Prediction of improvement in left ventricular function after ventricular aneurysmectomy using Fourier phase and amplitude analysis of radionuclide cardiac blood pool scans.

Postoperative improvement in left ventricular (LV) function is a common objective of LV aneurysmectomy, but is difficult to predict. The first Fourier component of time-activity curves of pre- and postoperative gated radionuclide angiographic studies was evaluated for this purpose in 20 patients who had undergone aneurysmectomy. LV aneurysms had portions that characteristically exhibited marked phase delay with varying degrees of amplitude. Total aneurysmal amplitude was obtained preoperatively by summing the amplitude component of all pixels that exhibited phase delay, suggesting paradoxical motion. LV ejection fraction (EF) before and after aneurysmectomy and the absolute postoperative increase in LVEF were calculated. Nine of 20 patients had an absolute increase of EF less than 10% despite resection of large aneurysms. A strong correlation was found between the absolute increase in EF after aneurysmectomy and the total amplitude within paradoxically moving areas (r = 0.93, p less than 0.0001). Thus, preoperative measurement of the total paradoxical amplitude predicts absolute change in EF and may be important in selecting patients for aneurysmectomy. The data also suggest that the total aneurysmal amplitude reflects the stroke volume ejected into an aneurysm in systole and that paradoxical expansion of an aneurysm contributes to LV dysfunction in some of these patients.