When the Nobel Prize in Physiology and Medicine was awarded to Andre Cournand and Werner Forssmann in 1956 for developing cardiac catheterization, the Nobel Committee was not aware about the pioneering work of Dr Otto Klein. However, W.
Forssmann mentioned him in his Nobel Lecture on 11 December 1956: 'Nevertheless, in 1930, about 6 months after my first publication, Otto Klein reported from Nonnrenbruch's Prague clinic on a series of patients whose heart minute-volumes he had ascertained according to Fick's principle, by means of the heart catheter. This procedure has its place even today in the standard practice of heart and lung clinics' (https://www.nobel prize.org/prizes/medicine/1956/forssmann/lecture/).