Common atrioventricular canal in a newborn foal–case report and review of the literature.

This research investigates a case of a rare congenital heart defect known as common atrioventricular canal (AVC) in a newborn foal, showcasing the techniques used in diagnosis and suggesting that AVC could potentially be a more common equine heart defect than initially thought.

Introduction

The common atrioventricular canal (AVC) is a type of endocardial cushion defect, a congenital (present from birth) heart defect, where there are issues with the heart’s structure developing before birth. These defects are rare, especially in the veterinary world. Nonetheless, the authors argue that AVC might be more common in equine species than previously assumed.

Research Process

• The authors encountered a case of a rare cardiac defect in a newborn foal, identified as a complete, balanced common AVC type C, according to Rastelli’s classification scheme. This identification was based on various diagnostic techniques such as two-dimensional, contrast and colour Doppler echocardiography, a technique that uses sound waves to produce images of the heart and assess its functioning.
• Upon detecting anomalies during the echocardiographic inspection, they proceeded with further diagnostic actions. These included a physical examination, collecting and analysing blood gas parameters, standard laboratory tests, electrocardiography (a test that checks heart’s rhythm and electrical activity) and thoracic radiography (a type of X-ray).
• After the foal’s death, they conducted postmortem gross pathology to confirm the diagnosis, a process where the causative abnormalities are visually identified and examined through an autopsy.

Results and Discussion

• In light of all evidence, the diagnosis of AVC was confirmed. This observation led the researchers to review the existing literature related to this kind of cardiac anomaly.
• Through their review, they noted that AVC might account for more equine congenital cardiac defects than it is currently accredited for. Their suspicion is based on the notion that certain previously described equine cardiovascular abnormalities might have been misinterpreted. They suggest these could be variants of AVC, emerging from a failure of the endocardial cushions to merge correctly during foetal development.
• Thus, they emphasise the need for a meticulous diagnostic approach when handling cases of equine congenital heart disease, to avoid misdiagnosis and ensure accurate prevalence data.