Occurrence and distribution of left ventricular bands and normal anatomical features in 78 feline hearts

INTRODUCTION/OBJECTIVES: Left ventricular bands (LVBs) are common in feline hearts. Their importance and general features are incompletely described. This study aimed to characterize LVBs in feline hearts based on anatomical location, quantity, histological features, and attachment sites.

ANIMALS, MATERIALS AND METHODS: Hearts from 78 domestic cats with or without heart disease were included in this study. Cardiac weight and dimensions were measured, and LVBs were categorized as singular bands or nets, with further characterization by location, length, appearance, and histological examination of attachment sites.

RESULTS: Median cardiac weight was 4.34 g/kg (interquartile range: 2.1 g/kg). Left ventricular bands were present in all hearts, with 11% having only singular bands, 32% containing only nets, and 42% having nets covering the entire left ventricle (LV). The most common LVB attachment sites were the LV mid-region involving the posterior papillary muscle. Nets were most common in the mid-region including the papillary muscles (93%), followed by basilar (60%) and apical (59%) regions. All LVBs contained collagen, myocytes, adipose tissue, endothelial cells, and fibroblasts. No excess fibrosis, myocardial hypertrophy, or endocardial thickening at the attachment sites was identified.

STUDY LIMITATIONS: The study included mainly domestic stray cats aged 12 weeks to 15 years, with few purebred or diseased individuals. The hearts were examined by one person, which may introduce subjectivity.

CONCLUSIONS: Left ventricular bands are commonly found in the mid LV section of feline hearts, primarily involving the posterior papillary muscle, suggesting normal variation. Left ventricular bands contain myocytes, not Purkinje fibers, and are not fibrous tendons. Myocyte hypertrophy or excess fibrosis is absent at attachment sites.