• Sinoatrial node reentrant tachycardia (SANRT) is caused by a reentry circuit localised to the SA node, resulting in a P-wave of normal shape and size (morphology) that falls before a regular, narrow QRS complex. (wikipedia.org)
  • Reentrant supraventricular tachycardias (SVT) involve reentrant pathways with a component above the bifurcation of the His bundle. (msdmanuals.com)
  • If these maneuvers are ineffective, treatment is with IV adenosine or nondihydropyridine calcium channel blockers for narrow QRS rhythms or for wide QRS rhythms known to be a reentrant SVT with aberrant conduction that requires atrioventricular nodal conduction. (msdmanuals.com)
  • AV nodal reentrant tachycardia occurs most often in otherwise healthy patients. (msdmanuals.com)
  • Accessory pathway reentrant tachycardia involves tracts of conducting tissue that partially or totally bypass normal AV connections (bypass tracts). (msdmanuals.com)
  • [ 1 ] Currently, Wolff-Parkinson-White (WPW) syndrome is defined as a congenital condition involving abnormal conductive cardiac tissue between the atria and the ventricles that provides a pathway for a reentrant tachycardia circuit, in association with supraventricular tachycardia (SVT). (medscape.com)
  • Diltiazem converts paroxysmal supraventricular tachycardia (PSVT) to normal sinus rhythm by interrupting the reentry circuit in AV nodal reentrant tachycardias and reciprocating tachycardias, e.g. (nih.gov)
  • Most have a narrow QRS complex, although, occasionally, electrical conduction abnormalities may produce a wide QRS complex that may mimic ventricular tachycardia (VT). (wikipedia.org)
  • In 1930, Wolff, Parkinson, and White described a series of young patients who experienced paroxysms of tachycardia and had characteristic abnormalities on electrocardiography (ECG). (medscape.com)
  • Abnormalities in any of these factors can result in bradycardia or tachycardia that are not related to any specific cardiac disorder. (mhmedical.com)
  • Abnormalities in impulse formation result in sinus bradycardia and tachycardia, premature atrial and ventricular contractions, and ectopic or automatic rhythms from the atria, AV node, or ventricles. (mhmedical.com)
  • However, especially in the presence of congenital or acquired structural or conduction abnormalities, a subset of dysrhythmias (ie, sustained VT and VF) may pose an immediate threat to life by causing profound hemodynamic instability. (medscape.com)
  • F. The most common form of paroxysmal supraventricular tachycardia (PSVT) is AV nodal reentry due to dual pathways of excitation in the region of the AV node (see Figure 1). (rjmatthewsmd.com)
  • When there is a disturbance in the normal conduction through the fast pathway, the slow pathway may be activated to conduct the excitation wave to the bundle of His, as well as retrograde back to the fast one, and then back again down the slow pathway continuously to produce the PSVT (see Figure 1). (rjmatthewsmd.com)
  • Management of PSVT due to AV nodal reentry. (rjmatthewsmd.com)
  • Third-degree atrioventricular (AV) block, also referred to as third-degree heart block or complete heart block (CHB), is an abnormal heart rhythm resulting from a defect in the cardiac conduction system in which there is no conduction through the atrioventricular node (AVN), leading to complete dissociation of the atria and ventricles. (medscape.com)
  • Supraventricular tachycardias (SPVT) usually have narrow QRS complexes, but they may be wide because of aberrant counduction through the intraventricular conducting tissue, participation of a bypass tract in the intraventricular depolarization pattern,or in the presence of a coexiting bundle branch block. (rjmatthewsmd.com)
  • The therapeutic benefits of diltiazem in supraventricular tachycardias are related to its ability to slow AV nodal conduction time and prolong AV nodal refractoriness. (nih.gov)
  • These abnormal rhythms start from either the atria or atrioventricular node. (wikipedia.org)
  • The electrical impulse that signals your heart to contract begins in an area of the heart called the sinoatrial node (also called the sinus node or SA node). (medlineplus.gov)
  • The electrical impulse normally originates in the sinoatrial (SA) node. (mhmedical.com)
  • Conduction through the AV node is slowed so that atrial contraction is complete before ventricular contraction occurs. (mhmedical.com)
  • Diltiazem exhibits frequency (use) dependent effects on AV nodal conduction such that it may selectively reduce the heart rate during tachycardias involving the AV node with little or no effect on normal AV nodal conduction at normal heart rates. (nih.gov)
  • It has no effect on the sinus node recovery time or on the sinoatrial conduction time in patients without SA nodal dysfunction. (nih.gov)
  • In the heart, normal impulse initiation begins in the sinoatrial node (SAN). (medscape.com)
  • Following intra-atrial conduction to the area of the lower intra-atrial septum, this wavefront reaches the inputs to the atrioventricular node (AVN). (medscape.com)
