Atrial fibrillation: irregular ventricular rhythm

2021-05-31 04:09 PM

The AV node will not transmit a second pulse within 0.35 s after the first pulse, additional pulses ranging from 0 to 0.6 s occurring before one of the irregular atrial fibrillation pulses reaches the atrioventricular node.

During atrial fibrillation, the impulse travels from the atria to the AV node rapidly but irregularly. Because the AV node will not transmit the second pulse within 0.35s after the first pulse. Thus, an extra pulse in the range of 0-0.6 s precedes one of the irregular atrial fibrillation pulses to the AV node. As a result, the effective ventricular interval between pulses ranges from a minimum of 0.35 to 0.95 seconds, causing a very irregular heartbeat. In fact, this irregularity, as shown in the figure, is one of the clinical manifestations that can be detected and used to diagnose the disease. Along with that, because of the atrial tachycardia in atrial fibrillation, the ventricles also beat with a tachycardia, usually between 125-150 beats/min.

Figure. Atrial fibrillation (lead II). The waves that can be seen are QRS and T waves.

Like ventricular fibrillation, atrial fibrillation can return to normal with electrical shock. This method is essentially identical to ventricular defibrillation - which sends a strong current through the heart, returning the heart muscles to an inert state for a few seconds, after which a normal rhythm is restored if the heart can re-establish. normal rhythm.