Morphological Variations in the Canine (Canis familiaris) Right Ventricle Trabecula Septomarginalis Dextra and a Proposed Classification Scheme.

The trabecula septomarginalis dextra is a structure routinely mentioned in veterinary anatomy. While there are several studies on the morphology of this structure in select animal species, there are some characteristics that are not adequately described. The purpose of this study was to describe and classify this trabecula in the domestic dog using the number of branches that insert onto the ventricular free wall. In the 39 examined hearts, 17.95% were single stranded (type I) and 2.56% were y-shaped (IA). Then, 28.21% were web-like with 3 to 4 points of insertion (IB) and 51.28% were web-like with 5 or more points of insertion (IC). While the purpose of this study was to describe the morphology of this trabecula, it also showed there is variability in this structure within the same species. This undocumented variability could present a problem to researchers who use dogs as an animal model when testing catheters for invasive cardiac monitoring or cardiac stem cell therapy. Also a web-like trabecula could create problems during pacemaker lead placement for the treatment of symptomatic bradycardia because of the potential for catheter entanglement in these branches.