Schematic representation of normal sinus rhythm showing standard wave, segments, and intervals
The term normal sinus rhythm (NSR) is sometimes used to denote a specific type of sinus rhythm where all other measurements on the ECG also fall within designated normal limits, giving rise to the characteristic appearance of the ECG when the electrical conduction system of the heart is functioning normally; however, other sinus rhythms can be entirely normal in particular patient groups and clinical contexts, so the term is sometimes considered a misnomer and its use is sometimes discouraged.[3][4]
In humans, for an ECG to be described as showing a sinus rhythm, the shape of the P wave in each of the 12 standard ECG leads should be consistent with a "typical P vector" of +50° to +80°.[2] This means that the P wave should be:
always positive in lead I, lead II, and aVF
always negative in lead aVR
any of biphasic (-/+), positive or negative in lead aVL
positive in all chest leads, except for V1 which may be biphasic (+/-)[2]
If the P waves do not meet these criteria, they must be originating from an abnormal site elsewhere in the atria and not from the sinus node; the ECG cannot, therefore, be classed as showing a sinus rhythm.[2]
In general, each P wave in a sinus rhythm is followed by a QRS complex, and the sinus rhythm therefore gives rise to the whole heart's depolarization. Exceptions to this include complete heart block and certain ventricular artificial pacemaker rhythms, where the P waves may be completely normal in shape, but ventricular depolarization bears no relation to them; in these cases, the speed of the "sinus rhythm of the atria" and the speed of the ventricular rhythm must be calculated separately.[2]
Characteristics of normal sinus rhythmedit
By convention, the term "normal sinus rhythm" is taken to imply that not only are the P waves (reflecting activity of the sinus node itself) normal in morphology but that all other ECG measurements are also normal.[3][5] Criteria therefore include:
Normal heart rate (classically 60 to 100 beats per minute for an adult).
Regular rhythm, with less than 0.16-second variation in the shortest and longest durations between successive P waves
The sinus node should pace the heart – therefore, P waves must be round, all the same shape, and present before every QRS complex in a ratio of 1:1.
QRS complex positive in leads I, II, aVF and V3–V6, and negative in lead aVR.[3]
Referencesedit
^Hampton, John R (2013). The ECG Made Easy (8th ed.). Edinburgh: Churchill Livingstone. p. 4. ISBN9780702046421.
^ abcdefGertsch, Marc (2004). "3. The Normal ECG and its (Normal) Variants". The ECG: A Two-Step Approach to Diagnosis (1 ed.). Springer-Verlag Berlin Heidelberg. pp. 19–21. doi:10.1007/978-3-662-10315-9. ISBN978-3-540-00869-9. OCLC 942900796.
^ abcConover, Boudreau Conover (2003). Understanding Electrocardiography (8th ed.). St Louis: Mosby. p. 46. ISBN9780323019057.
^Geiter, Henry B. (2006). E–Z ECG Rhythm Interpretation (1st ed.). Philadelphia: F.A. Davis. p. 106. ISBN9780803620353.
^Acar, RD; Bulut, M; Acar, Ş; Izci, S; Fidan, S; Yesin, M; Efe, SC (2015). "Evaluation of the P Wave Axis in Patients With Systemic Lupus Erythematosus". Journal of Cardiovascular and Thoracic Research. 7 (4): 154–57. doi:10.15171/jcvtr.2015.33. PMC4685281. PMID 26702344.
External linksedit
"Normal Sinus Rhythm". Archived from the original on 15 December 2012.
