| 1. |
- Gottfridsson, Peter, et al.
(författare)
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Global longitudinal strain: effects by load and autonomic nervous system expression
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: Intrathoracic pressure related to breathing or positive pressure ventilatory support has effects on venous return to the heart and transmyocardial pressures. In addition, autonomic nerve system activity affects cardiac inotropy, chronotropy, and loading. Knowledge of these physiological interactions is relevant when interpreting atrial and ventricular strain results as part of heart function assessment by echocardiography in patients with ventilatory support. Purpose: We aimed to assess 2-D global longitudinal strain (GLS%) for all four heart chambers (atria and ventricles) during controlled changes in intrathoracic pressure, as well as sympathetic nerve system activation. We hypothesized that GLS% is affected by both load and sympathetic tone. Methods: With ethical approval and participant consent, 20 healthy volunteers (medical students) performed a controlled Valsalva manoeuvre, a mask positive pressure inspiration (CPAP) manoeuvre (25 cm H2O) and a Hand Grip manoeuvre (squeezing a rolled towel with 75% of maximum force with one hand for 2 minutes). We monitored continuous blood pressure and heart rate (using a Finapres) during the manoeuvres to make sure that the manoeuvres caused the desired physiologic effects.GLS% of the individual chambers were measured before and during these manoeuvres using commercially available post- processing software, from the 4-chamber view. 2 different operators measured independently the GLS% for every manoeuvre. Paired measurement comparisons were performed (paired t test). Results: Both the Valsalva maneuverer and CPAP caused reductions in GLS % in all four chambers. The Hand Grip manoeuvre did not cause any change in GLS % in any chamber.Conclusion: Since both CPAP and late Valsalva causes a reduction in preload, we assume that a decrease in preload causes a reduction in GLS% in the heart chambers. Both Valsalva and Handgrip manoeuvres causes a raised sympathicus tone which does not seem to affect GLS% in any chamber. (In the Hand Grip manoeuvre there was a rise in blood pressure and pulse during the manoeuvre, as a sign of increased sympathetic tone.)From these preliminary findings, we conclude that for healthy young individuals GLS% appears to decrease in all chambers during Valsalva and CPAP, while no change in GLS% is caused by the Hand Grip manoeuvre.
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| 2. |
- Gottfridsson, Peter, et al.
(författare)
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Left atrial contraction strain and controlled preload alterations, a study in healthy individuals
- 2022
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Ingår i: Cardiovascular Ultrasound. - : BioMed Central. - 1476-7120. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In order to assess left atrial contractile function in disturbed circulatory conditions, it is necessary to have a clear understanding of how it behaves in a normal resting state with changes in loading conditions. However, currently the understanding of this relationship is incomplete. We hypothesize that in healthy individuals, left atrial contraction strain and its peak strain rate are increased or decreased by increasing or decreasing preload, respectively.METHODS: Controlled maneuvers used to change preload included continuous positive airway pressure by mask (CPAP 20 cmH2O) for preload decrease, and passive leg raise (15 degrees angle) for preload increase. Cardiac ultrasound 4-chamber views of the left atria and left ventricle were acquired at baseline and during maneuver. Acquired images were post processed and analyzed offline. Comparisons were made using paired t-test and means with 95% confidence interval.RESULTS: There were 38 participants, complete results were obtained from 23 in the CPAP maneuver and 27 in the passive leg raise maneuver. For the CPAP group, left atrial contraction strain was 11.6% (10.1 to 13.1) at baseline and 12.8% (11.0 to 14.6) during the maneuver (p = 0.16). Left atrial contraction peak strain rate was - 1.7 s- 1 (- 1.8 to - 1.5) at baseline and - 1.8 s- 1 (- 2.0 to - 1.6) during the maneuver (p = 0.29). For the passive leg raise-group, left atrial contraction strain was 10.1% (9.0 to 11.2) at baseline and 10.8% (9.4 to 12.3) during the maneuver (p = 0.28). Left atrial contraction peak strain rate was - 1.5 s- 1 (- 1.6 to - 1.4) at baseline and - 1.6 s- 1 (- 1.8 to - 1.5) during the maneuver (p = 0.29). Left atrial area, an indicator of preload, increased significantly during passive leg raise and decreased during CPAP.CONCLUSION: In healthy individuals, left atrial contraction strain and its peak strain rate seem to be preload-independent.TRIAL REGISTRATION: The study was 2018-02-19 registered at clinicaltrials.gov ( NCT03436030 ).
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| 3. |
- A'roch, Roman, 1959-
(författare)
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Left ventricular function's relation to load, experimental studies in a porcine model
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 4. |
- A'Roch, Roman, 1959-, et al.
