A cardiac arrhythmia that is caused by interaction of two independently initiated cardiac impulses of different rates from two separate foci. Generally one focus is the SINOATRIAL NODE, the normal pacemaker. The ectopic focus is usually in the HEART VENTRICLE but can be in the HEART ATRIUM or the ATRIOVENTRICULAR NODE. Modulation of the parasystolic rhythm by the sinus rhythm depends on the completeness of entrance block surrounding the parasystolic focus.
Recording of the moment-to-moment electromotive forces of the HEART as projected onto various sites on the body's surface, delineated as a scalar function of time. The recording is monitored by a tracing on slow moving chart paper or by observing it on a cardioscope, which is a CATHODE RAY TUBE DISPLAY.

The diagnostic criteria for classic parasystole. (1/7)

OBJECTIVE: To establish a diagnostic criteria of parasystole with high sensitivity and high specificity. METHODS: After excluded from nonparasystole and each variant parasystoles, based on the electrocardiographic data obtained from 61 patients with classic parasystole, we selected the quantitative indices which could reflect the features of ectopic focus with complete entrance block as the diagnostic criteria for parasystole. RESULTS: The common features of the electrocardiograms of this group were: 1) Take the earliest recorded eight interectopic intervals in which at least four intervals containing sinus beats or other beats having activated to the area within the ectopic focus. When in case of deficiency, it will fill up a vacancy in order. The ratios of the shortest coupling interval to the shortest ectopic cycle length (ECL) were all less than 80%; 2) The coefficients of variation of the eight ECLs were all less than 6%; 3) The maximal differences of coupling intervals were all equal to or more than 0.11 second. CONCLUSION: Three quantitative indices as necessary conditions have been used as diagnostic criteria for parasystole with high sensitivity and high specificity.  (+info)

Extrapotentials and allorhythmias as an expression of experimental parasystole. (2/7)

The aim of the study was to investigate the dynamics of experimental parasystole taking into consideration the peculiarities of recurrent arrhythmias recorded in clinical settings. MATERIAL AND METHODS: The experiments were conducted on isolated right atria of seven chinchilla rabbits. Parasystolic arrhythmias using periodical one-site electrostimulation were provoked in one atrium, where the sinus node was not affected, and in two atria with the spontaneous low value activity of pacemakers. The parasystolic arrhythmias by the dual-site periodical pacing were provoked in four atria, in which the spontaneous activity had disappeared, while the membrane potential of cardiomyocytes remained at the level of 70 to 80 mV. RESULTS: The parasystolic arrhythmias of the shape of single extrapotentials were obtained in atria when the periods of excitation impulses were within the limits of 0.9-1.2 s, and the differences between these periods being relatively small (0.04-0.2 s). The increase of these differences resulted the various allorhythmias. In cases of single extrapotentials, the recurrence periods of arrhythmias reached 5.6-29 s; while in cases of allorhythmias they shortened to 2.4-4.8 s. CONCLUSION: The parasystoles in isolated atria of rabbits can be induced by two competitive excitation sources. They may manifest themselves through single extrapotentials or allorhythmias, whose form depends on the duration of the periods of excitation impulses, the difference between these durations, as well as on effective refractory periods of atrial cardiomyocytes. The determination and evaluation of the recurrence period of these arrhythmias can serve in any given clinical situation as a supplementary criterion.  (+info)

Variation in parasystolic cycle length. (3/7)

At the time of the first visit to our clinic, an electrocardiographic examination of a 73-year-old female patient revealed ventricular premature contractions (VPCs) with variable coupling intervals that were diagnosed as parasystole. Characteristically many of the parasystoles had no sinus contractions between two consecutive VPCs, which we referred to as pure parasystole. We first repeatedly examined variations in the length of the parasystolic cycles between January 6, 1997 and March 2, 2003 using electrocardiography. The time courses recorded over this period showed that the length of the parasystolic cycle did not remain constant, but varied irregularly within a relatively narrow range. We also recorded the length of the parasystolic cycles over 3 hours using Holter monitoring. The interectopic intervals plotted against mean sinus cycle length showed that the cycle length of pure parasystoles remained almost constant at about 1,300 ms over the 3 hours. We also examined the cycle length during exercise and found that it was slightly prolonged thereafter, while the sinus cycle length was clearly shortened after exercise. The average of six deep breathing tests showed that parasystolic cycle length did not significantly differ between deep inspiration and deep expiration, whereas the sinus cycle length during expiration was significantly longer than that during inspiration. These results indicate that the responses to both exercise and deep breathing obviously differed between the parasystolic and sinus cycle lengths.  (+info)

