The Radiological And ECG Characteristics Of Different Sites In Right Ventricular Pacing: Evaluation Using Echocardiography

Objective: To investigate the radiographic criteria and the electrocardiogram(ECG) criteria of the paced QRS complex to help distinguish pacing the septum from the other sites, used two-dimensional echocardiography to determine the true position of the leads.Methods: A hundred patients were implanted with double-chamber pacemakers. Fluoroscopic radiographs were recorded in three views: 45°LAO,left lateral(LL) and posterior-anterior(PA). The12-lead ECG was recorded too. Measure the parameters of radiography: the angle was created by drawing a horizontal line on the 45°LAO and the line parallel to the distal of the lead. The height of lead was assessed by the number of verteraes in PA. The orientation of lead in LL. Measure the parameters of the12-lead ECG:(1) QRS duration in lead II.(2) QRS axis was calculated.(3) Amplitudes of R waves in lead II.(4) QRS complex in lead I(whether has the q-wave or the QRS was negative).(5) QRS complex in lead III.(6) QRS notching in the limb leads.(7) QRS transition in the precordial leads. The patients were divided into 4 groups according to the echocardiography result: septal right ventricular outflow tract group(RVOT), RVOT anterior free wall group, mid septum group, and anterior septum group(near to the anterior free wall).To analyses the angiography and the electrocardiogram characteristics of these 4 groups.Results:(1) In the 40°left anterior oblique(LAO) view, the angle of lead attachment of was significantly bigger when pacing from the RVOT anterior free wall and the anterior septum compared with the septal RVOT and the mid septum(AUC=0.785,p<0.05), the cut-off is 56°,the sensitivity and specificity are 77% and 92% separately. And there is little difference between septal RVOT and the mid septum, the angle of lead attachment are 61.0°and 50.5°separately(p<0.05).(2) In the 90°left lateral(LL) view, the proportion of posterior projection of the lead tip was significantly more when pacing from the septal RVOT and the mid septum compared with the RVOT anterior free wall and the anterior septum.(3) In the posterior-anterior(PA) fluoroscopic view, the number of verteraes was significantly more when pacing from the septal RVOT and the RVOT anterior free wall compared with the anterior septum and the mid septum(AUC=0.727,P<0.05), the cut-off is 1.75, the sensitivity and specificity are 64% and 72% separately.(4) The QRS duration in the inferior leads was significantly bigger when pacing from the RVOT anterior free wall and the anterior septum compared with the septal RVOT and the mid septum(AUC=0.811,P<0.05), the cut-off of the QRS duration is 150 ms, the sensitivity and specificity are 77% and 67% separately. The proportion of transition by V3 in the anterior leads was significantly more when pacing from the septal RVOT and the RVOT anterior free wall compared with the anterior septum and the mid septum. The combination of the angle of lead tip in LAO 45°and the QRS duration could predict the true position of the leads with a sensitivity of 94.2% and specificity of 79.2%( AUC = 0.87, P <0.05).Conclusion: Cardiac radiography and ECG can help determine septal lead site.(1) The angle of lead attachment in 45°LAO can help distinguish pacing the septum from the other sites.(2) A posterior projection of the lead indicates septal placement, but using this parameter as criteria will increase the complexity of the operation.(3) When the number of verteraes in PA=1.75, indicates the lead is near the His bundle, we will get the narrowest QRS.(4) QRS duration≤150ms indicates septal placement.(5)The combination of the angle of lead tip in LAO 45°and the QRS duration could increase the sensitivity and specificity to determine septal placement.