Impact of preload alteration on left ventricular mechanical dyssynchrony using tissue velocity imaging echocardiography.
ABSTRACT We lack full understanding on the determinants of left ventricular (LV) systolic mechanical dyssynchrony. We here tried to evaluate the effect of preload alterations on LV dyssynchrony using echocardiographic tissue velocity imaging.
Thirty-eight patients with a history of heart failure who were in sinus rhythm (24 men, mean age of 61 ± 12 years [range, 26-82]) were consecutively recruited. Twenty-four patients were allocated into a mild diastolic dysfunction group (Gr 1), and 14 to an advanced diastolic dysfunction group, which included pseudonormalization or restrictive mitral inflow patterns (Gr 2). The leg-raising maneuver was performed for 5 minutes in Gr 1, whereas two tablets (1.2 mg) of sublingual nitroglycerin (SLNG) were given to Gr 2 to manipulate preload status. An index representing LV systolic mechanical dyssynchony (DYSsys) was defined as the maximal differences in time intervals from the QRS onset to the systolic peak velocities in 4 basal segments derived from the apical four- and two-chamber views.
DYSsys decreased significantly after SLNG administration (74.2 ± 50.2 vs. 46.9 ± 34.8 ms, P < 0.01), whereas it showed a significant elevation after leg-raising maneuver (76.3 ± 33.5 vs. 88.8 ± 37.5 ms, P < 0.05). Maximal difference in DYSsys between before and after SLNG administration in a patient of Gr 2 was estimated to be 120.2, whereas with the leg-raising maneuver, maximal difference in DYSsys in a patient of Gr 1 was found to be 66.8. Changes in heart rate induced by preload manipulation did not display any association with changes in DYSsys.
DYSsys is significantly affected by preload alterations, and thus it can be considered a "dynamic" parameter that could be modified depending on the loading status. Therefore, loading status of individual patients should be considered when DYSsys is assessed.
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ABSTRACT: The purpose of this study was to investigate whether transcatheter renal sympathetic denervation (RSD) interfere with the development of left ventricular (LV) mechanical dyssynchrony during the progression of heart failure (HF). Nineteen beagles were randomly divided into sham-operated group (six dogs), control group (seven dogs), and RSD group (six dogs). Sham-operated group were implanted with pacemakers without pacing; Control group were implanted with pacemakers and underwent 3 weeks of rapid right ventricular pacing; and RSD group underwent catheter-based RSD bilaterally and were simultaneously implanted with pacemakers. Both LV strain and LV dyssynchrony were analyzed via 2D speckle-tracking strain echocardiography to evaluate LV function. Longitudinal dyssynchrony was determined as the standard deviation for time-to-peak speckle-tracking strain on apical 4- and 2-chamber views. Radial and circumferential dyssynchrony was determined as the standard deviation for time-to-peak speckle-tracking strain in mid- and base-LV short-axis views. Each myocardial function was also evaluated by averaging the peak systolic strains. LV systolic pressure (LVSP) and LV end-diastolic pressure (LVEDP) were measured. The LV interstitial fibrosis was determined by histological analysis. Plasma angiotensin II (Ang II), aldosterone and norepinephrine (NE) levels were also measured. After 3 weeks, all of the dogs in both the control and RSD groups showed greater LV end-diastolic volume compared with the sham-operated group; however, the dogs in the RSD group had a higher LV ejection fraction (LVEF) than the dogs in the control group (p<0.001). The LV systolic strains were higher in the RSD group than in the control group (p<0.001 for longitudinal, circumferential and radial strain, respectively). The levels of LV dyssynchrony were lower in the RSD group than in the control group (p<0.001 for longitudinal, circumferential and radial dyssynchrony, respectively). Compared with dogs with control alone, RSD dogs had lower LV end-diastolic pressures and less fibrous tissue. The levels of plasma Ang II, aldosterone and NE were lower in the RSD group than in the control group. RSD inhibites the development of left ventricular mechanical dyssynchrony during the progression of heart failure in dogs.Cardiovascular Ultrasound 11/2014; 12:47. DOI:10.1186/1476-7120-12-47 · 1.28 Impact Factor
Journal of cardiovascular ultrasound 12/2012; 20(4):172-3. DOI:10.4250/jcu.2012.20.4.172
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ABSTRACT: The relationship between myocardial electrical activation by electrocardiogram (ECG) and mechanical contraction by echocardiography in left bundle-branch block (LBBB) has never been clearly demonstrated. New strict criteria for LBBB based on a fundamental understanding of physiology have recently been independently published for both ECG and echocardiography. The relationship between the 2 modalities and the relation to cardiac resynchronization therapy (CRT) response was investigated. Sixty-six patients with LBBB by conventional criteria had a standard 12-lead ECG and 2-dimensional strain echocardiography performed before CRT implantation. Criteria for LBBB by echocardiography included early termination of contraction in one wall and prestretch and late contraction in opposing wall(s). New strict criteria by ECG included QRS duration ≥140 ms (men) or 130 ms (women), QS or rS in leads V1 and V2, and mid-QRS notching or slurring in ≥2 of leads V1, V2, V5, V6, I, and aVL. Response was defined as >15% decrease in left ventricular end-systolic volume after 6 months. In 64 of 66 patients, ECG analysis was possible. Echo and ECG readings for LBBB presence were concordant in 54 (84%) of 64. Thirty-seven (82%) of 45 patients with LBBB by strict ECG criteria responded to CRT, whereas only 4 (21%) of the 19 patients without LBBB responded (sensitivity 90% and specificity 65%). Thirty-six (95%) of 38 patients with concordance for the presence of LBBB responded to CRT. In patients with concordance for the absence of LBBB, 15 (94%) of 16 did not respond. For the first time, a close relation has been demonstrated between electrical activation by ECG and mechanical contraction by echocardiography. These findings may help identify CRT candidates.American heart journal 08/2013; 166(2):340-8. DOI:10.1016/j.ahj.2013.04.005 · 4.56 Impact Factor