Effects of right ventricular pacing on regional myocardial glucose metabolism

Permanent right ventricular apical pacing (RVP) is associated with a wide range of myocardial abnormalities. The purpose of this study was to determine the changes over time of RVP on myocardial blood flow (MBF) and glucose metabolism as assessed by positron emission tomography (PET). In eight candidates for permanent pacemaker implantation PET imaging was performed with 13N-ammonia and 18F-Fluorodeoxyglucose (FDG) to assess MBF and glucose metabolism before (PET1) and repeated after 3 months of RVP (PET2). For the analysis, the left ventricle was divided into three parts (apex, mid-ventricular and base) and subdivided into six segments (inferior, posterior, lateral, anterior, antero-septal and infero-septal). After RVP, defects of FDG uptake were found in the left ventricle near the stimulation site, without corresponding changes in MBF. Changes over time in the mean FDG uptake were statistically significant between PET1 and PET2 in the apical inferior, apical-posterior, apical-anterior, apical antero-septal, apical infero-septal, mid-inferior and mid-infero-septal segments. This study shows that RVP induces major changes in the distribution of FDG uptake in the left ventricular myocardium. FDG uptake significantly decreases in the regions surrounding the pacing site.