Studying the Precision, Accuracy and Signal/Noise Ratio in Cardiac Contractility Signal Processing

Phonocardiogram exercise testing (PCGET) is a recently developed method to evaluate cardiac contractility and the cardiac reserve of patients with heart disease and of healthy subjects. In order to improve further PCGET method and test the validity of PCGET method, a study on its precision, accuracy, sensitivity, specificity, and signal/noise ratio was performed. Thirty volunteers performed PCGET. When different examiners measured the SI amplitude in the same cardiac cycle of the same subject, the data obtained by examiner A were: Mean(x)+SD=5.05 plusmn 0.0451; the data obtained by examiner B were: Mean(x)+SD=4.95 plusmn 0.0346; E=1.699, P>0.05. When different examiners measured the same cardiac cycle (s)of the same subject, the data obtained by examiner A were: Mean(x)+SD=0.789 plusmn 0.0018; the data obtained by examiner B were: Mean(x)+SD=0.787 plusmn 0.0017; F=1.167, P>0.05. Precision, accuracy, sensitivity, specificity of PCGET were high. The results suggest that PCGET increased S/N ratio; PCGET is a noninvasive, convenient, quick, and inexpensive technique to quantitatively evaluate cardiac contractility and cardiac reserve for patients or healthy subjects.