria and ventricles that anchors the four cardiac valves.
Cardiac stress test
A cardiac stress test measures how the heart performs under increased workload, usually treadmill exercise with ECG monitoring, to detect coronary artery disease; drugs replace exercise when patients cannot walk sufficiently.
Cardiac work, energetics and reserve
Cardiac work, energetics and reserve: how the heart converts oxygen into pumping work, measured via pressure-volume loops, PVA, Emax, efficiency, and coronary flow reserve.
Cardiomyopathy
Cardiomyopathy, heart muscle disease, includes dilated, hypertrophic, restrictive, arrhythmogenic, takotsubo, and peripartum types; causes heart failure and arrhythmias; diagnosed mainly by echocardiography.
Cardioplegia
Cardioplegia: drug-induced, reversible cardiac arrest during cardiac surgery using high-potassium solutions (St. Thomas, blood 4:1, del Nido, HTK), delivered ante- or retrograde for myocardial protection.
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.
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.
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.
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.
Cell-mediated immunity
Cell-mediated immunity (cellular immunity): adaptive immune response carried out by T lymphocytes rather than antibodies, defending against intracellular microbes via cytotoxic CD8+ and helper CD4+ T cells.