Document Detail

Left ventricular energy in mitral regurgitation: a preliminary report.
MedLine Citation:
PMID:  1449435     Owner:  NLM     Status:  MEDLINE    
Energy exchange based on Newtonian principles is the most appropriate way to express the function of any pump--including the heart. Using information obtained at cardiac catheterisation, we have measured the total work energy (ET) of the left ventricle (LV) (mean 1.63 F) in patients with severe mitral regurgitation (mean regurgitant fraction 0.66). ET was approximately 84% above normal. Of the regurgitant energy (RE) (mean 0.95 F), on average , 3/4 (73.6%) was kinetic (KE) and 1/4 (23.4%) potential (PE). Both components represent wasted LV energy: the kinetic energy associated with turbulence lost as heat, the potential energy responsible for a rise in Left Atrial (LA) pressure. The amount of PE as a percentage of total regurgitant energy (RE) varied considerably from one patient to another (10.5% to 54.4%). Hence, colour flow mapping which detects only KE of turbulent jet flow must underestimate LV energy loss and, because of patient to patient variation, cannot consistently reflect severity of regurgitation. Measurements of PE correlate well with wedge P-wave height. Corresponding non-invasive estimates were made using sphygmodynamometer-calibrated indirect carotid pulse tracings and echocardiographic measurements. These were not significantly different from the invasive measurements. Unfortunately, the calculation of PE is indirect and involves subtraction, so that measurements for individual patients were not accurate enough for clinical use. Part of the non-invasive calculation involved an estimate of left atrial pressure based on the blood pressure measurement and Doppler velocity of regurgitation; this should be a useful measurement in itself.(ABSTRACT TRUNCATED AT 250 WORDS)
A I MacIsaac; I G McDonald; R L Kirsner; S A Graham; D Tanzer
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Australian and New Zealand journal of medicine     Volume:  22     ISSN:  0004-8291     ISO Abbreviation:  Aust N Z J Med     Publication Date:  1992 Oct 
Date Detail:
Created Date:  1992-12-30     Completed Date:  1992-12-30     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  1264322     Medline TA:  Aust N Z J Med     Country:  AUSTRALIA    
Other Details:
Languages:  eng     Pagination:  532-40     Citation Subset:  IM    
Cardiac Investigation Unit, St Vincent's Hospital, Melbourne, Vic., Australia.
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MeSH Terms
Energy Metabolism*
Heart Catheterization
Image Processing, Computer-Assisted
Middle Aged
Mitral Valve Insufficiency / physiopathology*
Ventricular Function, Left*

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