High power radiofrequency ablation of incessant atrioventricular re-entrant tachycardia in a patient with a Para-Hisian accessory pathway. (4/7)

Radiofrequency ablation is the interventional therapy of choice for the definitive cure of patients with tachycardias facilitated by accessory pathways. Ablation of an accessory pathway at sites close to the His bundle is inevitably associated with an increased risk of causing complete atrioventricular block. Here we describe the case of a patient with pre-excitation syndrome and episodes of supraventricular tachycardia, in whom an electrophysiological study identified an accessory pathway so close to the His bundle that discrete sites between the pathway and the His bundle were extremely difficult to find. After a first, unsuccessful attempt at ablation the patient developed incessant supraventricular tachycardia. The accessory pathway was successfully ablated in a second session using high power radiofrequency current, although this entailed a great increase in the risk of causing complete atrioventricular block.  (+info)

Biological sensitivity to context: the interactive effects of stress reactivity and family adversity on socioemotional behavior and school readiness. (5/7)

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The role of local voltage potentials in outflow tract ectopy. (6/7)

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Effect of standing on ventricular parasystole: shortening of the parasystolic cycle length. (7/7)

OBJECTIVE: To investigate the effect of standing on the parasystolic cycle length in cases of "true" ventricular parasystole. METHODS: Parasystolic cycle length and sinus cycle length were measured during lying and standing in eight men with true ventricular parasystole. These cycle lengths were also measured after exercise in the lying position. RESULTS: In all cases, parasystolic cycle length and sinus cycle length both shortened on standing, by a mean of 6.4% and 17.8%, respectively, compared to lying. In all cases, the rate of shortening of the parasystolic cycle length was less than that of the sinus cycle length. Parasystolic cycle length was prolonged after exercise, in contrast to a shortening of the sinus cycle length. CONCLUSIONS: Influences on the parasystolic cycle length are not always in the same direction as on the sinus cycle length. This suggests that the effect of autonomic changes on parasystolic rhythm is not always parallel to that on sinus rhythm.  (+info)

Parasystole is an unusual form of cardiac arrhythmia, which refers to an abnormal heart rhythm. In parasystole, an additional focus or "ectopic focus" within the heart's electrical conduction system generates impulses independently from the sinoatrial node (the heart's natural pacemaker). These extra impulses can disrupt the normal heart rhythm and cause premature beats or skipped beats.

The key characteristic of parasystole is that its occurrence is influenced by the relationship between the intrinsic rate of the ectopic focus and the sinus node's rate. The ectopic focus may only conduct impulses to the rest of the heart when it is not being suppressed by the dominant sinus rhythm, leading to intermittent irregularities in the heartbeat pattern.

Parasystole is generally considered a benign condition and often doesn't require treatment unless it causes significant symptoms or poses a risk for more severe arrhythmias. However, if associated with structural heart disease or other underlying conditions, further evaluation and management may be necessary.

Electrocardiography (ECG or EKG) is a medical procedure that records the electrical activity of the heart. It provides a graphic representation of the electrical changes that occur during each heartbeat. The resulting tracing, called an electrocardiogram, can reveal information about the heart's rate and rhythm, as well as any damage to its cells or abnormalities in its conduction system.

During an ECG, small electrodes are placed on the skin of the chest, arms, and legs. These electrodes detect the electrical signals produced by the heart and transmit them to a machine that amplifies and records them. The procedure is non-invasive, painless, and quick, usually taking only a few minutes.

ECGs are commonly used to diagnose and monitor various heart conditions, including arrhythmias, coronary artery disease, heart attacks, and electrolyte imbalances. They can also be used to evaluate the effectiveness of certain medications or treatments.

