Dynamics of left ventricular diastolic filling during exercise: a Doppler echocardiographic study of boys 10 to 14 years old.

STUDY OBJECTIVE Factors influencing diastolic filling of the left ventricle may serve as critical determinants of both maximal cardiac output and oxygen uptake. This study was conducted to assess diastolic filling dynamics of the left ventricle during progressive upright cycle exercise in children. METHODS Twelve boys aged 10 to 14 years underwent cycle testing with determination of transmitral flow velocities and pressure gradients as well as cardiac stroke volume using Doppler echocardiography. RESULTS Estimated diastolic filling period shortened from 0.479 +/- 0.043 s at rest to 0.138 +/- 0.015 s at peak exercise. The peak and mean transmitral pressure gradient rose fourfold from rest to peak exercise. Mitral flow volume per beat rose by only 40% and remained stable beyond mild-to-moderate intensity work. CONCLUSIONS Increases in transmitral pressure gradient with exercise may serve principally to augment velocity of ventricular filling with the progressively shortening diastolic time period.