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| | Sinoatrial Node Dysfunction |
 | | This wide range of rates corresponds with the wide activity levels that humans engage in and the wide range in demands for cardiac output. | | | Treatment for SA node dysfunction includes elimination of any offending medication (Table 1 above), and if necessary, implantation of a pacemaker system. | | | As mentioned above, it is often associated with atrial tachyarrhythmias such as atrial fibrillation or flutter. |
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http://www.kpep.org/bradyarrhythmias/sinus_node_dysfunc.htm
(470 words)
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| | Heart Health Nutrient - Nature's Essence |
| | This report summaries results of clinical trials of Nature's Essence Heart Nutrient carried out in 12 hospitals for treatment of weak sinoatrial node, weak cardiac function, myocardial ischemia, tachysystole and heart pain. | | | Nature's Essence Heart Nutrient is a clinically tested traditional Chinese herbal dietary supplement made in China, approved by China government as traditional Chinese medicine. | | | It promotes heart health by stimulating the sinoatrial node, enhancing cardiac muscle contraction, and improving blood supply to the cardiac muscle. |
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http://www.organix.net/organix/hearthtm.htm
(836 words)
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| | School of Biomedical Sciences |
| | SAN dysfunction increases in incidence with age and roughly affects 1 in 600 of the Western population, leading to implantation of an artificial pacemaker to maintain a normal level of cardiac activity. | | | Our established model system of cellular oxidative stress, induced by UV generated free radicals, enabled the conclusion of an attenuated response by antioxidant supplementation. | | | The sinoatrial node (SAN) or pacemaker of the heart is a complex heterogeneous tissue, responsible for normal function of the healthy mammalian heart. |
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http://www.leeds.ac.uk/bms/staff/saj/index.php
(1314 words)
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| | Sinoatrial Node Heart Pain Dreams Unity Electromagnetic Field Pollution |
| | The pain, the clutching of my heart, the keeling over every now and then as my body contorted in response, and the shocks of pain down my left arm continue through today. | | | Argues that such dreams reflect a state of unity and emotional fulfillment. | | | A journal entry detailing bouts of severe pain in the sinoatrial node of my heart. |
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http://www.singingmountain.org/y2003jun1.html
(375 words)
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| | University of Miami School of Medicine - Glossary - Sinoatrial node |
| | This quick response is important during exercise when the heart has to increase its beating speed to keep up with the body's increased demand for oxygen. | | | This stunningly designed system generates electrical impulses and conducts them throughout the muscle of the heart, stimulating the heart to contract and pump blood. | | | Sinoatrial node: The sinoatrial node (the SA node) is one of the major elements in the cardiac conduction system, the system that controls the heart rate. |
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http://www.med.miami.edu/glossary/art.asp?articlekey=5495
(314 words)
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| | The Sinoatrial Node |
| | Voltage measurements on the skin of the chest are called an electrocardiogram or ECG. | | | The depolarization and repolarization of the SA node and the other elements of the heart's electical system produces a strong pattern of voltage change which can be measured with electrodes on the skin. | | | In the case of the SA node, there is input frorm the physiology of the body related to oxygen demand and other factors which control the rate of firing of the SA node and therefore the heartrate. |
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http://hyperphysics.phy-astr.gsu.edu/hbase/biology/sanode.html
(278 words)
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| | Biomedical Sciences |
| | We are expressing a number of ion channels in oocytes and, using site-directed mutagenesis, we can examine the structure-function relationships of the channels. | | | The sinoatrial node is a non-uniform tissue in terms of its structure, electrophysiology and function. | | | The heart is controlled by the vagal nerves. |
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http://www.leeds.ac.uk/bms/staff/mrb
(877 words)
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| | AnatomySAnode |
| | If parasympathetic stimulation is increased, for instance by massaging the carotid sinus (baroreceptors), the heart rate decreases. | | | These cells are responsible for initiating the electrical impulse that stimulates the heart muscles to contract rhythmically. | | | The existence of these three tracts is controversial since their presence has not been firmly proven. |
