Left Ventricular Outflow Tract Tachycardia
Less commonly than RVOT tachycardias there are tachycardias that arise from the left ventricular outflow tract and the aortic cusp region. These tachycardias may have a very different ECG appearance from RVOT but some left outflow tract tachycardias have more subtle differences for example with earlier R wave transition in the precordium of V2-V3. The pharmacologic responsiveness is generally similar to that of RVOT tachycardias. The threshold for catheter ablation however is generally felt to be higher because of increased risk: left sided access is associated with higher risk of stroke, the coronary artery origins are located near the coronary cusps, the aorta may be mechanically damaged, and the conduction system may be nearby.
The next most common site for patients with normal heart ventricular tachycardias is the region of the fascicles, a part of the conduction system that carries the electrical signals to the left side of the heart. These tachycardias are typically of a right bundle branch block pattern.
3-dimensional mapping may be used to determine the site of the tachycardia extremely accurately.
