Quantification of contractile mechanics in the rat heart from ventricular pressure alone
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Chih-Hsien Wang1,2, Ru-Wen Chang3, Chun-Yi Chang4, Ming-Shiou Wu5, Hsien-Li Kao5, Liang-Chuan Lai3, Tai-Horng Young6, Hsi-Yu Yu1, Yih-Sharng Chen1 and Kuo-Chu Chang3
1Department of Surgery, National Taiwan University Hospital, Taipei 100, Taiwan
2Department of Surgery, National Taiwan University Hospital, Hsinchu Branch, Hsinchu 300, Taiwan
3Department of Physiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
4Department of Emergency Medicine, Taipei Veterans General Hospital, Chu-Tung Branch, Hsinchu 310, Taiwan
5Department of Internal Medicine, National Taiwan University Hospital, Taipei 100, Taiwan
6Institute of Biomedical Engineering, College of Medicine and Engineering, National Taiwan University, Taipei 100, Taiwan
Kuo-Chu Chang, email: email@example.com
Keywords: cardiac contractility; pressure-ejected volume curve; end-systolic elastance; left ventricular pressure; triangular aortic flow
Received: June 20, 2017 Accepted: September 23, 2017 Published: October 10, 2017
To quantitate the contractile mechanics of the heart, the ventricle is considered an elastic chamber with known end-systolic elastance (Ees). Ees can be calculated from a single pressure-ejected volume curve, which requires simultaneous records of left ventricular (LV) pressure and the aortic flow (Qm). In clinical settings, it is helpful to evaluate patients’ cardiac contractile status by using a minimally invasive approach to physiological signal monitoring, wherever possible, such as by using LV pressure alone. In this study, we evaluated a method for determining Ees on the basis of the measured LV pressure and an assumed aortic flow with a triangular wave shape (Qtri). Qtri was derived using a fourth-order derivative of the LV pressure to approximate its corresponding Qm. Values of EestriQ obtained using Qtri were compared with those of EesmQ obtained from the measured Qm. Healthy rats (NC; n = 28) and rats with type 1 diabetes (DM; n = 26) and chronic kidney disease (CKD; n = 20) were examined. The cardiodynamic conditions in both the DM and CKD groups were characterized by a decline in EesmQ and EestriQ. A significant regression line for Ees was observed (P < 0.0001): EestriQ = 2.6214 + 1.0209 × EesmQ (r2 = 0.9870; n = 74). Our finding indicates that the systolic pumping mechanics of the heart can be derived from a single LV pressure recording together with the assumed Qtri.
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