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[1] [2] This means that all atrial cells can contract together, and then all ventricular cells. Different shapes of the cardiac action potential in various parts of the heart 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 ...
Early afterdepolarizations (EADs) occur with abnormal depolarization during phase 2 or phase 3, and are caused by an increase in the frequency of abortive action potentials before normal repolarization is completed. [1]
The most obvious abnormal finding will be abnormal P waves. One of three options can occur: [12] 1. There are no P waves. This is because of either failure of retrograde flow to the atria or the P wave is hidden in the QRS. If the P wave is hidden that implies the atria depolarize at the same time as the ventricles. 2.
In contrast, that same depolarization would produce minimal deflection in V 1 and V 2 because the vectors are perpendicular, and this phenomenon is called isoelectric. Normal rhythm produces four entities – a P wave, a QRS complex, a T wave, and a U wave – that each have a fairly unique pattern. The P wave represents atrial depolarization.
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.
Class Ic drugs do not affect action potential duration and have the strongest effect on the initiation phase 0 of depolarization Contraindicated immediately after myocardial infarction; Prevent paroxysmal atrial fibrillation; Treat recurrent tachycardia associated with abnormal conduction pathways, such as Wolff–Parkinson–White syndrome; II
Location of the pacemaker can also change its effect on the SA node and its rhythm. An ectopic pacemaker located in the atria is known as an atrial pacemaker and can cause the atrial contraction to be faster. [10] An ectopic pacemaker situated near the AV node and the septum is known as a junctional pacemaker. [11]
Right Atrial Enlargement (RAE) increases the p wave, representing atrial depolarization, on an ECG to an amplitude > 2.5mm in lead II, an abnormality referred to as p-pulmonale, likely due to weakened right atrial myocardium close to the Sinoatrial (SA) node.