Infobox Disease Name Parasystole Image Caption DiseasesDB ICD10 ICD9 ICDO OMIM MedlinePlus eMedicineSubj eMedicineTopic MeshID D017574 Parasystole is a kind of arrhythmia caused by the presence and function of a secondary cardiac pacemaker pacemaker in the heart, which works in parallel with the SA node . Parasystolic pacemakers are protected from depolarization by the SA node by some kind of entrance block . This block can be complete or incomplete. Parasystolic pacemakers can exist in both the Atrium heart atrium or the Ventricle heart ventricle . Atrial parasystolia are characterized by narrow QRS complexes Two forms of ventricular parasystole have been described in the literature, fixed parasystole and modulated parasystole. 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. Hence, the ectopic pacemaker is expected to fire at a fixed rate. Therefore, on ECG , the coupling intervals of the manifest ectopic beat s will wander through the basic cycle of the sinus rhythm . Accordingly, the traditional electrocardiographic criteria used to recognize the fixed form of parasystole are the presence of variable coupling intervals of the manifest ectopic beats inter ectopic intervals that are simple multiples of a common denominator fusion beat s. 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. If there is an electrical communication between the two, then the depolarization of the surrounding .... Therefore, appropriate diagnosis of modulated parasystole relies upon the construction of a phase response ... ventricular parasystole http medstat.med.utah.edu kw ecg mml ecg 450.html atrial parasystole Heart diseases ... more details
Unreferenced date December 2009 Image Bigeminy2010.JPG thumb 350px A rhythm strip demonstrating bigeminy Bigeminy Latin Bi Two Gemini twins is a descriptor for a heart cardiac arrhythmia arrhythmia in which abnormal heart beats occur every other concurrent beat. A typical example is with bigeminal premature ventricular beats, also known as a premature ventricular contraction premature ventricular contractions complexes PVC . Following the PVC there is a pause and then the normal beat returns only to be followed by another PVC. The continuation of this pairing of beats is an example of bigeminy. These descriptors can increase depending on the number of beats involved in the abnormal system. If every other beat is abnormal, you can describe it as bigeminal. If every third beat is aberrant, it is trigeminal every fourth would be quadrigeminal. Typically, if every fifth or more beat is abnormal, the aberrant beat would be termed occasional. Bigeminy is contrasted with couplets , which are paired abnormal beats. If, for example, these concurrent PVCs number three, they are called triplets and are considered as a brief run of non sustained Tachycardia Ventricular tachycardia or NS VT. PVCs are not the only aberrant beat that makes use of these adjectives others are premature atrial contraction s, parasystole , and escape complex es. Examples Bigeminal premature ventricular contractions Normal, PVC, Normal, PVC... Trigeminal premature atrial contractions Normal, Normal, PAC, Normal, Normal, PAC... Quadrageminal premature ventricular contractions Normal, Normal, Normal, PVC Normal, Normal, Normal, PVC... Occasional escape complexes Normal, Normal, Normal, Normal, Pause, Escape... Bigeminal Couplets Normal, Normal, PVC, PVC, Normal, Normal, PVC, PVC... NS VT Normal, Normal, PVC, PVC, PVC, PVC, Normal, Normal, PVC....etc Heart diseases DEFAULTSORT Numbering Aberrant Rhythms Category Cardiovascular diseases Category Cardiac electrophysiology de Bigeminus ... more details
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