The complex question of peri-infarction blocks is examined. Whereas this term was once used for conduction disturbances now interpreted as fascicular blocks, a distinction is drawn here between these and parietal, post-Hisian blocks and infarctual blocks. Their vectorcardiographic picture are described, along with the possible expression of segmentary blocks at the peripheral branches of the posterior fascicle of the left branch. These electrogenetic interpretations are discussed in the light of data obtained by phonomechanographic methods in cases of parietal block.