Echocardiographic assessment of atrial tumour size and endogeneously generated contrast images. An experimental study.

Experimental models, in vitro and in vivo, were designed to simulate the motion of an atrioventricular valve leaflet and an atrial tumour. Cross-sectional echocardiography was used to investigate any changes in apparent tumour size related to its motion. Both parts of the study suggest that endogenous contrast, due to surfaces of different acoustic densities generated around the rapidly moving tumour, contributes to the echographic pattern of the tumour.

Inhibition of demand pacemakers by myopotentials.

The inhibition of unipolar demand pacemakers by myopotentials was studied in 215 paced patients with or without symptoms and in steady pacing rhythm. ECG recordings were taken of all patients at rest and during effort in which maximal muscular strength from the pectoralis major (PM) and rectus abdominis (RA) muscles was required. In 75 patients (34.