Automatic on-line measurement of systolic time intervals using a personal computer

A personal computer-based system for automatically evaluating external systolic time intervals (STI) suitable for practical clinical use is presented. In 56 consecutive unselected subjects, ranging in age from 16 to 77 years (mean = 51 years), the STI recorded with standard technique were computed manually and automatically. Manual and automatic techniques correlated closely in all indices studied (Q-Q interval: r = 0.995; electromechanical systole: r = 0.975; pre-ejection period (PEP): r = 0.985; left ventricular ejection time (LVET): r = 0.973, PEP/LVET: r = 0.981, p less than 0.001). These results demonstrate that automatic evaluation of STI can be effectively made with good reliability using inexpensive hardware.