... fixed parasystole and modulated parasystole. Fixed ventricular parasystole occurs when an ectopic pacemaker is protected by ... Extrasystole ventricular parasystole atrial parasystole v t e (Articles needing additional medical references from February ... Parasystole is a kind of arrhythmia caused by the presence and function of a secondary pacemaker in the heart, which works in ... According to the modulated parasystole hypothesis, rigid constancy of a pacemaker might be expected if the entrance block were ...
Over the next several years later they explored modulated parasystole and reflection as mechanisms of cardiac arrhythmias. In ...
... parasystole MeSH C23.550.073.845 - tachycardia MeSH C23.550.073.845.695 - tachycardia, paroxysmal MeSH C23.550.073.845.880 - ...
... parasystole MeSH C14.280.067.780 - pre-excitation syndromes MeSH C14.280.067.780.560 - Lown-Ganong-Levine syndrome MeSH C14.280 ...
... fixed parasystole and modulated parasystole. Fixed ventricular parasystole occurs when an ectopic pacemaker is protected by ... Extrasystole ventricular parasystole atrial parasystole v t e (Articles needing additional medical references from February ... Parasystole is a kind of arrhythmia caused by the presence and function of a secondary pacemaker in the heart, which works in ... According to the modulated parasystole hypothesis, rigid constancy of a pacemaker might be expected if the entrance block were ...
"Parasystole" is a descriptor in the National Library of Medicines controlled vocabulary thesaurus, MeSH (Medical Subject ... This graph shows the total number of publications written about "Parasystole" by people in this website by year, and whether " ... Below are the most recent publications written about "Parasystole" by people in Profiles. ...
"Parasystole" is a descriptor in the National Library of Medicines controlled vocabulary thesaurus, MeSH (Medical Subject ... This graph shows the total number of publications written about "Parasystole" by people in this website by year, and whether " ... Below are the most recent publications written about "Parasystole" by people in Profiles. ...
395. What is parasystole? / What is pseudotachycardia? / Ddx irregularly irregular ...
Difference equation model of ventricular parasystole as an interaction between cardiac pacemakers based on the phase response ...
Bradycardia arrhythmia may have many causes, both cardiac and non-cardiac. Non-cardiac causes are usually secondary, and can involve recreational drug use or abuse, metabolic or endocrine issues, especially hypothyroidism, an electrolyte imbalance, neurological factors, autonomic reflexes, situational factors, such as prolonged bed rest, and autoimmunity.[9] Cardiac causes include acute or chronic ischemic heart disease, vascular heart disease, valvular heart disease, or degenerative primary electrical disease. Ultimately, the causes act by three mechanisms: depressed automaticity of the heart, conduction block, or escape pacemakers and rhythms.[10] In general, two types of problems result in bradycardias: disorders of the SA node, and disorders of the AV node.[11] With SA node dysfunction (sometimes called sick sinus syndrome), there may be disordered automaticity or impaired conduction of the impulse from the SA node into the surrounding atrial tissue (an "exit block"). Second-degree ...
REENTRY VERSUS PARASYSTOLE. 15. TRIGGERED ACTIVITY AND TORSADE DE POINTES. 20. SUPERNORMAL CONDUCTION. 22. ...
Parasystole(英语:Parasystole). *遊走性節律點. 長QT綜合症 ...
Compared with those without parasystole, patients with parasystole had a significantly higher rate of VF (36% vs 11%; P < 0.01 ... but not VT (42% vs 29%; P = 0.12). Patients with parasystole, compared with those without parasystole, had a higher prevalence ... Ventricular Parasystole in Cardiomyopathy Patients: A Link Between His-Purkinje System Damage and Ventricular Fibrillation. ... Ventricular parasystole was identified in 33 patients (9%); parasystolic foci were predominantly from the His-Purkinje system. ...
A potentially lethal cardiac arrhythmia that is characterized by uncoordinated extremely rapid firing of electrical impulses (400-600/min) in HEART VENTRICLES. Such asynchronous ventricular quivering or fibrillation prevents any effective cardiac output and results in unconsciousness (SYNCOPE). It is one of the major electrocardiographic patterns seen with CARDIAC ARREST ...
For patient information, click here Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ogheneochuko Ajari, MB.BS, MS [2]; Sapan Patel M.B.B.S;Template:Lovepreet Randhawa Synonyms and keywords: Varicosities; phlebectasia ...
For patient information, click here Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Abdelrahman Ibrahim Abushouk, MD[2]; Sachin Shah, M.D. Synonyms and keywords: Congestive cardiomyopathy; DCM ...
... parasystole; parasystolic beat; parataxia; parataxic; parataxis; paratenesis; paratenic host; paratenon; paraterminal; ...
Among the conditions that may mimic Mobitz II block are atypical Mobitz I block, junctional parasystole, and concealed ...
