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- 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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| 2. |
- 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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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
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| 7. |
- Ricard, Jean-Damien, et al.
(författare)
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A European survey of nosocomial infection control and hospital-acquired pneumonia prevention practices
- 2012
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Ingår i: Journal of Infection. - : Elsevier BV. - 0163-4453 .- 1532-2742. ; 65:4, s. 285-291
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: We aimed to examine organizational, structural and routine infection control measures provided by European ICUs and staff practices in ventilator-associated pneumonia prevention in relation with current recommendations.Methods: European ICU staffs were invited to complete a web-based 20 closed-item questionnaire.Results: 675 nurses and 886 physicians from 13 countries answered the questionnaire. Median number of respondents per country was 118.0 (64.5-155.5). Availability and organizational aspects of infection control revealed wide variations between countries. Among them, single-patient rooms was the aspect with the lowest availability (median availability 38%), but the largest variation ranging from 15 to 84%. Self-reported median adherence rate to recommendations was 72% (34.5-83.0) with a strong correlation between nurses and physicians responses (r(2) = 0.96; p < 0.0001). Sub-glottic drainage (31%), and infrequent ventilatory-circuit change (24%) were the measures with the lowest adherence rate whereas preferential use of oral intubation (90%) and of NIV (84%) and use of HMEs (82%) were the three with the highest rate. Organization of infection control was consistently self-reported. Disparities among countries were more frequent for specific actions regarding airway management, and even moreso for controversial issues (subglottic drainage, closed-suction systems).Conclusion: This European survey shows a 72% overall adherence rate to VAP prevention measures; with strong agreements between physician and nurses but considerable differences among countries for availability and organization aspects of infection control, providing healthcare authorities with figures for future programs.
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