For 219 children between 3 and 15 years with the most frequent congenital and acquired heart failures it was investigated in what way the STI differ consistently from the corresponding standard values. It was found that all the STI of children with cardiovascular diseases can vary from the normal values scaled by heart rate even in disorders of the right heart. The STI naturally have the greatest diagnostical significance in the evaluation of failures of the left heart, especially aortic stenosis (shortened PEP lengthened QS2 and LVET), and of heart partition defects (shortened LVET, prolonged PEP, normal QS2). Statistically individual groups of heart disorders can be differentiated from one another by the STI rather well.