Parachute left atrioventricular valve causing stenosis and regurgitation in a Thoroughbred foal.

This is a case study on a rare congenic cardiac condition in a thoroughbred foal, known as Parachute left atrioventricular valve, which caused obstruction of heart flow and heart murmurs. The researchers diagnosed this by echocardiography and linked it to the foal’s poor health condition and exercise intolerance.

Introduction

• The researchers start by acknowledging that congenital cardiac abnormalities are rare, especially in horses. When such abnormalities occur, they rarely affect the atrioventricular (AV) valve. The authors specifically mention left-sided cardiac anomalies leading to flow obstruction as particularly rare, infrequently seen in horses compared to humans.
• They highlight that this particular study is special because it deals with a rarely reported anomaly called parachute left AV valve. This congenital anomaly is characterized by the presence of a single papillary muscle receiving all chordae tendineae from the left AV valve. It might occur as a standalone anomaly or in combination with other congenital left heart deformities.

Case description

• The study focuses on an 8-month-old Thoroughbred colt that showed signs of illness and exercise intolerance. The colt was also reported to be less active compared to its age mates and displayed a loud left-sided holosystolic murmur. The colt exhibited no history of previous illnesses.
• On examination, the colt was bright, alert, and responsive but bore a slightly enlarged abdomen and a dense hair coat. The heart rate and respiratory rate were taken and the murmur auscultated. The research also included findings from an electrocardiography and an arterial blood gas analysis. These tests confirmed a regular cardiac rhythm and normal oxygenation.

Diagnosis

• Considering the set of symptoms and the results from the physical examination and tests, the researchers were able to diagnose a condition known as the parachute left atrioventricular valve in the colt. This health issue was causing the stenosis and regurgitation reported in the foal, leading to the health problems noted.