Long-Term Right Ventricular Volume Overload Increases Myocardial Fluorodeoxyglucose Uptake in the Interventricular Septum in Patients With Atrial Septal Defect

Abstract

Background-Several-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) in 11 patients with atrial septal defect (ASD) and 11 control subjects. In the FDG study, we calculated myocardial metabolic rate of glucose (MMR) in interventricular septum (IVS) and left ventricular (LV) free wall. MMR was significantly increased in IVS compared with LV free wall in the ASD patients (420Ϯ35 versus 333Ϯ32 mol ⅐ kg Ϫ1 ⅐ min Ϫ1 ; PϽ0.05) but not in the control group (347Ϯ27 versus 357Ϯ25 mol ⅐ kg Ϫ1 ⅐ min Ϫ1 ). In both ASD and control groups, SPECT count was not significantly different between IVS and LV free wall in Tl (ASD, 160Ϯ11 versus 177Ϯ12; control, 141Ϯ12 versus 157Ϯ14 counts per 15 minutes) and BMIPP studies (ASD, 203Ϯ14 versus 212Ϯ18; control, 162Ϯ16 versus 176Ϯ16 counts per 15 minutes). MMR in the IVS/LV free wall ratio in the ASD group significantly correlated with indices related to RV volume overload. Conclusions-Given the assumption that long-term RV volume overload did not affect the lumped constant, the present study suggests that, unlike myocardial perfusion or fatty acid analogue uptake, myocardial glucose utilization in IVS relative to LV free wall is increased in relation to long-term RV volume overload in patients with ASD. (Circulation.

Increased [18F]Fluorodeoxyglucose Accumulation in Right Ventricular Free Wall in Patients With Pulmonary Hypertension and the Effect of Epoprostenol

“…In right ventricular (RV) pressure overload due to pulmonary artery constriction in rats, we demonstrated not only that myocardial glucose utilization in the RV free wall increased, but the regional profiles of substrate utilization in the interventricular septum and the LV free wall were also altered (5). Our previous clinical study with positron emission tomography (PET) demonstrated that myocardial [ 18 F]fluorodeoxyglucose (FDG) accumulation was increased in the interventricular septum compared with the LV free wall in patients with chronic RV volume overload due to atrial septal defect, and that the FDG accumulation in the RV free wall was also increased in those patients compared with the control subjects, although we did not correct the radioactivity for the RV free wall thickness (7). However, it is unclear whether FDG accumulation in the RV free wall, corrected for the partial volume effect, which is derived from the relatively thin RV free wall thickness, increases in patients with chronic RV pressure overload.…”

Flattening of the interventricular septum (D-shaped left ventricle) in addition to high right ventricular tracer uptake and increased right ventricular volume found on gated SPECT studies strongly correlates with right ventricular overload

“…The increase 7 in metabolic uptake in the interventricular septum in FDG-PET scans has been observed in patients with atrial septal defect but again there is no report about occurrence of septal flattening. 18 We present the first observational study of eight patients who showed flattening of the interventricular septum during gated SPECT imaging with echocardiographic confirmation of pulmonary hypertension or right ventricular overload. Interestingly, despite significant pulmonary hypertension in the majority of the patients with flattening of the septum seen on gated SPECT imaging, only 50% had septal flattening documented by echocardiography.…”

Right-ventricular function by nuclear cardiology

“…These findings have been similarly recapitulated in humans as well. In a small study, an increase in glucose uptake in the interventricular septum relative to the LV free wall of atrial septal defect patients was seen compared with controls as assessed by FDG-PET, which correlated with indices of RV overload [47]. Oikawa et al hypertension and the response to treatment.…”