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http://sprojects.mmi.mcgill.ca/cardiophysio/AnatomySAnode.htm
(376 words)
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| | ECGs AND PACEMAKERS |
| | This article describes the physiology of the conduction pathway and outlines the principles behind nonconducted impulses currently categorized as first-, second-, and third-degree (complete) atrioventricular block. | | | First-degree atrioventricular block with a wide QRS complex may be associated with delayed conduction in the atrioventricular node or bundle of His but is most often associated with delayed conduction in the bundle branches. | | | As is the case with other cardiac tissue, depolarization of the atrioventricular node is followed by a built-in recovery time; a time lag occurs before the next impulse can pass through (the repolarization time). |
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http://www.aacn.org/aacn/jrnlccn.nsf/c54ad59fdf5d6228882565a0006a1369/5fe2adbebe94952f882569f400056d54?OpenDocument
(3938 words)
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| | Indian Pacing and Electrophysiology Journal - Simmers |
| | Hendry et al attempted surgical treatment, again of inappropriate sinus tachycardia rather than SART, by simply excising the sinus node area of the right atrium | | | Sinoatrial reentry tachycardia is a relatively uncommon arrhythmia in the literature, but may be prone to underdiagnosis due to electrocardiographic similarity to sinus tachycardia and misinterpretation of symptoms as psychosomatic. | | | Sustained symptomatic sinus node reentrant tachycardia: incidence, clinical significance, electrophysiologic observations and the effects of antiarrhythmic agents. |
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http://www.ipej.org/0303/simmers.htm
(2834 words)
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| | sinoatrial node (anatomy) - General Practice Notebook |
| | Please read through our terms and conditions: 1. | | | The sinuatrial node of the heart is the first component of the conducting system of the heart. | | | The artery of the sinuatrial node traverses the node; it is purported that it may serve a physiological function by conveying aortic pressure to nodal tissue. |
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http://www.gpnotebook.co.uk/medwebpage.cfm?ID=1436155964
(1025 words)
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| | Cellml.org - Modelling The Effect Of Intracellular Ca2+ On Sinoatrial Node Action Potentials, 2001 |
| | In addition, they included a sustained inward current based on the experiments and equations of Shinagawa et al (2000) (see Figure 1 below). | | | These models have the same equations to define the ionic currents but they vary in their parameters. | | | For an example of a more complete documentation for an electrophysiological model, see The Hodgkin-Huxley Squid Axon Model, 1952. |
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http://www.cellml.org/examples/repository/B_SAN_model_2001_doc.html
(485 words)
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| | Virtual Cath Lab |
| | The depolarization wave spreads down these specialized cardiac conduction system fibers over the atria by way of internodal and interatrial pathways known as | | | Although the depolarization of the SA node is the first step of the cardiac cycle, it does not produce enough energy to be recorded by the electrocardiograph. | | | It is horseshoe shaped and located just beneath the epicardium. |
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http://user.gru.net/clawrence/vccl/chpt2/SINO.htm
(152 words)
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| | eMedicine - Sinus Node Dysfunction : Article by M Silvana Horenstein, MD |
| | Because of the patient's symptoms and his sinus node dysfunction, he received an atrial pacemaker. | | | Other causes of syncope in children, such as a breath-holding spell, a hypoxic spell, aortic stenosis, cerebral and spinal chord disorders (eg, trauma, polyneuropathies, migraine, inner ear/vestibular dysfunction, micturition syncope), subclavian artery steal, hypoglycemia, drugs, hyperventilation, and hysterical reactions | | | However, the current belief is that the diagnosis should rely on noninvasive methods rather than measuring SN recovery time or sinoatrial conduction time in the EP laboratory because results can be normal despite the patient having symptoms of SND or vice versa. |
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http://www.emedicine.com/ped/topic2533.htm
(5305 words)
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| | oehmen |
