He was born with a life-threatening heart defect.
"was born with" – age clock started at zero.
Whose life was threatened?
The person – any natural person – comes with a state that is alive/dead. This state was threatened. How do you threaten a state? – You threaten to change it – a change relation is needed.
A defect means the object – the heart – did not work properly, or more simply, behaved abnormally. This affects all relations or states which the heart drives or by which it is controlled – circulation, heart rate, volume, blood pressure(s).
We have a male person, who at age zero had threat to alive state, defect in heart – the male could now be 5 or 50 years old. What does the model look like?
Current age – 0-90 years
The statement could easily be
He was born with a life-threatening heart defect and died the next day.
Or
He was born with a life-threatening heart defect and now, in old age, hypertension is weakening the repair.
Do we put in defect pathways, have them not exist for the moment, assume everything is normal unless told otherwise? Could we really build all abnormal conditions into the model, or would we still need to change it for unusual circumstances – he lost a leg from smoking.
Some conditions are so common that they should be handled in the normal model – the flu, osteoporosis, arteriosclerosis – they are normal for particular age ranges.
We can’t spend half an hour setting up the model for a run of the mill sick patient, but we can spend an hour on new model construction and hypothesising when the diagnosis is difficult.