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Atrial fibrillation Atrial Fibrillation with Rapid Ventricular Rate (Example 1) Atrial Fibrillation with Rapid Ventricular Rate (Example 2) Atrial Fibrillation with Rapid Ventricular Rate (Example 3) Atrial Fibrillation with Rapid Ventricular Rate (Example 4) Atrial Fibrillation with Rapid Ventricular Rate (Example 5) Atrial Fibrillation with normal Ventricular Rate (Example 1) Atrial Fibrillation with normal Ventricular Rate (Example 2) Atrial Fibrillation with normal Ventricular Rate (Example 3) Atrial Fibrillation with bradycardia (Example 1) Atrial Fibrillation with bradycardia (Example 2) Atrial fibrillation occurs when many sites in the atria rapidly fire action potentials. The result is a VERY fast atrial rate (about 400-600 beats per minute). Since the atrial rate is so fast and the action potentials produced are of such low amplitude, P waves will NOT be seen on the EKG in people with atrial fibrillation. The atrial action potentials all attempt to conduct through the AV node, however the AV node becomes intermittently refractory and will only allow a certain number of atrial action potentials to reach the ventricles. This is why the ventricular rate is NOT also 400-600, but rather around 100-200 beats per minute. Since the AV node is intermittently (and not regularly) refractory, the QRS complexes that are produced when an atrial action potential does reach the ventricles will occur in an irregular pattern. Thus an EKG showing atrial fibrillation will have NO visible P waves and an irregularly irregular ventricular rhythm. The ventricular rate is frequently fast unless the patient is on AV node blocking drugs (such as beta-blockers). When the ventricular rate is greater than 100 in the presence of atrial fibrillation, the person is said to have atrial fibrillation with a "rapid ventricular response" or "RVR". Atrial fibrillation is sometimes abbreviated as "Afib". Thus a "rapid afib", or atrial fibrillation with RVR is sometimes abbreviated as "afib with RVR". |
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