HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 292/6/H2764    most recent 00540.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zhong, L. Articles by Kassab, G. S. Search for Related Content PubMed PubMed Citation Articles by Zhong, L. Articles by Kassab, G. S.

Validation of a novel noninvasive cardiac index of left ventricular contractility in patients

¹Department of Cardiology, National Heart Centre, ²Division of Engineering, Science, and Technology, University of New South Wales-Asia, and ³College of Engineering, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore; and Departments of ⁴Biomedical Engineering, ⁵Surgery, and ⁶Cellular and Integrative Physiology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana

Submitted 25 May 2006 ; accepted in final form 15 January 2007

Although there are several excellent indexes of myocardial contractility, they require accurate measurement of pressure via left ventricular (LV) catheterization. Here we validate a novel noninvasive contractility index that is dependent only on lumen and wall volume of the LV chamber in patients with normal and compromised LV ejection fraction (LVEF). By analysis of the myocardial chamber as a thick-walled sphere, LV contractility index can be expressed as maximum rate of change of pressure-normalized stress (d*/dt_max, where * = /P and and P are circumferential stress and pressure, respectively). To validate this parameter, d*/dt_max was determined from contrast cine-ventriculography-assessed LV cavity and myocardial volumes and compared with LVEF, dP/dt_max, maximum active elastance (E_a,max), and single-beat end-systolic elastance [E_es(SB)] in 30 patients undergoing clinically indicated LV catheterization. Patients with different tertiles of LVEF exhibit statistically significant differences in d*/dt_max. There was a significant correlation between d*/dt_max and dP/dt_max (d*/dt_max = 0.0075dP/dt_max – 4.70, r = 0.88, P < 0.01), E_a,max (d*/dt_max = 1.20E_a,max + 1.40, r = 0.89, P < 0.01), and E_es(SB) [d*/dt_max = 1.60E_es(SB) + 1.20, r = 0.88, P < 0.01]. In 30 additional individuals, we determined sensitivity of the parameter to changes in preload (intravenous saline infusion, n = 10 subjects), afterload (sublingual glyceryl trinitrate, n = 10 subjects), and increased contractility (intravenous dobutamine, n = 10 patients). We confirmed that the index is not dependent on load but is sensitive to changes in contractility. In conclusion, d*/dt_max is equivalent to dP/dt_max, E_a,max, and E_es(SB) as an index of myocardial contractility and appears to be load independent. In contrast to other measures of contractility, d*/dt_max can be assessed with noninvasive cardiac imaging and, thereby, should have more routine clinical applicability.

cardiac mechanics; ventricular elastance; ventriculography; wall stress

This article has been cited by other articles:

				L. Zhong, Y. Su, S.-Y. Yeo, R.-S. Tan, D. N. Ghista, and G. Kassab Left ventricular regional wall curvedness and wall stress in patients with ischemic dilated cardiomyopathy Am J Physiol Heart Circ Physiol, March 1, 2009; 296(3): H573 - H584. [Abstract] [Full Text] [PDF]