| External counterpulsation (EGP) is a noninvasive assisted circulation device. It plays a positive and curative role in increasing the blood supply for the heart and brain; promoting collateral circulation of the ischemic tissue and organs; This noninvasive technique provides augmentation of diastolic blood flow and coronary blood flow similar to the intraortic balloon pump, utilizing the serial inflation of three sets of cuffs which wrap around the calves, thighs and buttocks. Inflation and deflation is timed to the patient' s Electrocardiograph (ECG) and the arterial pressure waveform is monitored noninvasively. The overall hemodynamic effect is to provide diastolic augmentation and thus increase coronary perfusion pressure, to unload systolic cardiac workload and therefore decrease myocardial oxygen demand.An intelligent test and control system, which consists of advanced computer and 16-bit microcontroller, is developed for controlling counterpulsation and monitoring the system and patient. A new algorithm about the inflation and deflation timing is adopted in this system, which makes the diastolic augmentation emerge as soon as the aortic valve closed. In this case, the blood has enough time to pour into the organs that are short of blood, by doing so, a best effect of the ECP will be achieved.In this paper, "three thresholds" method is adopted to distinguish the R wave from the characteristic of ECG signal. Integrated with the finger pulse wave, the system can extract the start point of the inflation and deflation timing. Ensure the patients' safety, the "error early warning" function is designed in this system.The electromagnetic compatibility (EMC) was an ability for electronicequipment to work well under the anticipant electromagnetic environment, it is an important technical performance for electronic equipment especially the medical devices. So some kinds of analogue and digital circuitries were designed for ECP to enhance the EMC ability of the system.
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