What is the RR interval on ECG?
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[Variation in the R-R intervals on the electrocardiogram. A new diagnostic method in cardiology][Article in Czech] M Vrána et al. Cor Vasa. 1993. AbstractPeriodic heart rate fluctuation depends on the oscillation of sympathetic and vagal activation of the heart. Periodic retardation and acceleration of heart rate related to respiration and to blood pressure changes can be registered on the ECG as the "variability of R-R intervals". Testing procedures of the variability of R-R intervals at rest, during deep breathing, daily activities, during exercise and other stress tests are described in the paper. For the evaluation of the R-R interval's variability, current statistical methods are used (e.g. mean with standard deviation, variation coefficient, mean beat to beat differences in R-R intervals etc.). Power spectral analysis in the variability of 200-600 successive R-R intervals commonly performed today uses either rapid Fourier transformation or the autoregulation model. The analysis shows high- and low frequency peaks corresponding to the rapid and slow oscillations in heart rate. Evaluation of the R-R interval variability, especially using power spectrum analysis, gave good results in testing drugs, e.g., beta blockers, calcium antagonists and antiarrhythmic drugs. Variability of R-R intervals is reduced in conditions affecting the cardiac autonomous nervous system such as diabetes. It is also decreased in patients with ischaemic heart disease and in those with cardiac failure of different aetiology. The decrease is not an expression of the disease itself: it shows an alteration in neurovegetative tonicity in the particular disease condition. The decreased variability of R-R intervals in patients with ischaemic heart disease has an important prognostic value. The predominance of the sympathetic over the depressed vagal activity signalizes an increased risk of sudden coronary death. Similar articles
Publication typesMeSH termsAlso found in: Dictionary, Thesaurus, Legal, Encyclopedia. the time elapsing
between two consecutive R waves in the electrocardiogram. Farlex Partner Medical Dictionary © Farlex 2012 In an electrocardiogram, the interval from the onset of one R wave to the onset of the next one, one complete cardiac cycle. See also: interval Medical Dictionary, © 2009 Farlex and Partners Print version of Knowledge bytes used in this lesson. Close the window to return to the lesson after printing. The rate of paper (i.e. of recording of the EKG) is 25 mV/s which results in:
The voltage recorded from the leads is also standardized on the paper where 1 mm = 1 mV (or between each individual block vertically) This results in:
Heart rate calculation: Normal range at rest is between 60-100 beats per minute (bpm). The basic way to calculate the rate is quite simple. You take the duration between two identical points of consecutive EKG waveforms such as the R-R duration. Take this duration and divide it into 60. The resulting equation would be: Rate = 60/(R-R interval) A quicker way to obtain an approximate rate is
Rhythm can be quite variable. It could be
P wave Represents discharge of SA node and depolarization of both atria
QRS QRS complex is a series of wave forms following P wave. Naming convention:
Q wave
T wave First upward deflection after QRS complex. Represents: ventricular repolarization
U wave What it represents is not certain. This upright wave, when present, follows the T wave.
PR interval Represents: atria to ventricular conduction time (through His bundle) It includes P wave and PR segment. Normal duration: 0.12-2.0 seconds (3-5 horizontal boxes). This is measured from the onset of the P wave to the onset of the QRS complex regardless if the initial wave is a Q or R wave. Abnormal duration:
ST segment Represents early phase of repolarization of ventricles. Begins at the end of S wave and ends at the beginning of T wave. In normal situations, it serves as the isoelectric line from which to measure the amplitudes of the other waveforms. ST segments are usually isoelectric and normal. When examining the ST segment, evaluate elevations or depressions 0.06 seconds after the J point (since the ST segment can at times be sloping). Abnormal:
QT and QTc (corrected QT) interval QT represents the duration of activation and recovery of the ventricular muscle. This duration varies inversely with the heart rate Since the duration of QT varies inversely with the heart rate, the QT is not used, but rather the corrected QT is. QTc interval QTc = QT + 1.75 (ventricular rate - 60)
What is normal RR interval in ECG?Normal ECG values for waves and intervals are as follows: RR interval: 0.6-1.2 seconds. P wave: 80 milliseconds. PR interval: 120-200 milliseconds.
What is good RR interval?An average RR interval of as long as 2000ms at rest (which is equivalent to a resting heart rate of 30beats/min) and a PR interval of 400ms have been reported in healthy highly trained endurance athletes.
Is RR interval same as heart rate?The “heart rate” can be described as a true rate in beats per minute (HR) or as the RR interval in milliseconds. The RR interval and HR are hyperbolically related (HR x RR interval = 60000; see figure 1). Changes in these parameters are mediated in large part by the autonomic nervous system.
What is abnormal RR interval?Abnormal R–R intervals differ from sinus rhythm in their length and they represent disturbances of both technical and physiological origins and are present in almost all Holter ECG recordings. Physiological artifacts occur especially in patients suffering from different cardiovascular diseases.
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