Hypoplasia of the coronary sinus with coronary venous drainage into the left ventricle by way of the Thebesian system.

A 60-year-old woman with recent onset of exertional chest pain, left anterior hemiblock and negative stress electrocardiogram was found to have hypoplasia of the coronary sinus with drainage of the major coronary venous blood by way of the Thebesian system into the left ventricle. This abnormality appeared to be of no great functional significance.