Identify the rhythm and tachycardia mechanism in the following images. Also, where would the ablation be performed?
*Hint – This mapping system displays the earliest activation with white and the latest with purple
*Hint – Displayed is the geometry of the right atrium.
Answer
CCW Typical Atrial Flutter
This image is three different views of the right atrium. The complete circuit may be viewed in the LAO view in this example (middle image). The earliest activation (white) is on the lateral wall. The wave of depolarization travels in the counterclockwise direction…red, orange, yellow, green, light blue, dark blue, and purple. It is traveling down the lateral wall, through the cavotricuspid isthmus (CTI), up the septal wall, over the roof, and then repeating down the lateral wall. The “early meets late” is observed on the lateral wall. This is a function of the mapping system as this is a continuing circuit. There is no beginning nor end. Ablation of this rhythm would be performed across the CTI.
– The RAO view helps to visualize the ablation starting point at the TV annulus to the endpoint of the IVC.
– The LAO view helps the physician locate the catheter at 6:00 position.
– The LAO/Caudal view is helpful to watch the ablation catheter as it is pulled back from the TV to the IVC.
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For more information: EP Essentials – Understanding EP: A Comprehensive Approach
