Change search
ReferencesLink to record
Permanent link

Direct link
Left ventricular twist is load-dependent
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
Dept of Anesthesiology and Perioperative Medicine, University hospital of Brussels. Belgium.
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.ORCID iD: 0000-0002-5325-2688
Show others and affiliations
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Background: Left ventricular rotation and twist can be assessed noninvasively by speckle tracking echocardiography. We sought to characterize the effects of acute load change and change in inotropic state on rotation parameters as a measure of LV contractility.

Methods: Seven anesthetised juvenile pigs were studied, using direct measurement of left ventricular (LV) pressure and volume and simultaneous transthoracic echocardiography. Transient inflation of an inferior vena cava balloon catheter (IVCBO) produced controlled load reduction.  First and last beats in the sequence of eight were analysed with speckle tracking (STE) during the load alteration and analysed for change in rotation/twist during controlled load alteration at same contractile status.  Two pharmacological inotropic interventions were also included to examine the same hypothesis in additionally conditions of increased and decreased myocardial contractility in each animal.

Results: The IVCBO load change compared for first to last beat resulted in LV twist increase (11.67° ±2.65° vs. 16.17° ±3.56° respectively, p < 0.004) during the load alteration and under adrenaline stimulation LV twist increase 12.56° ±5.1° vs. 16.57° ±4.6° (p < 0.013), and though increased, didn’t reach significance in nega­tive inotropic condition.  Untwisting rate increased significantly at baseline from    -41.7°/sec ±41.6°/sec vs. -122.6°/sec ±55.8°/sec (P < 0.039) and under adrenaline stimulation untwisting rate increased  (-55.3°/sec ±3.8°/sec vs.  -111.4°/sec ±24.0°/sec (p<0.05), but did not systematically changed in negative inotropic condition.

Conclusions: Peak systolic LV twist and peak early diastolic untwisting rate are load dependent.  Changes in LV load should be considered when interpreting  LV rotation/ twist.

Keyword [en]
echocardiography, ventricular function, rotation, torsion, load
URN: urn:nbn:se:umu:diva-43604OAI: diva2:414813
Available from: 2011-05-05 Created: 2011-05-04 Last updated: 2015-09-15Bibliographically approved
In thesis
1. Left ventricular function's relation to load, experimental studies in a porcine model
Open this publication in new window or tab >>Left ventricular function's relation to load, experimental studies in a porcine model
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Loading conditions are recognized to influence ventricular function according to the Starling relationship for length/stretch and force.  Many modern echocardiographic parameters which have been announced as describing ventricular function and contractile status, may be confounded by uncontrolled and unmeasured load.  These studies aimed to measure the relation between four differ­ent types of assessments of ventricular dysfunction and degrees of load.  Study examined the ‘myo­cardial performance index’ (MPI).  Study II examined long axis segmental mechanical dyssynchrony.  Study III examined tissue velocities, and Study IV examined ventricular twist.  All studies aimed to describe the relation of these parameters both to load and to inotropic changes.

Methods:  In anesthetized juvenile pigs, left ventricular (LV) pressure and volume were measured continuously and their relationship (LVPVR) was analysed.  Preload alterations were brought about by inflation of a balloon tipped catheter in the inferior vena cava (IVCBO).  Inotropic interventions were brought about by either an overdose of anesthetic (combine intravenous pentobarbital and inhaled isoflurane, Study I), or beta blocker and calcium channel blocker given in combination (Stud­ies III and IV).  In one study (II), global myocardial injury and dysfunction was induced by endotoxin infusion.  MPI measurements were derived from LVPVR heart cycle intervals for isovolumic contrac­tion and relaxation as well as ejection time.  Long axis segmental dyssynchrony was derived by ana­lyzing for internal flow and time with segmental dyssynchronous segment volume change during systole, hourly before and during 3 hours of endotoxin infusion.  Myocardial tissue velocities were measured during IVCBO at control, during positive and then later negative inotropic interventions.  The same for apical and base circumferential rotational velocities by speckle tracking.  Load markers (including end-diastolic volume) were identified for each beat, and the test parameters were analysed together with load for a relation.  The test parameters were also tested during single apneic beats for a relation to inotropic interventions.

Results: MPI demonstrated a strong and linear relationship to both preload and after-load, and this was due to changes in ejection time, and not the isovolumic intervals.  Long axis segmental dyssyn­chrony increased during each hour of endotoxin infusion and global myocardial injury.  This dysyn­chrony parameter was independent of load when tested by IVCBO. Peak systolic velocities were strongly load-independent, though not in all the inotropic situations and by all measurement axes.  Peak systolic strain was load-dependent, and not strongly related to inotropic conditions.  Peak sys­tolic LV twist and untwist were strongly load-dependent.

Conclusions: MPI is strongly load-dependent, and can vary widely in value for the same contractile status if the load is varied.  Mechanical dyssynchrony measures are load-independen in health and also in early global endotoxin myocardial injury and dysfunction.  Peak sytole velocities are a clinically robust parameter of LV regional and global performance under changing load, though peak systolic strain seems to be load-dependent.  Left ventricular twist and untwist are load-dependent in this pig model.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2011. 67 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1425
heart function, preload, afterload, contractility, myocardial tissue velocity, speckle tracking
National Category
Anesthesiology and Intensive Care
Research subject
urn:nbn:se:umu:diva-43605 (URN)978-91-7459-225-2 (ISBN)
Public defence
2011-05-27, Sal B, 9 tr, Tandläkarhögskolan, Norrlands Universitetssjukhus, Umeå, 13:00 (English)
Available from: 2011-05-06 Created: 2011-05-04 Last updated: 2011-05-09Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
A'roch, RomanGustafsson, UlfJohansson, GöranHaney, Michael
By organisation

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 57 hits
ReferencesLink to record
Permanent link

Direct link