166 articles
Blalock–Thomas–Taussig shunt
Blalock–Thomas–Taussig shunt (modified BTT shunt, mBTS): palliative systemic-to-pulmonary artery connection for cyanotic congenital heart disease, first performed by Blalock, Thomas, and Taussig at Johns Hopkins on November 29, 1944; modern form uses a PTFE graft.
Blood pressure
Blood pressure is the force of blood against artery walls, reported as systolic/diastolic in mm Hg; normal is under 120/80, high at 130/80 or above, measured by cuff methods and confirmed with ambulatory or home monitoring.
Blood volume
Blood volume, also called volemia, is the total amount of blood circulating in the arteries, capillaries, veins, and heart, about 5 liters in an average adult, varying with body size.
Bundle branch block
Bundle branch block (BBB), left (LBBB) or right (RBBB), is a delay or block in the conduction pathway to one ventricle, causing wide QRS on ECG; LBBB signals heart disease and raises heart failure risk (RR 3.44), while management spans pacemakers, CRT, and conduction system pacing.
Bundle branches (heart)
The bundle branches are the two divisions of the heart's conduction system that carry the cardiac impulse from the bundle of His to the left and right ventricles.
Bundle of His
Bundle of His (atrioventricular bundle), discovered by Wilhelm His Jr. in 1893, is the 1.8 cm cardiac conduction strand linking the AV node to the bundle branches; target of His bundle pacing, now compared with left bundle branch pacing.
Cardiac conduction
Cardiac conduction is the heart's electrical conduction system: sinoatrial and atrioventricular nodes, His bundle, bundle branches, and Purkinje fibers, which initiate and coordinate roughly 3 billion heartbeats over a lifetime.
Cardiac conduction system
Cardiac conduction system: the sinoatrial node, atrioventricular node, bundle of His, bundle branches, and Purkinje fibers that initiate and spread the heartbeat; discovered in reverse order (Purkinje 1839 to sinus node 1907) and now targeted by conduction system pacing.
Cardiac cycle
Cardiac cycle: the sequence of atrial and ventricular contraction and relaxation from one heartbeat to the next, divided by valve events into systole and diastole, with phases, pressures, volumes, ECG timing, heart sounds, and the Wiggers diagram.
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 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 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 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.
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 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.
Central venous pressure
Central venous pressure (CVP) is the pressure in the vena cava near the right atrium, normally 8 to 12 mmHg, measured with a central venous catheter.
Cervical aortic arch
Cervical aortic arch (CAA), a rare congenital anomaly first described by Reid in 1914, in which the aortic arch sits above the clavicles; often a pulsatile neck mass, classified by Haughton types A–E, treated surgically when symptomatic.
Chordae tendineae
Chordae tendineae, also called heart strings or tendinous cords, are collagen cords anchoring the mitral and tricuspid valve leaflets to the ventricular papillary muscles, preventing valve prolapse during contraction; rupture causes regurgitation and is repaired with ePTFE sutures.
Circulatory transition at birth
Circulatory transition at birth is the switch from fetal to adult circulation: lung aeration and cord clamping reverse pressure gradients, closing the foramen ovale, ductus arteriosus, and ductus venosus.
Compliance (physiology)
Compliance (physiology): the ease of volume expansion per pressure change (C=ΔV/ΔP) in heart chambers and vessels; ventricular diastolic compliance, venous capacitance 30 times arterial, and clinical diastolic dysfunction.
Congenital Gerbode defect
The congenital Gerbode defect is a rare abnormal communication shunting blood from the left ventricle directly into the right atrium, accounting for less than 1% of congenital cardiac defects.
Congenital heart block
Congenital heart block: fetal/neonatal AV conduction disorder, usually autoimmune from maternal anti-SSA/Ro and anti-SSB/La antibodies (neonatal lupus), detected 16-24 weeks, ~20% mortality, most survivors need pacemakers.
Congenital heart defect
A congenital heart defect is a structural abnormality of the heart or great vessels present at birth, affecting nearly 1% of live births and leading causes of infant mortality.
Congenital pulmonary vein atresia
Congenital pulmonary vein atresia: rare congenital obstruction of pulmonary veins at the left atrial junction, from failed common pulmonary vein incorporation; forms include common, unilateral, and individual atresia, presenting with tachypnea, pneumonia, or hemoptysis.
Cor triatriatum
Cor triatriatum: rare congenital heart defect, also called cor triatriatum sinister or dexter, in which a fibromuscular membrane divides an atrium into three chambers; about 0.1% of congenital heart disease, treated by surgical membrane resection.
Cor triatriatum dexter
Cor triatriatum dexter (cor triatriatum dextrum, CTD): rare congenital heart defect in which a persistent right sinus venosus valve membrane divides the right atrium into two chambers, causing cyanosis, dyspnoea, or right heart failure, often with atrial septal defect.