Evaluating two new indicators of cardiac reserve.

The receiver operator characteristic (ROC) curve and likelihood ratio (LR) are two effective methods to comprehensively and accurately evaluate a diagnostic test, which can select the cutoff point for a diagnostic indicator and judge the efficiency of a diagnostic test by calculating area under the ROC curve (AUCROC). To evaluate the value of these two new indicators for cardiac reserve in evaluating cardiac function, we carried out the study discussed in this article. A cardiac contractility monitor (CCM), based on a notebook computer was used The hardware of the CCM consists of a phonocardiographic sensor, a heart sound signal preprocessing box, a notebook computer, and a printer. The basic points for heart sound quantitative analysis were: 1) measuring the duration and the amplitude of relevant heart sound components and 2) generating relevant indicators based on the data obtained from the above measurements. The phonocardiogram exercise test was used for this study.