Regional shortening patterns in canine right ventricle.

The right ventricular outflow tract (OT) is a functionally distinct area of the right ventricle. However, there is little information on the contrdingly, inflow tract (IT) and OT chords and right ventricular free wall segmental changes were measured with implanted ultrasound crystals. The timing and extent of shortening of IT and OT chords and free wall segments were determined both at rest and after stellate ganglion stimulation. At rest, IT chord shortening began 51 ms before OT shortening. OT expansion occurred during this period. IT chord shortening began 51 ms before OT shortening. OT expansion occurred during this period. IT chord shortening was 38% while OT shortening was 34%. In contrast, OT segments did not show systolic expansion. IT segment shortening was 13% while OT shortening was 21%. With stellate stimulation, IT-OT gradients of 15-25 mmHg developed. The lag between IT and OT shortening decreased to 30 ms and segmental shortening increased. We conclude that the OT is a physiologically distinct region which contracts later and remains contracted longer than the IT. Both septal and free wall movements contribute to these changes.