Purkinje fibers

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Purkinje fibers
Section of the heart showing the ventricular septum.
The QRS complex is the large peak in the diagram at the bottom.
Dorlands/Elsevier	f_05/12361434

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Overview

Purkinje fibers (or Purkyne tissue) are located in the inner ventricular walls of the heart, just beneath the endocardium. These fibers are specialized myocardial fibers that conduct an electrical stimulus or impulse that enables the heart to contract in a coordinated fashion.

Histology

Because of their specializations to rapidly conduct impulses (numerous sodium ion channels and mitochondria, fewer myofibrils than the surrounding muscle tissue), Purkinje fibers take up stain differently than the surrounding muscles cells, and on a slide, they often appear lighter and larger than their neighbors.

Function

Purkinje fibers work with the sinoatrial node (SA node) and the atrioventricular node (AV node) to control the heart rate.

During the ventricular contraction portion of the cardiac cycle, the Purkinje fibers carry the contraction impulse from the left and right bundle branches to the myocardium of the ventricles. This causes the muscle tissue of the ventricles to contract and force blood out of the heart — either to the pulmonary circulation (from the right ventricle) or to the systemic circulation (from the left ventricle).

The impulse through the Purkinje fibers is associated with the QRS complex.

Purkinje fibers also have the ability of automaticity - they generate action potentials, but at a slower rate than sinoatrial node and other atrial ectopic pacemakers. Thus they serve as the last resort when other pacemakers fail.

Etymology

They were discovered in 1839 by Jan Evangelista Purkinje, who gave them his name.

See also

• Electrical conduction system of the heart

External links

• subendocardial+branches+of+atrioventricular+bundles at eMedicine Dictionary
• Organology at UC Davis Circulatory/heart/purkinje/purkinje1
• Anatomy Atlases - Microscopic Anatomy, plate 05.78
• MedEd at Loyola Histo/practical/cardio/hp8-21.html
• Histology Atlas
• Histology Atlas

v • d • e Anatomy of torso, cardiovascular system: heart
Structures	atria (interatrial septum, musculi pectinati) • ventricles (interventricular septum, trabeculae carneae, chordae tendinae, papillary muscle) • valves • cusps
Regions	base • apex • grooves (coronary/atrioventricular, interatrial, anterior interventricula, posterior interventricular) • surfaces (sternocostal, diaphragmatic) • borders (right, left)
Right heart	(vena cavae, coronary sinus) → right atrium (auricle, fossa ovalis, limbus of fossa ovalis, crista terminalis, valve of the inferior vena cava, valve of the coronary sinus) → tricuspid valve → right ventricle (conus arteriosus, moderator band/septomarginal trabecula)  → pulmonary valve → (pulmonary artery and pulmonary circulation)
Left heart	(pulmonary veins) → left atrium (auricle) → mitral valve → left ventricle → aortic valve (aortic sinus) → (aorta and systemic circulation)
Layers	pericardium: fibrous pericardium • serous pericardium (pericardial cavity, epicardium/visceral layer) • pericardial sinus myocardium • endocardium • cardiac skeleton (fibrous trigone, fibrous rings)
Conduction system	Cardiac pacemaker • SA node • AV node• bundle of His • Purkinje fibers

v • d • e Electrocardiography
Overview	History of the EKG • EKG interpretation basics • Normal sinus rhythm
EKG Complexes	P wave • QRS complex • ST Segment • T wave • U wave Osborn wave • H wave • K wave • Delta wave NSSTW changes
EKG Intervals	PR Interval • QRS Interval • ST Interval • QT Interval
Conduction System & Bradycardia	Cardiac pacemaker • SA node • AV node• Bundle of His • Purkinje fibers • Sinus bradycardia • First Degree AV Block • Second Degree AV Block • Complete or Third-Degree AV Block • Concealed conduction • AV Junctional Rhythms • LBBB • LAHB • LPHB • RBBB • Trifascicular block
Atrial Arrhythmias	Sinus tachycardia • Premature Atrial Contractions (PACs) • Ectopic Atrial Rhythm • Paroxysmal Atrial Tachycardia (PAT) • Paroxysmal Atrial Tachycardia (PAT) with Block • Multifocal Atrial Tachycardia (MAT) • Atrial Flutter • Atrial Fibrillation • Wandering atrial pacemaker
Ventricular Arrhythmias	Differential Diagnosis of Tachycardia with a Wide QRS Complex • Accelerated Idioventricular Rhythm • Ventricular Parasystole • Premature Ventricular Contractions (PVCs) • Ventricular tachycardia • Ventricular Fibrillation • Sudden cardiac death
EKG Abnormalities in Disease States	Hypertrophy & Dilatation • Right atrial enlargement • Left atrial enlargement • Biatrial enlargement • Left Ventricular Hypertrophy • Right Ventricular Hypertrophy • Biventricular Hypertrophy • Acute myocardial infarction • NSTEMI • STEMI • Right ventricular myocardial infarction • Atrial infarction Pre-excitation Syndromes • Wolff-Parkinson-White Syndrome • Lown Ganong Levine Syndrome • Mahaim Type Preexcitation Cardiomyopathies • Arrhythmogenic Right Ventricular Dysplasia • Dilated Cardiomyopathy • Hypertrophic Cardiomyopathy Drug Effects on the EKG • Adenosine • β-blockers • Digitalis • Quinidine • Procainamide • Disopyramide • Lidocaine • Tocainide and Mexiletine • Phenytoin • Encainide, Flecainide and Propafenone • Amiodarone • Bretylium • Ca Channel Blockers • Phenothiazines • Tricyclic Antidepressants • Lithium Congenital Heart Disease • Dextrocardia • Atrial Septal Defect • Ventricular Septal Defect • Tetralogy of Fallot • Conjoined Twins or Siamese Twins Electrolyte Disturbances • Hyperkalemia • Hypokalemia • Hypercalcemia • Hypocalcemia • Nonspecific Changes Other Heart Diseases • Pericarditis • Myocarditis • Tamponade • Heart Transplantation • Sick Sinus Syndrome • Long QT Syndrome Inherited Disease • Brugada Syndrome Systemic Diseases • CNS Disease • Cardiac Tumors Heart Transplantation • EKG Changes in patient with Heart Transplantation Exogenous Effects • Hypothermia • Chest Trauma • Insect Bites • Electric Injuries
Technical Issues and Potential Errors in Interpretation	Artifacts • Lead Placement Errors • The EKG in a Patient with a Pacemaker

fr:Fibre de Purkinje

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Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .