Linked Life Data

19060125

Source:http://linkedlifedata.com/resource/pubmed/id/19060125

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2009-1-27
pubmed:abstractText
The time-varying elastance concept provides a comprehensive description of the intrinsic mechanical properties of the left ventricle that are assumed to be load independent. Based on pressure-volume measurements obtained with combined pressure conductance catheterization in six open-chest anesthetized sheep, we show that the time to reach end systole (defined as maximal elastance) is progressively prolonged for increasing ventricle pressures, which challenges the original (load-independent) time-varying elastance concept. Therefore, we developed a method that takes into account load dependency by normalization of time course of the four cardiac phases (isovolumic contraction, ejection, isovolumic relaxation, filling) individually. With this normalization, isophase lines are obtained that connect points in pressure-volume loops of different beats at the same relative time in each of the four cardiac phases, instead of isochrones that share points at the same time in a cardiac cycle. The results demonstrate that pressure curves can be predicted with higher accuracy, if elastance curves are estimated using isophase lines instead of using isochrones [root-mean-square error (RMSE): 3.8 +/- 1.0 vs. 14.0 +/- 7.4 mmHg (P < 0.001), and variance accounted for (VAF): 94.8 +/- 1.3 vs. 78.6 +/- 14.8% (P < 0.001)]. Similar results were found when the intercept volume was assumed to be time varying [RMSE: 1.7 +/- 0.3 vs. 13.4 +/- 7.4 mmHg (P < 0.001), and VAF: 97.4 +/- 0.5 vs. 81.8 +/- 15.5% (P < 0.001)]. In conclusion, phase-dependent time normalization reduces cardiac load dependency of timing and increases accuracy in estimating time-varying elastance.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0363-6135
pubmed:author
pubmed:issnType
Print
pubmed:volume
296
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
H342-9
pubmed:meshHeading
pubmed:year
2009
pubmed:articleTitle
Cardiac phase-dependent time normalization reduces load dependence of time-varying elastance.
pubmed:affiliation
Department of Pulmonary Diseases, VU University Medical Center, Amsterdam, The Netherlands. t.kind@vumc.nl
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't