To the Editor— Leftward on left anterior oblique is not always septal!

We read with great interest the article by Iribarne and colleagues which describes a case of a pacemaker lead perforation. There are 2 issues that we would like to highlight, which we felt are vital for your readership. Mechanism of perforation: The authors surmise that despite the lead’s being placed on the true septum, perforation occurred through the interventricular septum, across the left ventricle (LV) chamber, through the LV free wall, and finally through the parietal pericardium and into the pleural space. In reality, however, the published computed tomography (CT) images show that the lead had instead perforated through the right ventricle (RV) free wall that is close to the septum (anteroseptal junction) and not through the interventricular septum (Figure 1A: CT image is taken from Iribarne and colleagues Figure 2, with added arrow showing lead trajectory and dotted line showing LV endocardial border). It is critical for every implanting physician to be aware that a pacemaker lead tip pointing leftward on the left anterior oblique view does not indicate with certainty that the tip is on the ventricular septum. The tip may be on the anteroseptal or inferoseptal junction, which are anatomic recesses located even more leftward than the true ventricular septum owing to the crescent shape of the RV. Lead positioning at these leftward locations carries an increased risk of perforation through the thin free wall of the RV, just as was seen