Atrial Flutter: Characteristics and ECG Manifestation

Introduction

Atrial flutter is a form of supraventricular tachycardia characterised by rapid and regular electrical activity in the heart's upper chambers, known as the atria. Understanding its features and ECG manifestation is essential for accurate diagnosis and appropriate management.

Characteristics of Atrial Flutter

• Rapid and Regular Atrial Rate: Atrial flutter is distinguished by a fast and regular atrial rate, typically ranging from 250 to 350 beats per minute. However, the AV node limits the number of impulses reaching the ventricles, resulting in a slower, typically regular ventricular rate.
• Regular or Irregular Rhythm: The rhythm of atrial flutter may be regular if there is a consistent pattern of atrial to ventricular conduction, such as the 2 to 1 or 3 to 1 atrial to ventricular ratio. However, it can also be irregular if the AV node conduction varies.
• Absent P Waves: In atrial flutter, the normal upright P waves representing atrial depolarization are absent. Instead, undulating flutter waves, also known as F waves or sawtooth waves, are observed on the ECG, indicating the rapid and regular atrial activation following the reentrant pathway.
• Ventricular Rate: The ventricular rate in atrial flutter is typically slower than the atrial rate due to the AV node's limitation of impulses to the ventricles. The ventricular rate may be regular (e.g., 150, 100, or 75 beats per minute) based on the atrial to ventricular conduction ratio or irregular if the conduction pattern varies.
• QRS Complex: The duration of the QRS complex, representing normal ventricular depolarization, is usually within the normal range, less than 0.12 seconds. However, underlying conduction abnormalities or the presence of accessory pathways may prolong the QRS complex duration.

ECG Manifestation of Atrial Flutter

Atrial flutter is identified on an ECG by:

• Absence of P Waves: The ECG shows the absence of normal P waves, which are replaced by irregular flutter waves reflecting the rapid and regular atrial activation.
• Rapid Atrial Rate: The atrial rate is notably fast and regular, while the ventricular rate may be regular or irregular depending on the atrial to ventricular conduction pattern.

Importance of Accurate Diagnosis

Accurate diagnosis of atrial flutter is crucial due to its significant clinical implications and associated risks and symptoms. Specific treatment strategies may be necessary to manage the condition effectively.