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: Left-ventricular dyssynchrony (LVD) adversely affects systolic performance and has not been previously evaluated in children with end-stage renal disease (ESRD). We hypothesized (1) that LVD in children with ESRD would be significantly increased compared with controls and (2) that volume load and left-ventricular hypertrophy (LVH) would be associated with increased LVD. This was a prospective observational study in which real-time three-dimensional echocardiographic data were acquired in 27 stable children with ESRD (13 peritoneal dialysis [PD] and 14 hemodialysis [HD]) and 29 normal controls. Data were acquired before and after an HD session. Dyssynchrony index (SDI) was defined per standard formulae and was normalized to cardiac cycle duration (SDIp). Left-ventricular mass (LVM) was obtained from M-mode echocardiography and was normalized to height(2.7) (LVM index). The mean age (13.8 vs. 11.3 years) and SDI, SDIp, LVM, and LVM index were significantly greater among children with ESRD than among controls (p < 0.05). Demographics and heart rates were comparable between HD and PD subgroups, whereas SDI 16 and 12 segments, SDIp 16 segments, and LVM were significantly greater in the HD group. SDI and SDIp 16 segments improved after an HD session (p < 0.05); LVM and LVM index remained unchanged. LVD was significantly greater in patients with LVH compared with those without LVH. Children with ESRD had significant LVD and increased LVM compared with controls. Increased LVD in those undergoing HD rather than PD, as well as the improvement in synchrony after HD, suggest that volume may modulate LVD. LVD was increased in children with LVH. LVD in children with ESRD may have pathogenic implications.Pediatric Cardiology 03/2012; 33(7):1124-30. · 1.20 Impact Factor
- Journal of cardiovascular ultrasound 12/2012; 20(4):172-3.
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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. · 4.65 Impact Factor