In an experimental canine model, the arrival of reflected waves initiated a deceleration in left ventricular minor axis shortening, with aortic occlusion reducing the maximum shortening velocity by 20%.
Does aortic occlusion alter wave reflection and affect left ventricular long and minor axis shortening in an anesthetized dog model?
Reflected wave arrival has a detrimental effect on left ventricular function, particularly the minor axis, supporting the concept that therapies reducing wave reflection may be beneficial in cardiovascular disease.
Absolute Event Rate: 1.2% vs 1.5%
Increased wave reflection is an independent predictor of cardiovascular events, possibly due to effects on left ventricular (LV) function. We investigated the relationship between reflected waves in early systole, the forward decompression wave in mid-late systole and LV mechanical behavior. Invasively acquired ascending aortic velocity, pressure, and LV long and minor axes' dimensions were measured simultaneously in 11 anesthetized dogs during both control conditions and aortic occlusion to cause additional early wave reflection. Wave intensity analysis (WIA) was used to identify the arrival of the reflected wave and the onset of a forward decompression wave in mid-late systole. The arrival time of the reflected wave coincided with the time when minor axis shortening began to decline from its peak, even during aortic occlusion when this time is 12 ms earlier. The initial decline in long axis shortening corresponded to the time of the peak of the reflected wave. The forward decompression wave was consistently observed to have a slow and then rapid phase. The slow phase onset coincided with time of maximum shortening velocity of the long axis. The onset of the later larger rapid phase consistently coincided with an increased rate of deceleration of both axes during late systole. Forward decompression waves are generated by the LV when the long axis shortening velocity falls. Reflected wave arrival has a detrimental effect on LV function, particularly the minor axis. These observations lend support to suggestions that therapies directed toward reducing wave reflection may be of value in hypertension and cardiovascular disease.
Park et al. (Thu,) conducted a other in Healthy (animal model) (n=11). Aortic occlusion vs. Control conditions (baseline) was evaluated on Maximum velocity of shortening of the LV minor axis (MmaxU) in m/s. In an experimental canine model, the arrival of reflected waves initiated a deceleration in left ventricular minor axis shortening, with aortic occlusion reducing the maximum shortening velocity by 20%.