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Encyclopedia > Bundle of His
Bundle of His
Bundle of His is near ventricular septum.
Heart cut away showing Bundle of His

Schematic representation of the atrioventricular bundle of His. The bundle, represented in red, originates near the orifice of the coronary sinus, undergoes slight enlargement to form the AV node. The AV node tapers down into the bundle of HIS, which passes into the ventricular septum and divides into two bundle branches, the left and right bundles. Sometimes the 'left and right bundles of His' are called Purkyne or Purkinge fibres. The ultimate distribution cannot be completely shown in this diagram.
Latin fasciculus atrioventricularis
Dorlands/Elsevier b_26/12200650

The bundle of His is a collection of heart muscle cells specialized for electrical conduction that transmits the electrical impulses from the AV node (located between the atria and the ventricles) to the point of the apex of the fascicular branches. The fascicular branches then lead to the Purkinje fibers which innervate the ventricles, causing the cardiac muscle of the ventricles to contract at a paced interval. These specialized muscle fibres in the heart were named after the Swiss cardiologist Wilhelm His, Jr., who discovered them in 1893. Image File history File links Download high-resolution version (700x800, 666 KB) Prinzip der EKG-Darstellung, langsam Summary en: Principle of ECG formation, schnell de: Prinzip der EKG-Darstellung, schnell Autor: Kalumet, selbst erstellt, 28. ... Interventricular septum: The stout wall separating the lower chambers (the ventricles) of the heart from one another. ... Bundle of His, from Grays Anatomy 1918 This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... An aortic sinus is one of the anatomic dilations of the ascending aorta which occurs at the aortic root, i. ... The atrioventricular node (abbreviated AV node) is the tissue between the atria and the ventricles of the heart, which conducts the normal electrical impulse from the atria to the ventricles. ... Interventricular septum: The stout wall separating the lower chambers (the ventricles) of the heart from one another. ... Purkinje fibers (or Purkyne tissue) are located in the inner ventricular walls of the heart, just beneath the endocardium. ... Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ... Elseviers logo. ... A. A schematic view of an idealized action potential illustrates its various phases as the action potential passes a point on a cell membrane. ... The atrioventricular node (abbreviated AV node) is the tissue between the atria and the ventricles of the heart, which conducts the normal electrical impulse from the atria to the ventricles. ... Purkinje fibers (or Purkyne tissue) are located in the inner ventricular walls of the heart, just beneath the endocardium. ... Cardiac muscle is a type of involuntary mononucleated, or uninucleated, striated muscle found exclusively within the heart. ... Cardiology is the branch of medicine dealing with disorders of the heart and blood vessels. ... Wilhelm His, Jr. ... Year 1893 (MDCCCXCIII) was a common year starting on Sunday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Tuesday of the 12-day slower Julian calendar). ...


Cardiac muscle is very specialized, as it is the only type of muscle that has an internal rhythm; i.e., it is myogenic which means that it can naturally contract and relax without receiving electrical impulses from nerves. When a cell of cardiac muscle is placed next to another, they will beat in unison. Cardiac muscle is a type of involuntary mononucleated, or uninucleated, striated muscle found exclusively within the heart. ... Structure of a skeletal muscle Muscle is one of the four tissue types. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ...


The fibers of the Bundle of His allow electrical conduction to occur more easily and quickly than typical cardiac muscle. They are an important part of the electrical conduction system of the heart as they transmit the impulse from the AV node (the ventricular pacemaker) to the rest of the heart. The bundle of His branches into the three bundle branches: the right, left anterior and left posterior bundle branches that run along the interventricular septum. The bundles give rise to thin filaments known as Purkinje fibers. These fibers distribute the impulse to the ventricular muscle. Together, the bundle branches and Purkinje network comprise the ventricular conduction system. It takes about 0.03-0.04s for the impulse to travel from the bundle of His to the ventricular muscle. The normal electrical conduction in the heart allows the impulse that is generated by the sinoatrial node (SA node) of the heart to be propagated to (and stimulate) the myocardium (Cardiac muscle). ... Grays Fig. ...


Pathology

It is extremely important for these nodes to exist as they ensure the correct control and co-ordination of the heart and cardiac cycle. They ensure that cardiac contraction follows the correct sequence and takes place in a coordinated manner. If the cardiac muscle just contracted and relaxed randomly at their own natural rhythm the cycle would become disordered and the heart would become unable to carry on its function of being a pump.


Sometimes when the heart undergoes great damage to one part of the cardiac muscle or the person incurs an electric shock, the cardiac cycle can become uncoordinated and chaotic. Some parts of the heart will contract whilst others will relax so that instead of contracting and relaxing as a whole, the heart will flutter abnormally. This is called ventricular fibrillation and can be fatal if not treated within 10 minutes, a standard clinical heuristic being that survivability decreases 10% per minute. Ventricular fibrillation (V-fib or VF) is a cardiac condition which consists of a lack of coordination of the contraction of the muscle tissue of the large chambers of the heart that eventually leads to the heart stopping altogether. ...


Fibrillation can be detected by an electrocardiogram which measures the waves of excitation passing through the heart and plotting a graph of potential difference (voltage) against time. If the heart and cardiac cycle is functioning properly the electrocardiogram shows a regular, repeating pattern. However if there is fibrillation there will be no apparent pattern. In a hospital the monitor would make a sound and alert the doctors to treat the fibrillation by passing a huge current through the chest wall and shocking the heart out of its fibrillation. This causes the cardiac muscle to stop completely for 5 seconds and when it begins to beat again the cardiac cycle would have resumed to normal and the heart will be beating in a controlled manner again.


If the Bundle of His is blocked, it will result in dissociation between the activity of the atria and that of the ventricles, otherwise called a third degree heart block. The other cause of a third degree block would be a block of the right, left anterior, and left posterior bundle branches. A third degree block is very serious medical condition that will most likely require an artificial pacemaker. Third degree heart block, also known as complete heart block or third degree AV block, is a defect of the electrical system of the heart, in which the impulse generated in the atria (typically the SA node on top of the right atrium) does not propagate to the ventricles. ... A pacemaker A pacemaker (or artificial pacemaker, so as not to be confused with the hearts natural pacemaker) is a medical device designed to regulate the beating of the heart. ...


His Bundle Pacing

In 2000, Dr. Pramod Deshmukh, an electrophysiologist in Sayre, PA announced that he had successfully performed Direct His-Bundle pacing that produced synchronous ventricular depolarization and improved cardiac function relative to apical pacing. This breakthrough was hailed by Dr. Melvin M. Scheinman, considered by many to be the father of electrophysiology, for what he called a "tour de force" deserving "strong accolades" for the technical accomplishment. Sayre is a borough located in Bradford County, Pennsylvania. ... Current Clamp is a common technique in electrophysiology. ...


External links


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