Abstract: Objective To develop a radiology algorithm and test its the accuracy in distinguish pacing in the septum from the other parts. Methods One hundred patients were implanted with double-chamber pacemakers. Sites of the leads were verified by two-dimensional echocardiography, and the patients were divided into 4 groups according to the echocardiography: septal right ventricular outflow tract group(RVOT), RVOT anterior free wall group, mid septum group, and anteri⁃
or septum group (near to the anterior free wall ). An algorithm was developed according to radiological characteristics in the 45°left anterior oblique (LAO45°) view and the 30° right anterior oblique (RAO30°) view. Then its sensitivity, specificity,positive predictive value (PPV) and negative predictive value (NPV) were tested . Results The algorithm has high sensitivity and specificity, which were 90% and 97% respectively. The positive predictive value and negative predictive value were 90% and 97% respectively. Conclusion The radiology algorithm we developed have a high sensitivity and specificity in identifying the site of the leads.

Key words: ventricular septum, cardiac pacing, artificial, echocardiography, fluoroscopy, radiology algorithm