166 articles
Patent foramen ovale
A patent foramen ovale is a flap-like opening between the heart's right and left atria that fails to seal after birth, present in about 25% of adults.
Pediatric tachyarrhythmias
Pediatric tachyarrhythmias are abnormally fast heart rhythms in fetuses, infants, children, and adolescents. Supraventricular tachycardia is the most common, often from accessory pathways that frequently resolve with age.
Pericardium
The pericardium, also known as the pericardial sac or heart sac, is the double-layered fibrous sac enclosing the heart, lubricating its movement and anchoring it within the chest.
Perioperative tachyarrhythmia
Perioperative tachyarrhythmia is a rapid heart rhythm, above 100 beats per minute, arising during or after surgery and anesthesia; atrial fibrillation accounts for about 90% of cases.
Persistent eustachian valve
Persistent eustachian valve (ORPHA:99120, ICD-10 Q26.8): rare congenital IVC anomaly with postnatal persistence of the eustachian valve remnant; often asymptomatic, but can cause IVC obstruction, thrombosis, endocarditis, or right-to-left shunt with patent foramen ovale.
Persistent fetal circulation
Persistent fetal circulation, also called persistent pulmonary hypertension of the newborn (PPHN), is failure of fetal-to-neonatal circulatory transition causing right-to-left shunting, cyanosis, and refractory hypoxemia in about 1–2 per 1,000 live births.
Persistent fifth aortic arch
Persistent fifth aortic arch (PFAA), double-lumen aortic arch: rare congenital anomaly from failure of the fifth embryonic arch to regress; Weinberg types A to C; associated with coarctation, interrupted arch, VSD, pulmonary atresia.
Physiologic and autonomic bradycardia
Physiologic and autonomic bradycardia is a slow heart rate arising from normal autonomic regulation, chiefly increased parasympathetic (vagal) tone, seen during sleep, rest, and reflex states like vasovagal reactions.
Pre-excitation syndrome
Pre-excitation syndrome, chiefly Wolff-Parkinson-White (WPW), is a cardiac condition where an accessory pathway bypasses the AV node, causing early ventricular activation, delta waves, AVRT, and risk of pre-excited atrial fibrillation; curable by catheter ablation.
Preload (cardiology)
Preload (cardiology): the end-diastolic load on a heart ventricle, defined as passive wall stress at end-diastole and clinically surrogated by EDV or EDP. Central to the Frank–Starling law and to fluid responsiveness testing (PLR, PPV, EEO, mini-fluid challenge) in critical care.
Premature closure of the arterial duct
Premature closure of the arterial duct (ductus arteriosus), ORPHA:95486, ICD-10 Q25.8: rare fetal constriction or closure of the duct without structural heart defects, usually from maternal NSAIDs, causing right heart overload, hydrops, or fetal death.
Procainamide
Procainamide, a class IA sodium channel blocker and amide analog of procaine, treats life-threatening ventricular arrhythmias and stable VT; known for lupus-like syndrome, QT prolongation, and PROCAMIO trial superiority over amiodarone.
Pulmonary artery banding
Pulmonary artery banding (PAB) is a palliative heart operation, introduced by Muller and Dammann in 1951-1952, that constricts the pulmonary artery to cut excessive lung blood flow in congenital defects, single-ventricle palliation, and infant heart failure.
Pulmonary atresia with intact ventricular septum
Pulmonary atresia with intact ventricular septum (PA-IVS) is a rare congenital heart defect in which the pulmonary valve fails to develop, causing cyanosis in newborns.
Pulmonary valve
Pulmonary valve (pulmonic valve, valva trunci pulmonalis): the heart's three-cusp semilunar valve between right ventricle and pulmonary trunk; opens in systole, closes in diastole; disorders include stenosis, regurgitation, atresia.
Pulse
Pulse: the arterial pulse and heart rate, a vital sign. Normal adult resting rate 60-100 bpm; measured at radial, carotid, and other sites; history from Herophilus to sphygmograph and modern PPG wearables.
Pulse pressure
Pulse pressure (PP) is systolic minus diastolic blood pressure, normally about 40 mmHg. Determined by stroke volume, arterial stiffness, and wave reflection; a wide PP predicts cardiovascular risk, a narrow PP suggests shock or tamponade.
Purkinje fibers
Purkinje fibers: specialized glycogen-rich cardiac muscle cells forming the terminal subendocardial network of the heart's conduction system, discovered by Jan Evangelista Purkinje in 1839 in sheep, conducting at 2–3 m/s and acting as backup ventricular pacemaker.
Right aortic arch
Right-sided aortic arch (RAA), a congenital variant where the aortic arch courses right of the trachea, occurring in about 0.1% of people; main types are mirror-image branching and aberrant left subclavian artery, the latter forming a compressive vascular ring.
Right-to-left shunt
Right-to-left shunt: abnormal flow of deoxygenated blood into the systemic circulation, causing cyanosis. Causes include Eisenmenger shunt reversal, complex congenital heart disease, PFO, and pulmonary AVMs; diagnosed by bubble echocardiography.
Romano–Ward syndrome
Romano–Ward syndrome is the most common, autosomal dominant form of congenital long QT syndrome, in which the heart recharges slowly between beats, risking fainting and sudden death without deafness.
Scimitar syndrome
Scimitar syndrome: rare congenital anomaly with right pulmonary venous drainage into the inferior vena cava, right lung hypoplasia, and systemic arterial supply; named by Neill in 1960; survival 88% at age 30.
Single-ventricle physiology
Single-ventricle physiology: one functional ventricle pumps to both lungs and body with mixing of blood. Treated by staged Norwood, Glenn, and Fontan palliation; Fontan circulation causes venous hypertension, liver disease, and transplant-dependent failure.
Sinoatrial node
The sinoatrial node, also called the SA node, is a cluster of cells in the right atrium that generates the heartbeat's electrical rhythm as the heart's natural pacemaker.
Sinus node dysfunction
Sinus node dysfunction, formerly sick sinus syndrome, is impaired sinoatrial node impulse generation or conduction causing bradycardia, pauses, or chronotropic incompetence; treated with dual-chamber pacemakers per DANPACE and MOST trial evidence.
Sinus rhythm
Sinus rhythm is the normal heart rhythm initiated by the sinoatrial node, the heart's natural pacemaker, at a rate of 60 to 100 beats per minute.
Sinus tachycardia
Sinus tachycardia: a regular heart rhythm from the sinoatrial node at over 100 bpm, usually an appropriate response to exercise, fever, or stress; also covers inappropriate sinus tachycardia (IST), a diagnosis of exclusion defined by resting HR >100 bpm.
Stroke volume
Stroke volume is the volume of blood ejected by a ventricle with each contraction, typically 60 to 100 mL per beat in healthy adults at rest.
Supravalvular aortic stenosis
Supravalvular aortic stenosis (SVAS), also called supravalvar aortic stenosis or elastin arteriopathy, is congenital narrowing of the ascending aorta above the aortic valve, caused by ELN gene mutation or deletion at 7q11.23, alone or in Williams-Beuren syndrome.
Systole
Systole (Greek systolē, contraction): the cardiac cycle phase of heart-muscle contraction and blood ejection, from AV valve closure to semilunar valve closure; includes isovolumetric contraction and ejection; opposite of diastole.