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Wang CH, Chang RW, Wu ET, Chang CY, Kao HL, Wu MS, Cheng YJ, Chen YS, Chang KC. Quantification of cardiac pumping mechanics in rats by using the elastance-resistance model based solely on the measured left ventricular pressure and cardiac output. Pflugers Arch 2019; 471:935-947. [PMID: 30904932 PMCID: PMC6591189 DOI: 10.1007/s00424-019-02270-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/28/2019] [Accepted: 03/01/2019] [Indexed: 11/28/2022]
Abstract
The cardiac pumping mechanics can be characterized by both the maximal systolic elastance (Emax) and theoretical maximum flow (Qmax), which are generated using an elastance–resistance model. The signals required to fit the elastance–resistance model are the simultaneously recorded left ventricular (LV) pressure and aortic flow (Qm), followed by the isovolumic LV pressure. In this study, we evaluated a single-beat estimation technique for determining the Emax and Qmax by using the elastance–resistance model based solely on the measured LV pressure and cardiac output. The isovolumic LV pressure was estimated from the measured LV pressure by using a non-linear least-squares approximation technique. The measured Qm was approximated by an unknown triangular flow (Qtri), which was generated by using a fourth-order derivative of the LV pressure. The Qtri scale was calibrated using the cardiac output. Values of EmaxtriQ and QmaxtriQ obtained using Qtri were compared with those of EmaxmQ and QmaxmQ obtained from the measured Qm. Healthy rats and rats with chronic kidney disease or diabetes mellitus were examined. We found that the LV Emax and Qmax can be approximately calculated using the assumed Qtri, and they strongly correlated with the corresponding values derived from Qm (P < 0.0001; n = 78): EmaxtriQ = 51.9133 + 0.8992 × EmaxmQ (r2 = 0.8257; P < 0.0001); QmaxtriQ = 2.4053 + 0.9767 × QmaxmQ (r2 = 0.7798; P < 0.0001). Our findings suggest that the proposed technique can be a useful tool for determining Emax and Qmax by using a single LV pressure pulse together with cardiac output.
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Affiliation(s)
- Chih-Hsien Wang
- Department of Surgery, National Taiwan University Hospital, No. 7, Chung-Shan S. Rd., Taipei, 100, Taiwan
| | - Ru-Wen Chang
- Department of Physiology, College of Medicine, National Taiwan University, No. 1, Sec. 1, Jen-Ai Road, Taipei, 100, Taiwan
| | - En-Ting Wu
- Department of Pediatrics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Taipei, 100, Taiwan
| | - Chun-Yi Chang
- Department of Emergency Medicine, Taipei Veterans General Hospital, Chu-Tung Branch, Hsin-Chu, 310, Taiwan
| | - Hsien-Li Kao
- Department of Internal Medicine, National Taiwan University Hospital, No. 7, Chung-Shan S. Rd., Taipei, 100, Taiwan
| | - Ming-Shiou Wu
- Department of Internal Medicine, National Taiwan University Hospital, No. 7, Chung-Shan S. Rd., Taipei, 100, Taiwan
| | - Ya-Jung Cheng
- Department of Anesthesiology, National Taiwan University Hospital, No. 7, Chung-Shan S. Rd., Taipei, 100, Taiwan
| | - Yih-Sharng Chen
- Department of Surgery, National Taiwan University Hospital, No. 7, Chung-Shan S. Rd., Taipei, 100, Taiwan
| | - Kuo-Chu Chang
- Department of Physiology, College of Medicine, National Taiwan University, No. 1, Sec. 1, Jen-Ai Road, Taipei, 100, Taiwan.
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Yeih DF, Lin LY, Yeh HI, Lai YJ, Chiang FT, Tseng CD, Chu SH, Tseng YZ. Temporal changes in cardiac force- and flow-generation capacity, loading conditions, and mechanical efficiency in streptozotocin-induced diabetic rats. Am J Physiol Heart Circ Physiol 2008; 294:H867-74. [DOI: 10.1152/ajpheart.00573.2007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Diabetes mellitus may result in impaired cardiac contractility, but the underlying mechanisms remain unclear. We aimed to investigate the temporal alterations in cardiac force- and flow-generation capacity and loading conditions as well as mechanical efficiency in the evolution of systolic dysfunction in streptozotocin (STZ)-induced diabetic rats. Adult male Wistar rats were randomized into control and STZ-induced diabetic groups. Invasive hemodynamic studies were done at 8, 16, and 22 wk post-STZ injection. Maximal systolic elastance (Emax) and maximum theoretical flow (Qmax) were assessed by curve-fitting techniques, and ventriculoarterial coupling and mechanical efficiency were assessed by a single-beat estimation technique. In contrast to early occurring and persistently depressed Emax, Qmax progressively increased with time but was decreased at 22 wk post-STZ injection, which temporally correlated with the changes in cardiac output. The favorable loading conditions enhanced stroke volume and Qmax, whereas ventriculoarterial uncoupling attenuated the cardiac mechanical efficiency in diabetic animals. The changes in Emax and Qmax are discordant during the progression of contractile dysfunction in the diabetic heart. In conclusion, our study showed that depressed Qmax and cardiac mechanical efficiency, occurring preceding overt systolic heart failure, are two major determinants of deteriorating cardiac performance in diabetic rats.
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Gupta MP. Factors controlling cardiac myosin-isoform shift during hypertrophy and heart failure. J Mol Cell Cardiol 2007; 43:388-403. [PMID: 17720186 PMCID: PMC2701247 DOI: 10.1016/j.yjmcc.2007.07.045] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2007] [Revised: 06/25/2007] [Accepted: 07/10/2007] [Indexed: 12/18/2022]
Abstract
Myosin is a molecular motor, which interacts with actin to convert the energy from ATP hydrolysis into mechanical work. In cardiac myocytes, two myosin isoforms are expressed and their relative distribution changes in different developmental and pathophysiologic conditions of the heart. It has been realized for a long time that a shift in myosin isoforms plays a major role in regulating myocardial contractile activity. With the recent evidence implicating that alteration in myosin isoform ratio may be eventually beneficial for the treatment of a stressed heart, a new interest has developed to find out ways of controlling the myosin isoform shift. This article reviews the published data describing the role of myosin isoforms in the heart and highlighting the importance of various factors shown to influence myosin isofrom shift during physiology and disease states of the heart.
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Affiliation(s)
- Mahesh P Gupta
- Department of Surgery, Basic Science Division, MC5040, University of Chicago, 5841 S. Maryland Avenue, Chicago, IL 60637, USA.
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