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The relation between mitral annulus motion and ejection fraction changes with age and heart size
Department of Clinical Physiology, Örebro Medical Centre Hospital, Sweden .
Department of Clinical Physiology, Örebro Medical Centre Hospital, Sweden .
2000 (English)In: Clinical Physiology, ISSN 0144-5979, E-ISSN 1365-2281, Vol. 20, no 1, 38-43 p.Article in journal (Refereed) Published
Abstract [en]

Mitral annulus motion (MAM) has recently been introduced as an index of left ventricular function. Several echocardiographic studies have shown good agreement between ejection fraction (EF) and MAM × 5, where MAM is the total mitral annulus motion, measured in mm, and EF is expressed as a percentage. This means that if MAM is used for estimation of left ventricular function, the conversion factor 5 is used, if the function is expressed as EF. In these studies, the mean age of the patients was over 60 years. The present study, including 102 patients, shows that in patients aged 20–40 years, the conversion factor is about 4·3, in patients aged 41–60 years it is about 4·6 and in patients aged 61–80 years it is about 5·0. It was also found that the ratio EF/MAM decreases with increasing height and left ventricular diameter, both variables closely connected to heart size. The results suggest that when MAM is used in assessment of left ventricular function, it is unwise to express the function in terms of EF. It is preferable to use MAM as a direct index of ventricular function, using reference values referred to aged and height. If the estimated function is expressed in terms of EF, different converting factors must be used depending on the age of the patients.

Place, publisher, year, edition, pages
2000. Vol. 20, no 1, 38-43 p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-26881DOI: 10.1046/j.1365-2281.2000.00221.xLocal ID: 11504OAI: oai:DiVA.org:liu-26881DiVA: diva2:247431
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2017-12-13Bibliographically approved
In thesis
1. Mitral annulus motion in left ventricular pumping
Open this publication in new window or tab >>Mitral annulus motion in left ventricular pumping
2001 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Mitralisringens rörelse under vänsterkammarens pumparbete
Abstract [en]

This thesis focus on the role of the mitral annulus motion (MAM) versus outer contour changes in the short axis, in left ventricular (LV) pumping. The influence of atrial contraction on LV dimensions and volumes and the relation between MAM and ejection fraction (EF) in sinus rhythm and in atrial fibrillation was also studied.

Echocardiography was used in all studies and in the study about circumflex artery motion angiography was also used.

In a study including 20 healthy adults the role of MAM, i.e. the systolic shortening of the left ventricle in the long axis, as the main mechanism of LV pumping was confirmed. There was also, however, a significant contribution to the stroke volume from an outer contour decrease in the short axis during systole. At the chordae tendineae level a cross sectional area decrease of 24% was measured. From calculations based on measures of the long axis shortening of the LV, the outer short axis diameter of the LV and calculated stroke volume, a mean systolic cross sectional area decrease of about 6% was found along the whole length of the ventricle. The higher cross-sectional area decrease at the chordae level is thougth to be caused by regional differences.

In previous studies the relation between EF and MAM has been assumed to be linear, but in a meta-analysis of 434 patients it was shown that the relation is non-linear and that a linear regression model overestimates EF in the low range of MAM. It was shown that the relation between EF and MAM in adults is influenced by age but only in the normal range of EF or MAM and not in patients with decreased EF (EF <0.5 or MAM < 10mm). The relation was also shown to be influenced by the LV wall thickness.

In 20 patients with atrial fibrillation the ratio EF/MAM was shown to be higher than in 20 age- and gender matched patients with sinus rhythm, due to a decrease in MAM, caused by the loss of atrial contraction.

The relation between EF and MAM is thus complex and it therefore seems logical not to "translate" MAM to EF. MAM should be used as such related to reference values in the assessment of LV systolic function.

In 13 patients who had atrial fibrillation the stroke volume was shown to increase after successful direct-current cardioversion due to an increase in long axis diastolic elongation of the LV and thereby increased diastolic volume, when atrial contraction was regained.

In 28 patients the angiographic measure of circumflex artery motion amplitude tended to be higher than MAM in the higher range of amplitudes while the opposite was found in the lower range of amplitudes.

In 13 patients with normal EF it was shown that the motion amplitude of a site epicardially at the most basal lateral part of the LV wall was significantly (P < 0.001) higher than endocardially, but in 13 patients with decreased EF (< 0.5) there was no significant difference between the two sites. The motion amplitude epicardially corresponds to the motion amplitude of the circumflex artery.

