Reconstruction of ventricular volume curves distorted by variations in heart rate

Variations in heart rate or frequent ectopic beats may seriously distort the results obtained from EcG-gated radionuclide ventriculography.A method is described for measuring the effective acquisition time for each frame from the patient's R-R interval distribution stored in computer memory.Normalising factors calculated from this R-R interval histogram are applied to each image frame.A computer simulation has been used to assess the effectiveness of the method in removing distortions in ventricular volume curves.In 95 consecutive patient studies five showed unacceptably large variations in heart rate and six patients had frequent ectopic beats.These studies were re-analysed using our reconstruction technique.A significant improvement in image quality was obtained which allowed ventricular wall motion to be observed throughout the cardiac cycle.Values of left ventricular ejection fraction derived from the reconstructed images always agreed within 0.03 with those obtained from a modified video recorder which allowed heart beats outside chosen limits to be excluded.