| Bundle of His | |
|---|---|
 |
|
| Bundle of His is near ventricular septum. Interventricular septum (or ventricular septum, or during development septum inferius) abbreviated IVS is the stout wall separating the lower chambers (the | |
 |
|
| 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 coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the Myocardium of the Heart. The atrioventricular node (abbreviated AV node) is an area of specialized tissue between the atria and the ventricles of the Heart, specifically 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. Interventricular septum (or ventricular septum, or during development septum inferius) abbreviated IVS is the stout wall separating the lower chambers (the Sometimes the 'left and right bundles of His' are called Purkyne or Purkinge fibres. For the nervous cells see Purkinje cell Purkinje fibers (or Purkyne tissue are located in the inner ventricular walls of the Heart, just The ultimate distribution cannot be completely shown in this diagram. |
|
| Latin | fasciculus atrioventricularis |
| Dorlands/Elsevier | b_26/12200650 |
The bundle of His, also known as the AV bundle or atrioventricular bundle, 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. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Elsevier, the world's largest Publisher of Medical and Scientific literature, forms part of the Reed Elsevier group In Neurophysiology, the action potential is a self-regenerating Wave of Electrochemical activity that allows Nerve cells to carry a signal The atrioventricular node (abbreviated AV node) is an area of specialized tissue between the atria and the ventricles of the Heart, specifically 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. For the nervous cells see Purkinje cell Purkinje fibers (or Purkyne tissue are located in the inner ventricular walls of the Heart, just The cardiac muscle is a type of involuntary striated Muscle found in the walls of the Heart.
Contents |
Eponym
These specialized muscle fibres in the heart were named after the Swiss cardiologist Wilhelm His, Jr., who discovered them in 1893. Switzerland (English pronunciation; Schweiz Swiss German: Schwyz or Schwiiz Suisse Svizzera Svizra officially the Swiss Confederation Cardiology (from Greek grc καρδίᾱ kardiā, "heart" and grc -λογία -logia) is the branch of Internal medicine Wilhelm His Jr (born December 29, 1863, died November 10, 1934) was a Swiss -born Cardiologist and Anatomist Year 1893 ( MDCCCXCIII) was a Common year starting on Sunday (link will display the full calendar of the Gregorian calendar (or a Common [1][2]
Function
Cardiac muscle is very specialized, as it is the only type of muscle that has an internal rhythm; i. The cardiac muscle is a type of involuntary striated Muscle found in the walls of the Heart. e. , it is myogenic which means that it can naturally contract and relax without receiving electrical impulses from nerves. Myogenic contraction refers to a Myocyte Contraction that originates from a property of the Myocyte itself When cardiac muscle cells are placed next to another, they will beat in unison. The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called
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 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 The intrinsic rate of the Bundle of His is between 40 - 60 bpm. [3] 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 bundle of His, also known as the AV bundle or atrioventricular bundle is a collection of heart muscle cells specialized for electrical conduction that transmits the electrical Interventricular septum (or ventricular septum, or during development septum inferius) abbreviated IVS is the stout wall separating the lower chambers (the 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.
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 condition in which there is uncoordinated contraction of the Cardiac muscle of the ventricles in the
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, and defibrillation is necessary. Defibrillation consists of delivering a therapeutic dose of electrical energy to the affected heart with a device called a defibrillator. This depolarizes a critical mass of the heart muscle, terminates the arrhythmia, and allows normal sinus rhythm to be reestablished by the body's natural pacemaker, in the sinoatrial node of the heart. 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 The contractions of the Heart are controlled by chemical impulses which fire at a rate which controls the beat of the heart The Sinoatrial node (abbreviated SA node or SAN, also called the sinus node) is the impulse generating (pacemaker tissue located in the Right atrium
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. Third degree AV block, also known as complete heart block, is a defect of the electrical system of the Heart, in which the impulse generated in the atria (typically The other cause of a third degree block would be a block of the right, left anterior, and left posterior bundle branches. The bundle of His, also known as the AV bundle or atrioventricular bundle is a collection of heart muscle cells specialized for electrical conduction that transmits the electrical A third degree block is a very serious medical condition that will most likely require an artificial pacemaker. For other uses see Pacemaker (disambiguation A pacemaker (or artificial pacemaker, so as not to be confused with the heart's natural pacemaker
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. Sayre is a borough in Bradford County, Pennsylvania, 59 miles (95 km northwest of Scranton.
References
Silverthorn, Dee U. Human Physiology: an integrated approach. Fourth Edition. University of Texas. Benjamin Cummings publishing, 2007.
External links
- -1469382599 at GPnotebook
- Atlas of anatomy at UMich ht_rt_vent - "Right atrioventricular bundle branch, anterior view"
- atrioventricular+bundle at eMedicine Dictionary
- Scheinman MM, Saxon LA (2000). GPnotebook is a British medical database for General practitioners (GPs The University of Michigan Ann Arbor ( U of M, U-M, UM or simply Michigan) is a top-ranked Coeducational public research eMedicine is an online clinical medical knowledge base that was founded in 1996 by Scott Plantz and Richard Lavely two medical doctors "Long-term His-bundle pacing and cardiac function". Circulation 101 (8): 836-7. PMID 10694517.
- Norman/Georgetown thoraxlesson4 (thoraxheartinternalner)
- http://www.healthyheart.nhs.uk/heart_works/heart03.shtml
Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic