A coroner said the delay by the ambulance service in giving care to Norfolk baby Bella Hellings was "wholly indefensible".
William Armstrong concluded the three-month-old died as a result of congenital heart disease after delays in medical assistance reduced her chances of survival.
He said: "We are told that at the time the ambulance service was experiencing significant demand and there were apparently insufficient resources to meet that demand.
"Twenty-six minutes is a very, very long period of time indeed.
"The delay in giving Bella the care that she needed was wholly indefensible. There was a catalogue of catastrophes and a chaotic response."