Basics: Difference between revisions

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=The different ECG waves=
=The different ECG waves=
[[Image:PQRS_origin_en.png|thumb| The origin of the diffrent waves on the ECG]]
[[Image:PQRS_origin_en.png|thumb| The origin of the different waves on the ECG]]
[[Image:Epi_endo_en.png|thumb| The QRS complex is formed by the sum of the electric avtivity of the inner (endocardial) and the outer (epicardial) cardiomyocytes]]
[[Image:Epi_endo_en.png|thumb| The QRS complex is formed by the sum of the electric avtivity of the inner (endocardial) and the outer (epicardial) cardiomyocytes]]
[[Image:Qrs-shapes.png|thumb| Example of the different QRS configuations]]  
[[Image:Qrs-shapes.png|thumb| Example of the different QRS configuations]]  
The [[P_wave|'''P wave''']] is the result of the atrial depolarization. This depolarization starts in the SA (sino-atrial) node. The signal produces by pacemakercells in the SA node is conducted by the conduction system to the right and left atria. Normal atrial repolarisation is not visible on the ECG (but can be visible during [[atrial infarction]] and [[pericarditis]]).  
The [[P_wave_morphology|'''P wave''']] is the result of the atrial depolarization. This depolarization starts in the SA (sino-atrial) node. The signal produces by pacemakercells in the SA node is conducted by the conduction system to the right and left atria. Normal atrial repolarisation is not visible on the ECG (but can be visible during [[atrial infarction]] and [[pericarditis]]).  


The [[QRS_morphology|'''QRS complex''' ]] is the average of the depolarization waves of the inned (endocardioal) and outer (epicardial) cardiomyocytes. As the endocardial cardiomyocytes depolarize slightly earlier than the outer layers, a typical QRS pattern occurs (figure).  
The [[QRS_morphology|'''QRS complex''' ]] is the average of the depolarization waves of the inner (endocardial) and outer (epicardial) cardiomyocytes. As the endocardial cardiomyocytes depolarize slightly earlier than the outer layers, a typical QRS pattern occurs (figure).  


The [[ST_morphology|'''T wave''']] represents the repolarisation of the ventricles. There is no cardiac muscle activity during the T wave.
The [[ST_morphology|'''T wave''']] represents the repolarisation of the ventricles. There is no cardiac muscle activity during the T wave.


One heart beat consists of a atrial depolarization --> atrial contraction --> p-wave, ventricular depolarization --> ventricular contraction --> ORS-complex and the resting phase (including the repolarization during the T-wave) between two heart beats.
One heart beat consists of an atrial depolarization --> atrial contraction --> p-wave, ventricular depolarization --> ventricular contraction --> ORS-complex and the resting phase (including the repolarization during the T-wave) between two heart beats.


Have a look at this excellent [[http://www-medlib.med.utah.edu/kw/pharm/hyper_heart1.html animation of the heart cycle]]
Have a look at this excellent [[http://www-medlib.med.utah.edu/kw/pharm/hyper_heart1.html animation of the heart cycle]]
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*S: the negative deflection after the R-wave
*S: the negative deflection after the R-wave


*small print letters (q, r, s) are used to describe deflections of small amplitude. For example: qRS = small q, high R, deep S.  
*small print letters (q, r, s) are used to describe deflections of small amplitude. For example: qRS = small q, tall R, deep S.  
*R`: i used to describe a second R-wave (as in a [[right bundlebranch block])
*R`: is used to describe a second R-wave (as in a [[right bundlebranch block])
See figure for some examples of this.
See figure for some examples of this.
{{clr}}
{{clr}}


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