デジタル信号処理二次微分指先容積脈波による循環動態評価に関する研究

Abstract

The purpose of these studies is to evaluate hemodynamics by the second derivative of the finger-tip plethysmogram (FPTG). We developed a new digital signal processing method for differentiation of the FPTG signal. By our new method, we can understand the exact correspondence in phase between the FPTG and its second derivative. (1) Subjects were ten patients with ischemic heart disease. ECG, the second derivative of the FPTG by the analog signal process (d²FPTGᴀ), and that by the digital signal process (d²FPTGᴅ) were recorded simultaneously. Time intervals from peak of the R wave of the ECG to each peak of the d²FPTGᴀ or d²FPTGᴅ were measured. The intervals determined from the d²FPTGᴀ were significantly longer than those obtained from the d²FPTGᴅ. In the d²FPTGᴅ, the interval from the "a" wave peak to the "e" wave peak can be measured as left ventricular ejection time (ET). During diagnostic cardiac catheterization, right atrial pacing was performed at the rates of 60, 70, 80, 90, 100, 110, and 120/min. At each pacing rate, we measured the ET a total of 50 times by pressure pulse waves of the left ventricle and ascending aorta, the FPTG, and the d²FPTGᴅ. The ET determined from the FPTG or the d²FPTGᴅ correlated very closely with that obtained from invasive data. (2) Subjects were 22 patients with ischemic heart disease. Following intravenous nicardipine administration, the "c" wave height of the d²FPTGᴅ decreased, and the "d" wave height increased significantly. Conclusions : (1) Measurement of the ET using the d²FPTGᴅ is beneficial for noninvasive evaluation of cardiac systolic performance. (2) Heights of the "c" wave and the "d" wave of the d²FPTGᴅ are beneficial parameters for estimation of left ventricular afterload.