| | Since the bidomain model assumes a cable-type configuration of cells and omits single-cell properties which may dramatically impact pacing behavior, it is not appropriate to apply bidomain models to three-dimensional models of the sinoatrial node tissue. | | | Existing propagation models, such as the bidomain model, which are designed to describe the behavior of electric fields in cardiac tissue make assumptions about heterogeneity of conduction in ventricular cells, which are arranged roughly, as cables. | | | The parallel computational development of this project will allow a new and more comprehensive understanding of one of the most fundamental physiological processes which has been classically considered intractable. |
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http://www.krellinst.org/Fellows/oehmen.html
(237 words)
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| | Conduction System |
| | The ends of the sinoatrial node fibers fuse with the surrounding atrial muscle fibers, and action potentials originating in the sinus node travel outward into these fibers. | | | The potential of the sinoatrial node fibers between discharges has a negativity o fonly -55 to -60 millivolts in comparison with a ventricular muscle fiber which depolarizes at -85 to -90 millivolts. | | | There is a difference in the function of the above mentioned channels in the sinoatrial node fibers. |
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http://oak.cats.ohiou.edu/~jr888793/conduction.html
(1724 words)
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| | Sinoatrial node - Wikipedia, the free encyclopedia |
| | Because the sinoatrial node is responsible for the rest of the heart's electrical activity, it is sometimes called the primary pacemaker. | | | Although all of the heart's cells possess the ability to generate the electrical impulses (or action potentials) which trigger cardiac contraction, the sinoatrial node is what normally initiates it, simply because it generates impulses slightly faster than the other areas with pacemaker potential. | | | Because cardiac myocytes, like all nerve cells, have refractory periods following contraction during which additional contractions cannot be triggered, their pacemaker potential is overridden by the sinoatrial node. |
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http://en.wikipedia.org/wiki/Sinoatrial_node
(390 words)
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| | Heart |
| | The sinoatrial node, often known as the cardiac pacemaker, is located in the upper wall of the right atrium and is responsible for the wave of electrical stimulation (See action potential) that initiates the atria to contract. | | | The heart's rhythmic contractions occur spontaneously, although the frequency or heart rate can be changed by nervous or hormonal influences such as exercise or the perception of danger. | | | In the event of severe pathology, the Purkinje fibers can also act as a pacemaker; this is usually not the case because their rate of spontaneous firing is considerably lower than that of the other pacemakers and hence is overridden. |
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http://www.brainyencyclopedia.com/encyclopedia/h/he/heart.html
(1255 words)
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| | Atrioventricular node - Wikipedia, the free encyclopedia |
| | The blood supply of the AV node is from a branch of the right coronary artery in 85 to 90 percent of individuals, and from a branch of the left circumflex artery in 10 to 15 percent of individuals. | | | This is the property of the AV node that prevents rapid conduction to the ventricle in cases of rapid atrial rhythms, such as atrial fibrillation or atrial flutter. | | | 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. |
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http://en.wikipedia.org/wiki/AV_node
(241 words)
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| | Beta-adrenergic and muscarinic receptor mRNA accumulation in the sinoatrial node area of adult and senescent rat hearts. |
| | The sinoatrial (SA) node is the cardiac pacemaker and changes in its adrenergic-muscarinic phenotype have been postulated as a determinant of age-associated modifications in heart rate variability. | | | This change was specific of the sinoatrial area since adult and senescent whole atrial or ventricular myocardium did not differ in their M2-R/beta-AR mRNA ratio, and was associated with a fragmentation of acetylcholinesterase staining of the senescent SA node. | | | Quantitative changes in the expression of genes encoding proteins involved in heart rate regulation specifically affect the sinoatrial area of the senescent heart. |
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http://www.arclab.org/medlineupdates/abstract_9578116.html
(184 words)
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| | The Cardiac Cycle |
| | The sinoatrial (SA) node is a small mass of specialised cardiac muscle situated in the superior aspect of the right atrium. | | | The pathway taken by each action potential generated by the SA node is represented schematically as | | | Since the fibres of the SA node fuse with the surrounding atrial muscle fibres, the action potential generated in the nodal tissue spreads throughout both atria at a rate of approximately 0.3 meter per second and produces atrial contraction. |