In the 13 patients with normal EF the motion amplitude of the closed mitral valves was significantly lower than the motion amplitude epi- and endocardially during systole, with a rather conic shape of the atrioventricular plane at the onset of systole. In end-systole the different parts of the left atrioventricular plane, the epicardial part, the endocardial part (mitral annulus) and the valves were almost on the same level.

Abstract [sv]

Den här avhandlingen fokuserar på den roll som mitralringsrörelsen (MRR), d v s vänster kammares (VK) förkortning i längsaxelriktning, och yttre konturforändringen i kortaxelriktning spelar under kammarens kontraktion. Förmakskontraktionernas inverkan på VK dimensioner och volymer samt relationen mellan MRR och ejektionsfraktion (EF) hos patienter med sinusrytm och förmaksflimmer studeras också.

Ekokardiografi (ultraljud av hjärtat) användes i alla studier och i studien om arteria cirkumflexas rörelse användes också angiografi (kranskärlsröntgen).

I ett delarbete med 20 friska vuxna bekräftas rollen av MRR, d v s den systoliska forkortningen av VK i längsaxeliktning, som den huvudsakliga mekanismen for VK:s pumparbete. I tillägg till detta finns dock ett signifikant bidrag till slagvolymen genom en forändring av den yttre konturen i kortaxelriktning under systole. På chordae tendineae nivå minskar tvärsnittsytan med ungefar 24% under systole. Genom beräkningar, som bygger på forkortningen av VK i längaxelriktning under systole, VK:s yttre kortaxel diameter och berälmad slagvolym, erhålls en systolisk minskning av tvärsnittsytan i medeltal på cirka 6% längs hela VK:s längd. Den större minskningen av tvärsnittsytan i höjd med chordae tendineae antas bero på regionala skillnader i ytterkonturen av VK under systole.

I tidigare studier harrelationen mellan EF och MRR antagits vara linjär, men i en metastudie med 434 patienter visas att relationen är icke-linjär och att en linjär regressionsmodell överskattar EF i det lägre intervallet av MRR. Det visas att relationen mellan EF och MRR hos vuxna påverkas av åldern i det normala intervallet av EF eller IviRR, men inte hos patienter med nedsatt EF (EF < 0.5 eller MRR < 10 mm). Det visas också att relationen mellan EF och MRR påverkas av VK:s väggtjocklek.

Hos 20 patientermed formaksflimmer visas att kvoten EF/MRR är högre än hos 20 ålders- och könsmatchade patienter med sinusrytm, beroende på en minskning av MRR genom förlusten av förmakskontraktionerna hos patienterna med förmaksflimmer.

Relationen mellan EF och MRR är sålunda komplex och det förefaller därför logiskt att inte "översätta" MRR till EF utan istället använda MRR som sådan i relation till referensvärden vid bedömning av V K: s systoliska funktion.

Hos 13 patientermed förmaksflimmervisas att slagvolymen ökar efter framgångsrik elkonvertering beroende på en ökad diastolisk förlängning av VIC och därigenom ökad diastolisk volym när förmakskontraktionerna återkommer.

Hos 28 patienter visas att de angiografiska måtten på cirkumflexans rörelseamplitud tenderar att vara högre än MRR i det högre intervallet av amplituder medan motsatsen gäller i det lägre intervallet av amplituder.

Hos 13 patienter med normal EF visas att rörelseamplituden for en punkt epikardiellt vid den mest basala laterala delen av VK-väggen är signifikant högre än endokardiet, men hos 13 patienter med nedsatt EF (< 0.5) är det ingen signifikant skillnad mellan de två mätställena. Den epikardiella rörelseamplituden motsvarar cirkumflexans rörelseamplitud.

Hos 13 patienter mednormal EF visas att rörelseamplituden för de stängda mitralldaffama under systele är signifikant lägre än rörelseamplituderna epi- och endokardiellt. Atrioventrikulärplanet intar en ganska konisk fmm i början av systole. Mot slutet av systele befinner sig de olika delarna av atrioventrikulärplanet, den epikardiella delen, den endokardiella delen (milralringen) och mitraiklaffama på nästan samma nivå.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2001. 53 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 661
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-27475 (URN)12129 (Local ID)91-7219-762-5 (ISBN)12129 (Archive number)12129 (OAI)
Public defence
2001-03-15, B-husets aula, Regionsjukhuset, Örebro, 10:00 (Swedish)
Opponent
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2012-09-04Bibliographically approved

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