The effect of the backward reflected wave (BCW) on left ventricular (LV) performance is a highly debated area. The aim of this study was to establish whether the arrival of a BCW has a detrimental effect on LV axis shortening.

Methods: Invasively acquired ascending aortic velocity, pressure and LV long and minor axes dimensions were measured simultaneously in 11 open-chest anaesthetised dogs. LV axes dimensions were measured by sonomicrometry and differentiated with respect to time to identify maximum shortening velocity. Wave Intensity analysis was used to identify the arrival time of BCW. Data were acquired during control and during occlusion conditions of the proximal thoracic aorta, created using a snare. Statistical agreement was assessed using the concordance correlation coefficients (CCC).

Results: During control the BCW arrived back at the heart at the time of LV minor axis maximum velocity of shortening (difference 3±4ms, CCC=0.96). Aortic occlusion was associated with a large increase in the magnitude and earlier arrival of the BCW. LV minor axis’ maximum velocity of shortening was attenuated by 20% and also occurred earlier, at the time of BCW arrival (mean difference 3±5ms, CCC=0.98). The LV long axis was less affected by arrival of BCW (Figure).

Conclusions: The arrival of BCW results in deceleration of the rate of shortening of the LV minor axis but does not cause deceleration of the long axis. The BCW appears to be detrimental to the canine LV minor axis function.