Document Detail

Cardiac output derived from left ventricular pressure during conductance catheter evaluations: an extended Modelflow method.
MedLine Citation:
PMID:  17541715     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: The Modelflow method computes cardiac output (CO) from arterial pressure (CO-MFao) by simulating a non-linear three-element Windkessel model of aortic input impedance. We present a novel technique to apply the Modelflow method to the left ventricular pressure (Plv) signal, to obtain an estimation of CO (CO-MFlv). METHODS: We extended the model by simulating the aortic valve as a resistance placed in series to the characteristic impedance. In our model the valve resistance is infinite in diastole, while it has a patient related value during systole. Twenty one patients with heart failure were studied with a combined pressure-conductance catheter positioned in the left ventricle and a micromanometer in the aorta. CO changes were induced during temporary sequential atrio-biventricular pacing with different atrio-ventricular and inter-ventricular intervals. After a single calibration we compared CO-MFlv with CO-MFao (516 measurement series) and with CO estimated by the conductance catheter volume technique (CO-cond) (267 series). RESULTS: CO ranged from 2.42 to 7.59 l/min with an overall mean of 4.36 (1.38) l/min. Comparing the two Modelflow methods, the bias was -0.04 (0.36) l/min, with limits of agreement of -0.77 and 0.70 l/min, and a coefficient of variation of 8.4%. Of the 516 changes in CO from baseline values, 112 were greater than 0.5 l/min and 110 of these (98%) were scored in the same direction by both methods. For comparisons between CO-MFlv and CO-cond the bias was -0.10 (0.49), with limits of agreement of -1.12 and 0.90 l/min, and a coefficient of variation of 12.5%. CONCLUSIONS: Cardiac output estimates by the modelflow method from aortic pressure and left ventricular pressure are interchangeable in patients without mitral and aortic abnormalities. After an initial calibration, CO-MFlv presents near zero bias and an adequate precision.
Sergio Valsecchi; Giovanni B Perego; Jan J Schreuder; Federica Censi; Jos R C Jansen
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Publication Detail:
Type:  Comparative Study; Journal Article     Date:  2007-06-01
Journal Detail:
Title:  Journal of clinical monitoring and computing     Volume:  21     ISSN:  1387-1307     ISO Abbreviation:  J Clin Monit Comput     Publication Date:  2007 Aug 
Date Detail:
Created Date:  2007-07-09     Completed Date:  2007-10-11     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  9806357     Medline TA:  J Clin Monit Comput     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  227-35     Citation Subset:  IM    
Medtronic Italia, Via Lucrezio Caro, Rome, Italy.
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MeSH Terms
Aged, 80 and over
Cardiac Output*
Heart Catheterization
Heart Failure / physiopathology
Heart Function Tests / methods*,  statistics & numerical data
Middle Aged
Models, Cardiovascular
Monitoring, Physiologic / methods*,  statistics & numerical data
Nonlinear Dynamics
Ventricular Function, Left*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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