(författare)
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Left ventricular mechanical dyssynchrony is load independent at rest and during endotoxaemia in a porcine model
- 2009
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Ingår i: Acta Physiologica. - : Wiley. - 1748-1708 .- 1748-1716. ; 196:4, s. 375-383
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Tidskriftsartikel (refereegranskat)abstract
- AIM: In diseased or injured states, the left ventricle displays higher degrees of mechanical dyssynchrony. We aimed at assessing mechanical dyssynchrony ranges in health related to variation in load as well as during acute endotoxin-induced ventricular injury. METHODS: In 16 juvenile anaesthetized pigs, a five-segment conductance catheter was placed in the left ventricle as well as a balloon-tipped catheter in the inferior vena cava. Mechanical dyssynchrony during systole, including dyssynchrony time in per cent during systole and internal flow fraction during systole, were measured at rest and during controlled pre-load reduction sequences, as well as during 3 h of endotoxin infusion (0.25 microg kg(-)1 h(-1)). RESULTS: Systolic dyssynchrony and internal flow fraction did not change during the course of acute beat-to-beat pre-load alteration. Endotoxin-produced acute pulmonary hypertension by left ventricular dyssynchrony measures was not changed during the early peak of pulmonary hypertension. Endotoxin ventricular injury led to progressive increases in systolic mechanical segmental dyssynchrony (7.9 +/- 1.2-13.0 +/- 1.3%) and ventricular systolic internal flow fraction (7.1 +/- 2.4-16.6 +/- 2.8%), respectively for baseline and then at hour 3. There was no localization of dyssynchrony changes to segment or region in the ventricular long axis during endotoxin infusion. CONCLUSION: These results suggest that systolic mechanical dyssynchrony measures may be load independent in health and during acute global ventricular injury by endotoxin. More study is needed to validate ranges in health and disease for parameters of mechanical dyssynchrony.
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| 5. |
- A'Roch, Roman, et al.
(författare)
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Left ventricular strain and peak systolic velocity : responses to controlled changes in load and contractility, explored in a porcine model
- 2012
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Ingår i: Cardiovascular Ultrasound. - : BioMed Central. - 1476-7120. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Tissue velocity echocardiography is increasingly used to evaluate global and regional cardiac function. Previous studies have suggested that the quantitative measurements obtained during ejection are reliable indices of contractility, though their load-sensitivity has been studied in different settings, but still remains a matter of controversy. We sought to characterize the effects of acute load change (both preload and afterload) and change in inotropic state on peak systolic velocity and strain as a measure of LV contractility.METHODS: Thirteen anesthetized juvenile pigs were studied, using direct measurement of left ventricular pressure and volume and transthoracic echocardiography. Transient inflation of a vena cava balloon catheter produced controlled load alterations. At least eight consecutive beats in the sequence were analyzed with tissue velocity echocardiography during the load alteration and analyzed for change in peak systolic velocities and strain during same contractile status with a controlled load alteration. Two pharmacological inotropic interventions were also included to generate several myocardial contractile conditions in each animal.RESULTS: Peak systolic velocities reflected the drug-induced changes in contractility in both radial and longitudinal axis. During the acute load change, the peak systolic velocities remain stable when derived from signal in the longitudinal axis and from the radial axis. The peak systolic velocity parameter demonstrated no strong relation to either load or inotropic intervention, that is, it remained unchanged when load was systematically and progressively varied (peak systolic velocity, longitudinal axis, control group beat 1- 5.72 +/- 1.36 with beat 8- 6.49 +/- 1.28 cm/sec, 95% confidence interval), with the single exception of the negative inotropic intervention group where peak systolic velocity decreased a small amount during load reduction (beat 1- 3.98 +/- 0.92 with beat 8- 2.72 +/- 0.89 cm/sec). Systolic strain, however, showed a clear degree of load-dependence.CONCLUSIONS: Peak systolic velocity appears to be load-independent as tested by beat-to-beat load reduction, while peak systolic strain appears to be load-dependent in this model. Peak systolic velocity, in a controlled experimental model where successive beats during load alteration are assessed, has a strong relation to contractility. Peak systolic velocity, but not peak strain rate, is largely independent of load, in this model. More study is needed to confirm this finding in the clinical setting.
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| 6. |
- A'roch, Roman, 1959-, et al.
(författare)
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Left ventricular twist is load-dependent
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 7. |
- A'Roch, Roman, et al.
(författare)
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Left ventricular twist is load-dependent as shown in a large animal model with controlled cardiac load
- 2012
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Ingår i: Cardiovascular Ultrasound. - : BioMed Central. - 1476-7120. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- 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 left ventricular (LV) contractility.METHODS: Seven anesthetised juvenile pigs were studied, using direct measurement of left ventricular pressure and volume and simultaneous transthoracic echocardiography. Transient inflation of an inferior vena cava balloon (IVCB) catheter 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. Paired comparisons were made for different load states using the Wilcoxon's Signed Rank test.RESULTS: The inferior vena cava balloon occlusion (IVCBO) load change compared for first to last beat resulted in LV twist increase (11.67degrees +/-2.65degrees vs. 16.17degrees +/-3.56degrees respectively, p < 0.004) during the load alteration and under adrenaline stimulation LV twist increase 12.56degrees +/-5.1degrees vs. 16.57degrees +/-4.6degrees (p < 0.013), and though increased, didn't reach significance in negative inotropic condition. Untwisting rate increased significantly at baseline from 41.7degrees/s +/-41.6degrees/s vs.122.6degrees/s +/-55.8degrees/s (P < 0.039) and under adrenaline stimulation untwisting rate increased (55.3degrees/s +/-3.8degrees/s vs.111.4degrees/s +/-24.0degrees/s (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. Differences in LV load should be included in the interpretation when serial measures of twist are compared.
