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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.
Graphic showing the relationship between positive electrodes, depolarization wavefronts (or mean electrical vectors), and complexes displayed on the ECG. Date 20 March 2007
Repolarization of the ventricle happens in the opposite direction of depolarization and is negative current, signifying the relaxation of the cardiac muscle of the ventricles. But this negative flow causes a positive T wave; although the cell becomes more negatively charged, the net effect is in the positive direction, and the ECG reports this ...
The P wave is a summation wave generated by the depolarization front as it transits the atria. Normally the right atrium depolarizes slightly earlier than left atrium since the depolarization wave originates in the sinoatrial node , in the high right atrium and then travels to and through the left atrium.
When electrical recordings are made from the skin, it is considered to be an ECG as described above. However, electrical recordings made from within the heart such as with an artificial cardiac pacemaker or during an electrophysiology study, the signals recorded are considered an "electrogram" instead of an ECG. These signals are not ...
Depolarization is essential to the function of many cells, communication between cells, and the overall physiology of an organism. Action potential in a neuron, showing depolarization, in which the cell's internal charge becomes less negative (more positive), and repolarization, where the internal charge returns to a more negative value.
The electrical axis of the heart is the net direction in which the wave of depolarization travels. It is measured using an electrocardiogram (ECG). Normally, this begins at the sinoatrial node (SA node); from here the wave of depolarisation travels down to the apex of the heart. The hexaxial reference system can be used to visualise the ...
English: Basic ventricular myocyte action potential (with labels). 0: depolarization: voltage-gated sodium channels open allowing influx of sodium ions 1: initial repolarization: inactivation of voltage-gated sodium channels; voltage-gated potassium channels begin to open allowing minor efflux of potassium ions