April 25, 2024
sinus, rhythm, sinus, rhythm, cardiac, rhythm, which, depolarisation, cardiac, muscle, begins, sinus, node, necessary, sufficient, normal, electrical, activity, within, heart, electrocardiogram, sinus, rhythm, characterised, presence, waves, that, normal, morp. A sinus rhythm is any cardiac rhythm in which depolarisation of the cardiac muscle begins at the sinus node 1 It is necessary but not sufficient for normal electrical activity within the heart 2 On the electrocardiogram ECG a sinus rhythm is characterised by the presence of P waves that are normal in morphology 2 Schematic representation of normal sinus rhythm showing standard wave segments and intervals The term normal sinus rhythm NSR is sometimes used to denote a specific type of sinus rhythm where all other measurements on the ECG also fall within designated normal limits giving rise to the characteristic appearance of the ECG when the electrical conduction system of the heart is functioning normally however other sinus rhythms can be entirely normal in particular patient groups and clinical contexts so the term is sometimes considered a misnomer and its use is sometimes discouraged 3 4 Example of a sinus rhythm with bifascicular block Other types of sinus rhythm that can be normal include sinus tachycardia sinus bradycardia and sinus arrhythmia Sinus rhythms may be present together with various other cardiac arrhythmias on the same ECG Contents 1 Characteristics 1 1 Characteristics of normal sinus rhythm 2 References 3 External linksCharacteristics editIn humans for an ECG to be described as showing a sinus rhythm the shape of the P wave in each of the 12 standard ECG leads should be consistent with a typical P vector of 50 to 80 2 This means that the P wave should be always positive in lead I lead II and aVF always negative in lead aVR any of biphasic positive or negative in lead aVL positive in all chest leads except for V1 which may be biphasic 2 If the P waves do not meet these criteria they must be originating from an abnormal site elsewhere in the atria and not from the sinus node the ECG cannot therefore be classed as showing a sinus rhythm 2 In general each P wave in a sinus rhythm is followed by a QRS complex and the sinus rhythm therefore gives rise to the whole heart s depolarization Exceptions to this include complete heart block and certain ventricular artificial pacemaker rhythms where the P waves may be completely normal in shape but ventricular depolarization bears no relation to them in these cases the speed of the sinus rhythm of the atria and the speed of the ventricular rhythm must be calculated separately 2 Characteristics of normal sinus rhythm edit By convention the term normal sinus rhythm is taken to imply that not only are the P waves reflecting activity of the sinus node itself normal in morphology but that all other ECG measurements are also normal 3 5 Criteria therefore include Normal heart rate classically 60 to 100 beats per minute for an adult Regular rhythm with less than 0 16 second variation in the shortest and longest durations between successive P waves The sinus node should pace the heart therefore P waves must be round all the same shape and present before every QRS complex in a ratio of 1 1 Normal P wave axis 0 to 75 degrees Normal PR interval QRS complex and QT interval QRS complex positive in leads I II aVF and V3 V6 and negative in lead aVR 3 References edit Hampton John R 2013 The ECG Made Easy 8th ed Edinburgh Churchill Livingstone p 4 ISBN 9780702046421 a b c d e f Gertsch Marc 2004 3 The Normal ECG and its Normal Variants The ECG A Two Step Approach to Diagnosis 1 ed Springer Verlag Berlin Heidelberg pp 19 21 doi 10 1007 978 3 662 10315 9 ISBN 978 3 540 00869 9 OCLC 942900796 a b c Conover Boudreau Conover 2003 Understanding Electrocardiography 8th ed St Louis Mosby p 46 ISBN 9780323019057 Geiter Henry B 2006 E Z ECG Rhythm Interpretation 1st ed Philadelphia F A Davis p 106 ISBN 9780803620353 Acar RD Bulut M Acar S Izci S Fidan S Yesin M Efe SC 2015 Evaluation of the P Wave Axis in Patients With Systemic Lupus Erythematosus Journal of Cardiovascular and Thoracic Research 7 4 154 57 doi 10 15171 jcvtr 2015 33 PMC 4685281 PMID 26702344 External links edit Normal Sinus Rhythm Archived from the original on 15 December 2012 Retrieved from https en wikipedia org w index php title Sinus rhythm amp oldid 1197564515, wikipedia, wiki, book, books, library,
