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The QRS complex is the combination of three of the graphical deflections seen on a typical ... It is normal to have a narrow QS and rSr' patterns in V 1, ...
Most have a narrow QRS complex, although, occasionally, electrical conduction abnormalities may produce a wide QRS complex that may mimic ventricular tachycardia (VT). In the clinical setting, the distinction between narrow and wide complex tachycardia (supraventricular vs. ventricular) is fundamental since they are treated differently.
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 ...
In general, it is an irregular, narrow complex rhythm. However, it may show wide QRS complexes on the ECG if a bundle branch block is present. At high rates, the QRS complex may also become wide due to the Ashman phenomenon. It may be difficult to determine the rhythm's regularity when the rate exceeds 150 beats per minute.
First, examine the QRS complex in both leads I and avF and determine if the QRS complex is positive (height of R wave > S wave), equiphasic (R wave = S wave), or negative (R wave < S wave). If lead I is positive and lead aVF is negative, then this is a possible LAD. To determine a true LAD, examine QRS in lead II.
Normal activation utilizes the bundle of His and Purkinje fibers to produce a narrow (QRS) electrical signal. Aberration occurs when the electrical activation of the heart, which is caused by a series of action potentials , is conducting improperly which can result in temporary changes in the morphology that looks like:
Junctional tachycardia is a form of supraventricular tachycardia characterized by involvement of the AV node. [1] It can be contrasted to atrial tachycardia.It is a tachycardia associated with the generation of impulses in a focus in the region of the atrioventricular node due to an A-V disassociation. [2]
In adults, it is seen as wide QRS complexes lasting ≥120ms with characteristic QRS shapes in the precordial leads, although narrower complexes are seen in children. [4] In lead V 1 , the QRS complex is often entirely negative (QS morphology), although a small initial R wave may be seen (rS morphology).