Left atrial contraction strain during a Valsalva manoeuvre: A study in healthy humans.

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. METHODS: 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.

Left atrial contraction strain and controlled preload alterations, a study in healthy individuals.

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 ).

Can Doppler echocardiography estimate raised pulmonary capillary wedge pressure provoked by passive leg lifting in suspected heart failure?

AIMS: Non-invasive estimation of left ventricular filling pressure (LVFP) during stress is important for explaining exertional symptoms in patients with heart failure (HF). The aim of this study was to evaluate ability of Doppler echocardiographic measures of elevated LVFP with passive leg lifting (PLL) in patients with suspected HF. METHODS: Twenty-nine patients with clinical signs of HF who underwent simultaneous Doppler echocardiography and right heart catheterization (RHC) at rest and during PLL were consecutively investigated. Seventeen patients had normal PCWP (≤15 mmHg) at rest and during PLL and 12 with normal PCWP at rest but >15 mmHg with PLL. Conventional echo and 2D strain were used to assess early diastolic blood flow velocity (E), LV strain rate during early diastole (LVSRe), left atrial SR during atrial contraction (LASRa) and myocardial tissue Doppler velocities to assess lateral e' and further calculate E/e' and E/LVSRe and their relationship with PCWP, at rest and during PLL. RESULTS: Resting LAVI (ß = 0·45, P = 0·009) and LASRa (ß = -0·51, P = 0·004) were independently related to PCWP during PLL. Also, LASRa (ß = -0·77, P<0·001), E/e' (ß = 0·40, P = 0·04) and E/LVSRe (ß = 0·47, P = 0·021) during PLL correlated with PCWP during PLL. Multiple regression analysis identified E/LVSRe (ß = 0·46, P = 0·001) and LASRa (ß = -0·58, P = 0·002) during PLL as being independently associated with PCWP during PLL. CONCLUSION: Left atrial volume and myocardial contraction (LASRa) at rest both predict unstable LV filling pressures measured as raised PCWP when provoked by PLL. Furthermore, LASRa at PLL seems to have the strongest association to PCWP during PLL.

Left ventricular twist is load-dependent as shown in a large animal model with controlled cardiac load.

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 (11.67° ±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°/s ±41.6°/s vs.-122.6°/s ±55.8°/s (P < 0.039) and under adrenaline stimulation untwisting rate increased (-55.3°/s ±3.8°/s vs.-111.4°/s ±24.0°/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.

Left ventricular strain and peak systolic velocity: responses to controlled changes in load and contractility, explored in a porcine model.

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.