Although 4D echocardiography has not been validated for use in the horse, it was used in this study to confirm the presence and identify the cusp affected by AVP by visualising apical movement of the cusp in concurrent orthogonal 2D images and by rendering these into an image that could be visualised from the ventricular surface.
Russell [7] conducted a study of unworn of Sylvilagus to identify a central cusp, and to compare it to the central cusp of various fossil lagomorphs.
There was agreement from equine echocardiographers that to identify which valve cusp prolapsed, orthogonal views were required.
Indeed, although most respondents used both views to identify the affected cusp, there was a discrepancy between the number who used two views to identify AVP and the number requiring two views to be confident in this assessment.
Indels were identified by the CUSP method and alignments were projected through a graphical viewer, StructView, described elsewhere [13].
To this end, Wood ([8], his 115th figure) identified the central cusp as the metacone, a position he continued to maintain for decades [9].
In addition to identifying the central cusp in living lagomorphs the study also pointed to pantotheres as a possible ancestor to lagomorphs.
Although Wood [8], [9] identifies the central cusp as the metacone, he explored the idea that only the protocone was representative of the primary tribosphenic cusps (e.g., protocone, paracone, and metacone), and rightly concludes, that if this were the case the 'premolar analogy' theory would not hold for lagomorphs due to the absence of the paracone.
Each subject had undergone clinical echocardiography with images sufficient to identify associated cardiac malformations and aortic valve cusp fusion morphology (Table 2).
c The reference line in the coronal image that controls the former axial plane is moved up and down to identify the lowest insertion point of the right coronary cusp, and the former axial plane is positioned exactly at the level of the right cusp insertion point.