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http://www.jdaross.cwc.net/cardiac_cycle.htm
(1160 words)
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| | Heart Physiology |
| | A network of nerve fibers coordinates the contraction and relaxation of the cardiac muscle tissue to obtain an efficient, wave-like pumping action of the heart. | | | These nerve fibers send impulses that cause the cardiac muscle tissue to contract. | | | The impulse spreads through the atria, prompting the cardiac muscle tissue to contract in a coordinated wave-like manner. |
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http://www.cardioconsult.com/Physiology
(435 words)
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| | Identifying Drug-Induced Changes in Electrocardiogram Results of Elderly Individuals |
| | The sinoatrial node, located at the junction of the superior vena cava and the right atrium, is the area of the heart which, under normal conditions, depolarizes most rapidly. | | | Thus, the sinoatrial node is often referred to as the pacemaker of the heart. | | | Acute: supraventricular arrhythmias (rarely clinically significant); chronic: decreased QRS voltage |
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http://www.ascp.com/public/pubs/tcp/1997/jan/idicerei.html
(2640 words)
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| | Sinoatrial Node |
| | The SA node is also sensitive to adrenaline which causes it to depolarize faster and to acetylcholine which causes it to depolarize slower. | | | The body always has many checks and balances to keep everything in a state of homeostasis. | | | How does the Sinoatrial node "know" that the muscles need more oxygen and to increase heart rate? |
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http://www.newton.dep.anl.gov/askasci/zoo00/zoo00128.htm
(324 words)
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| | [No title] |
| | Specialized heart muscle that serves as an pacemaker for the heart. | | | Part of the autonomic nervous system that usually functions to excite or speed up the systems it enervates. | | | The electrical impulse produce the muscular contraction of that heart that is responsible for the pumping action of the heart. |
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http://sprojects.mmi.mcgill.ca/cardiophysio/glossary.asp?l=S
(377 words)
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| | The Mosby Medical Encyclopedia: sinoatrial (SA) node@ HighBeam Research |
| | Implanting an artificial pacemaker is a common operation for individuals suffering from a defective sinoatrial node, and more than 150,000 persons are leading active lives with... | | | The Mosby Medical Encyclopedia: sinoatrial (SA) node@ HighBeam Research | | | Keith-Flack node, a cluster of hundreds of cells in the heart. |
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http://www.highbeam.com/library/doc0.asp?DOCID=1P1:28740147&refid=ip_encyclopedia_hf
(138 words)
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| | APStracts 5:0233H, 1998. |
| | Regional differences in the effects of 4-aminopyridine within the sinoatrial node. | | | It is concluded that 4 -AP-sensitive outward current plays a major role in action potential repolarization and pacemaker activity in the sinoatrial node and its role varies regionally. | | | Effects were greater in tissue from the periphery of the node than from the centre. |
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http://www.uth.tmc.edu/apstracts/1998/heart/June/233H.html
(246 words)
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| | Biophysical Journal: Diastolic Calcium Release Controls the Beating Rate of Rabbit Sinoatrial Node Cells: Numerical ... |
| | Pharmacological and biophysical experiments have suggested that those cyclic variations of submembrane Ca^sup 2+^ are an important determinant of the pacemaker firing rate, and thus represent a critical factor determining pacemaker cell dominance, as well as for achieving the maximum possible chronotropic effect under hormonal stimulation of the heart (Lakatta et al., 2003). | | | Single sinoatrial nodal cells were isolated from rabbit hearts as previously described (Vinogradova et al., 2000). | | | Pharmacological and biophysical experiments have suggested that the released Ca^sup 2+^ interacts with the plasma membrane via the ion current (I^sub NaCa^) produced by the Na^sup +^/Ca^sup 2+^ exchanger and constitutes an important determinant of the pacemaker rate. |
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http://www.findarticles.com/p/articles/mi_qa3938/is_200404/ai_n9388564
(1377 words)
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| | SINOATRIAL NODE |
| | Normal cardiac impulses start in the sinoatrial node and are transmitted to the ventricles, through the atrioventricular node, and into the bundle of His. | | | The impulse generating ("pacemaker") tissue located in the right atrium. |
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http://www.medhelp.org/glossary2/new/gls_4232.htm
(69 words)