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| 8. |
- A'roch, Roman, 1959-, et al.
(författare)
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Strain and peak systolic velocities : relation to load in a porcine model
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background: Tissue velocity echocardiography is increasingly used to evaluate global and regional cardiac function. Previous studies have suggested that the quantitative measurements obtained during ejection are reliable indices of contractility. Their load-sensitivity has been studied in different settings, but still remains a matter of controversy. We sought to characterize the effects of acute load change and change in inotropic state on peak systolic velocity and strain as a measure of LV contractility, and particularly to determine if these parameters were load-dependent. Methods: Thirteen anesthetised juvenile pigs were studied, using direct measurement of left ventricular (LV) pressure and volume and transthoracic echocardiography. Transient inflation of a vena cava balloon catheter produced controlled preload alterations. At least eight consecutive beats in the preload alteration sequence were analysed with tissue velocity echocardiography (TVE) during the preload alteration and analysed for change in peak systolic velocities (PSV) and strain (e) during same contractile status with a controlled preload alteration. Two pharmacological inotropic interventions were also included to generate several myocardial contractile conditions in each animal. Results: PSV reflected the drug-induced changes in contractility in both radial and longitudinal axis. During the acute load change, the PSV remain stable when derived from signal in the longitudinal axis and from the radial axis. The peak systolic velocity parameter demonstrated no strong relation to either load or inotropic intervention, that is, it remained unchanged when load was systematically and progressively varied. Peak systolic strain, however, showed a clear degree of load-dependence. Conclusion: Peak systolic velocity appears to be load-independent as tested by beat to beat load reduction, while peak systolic strain appears to be load-dependent in this model. Peak systolic velocity has a strong relation to contractility, independent of load, in serial measures, in this model. More study is needed to confirm this in the clinical setting.
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| 9. |
- Gottfridsson, Peter, et al.
(författare)
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Left atrial contraction strain during a Valsalva manoeuvre : A study in healthy humans
- 2023
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Ingår i: Clinical Physiology and Functional Imaging. - : John Wiley & Sons. - 1475-0961 .- 1475-097X. ; 43:3, s. 165-169
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cardiac mechanics are influenced by loading conditions as well as sympathetic tone. Left atrial (LA) contractile function assessed by two-dimensional (2D) strain has been described in the setting of controlled preload alterations; however, studies show conflicting findings about change or direction of change. We hypothesized that the controlled preload reduction and the sympathetic nervous system activation that occurs during a standardized Valsalva manoeuvre would bring about a change in LA contraction strain.aMETHODS: Healthy young adults of both sexes were recruited. Transthoracic echocardiographic ultrasound images were collected before and during a Valsalva manoeuvre. Standard imaging windows for LA strain assessment were used and the images were copied and stored for later offline analysis. These were assessed for adequate atrial wall visualization in 2D strain assessment. Paired comparisons were carried out using Student's T test.RESULT: Thirty-eight participants were included and there were 22 complete studies with paired pre- and during Valsalva manoeuvre. LA contraction strain at baseline was 10.5 ± 2.8% (standard deviation) and during the Valsalva manoeuvre 10.6 ± 4.6%, p = 0.86.CONCLUSION: The Valsalva manoeuvre, a combination of preload reduction and sympathetic nervous system activation, seems not to be associated with a change in LA contraction strain in healthy young individuals. LA contraction strain should be interpreted in the context of both atrial loading conditions and prevailing autonomic nervous system activity.
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| 10. |
- Gustafsson, Ulf, 1976-, et al.
(författare)
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The effect of acute myocardial ischemia on the rotation axis of the left ventricle
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: We have developed a method to assess the axis around which the left ventricle (LV) rotates. The aim was to assess the effect of acute regional ischemia on the otation axis. Method: Mid‐LAD occlusion was induced in six anesthetised pigs and echocardiographic images were recorded at baseline and after LAD occlusion. The rotation axis was calculated at three different levels of the LV throughout the cardiac cycle. Results: The direction of the rotation axis was significantly changed (p<0.01) after LAD occlusion, being directed towards the ischemic area. AV‐plane displacement was significantly reduced (p<0.05) during ischemia. No significant difference in twist or otation amplitudes was found. Conclusion: This new method of assessing rotational function seems as sensitive as AV‐plane displacement and superior to traditional rotation and twist parameters in detecting dysfunction in acute ischemic myocardium. The rotation axis method has the advantage of potentially identifying areas with dysfunction.
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