Parasystole [C14.280.067.672] * Pre-Excitation Syndromes [C14.280.067.780] * Tachycardia [C14.280.067.845] * Ventricular ...
A group of cardiac arrhythmias in which the cardiac contractions are not initiated at the SINOATRIAL NODE. They include both atrial and ventricular premature beats, and are also known as extra or ectopic heartbeats. Their frequency is increased in heart diseases ...
Differential Diagnosis of Tachycardia with a Wide QRS Complex • Accelerated Idioventricular Rhythm • Ventricular Parasystole • ...
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Lyman Brewer suggests that the first recorded account of ventricular fibrillation dates as far back as 1500 BC, and can be found in the Ebers papyrus of ancient Egypt. The extract recorded 3500 years ago may even date from as far back as 3500 BC. It states: "When the heart is diseased, its work is imperfectly performed: the vessels proceeding from the heart become inactive, so that you cannot feel them … if the heart trembles, has little power and sinks, the disease is advanced and death is near." A book authored by Jo Miles suggests that it may even go back farther. Tests done on frozen remains found in the Himalayas seemed fairly conclusive that the first known case of ventricular fibrillation dates back to at least 2500 BC.[20] Whether this is a description of ventricular fibrillation is debatable.[21] The next recorded description occurs 3000 years later and is recorded by Vesalius, who described the appearance of "worm-like" movements of the heart in animals prior to death. The ...
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Synonyms and keywords: Coronary artery disease; arteriosclerotic heart disease; ischemic heart disease; myocardial ischemia; CHD; CAD ...
Differential Diagnosis of Tachycardia with a Wide QRS Complex • Accelerated Idioventricular Rhythm • Ventricular Parasystole • ...
This arrhythmia can be underlain by several causes, which are best divided into cardiac and noncardiac causes. Noncardiac causes are usually secondary, and can involve recreational drug use or abuse; metabolic or endocrine issues, especially in the thyroid; an electrolyte imbalance; neurologic factors; autonomic reflexes; situational factors such as prolonged bed rest; and autoimmunity. Cardiac causes include acute or chronic ischemic heart disease, vascular heart disease, valvular heart disease, or degenerative primary electrical disease. Ultimately, the causes act by three mechanisms: depressed automaticity of the heart, conduction block, or escape pacemakers and rhythms.. In general, two types of problems result in bradycardias: disorders of the sinoatrial node (SA node), and disorders of the atrioventricular node (AV node).. With sinus node dysfunction (sometimes called sick sinus syndrome), there may be disordered automaticity or impaired conduction of the impulse from the sinus node into ...
parasystole 壁层胸膜 parietal pleura 震颤麻痹 Parkinsons disease ...
Differential Diagnosis of Tachycardia with a Wide QRS Complex • Accelerated Idioventricular Rhythm • Ventricular Parasystole • ...
Ventricular parasystole. *Ventricular premature beat. *Ventricular rhythm. *Ventricular standstill. *Ventricular tachycardia*V ...
Ventricular parasystole. *Ventricular premature beat. *Ventricular rhythm. *Ventricular standstill. *Ventricular tachycardia*V ...
  • Atrial parasystolia are characterized by narrow QRS complexes Two forms of ventricular parasystole have been described in the literature, fixed parasystole and modulated parasystole. (wikipedia.org)
  • Fixed ventricular parasystole occurs when an ectopic pacemaker is protected by entrance block, and thus its activity is completely independent from the sinus pacemaker activity. (wikipedia.org)
  • Parasystole is a kind of arrhythmia caused by the presence and function of a secondary pacemaker in the heart, which works in parallel with the SA node. (wikipedia.org)
  • According to the modulated parasystole hypothesis, rigid constancy of a pacemaker might be expected if the entrance block were complete, but if there is an escape route available for the emergence of ectopic activity, then clearly there must be an effective ionic communication, not complete insulation, between the two tissues. (wikipedia.org)
  • Therefore, appropriate diagnosis of modulated parasystole relies upon the construction of a "phase response curve" as theoretical evidence of modulation of the ectopic pacemaker cycle length by the electrotonic activity generated by the sinus discharges across the area of protection. (wikipedia.org)
  • Parasystole occurs when a protected focus discharges independently of the dominant pacemaker. (medscape.com)
  • The characteristics of parasystole include wide QRS complexes with a varying coupling interval between the ectopic (parasystolic) and the dominant (usually sinus) complex, fusion beats, and variable coupling interval. (medscape.com)
  • Variable coupling could be due to parasystole or multifocal ectopy. (medscape.com)