  • They run most commonly from the atria directly to the ventricles and less commonly from the atrium to a portion of the conduction system or from a portion of the conduction system to the ventricle. (msdmanuals.com)
  • Sustained tachyarrhythmias may eventually cause myocardial dysfunction, which is known as tachycardia-induced cardiomyopathy. (mhmedical.com)
  • Following myocardial infarction (MI), the myocardium is prone to calcium-driven alternans, which typically precedes ventricular tachycardia and fibrillation. (frontiersin.org)
  • In addition, ventricular tachycardia can quickly degenerate into ventricular fibrillation and death and merits different consideration. (wikipedia.org)
  • Ventricular fibrillation ( V-fib or VF ) is an abnormal heart rhythm in which the ventricles of the heart quiver instead of pumping normally. (mdwiki.org)
  • Arrhythmias are caused by problems with the heart's electrical conduction system. (medlineplus.gov)
  • In classic (or manifest) WPW syndrome, antegrade conduction occurs over both the accessory pathway and the normal conducting system during sinus rhythm. (msdmanuals.com)
  • Supraventricular tachycardia (SVT) is an umbrella term for fast heart rhythms arising from the upper part of the heart. (wikipedia.org)
  • This is in contrast to the other group of fast heart rhythms - ventricular tachycardia, which start within the lower chambers of the heart. (wikipedia.org)
  • A congenital heart lesion, Ebstein's anomaly, is most commonly associated with supraventricular tachycardia. (wikipedia.org)
  • Ventricular Premature Beats (VPB) Ventricular premature beats (VPB) are single ventricular impulses caused by reentry within the ventricle or abnormal automaticity of ventricular cells. (msdmanuals.com)
  • Increased automaticity occurs when atrial, nodal, or ventricular cells display autonomous repetitive depolarization at a higher rate than is normal. (mhmedical.com)
  • the ventricular rate may be less when AV conduction is incomplete. (rjmatthewsmd.com)
  • Heart block occurs when slowing or complete block of this conduction occurs. (medscape.com)
  • Simulations also demonstrated that β-adrenergic receptor stimulation in this specific region reduced the formation of conduction block and the probability of premature ventricular activation propagation. (frontiersin.org)
  • This type of tachycardia is sometimes associated with fever, hypoxemia, electrolyte disturbances, or infusion of intravenous sympathomimetic agents. (mhmedical.com)
  • Occasionally, first-degree AV block may be associated with other conduction disturbances, including bundle-branch block and fascicular blocks (bifascicular or trifascicular block). (medscape.com)
  • Sinus tachycardia is physiologic when a reasonable stimulus, such as the catecholamine surge associated with fright, stress, or physical activity, provokes the tachycardia. (wikipedia.org)
  • Sinus tachycardia can be considered an automatic tachycardia, but it is rarely spontaneous and characteristically resolves when the abnormal stimulus resolves. (mhmedical.com)
  • Block within the normal conduction system is the most obvious form of abnormal impulse conduction. (mhmedical.com)
  • Re-entry , the other form of abnormal impulse conduction, is an important mechanism underlying supraventricular tachycardia in infants. (mhmedical.com)
  • In general, a history of structural heart disease markedly increases the likelihood that the tachycardia is ventricular in origin. (wikipedia.org)
  • AV block results from various pathologic states causing infiltration, fibrosis, or loss of connection in portions of the healthy conduction system. (medscape.com)
  • Medical treatment of complete heart block is limited to patients with conduction disease in the AVN. (medscape.com)
  • Sound of a teen's heart during tachycardia. (wikipedia.org)
  • While high levels of overall cardiac sympathetic drive are a negative prognostic indicator of mortality following MI and during heart failure, β-adrenergic receptor stimulation in the infarct border zone reduced spatially heterogeneous alternans, and prevented conduction block and propagation of extrasystoles. (frontiersin.org)
  • Thus, first-degree AV block represents delay or slowing of conduction. (medscape.com)
  • In the less common situation in which a wide-complex tachycardia may be supraventricular, a number of algorithms have been devised to assist in distinguishing between them. (wikipedia.org)
  • This is exacerbated by changes in the expression of membrane ion channels and under-expression and reorganization of gap junctions ( Luke and Saffitz, 1991 ) in the infarct border zone also slowing conduction ( Tse, 2016 ). (frontiersin.org)
  • In the clinical setting, the distinction between narrow and wide complex tachycardia (supraventricular vs. ventricular) is fundamental since they are treated differently. (wikipedia.org)
  • Click THIS LINK for a downloadable pdf of Part 1: Non-Specific Intraventricular Conduction Delays. (ecgguru.com)