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  2. Electrocardiography - Wikipedia

    en.wikipedia.org/wiki/Electrocardiography

    The P wave represents atrial depolarization. The QRS complex represents ventricular depolarization. The T wave represents ventricular repolarization. The U wave represents papillary muscle repolarization. Changes in the structure of the heart and its surroundings (including blood composition) change the patterns of these four entities.

  3. Cardiac conduction system - Wikipedia

    en.wikipedia.org/wiki/Cardiac_conduction_system

    The delay in the AV node forms much of the PR segment on the ECG, and part of atrial repolarization can be represented by the PR segment. The distal portion of the AV node is known as the bundle of His. [8] The bundle of His splits into two branches in the interventricular septum: the left bundle branch and the right bundle branch.

  4. P wave (electrocardiography) - Wikipedia

    en.wikipedia.org/wiki/P_wave_(electrocardiography)

    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. The depolarization front is carried ...

  5. Cardiac action potential - Wikipedia

    en.wikipedia.org/wiki/Cardiac_action_potential

    Rate dependence of the action potential is a fundamental property of cardiac cells and alterations can lead to severe cardiac diseases including cardiac arrhythmia and sometimes sudden death. [3] Action potential activity within the heart can be recorded to produce an electrocardiogram (ECG). This is a series of upward and downward spikes ...

  6. Repolarization - Wikipedia

    en.wikipedia.org/wiki/Repolarization

    Repolarization is a stage of an action potential in which the cell experiences a decrease of voltage due to the efflux of potassium (K +) ions along its electrochemical gradient. This phase occurs after the cell reaches its highest voltage from depolarization. After repolarization, the cell hyperpolarizes as it reaches resting membrane ...

  7. PR interval - Wikipedia

    en.wikipedia.org/wiki/PR_interval

    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.

  8. Atrial fibrillation - Wikipedia

    en.wikipedia.org/wiki/Atrial_fibrillation

    315,000 with atrial flutter (2019) [ 10 ] Atrial fibrillation (AF, AFib or A-fib) is an abnormal heart rhythm (arrhythmia) characterized by rapid and irregular beating of the atrial chambers of the heart. [ 11 ][ 12 ] It often begins as short periods of abnormal beating, which become longer or continuous over time. [ 4 ]

  9. Systole - Wikipedia

    en.wikipedia.org/wiki/Systole

    Electrical waves track a systole (a contraction) of the heart. The end-point of the P wave depolarization is the start-point of the atrial stage of systole. The ventricular stage of systole begins at the R peak of the QRS wave complex; the T wave indicates the end of ventricular contraction, after which ventricular relaxation (ventricular diastole) begins.