Tricuspid atresia in a foal.

This study describes the case of a foal born with a serious heart defect, known as tricuspid atresia, along with several other complications. Despite attempts at surgical intervention, the foal did not survive.

Background

• In this study, researchers examined an Arabian crossbred foal that was suspected to have a congenital (present at birth) cardiac anomaly. Congenital heart defects are abnormalities in the heart’s structure that occur as a foal’s heart develops in the womb.

Findings and Diagnosis

• The foal showed heart abnormalities that included a grade V/V crescendo-decrescendo holosystolic murmur and thrill in the left 4th intercostal space. This suggests a heart defect of severe magnitude.
• The foal was slightly cyanotic, indicating that it was not getting enough oxygen, and was also polycythemic, which means it had an abnormally high level of red blood cells.
• The use of electrocardiography, a test that measures the electrical activity of the heart, suggested left ventricular hypertrophy, which is a thickening of the walls of the left ventricle.
• Angiography and cardiac and vascular pressure recordings enabled the researchers to diagnose the foal with pulmonic stenosis, a condition where the flow of blood from the right ventricle of the heart to the pulmonary artery is blocked at the pulmonic valve.

Postoperative Findings and Postmortem Examination

• Despite undergoing cardiac bypass and corrective surgery, the foal did not survive.
• Postmortem examination revealed a number of cardiac abnormalities:
• The right atrium, one of the four chambers of the heart, was abnormally large.
• There was atresia of the tricuspid orifice, which meant that the opening between the right atrium and the right ventricle was closed off.
• The foal had a large, fenestrated patent foramen ovale, which is an abnormal hole in the heart that didn’t close after the foal was born.
• There was an eccentric left ventricular hypertrophy – an enlargement of the heart’s left ventricle not caused by pressure overload.
• A large interventricular septal defect was present – a hole existed in the wall that separates the heart’s lower chambers.
• The right ventricle, another of the heart’s chambers, had a small lumen and a relatively thick wall.
• Further findings include:
• There was valvular and supravalvular pulmonic stenosis, meaning that the pulmonic valve and the area above it were narrowed, causing blockage of blood flow.
• The foal had poststenotic dilatation of the pulmonary artery – the artery was abnormally widened after the point of constriction.
• A single coronary artery, which usually branches from the aorta, originated from the anterior sinus of the aorta.

Conclusion

• This study offers valuable insights into the diagnosis and clinical management of congenital heart defects in foals. However, the congenital heart problem in this particular foal was quite severe, demonstrated by its inability to survive even after medical intervention. It underscores the importance of early detection and diagnosis of such defects in foals for better management and prognosis.