Clinical Research Papers

TJ Brinton*, WC Hu, SS Chio, CP Liu. Pulse Metric, Inc. San Diego, CA, USA and Veterans General Hospital-Kaohsiung, Taiwan, ROC

We previously developed and validated a non-invasive (NI) technique to derive the aortic pressure signal using a cuff sphygmomanometer. We have now developed a new method to derive maximum left ventricle dP/dt (dP/dt_LVmax) from the aortic pressure signal assuming gaussian curves for both aortic and left ventricle wave contours. We validated NI end systolic pressure (ESP) and dP/dt_LVmax obtained utilizing this new method with simultaneous measurements from an invasive (INV) micromanometer tipped catheter in twenty-two patients with myocardial infarction (MI) and eleven normal subjects. NI and INV ESP measurements had a good correlation (142± 17 vs. 133± 16 mmHg, r = 0.91). NI and INV dP/dt_LVmax were also in accordance (1097± 232 vs. 1279± 241 mmHg/sec, r = 0.75). To test the consistency of the NI measurement, we assessed dP/dt_LVmax at four different heart rate levels in both groups (increment of 15 beats/level from sinus rate). A positive inotropic response was observed in normal subjects and the correlation between the methods was excellent (r = 0.94). Although the positive response of dP/dt_LVmax was significantly blunted in MI patients (p < 0.05), the NI data showed a good correlation with INV data (r = 0.93). These results suggest that ventricle function may be assessed reliably in patients with cardiovascular disease using this new NI method. Due to the excellent correlation between the methods during dynamic conditions, the method should be clinically useful for evaluating changes in cardiac function during routine blood pressure monitoring.