S2 triggered gated blood pool imaging for assessment of diastole

Evaluation of diastolic function using ECG-Gated Blood Pool (EGBP) imaging is limited by inaccurate reproduction of the ventricular volume curve during diastole. Gating to an end-systolic event may reduce the influence of heart period variability, improving the fidelity of this curve during diastole. Heart Sound-Gated Blood Pool (HSGBP) imaging was employed to initiate acquisition at the Second Heart Sound (S2) using a previously reported Heart Sound Gate, and an accelerometer. Seven patients underwent EGBP imaging at 24 and 56 frames per second (fps), and HSGBP imaging at 24 fps. Utilizing EGBP imaging a mean ejection fraction (EF) of 54% was obtained at 24 fps, with HSGBP imaging yielding 53%. EF obtained by HSGBP and EGBP imaging correlated closely (r = 0.96, p < .002). The mean EF during 56 fps EGBP imaging was greater at 67%, consistent with previous reports. Additionally, peak filling rates by HSGBP and EGBP imaging correlated well (r = 0.95, p < .02). The fidelity of the diastolic ventricular volume curves for HSGBP and EGBP methods were comparable in four patients, and superior with HSGBP imaging in four patients. In conclusion, HSGP imaging is a feasible method for acquisition of the ventricular volume curve, and may assess diastolic function indices with greater accuracy. Further investigation of this application is warranted.