hole in the heart 
noun Medicine
A congenital defect in the heart septum, resulting in inadequate circulation of oxygenated blood (a cause of blue baby syndrome): [as modifier]: a hole in the heart operation...
- They diagnosed her with Ventricular Septal Defect - a hole in the heart's wall - a type of heart malfunction present at birth.
- The boy's mother said he had been treated for a hole in the heart and a leaky heart valve.
- In 1960 only one in five babies born with a complex heart defect, such as a hole in the heart, survived beyond childhood.