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| | MedlinePlus Medical Encyclopedia: Paroxysmal supraventricular tachycardia (PSVT) |
| | Paroxysmal supraventricular tachycardia (PSVT) can be initiated in the SA node; in the atria or the atrial conduction pathways; or in the AV node. | | | The signal is conducted through the atria (the upper heart chambers) and stimulates the atria to contract. | | | The electrical signal then passes through the atrioventricular node (AV node), and travels through the ventricles (the larger, lower chambers), stimulating them to contract. |
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http://www.nlm.nih.gov/medlineplus/ency/article/000183.htm
(905 words)
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| | Publications of Henggui Zhang |
| | "Computational studies of electrotonic interactions between sinoatrial node and atrium", | | | "Vagal control of sino-atrial node - experiments and simulations". | | | H Zhang, M.R.Boyett, A.V.Holden "Two dimensional studies of Electrotonic interactions between sinoatrial node and atrium and effects of acetylcholine", |
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http://personalpages.umist.ac.uk/staff/H.Zhang-3/hengguipub.htm
(1494 words)
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| | How does the heart beat? |
| | Your heartbeat is triggered by electrical impulses that travel down a special pathway through your heart. | | | This delay gives the atria time to contract before the ventricles do. | | | A cluster of cells in the center of the heart between the atria and ventricles, the AV node is like a gate that slows the electrical signal before it enters the ventricles. |
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http://www.clevelandclinic.org/heartcenter/pub/guide/heartworks/heartbeat.htm
(296 words)
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| | Depression Pain Sinoatrial Node Right Nipple Right Middle Finger Left Arm Wave Of Energy At Solar Plexus Shift ... |
| | Argues that a shift in consciousness needs to occur, whereby my self-concept is transcended and a Heart-centered consciousness dominates my waking consciousness. | | | Coincident with this energetic frustration is pain that occurs at the sinoatrial node of my heart and at a node near my right nipple, which shoots down the left arm and to the right middle finger, respectively. | | | Describes a growing depression that occurs at my solar plexus, like a wave of frustrated energy there. |
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http://www.singingmountain.org/y2003oct26.html
(410 words)
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| | SA node and AV node |
| | Electrical pulses in the heart are controlled by special groups of cells called nodes. | | | The SA (sinoatrial) node generates an electrical signal that causes the upper heart chambers (atria) to contract; the signal then passes through the AV (atrioventricular) node to the lower heart chambers (ventricles), causing them to contract, or pump. | | | The SA node is considered the pacemaker of the heart. |
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http://my.webmd.com/hw/health_guide_atoz/sts14215.asp
(123 words)
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| | Sinoatrial Node of the Heart |
| | name Lance status student age 12 Question - What is sinoatrial node and how does it affect the heart? |
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http://www.newton.dep.anl.gov/askasci/bio00/bio00040.htm
(139 words)
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| | Dr. Richard Nathan |
| | Nathan, R.D. Negative surface charge: its identification and regulation of cardiac electrogenesis. | | | Liu, Z.-W., Zou, A.-R., Demir, S.S., Clark, J.W. and Nathan, R.D. Characterization of a hyperpolarization-activated inward current in cultured pacemaker cells from the sinoatrial node. | | | Texas Advanced Research Program (010674-018), "Sodium Currents and the Intrinsic Pacemaker Activity of the Sinoatrial Node," 1/90-9/92, $174,772 (PI) |
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http://www.ttuhsc.edu/som/physiology/Nathan/cv.htm
(1879 words)
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| | Arrhythmia |
| | An arrhythmia is a change from the normal rate or control of the heart’s contractions. | | | All other arrhythmia occur independently to the SA node. | | | Arrhythmia, irregular heart beat, heart conduction system, electrical impulse, sinoatrial node. |
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http://heart-attack.sitesarea.com/q/heart-attack-arrhythmia.htm
(772 words)
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| | Merriam-Webster Online |
| | Get the Top 10 Search Results for "node" | | | For More Information on "node" go to Britannica.com | | | Now you can take the Eleventh Edition with you anywhere as Franklin's new Speaking Electronic Handheld! |
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http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=node
(221 words)
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