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Schematic representation of a normal sinus rhythm EKG wave. In electrocardiography, the PR interval is the period, measured in milliseconds, that extends from the beginning of the P wave (the onset of atrial depolarization) until the beginning of the QRS complex (the onset of ventricular depolarization); it is normally between 120 and 200 ms in duration.
A wandering atrial pacemaker can be either normal or irregular in rate, much like a sinus arrhythmia the rate is normally between 60 - 100 bpm when it is normal and less than 60 when it is slow, the distinguishing feature of this rhythm is a p wave that varies in size, shape, and direction, the PR interval can either be normal or irregular ...
Electrocardiography is the process of producing an electrocardiogram (ECG or EKG [a]), a recording of the heart's electrical activity through repeated cardiac cycles. [4] It is an electrogram of the heart which is a graph of voltage versus time of the electrical activity of the heart [ 5 ] using electrodes placed on the skin.
The normal PR interval is from 120 ms to 200 ms in length. This is measured from the initial deflection of the P wave to the beginning of the QRS complex. [3] In first-degree heart block, the AV node conducts the electrical activity more slowly. This is seen as a PR interval greater than 200 ms in length on the surface ECG.
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]
ECG recorded from a 17-year-old male with Lown-Ganong-Levine syndrome. LGL syndrome is diagnosed in a person who has experienced episodes of abnormal heart racing (arrhythmias) who has a PR interval less than or equal to 0.12 second (120 ms) with normal QRS complex configuration and duration on their resting ECG. [1]. [citation needed]
Heart rate variability visualized with R-R interval changes Electrocardiogram (ECG) recording of a canine heart that illustrates beat-to-beat variability in R–R interval (top) and heart rate (bottom). Heart rate variability (HRV) is the physiological phenomenon of variation in the time interval between heartbeats. It is measured by the ...
On the ECG, instantaneous heart rate is calculated using the R wave-to-R wave (RR) interval and multiplying/dividing in order to derive heart rate in heartbeats/min. Multiple methods exist: [citation needed] HR = 1000 · 60/(RR interval in milliseconds) HR = 60/(RR interval in seconds) HR = 300/number of "large" squares between successive R waves.