Regional shortening patterns in canine right ventricle

Area of Science:

• Cardiology
• Physiology
• Cardiac Mechanics

Background:

• The right ventricular outflow tract (OT) is functionally distinct.
• Limited information exists on its specific contractile properties compared to the inflow tract (IT).

Purpose of the Study:

• To investigate the distinct mechanical properties of the right ventricular OT and IT.
• To analyze the timing and extent of segmental changes in both regions at rest and during autonomic stimulation.

Main Methods:

• Implanted ultrasound crystals were used to measure changes in the IT and OT chords and free wall segments.
• Measurements were taken at rest and following stellate ganglion stimulation.

Main Results:

• At rest, IT chord shortening preceded OT shortening by 51 ms, with OT expansion observed during this phase.
• Segmental shortening was 13% for IT and 21% for OT.
• Stellate stimulation reduced the lag to 30 ms and increased segmental shortening, creating IT-OT pressure gradients.

Conclusions:

• The right ventricular OT is a physiologically distinct region with delayed contraction and prolonged contraction compared to the IT.
• Both septal and free wall movements contribute to the unique mechanics of the OT.
• Autonomic stimulation alters the timing and extent of contraction in both regions.