This nice example of atrial flutter offers many teaching opportunities. "Sawtooth" flutter waves are readily visible in Leads II, III, avF, and V1, typically good "P wave" leads. Other leads show small, discreet P waves that the beginning student might not recognize as flutter waves because they don't produce the sawtooth pattern. The P waves' rate, approximately 360/min., gives them away as atrial flutter. This is also a good example of a constant 4:1 conduction, resulting in a regular QRS rhythm and regular pulse, at a rate of about 90/min. This demonstrates that not all narrow-complex rhythms between 60 and 100 bpm are "NSR". The low voltage in the limb leads makes this a good ECG to demonstrate that the flutter waves are regular and do not pause when the QRS happens, illustrating the separate actions of the atria and the ventricles. For students just learning 12-lead interpretation, this ECG serves to show that acute ST elevation M.I. is not the only valuable information that can be obtained from a 12-Lead, and that some leads are better than others for showing dysrhythmias.
Patient's clinical data: 46-year-old black man
The computer's interpretation was "undetermined rhythm".
What is the source and mechanism of this rhythm?
This ECG shows a nice, clear atrial flutter with 4:1 conduction. Also, there are frequent PVCs. Good for students who have mastered the criteria for the basic arrythmias and who need to see combinations. That is, PVCs are not only seen with NSR, and it is important to state the underlying rhythm. For your more advanced students who understand how to plot frontal plane axis, the axis of the PVCs is nearly straight up - a very strong argument for the ventricular origin of the beats.
The first ECG is from an active, otherwise healthy 66-year-old man who experienced a sudden onset of symptomatic tachycardia. He presented to the Emergency Dept. feeling (understandably) very anxious, with poor perfusion to his skin, chest discomfort, and palpitations. As the ED staff prepared to electrically cardiovert him, he spontaneously converted to normal sinus rhythm at a rate of 93 / min. and a QRS duration of 90 ms.
After a normal diagnostic cardiac cath, he was sent to the EP lab and the circuit responsible for this rhythm was successfully ablated. He was discharged in good condition the next day.
This is a good ECG for all levels of students. For beginners, it shows that atrial flutter is one of the rhythms we call "SVT", and it does not always conduct in a variable rate, or a rate that allows "sawtooth" P waves to show easily. You can show them that the "sawtooth" pattern, brought about by P waves that are 250 - 350 per minute, is still there if one ignores the QRS complexes for a moment. This is a great ECG for discussions of rate and cardiac output, and making decisions regarding treatment based on the patient's hemodynamic condition. For more advanced students, this ECG can lead to a discussion of the accessory pathways and re-entrant pathways that cause rapid rhythms. For RBBB criteria, click HERE.
The second ECG shows the same patient after spontaneous conversion to sinus rhythm. The bundle branch block has disappeared, as it was rate-dependent.