Development On Portable Non-destructive Diagnostic System For Coronary Anery Stenosis

Coronary Artery Disease (CAD) is one of the most dangerous threats to human health, theCAD patients are increasingly growing in number in our country. The morbidity for CAD isgradually increasing with the trend of patients being young. For the CAD patients, because of thereis a severe degree of narrowing in coronary artery, coronary artery becomes stensis or occlusion,and then, it will lead to Myocardial Ischemia and Myocardial hypoxia. Seasonable diagnosis andcure are important for the CAD patients. Heart sound is an important indication which reflectsphysiology and pathology characteristics of heart, Analysis and study for heart sound is animportant means of CAD diagnosis. For the CAD patients, before there are the symptoms ofcardiogram abnormity, the high-frequency heart murmur in the cardiac sounds contains the reliableinformation for CAD diagnosis.The paper has designed a kind of portable nondestructive diagnostic instrument for coronaryartery stenosis based on PDA and bluetooth, which includes heart sound signal acquisition terminaland PDA terminal. The coronary artery stenosis diagnosis algorithm based on EMD and SVM ispresented, then, use the clinical heart sound data to test the performance of the algorithm. Data canbe transmitted successfully between PDA terminal and signal acquisition terminal through wirelessconnection which is set up by Bluetooth; Signal acquisition terminal has the function of dataacquisition and cardiac auscultation; The PDA terminal has the function of receive heart sound data,display real-time heart sound waveform, storage heart sound signal, playback heart sound signal,analyse coronary artery stenosis based on intelligent diagnosis algorithm and communicate with theremote expert diagnosis system on network.The main works in this paper are listed as follows:(1) Hardware design of heart sound signal acquisition terminal mainly includes the choice ofheart sound sensor, design of heart sound filter, design of keyboard circuit, design of reset circuit,design of volume controlling circuit, design of bluetooth interface circuit and choice ofmicrocontroller etc.(2) Software design of heart sound signal acquisition terminal mainly includes moduleinitialization of microcontroller, keyboard handling procedures etc.(3) Heart sound segmentation and intelligent diagnosis algorithm for coronary artery stenosis:Firstly, the method to segment the heart sound based on Hilbert transform and the extractionalgorithm for diastolic heart sound are studied. Secondly, the instantaneous frequency features ofdiastolic murmurs are analyzed by EMD and DESA algorithm; the instantaneous frequency features for diastolic murmurs contain the pathological information of coronary artery stenosis. Finally, theintelligent diagnosis method based on SVM for coronary artery disease is proposed, then, use theclinical heart sound data to test the algorithm and obtain high diagnosis ratio.(4) The software development based on PDA terminal: the software is developed based onLabVIEW, which has implemented the functions: receive heart sound data, display real-time heartsound signal, storage heart sound signal, playback heart sound signal, analyse heart sound signalbased on intelligent diagnosis algorithm and remote data transmission based on the TCP/IP networkprotocols.The instrument has realized the miniaturization, mobility, intellectualization of health careequipment, which can be used in families and communities and provides an effective means for theearly diagnosis of CAD.