#Atrial flutter 2 to 1 conduction generator

See this week's Instructors' Collection ECG of the WEEK for the SAME patient's 12-Lead ECG. It can be VERY helpful to look at multiple leads to look for flutter waves. Therefore, the physiological block that protects us from extreme rates will keep the heart rate around 150 bpm in atrial flutter. However, the AV node, if not affected by medication, is usually well able to conduct at a rate of 150 or more. The flutter waves are very easy to see in such a situation.

#Atrial flutter 2 to 1 conduction generator

Often, students are taught about atrial flutter using an electronic rhythm generator or a book with limited illustrations, and they become acustomed to seeing atrial flutter with 3:1 or 4:1 conduction. Therefore, a 2:1 conduction ratio would result in a heart rate of about 125 - 175 bpm). Atrial flutter usually produces flutter waves (P waves) at a rate of 250 - 350 per minute. Sinus tach usually has an obvious cause, such as exercise, severe hypovolemia, or age less than 6 months. One of the most frequently misdiagnosed rhythms, atrial flutter with 2:1 conduction often masquerades as sinus tach.

Read more about ECG Basics: Atrial Flutter With 2:1 Conduction And An Aberrantly-conducted Beat.

We welcome discussion of this interesting strip.

There are other differential diagnoses, such as ventricular tachycardia with a captured sinus beat. The slight width of all the QRS complexes suggests that there is a conduction delay, which cannot be diagnosed on one strip with no patient history available. Careful measurement will show that this QRS is very slightly early, while the others are all very regular. This probably represents aberrant conduction, possibly a hemiblock that occurs only in this beat. This beat is about the same width as the other QRS complexes, but is opposite in direction. There is one beat that is obviously different from the others. Multiple leads can more easily uncover the flutter waves running continuously 'behind' and 'through' the QRS complexes. This rhythm could also be mistaken for atrial tachycardia or other forms of supraventricular tachycardia (SVT, PSVT, AVNRT, etc.). It can masquerade as sinus tach, but a patient with sinus tach at such a fast rate would probably have an obvious cause for a rapid heart rate, such as hypovolemia, drug overdose, or exertion.

Since atrial flutter results in atrial depolarization at around 250 - 350 per minute, conducting every other P wave results in a rate of about 150.

Whenever the ventricular rate is near 150/min., we should always consider the possibility of atrial flutter with 2:1 conduction. The P waves (or flutter waves) here have a sharp point, and can be easily 'marched out', with a rate of about 300 per minute. We ALWAYS recommend multi-lead assessment for such evaluation. It is somewhat difficult to evaluate the baseline for P waves or flutter waves. It shows a regular tachycardia with a slightly-widened QRS complex at about. This strip was taken from a patient at rest.