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The first finding is that junctional rhythms are regular rhythms. This means that the time interval between beats stays constant. The next normal finding is a normal QRS. Since the impulse still travels down the bundle of His, the QRS will not be wide. Junctional rhythms can present with either bradycardia, a normal heart rate, or tachycardia. [9]
An impulse (action potential) that originates from the SA node at a relative rate of 60–100 bpm is known as a normal sinus rhythm. If SA nodal impulses occur at a rate less than 60 bpm, the heart rhythm is known as sinus bradycardia. If SA nodal impulses occur at a rate exceeding 100 bpm, the consequent rapid heart rate is sinus tachycardia ...
Location of the pacemaker can also change its effect on the SA node and its rhythm. An ectopic pacemaker located in the atria is known as an atrial pacemaker and can cause the atrial contraction to be faster. [10] An ectopic pacemaker situated near the AV node and the septum is known as a junctional pacemaker. [11]
The escape rhythm typically originates in the AV junction, producing a narrow complex escape rhythm. [ citation needed ] An anterior wall myocardial infarction may damage the distal conduction system of the heart, causing third-degree heart block.
The Purkinje fibers, named for Jan Evangelista Purkyně, (English: / p ɜːr ˈ k ɪ n dʒ i / pur-KIN-jee; [1] Czech: [ˈpurkɪɲɛ] ⓘ; Purkinje tissue or subendocardial branches) are located in the inner ventricular walls of the heart, [2] just beneath the endocardium in a space called the subendocardium.
A junctional escape beat is a delayed heartbeat originating not from the atrium but from an ectopic focus somewhere in the atrioventricular junction. [1] It occurs when the rate of depolarization of the sinoatrial node falls below the rate of the atrioventricular node . [ 2 ]
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 ]
If more than two such beats are seen, then the condition is termed junctional rhythm. On the surface ECG, premature junctional contractions will appear as a normally shaped ventricular complex or QRS complex, not preceded by any atrial complex or P wave or preceded by an abnormal P wave with a shorter PR interval. Rarely, the abnormal P wave ...