Regional Mechanical Dyssynchrony Research Articles

Regional mechanical dyssynchrony and shortened systole are present in people with Takotsubo syndrome

Background:Takotsubo syndrome is characterized by transient regional systolic dysfunction, left ventricular (LV) dilatation, and edema, often occurring without obstructive coronary artery disease. The mechanisms underlying this stress-induced condition, especially the role of mechanical dyssynchrony in affecting systolic function, remain poorly understood.Methods:In our study, we evaluated global LV function and mechanical dyssynchrony in 24 Takotsubo patients compared to 20 controls by analyzing pressure-volume loops and time-varying elastance. Additionally, we monitored changes in LV segmental volume and internal flow.Results:Here we show a significant reduction in global myocardial contractility and pronounced mechanical dyssynchrony in Takotsubo syndrome, particularly in the mid and apical LV segments, without disturbances in electrical conduction.Conclusions:Our findings reveal substantial mechanical dyssynchrony in Takotsubo patients, characterized by increased internal flow and a shortened systolic ejection time. This indicates a mechanical basis for the inefficient LV function in Takotsubo syndrome, independent of electrical conduction abnormalities.

Role of radionuclide assessment of global and regional mechanical dyssynchrony of the heart in prognosis of cardiac resynchronization therapy in patients with heart failure

Aim. To determine the prognostic significance of cardiac regional mechanical dyssynchrony (MD), assessed by radionuclide equilibrium ventriculography (REVG) in candidates for cardiac resynchronization therapy (CRT).Material and methods. The study included 65 patients with indications for CRT according to current guidelines. Prior to CRT, all patients underwent REVG to assess cardiac contractile function and MD. According to the phase analysis, indicators of global and regional cardiac MD were evaluated: phase standard deviation (PSD), histogram band width (HBW), entropy, and interventricular dyssynchrony. The regional assessment included an evaluation of phase histograms obtained from the analysis of the contraction of certain walls: left ventricular (LV) anterior, lateral, posterior wall, right ventricular (RV) free wall, and the interventricular septum. To evaluate the effectiveness of treatment 6 months after CRT, all patients underwent echocardiography, on the basis of which patients were divided into groups of responders and non-responders.Results. REVG revealed significant differences in the initial regional MD values between the groups of responders and non-responders: in responders, MD values of RV free wall (PSD: 39 (28-67) vs 28 (20-50), p=0,03) and LV anterior wall (PSD: 28,5 (16-40) vs 14 (11-24), p=0,0005) were higher, and the LV lateral wall was lower (PSD: 10 (7-14) vs 15 (9-26), p=0,007) than in non-responders. Multivariate logistic regression found following independent predictors of a positive response to CRT: heart failure of ischemic origin, LV HBW, RV free wall PSD, anterior wall PSD, LV lateral wall HBW (p<0,001). The sensitivity and specificity of the model was 93% and 91%, respectively.Conclusion. Regional MD scintigraphy parameters increase the predictive value of REVG in CRT candidates. The most informative in this regard are the PSD of RV free wall and LV anterior wall, as well as the HBW of LV lateral wall.

Myocardial perfusion imaging detects mechanical dyssynchrony in left ventricular infarcted and noninfarcted areas early after acute myocardial infarction in a porcine model.

Left ventricular mechanical dyssynchrony (LVMD) is closely associated with left ventricular dysfunction and poor prognosis in patients with acute myocardial infarction (AMI). However, whether mechanical dyssynchrony is present in the noninfarcted areas remains controversial. This research aimed to quantitatively evaluate the global and regional mechanical dyssynchrony early after AMI by phase analysis of single-photon emission computed tomography (SPECT) gated myocardial perfusion imaging (GMPI) and to further explore the related influencing factors. Of 11 Bama suckling pigs, eight animals were successfully subjected to left anterior descending artery occlusion by balloon to generate porcine AMI models and completed the study. SPECT GMPI was performed before AMI and at 1 day, 1 week, and 4 weeks after AMI. The global bandwidth (BW), SD, entropy, total perfusion deficit, summed rest score, regional BW, regional summed motion score, and regional summed thickening score were measured by SPECT GMPI. The global BW, SD, and entropy values significantly increased after AMI and showed no significant change among the three time points after AMI. The BW in the infarcted area (left anterior descending artery-dominated area) at 1 day, 1 week, and 4 weeks after AMI was significantly higher than that before AMI, as was the BW in the noninfarcted areas (left circumflex artery-dominated and right coronary artery-dominated areas), which revealed that there was less dyssynchrony in the noninfarcted areas than in the infarcted area at the three time points after AMI. The global BW was positively correlated with the scar burden measured by summed rest score (r=0.709-0.832, all P<0.05), whereas the regional BW in the noninfarcted areas after AMI showed moderate to good correlation with regional summed motion score (r=0.733-0.875, all P<0.05) and regional summed thickening score (r=0.713-0.889, all P<0.05). LVMD occurs early on the first day after AMI, with no significant worsening over the next 4 weeks. Mechanical dyssynchrony was present in both the infarcted and noninfarcted areas. The global LVMD is mainly influenced by the scar burden, and the regional mechanical dyssynchrony in the noninfarcted areas is closely associated with the abnormal regional wall thickening and motion, which are indicative of reduced myocardial contractility.

Method to create regional mechanical dyssynchrony maps from short‐axis cine steady‐state free‐precession images

PurposeTo develop a robust method to assess regional mechanical dyssynchrony from cine short‐axis MR images. Cardiac resynchronization therapy (CRT) is an effective treatment for patients with heart failure and evidence of left‐ventricular (LV) dyssynchrony. Patient response to CRT is greatest when the LV pacing lead is placed in the most dyssynchronous segment. Existing techniques for assessing regional dyssynchrony require difficult acquisition and/or postprocessing. Our goal was to develop a widely applicable and robust method to assess regional mechanical dyssynchrony.Materials and MethodsUsing the endocardial boundary, radial displacement curves (RDCs) were generated throughout the LV. Cross‐correlation was used to determine the delay time between each RDC and a patient‐specific reference. Delay times were projected onto the American Heart Association 17‐segment model creating a regional dyssynchrony map. Our method was tested in 10 normal individuals and 10 patients enrolled for CRT (QRS &gt; 120 ms, NYHA III‐IV, EF &lt; 35%).ResultsDelay times over the LV were 23.9 ± 33.8 ms and 93.1 ± 99.9 ms (P &lt; 0.001) in normal subjects and patients, respectively. Interobserver reproducibility for segment averages was 6.8 ± 39.3 ms and there was 70% agreement in identifying the latest contracting segment.ConclusionWe have developed a method that can reliably calculate regional delay times from cine steady‐state free‐precession (SSFP) images. Maps of regional dyssynchrony could be used to identify the latest‐contracting segment to assist in CRT lead implantation. J. Magn. Reson. Imaging 2014;39:958–965. © 2013 Wiley Periodicals, Inc.

The use of real-time three-dimensional echocardiography for assessing mechanical synchronicity

Background:Biventricular pacing (BIV) has been established as a credible adjuvant treatment for patients with moderate-to-severe systolic heart failure (class III-IV of the New York Heart Association (NYHA) classification) and left...

Early regional mechanical dyssynchrony induced by acute unipolar left ventricular pacing is unrelated to myocardial flow and metabolism

Early regional mechanical dyssynchrony induced by acute unipolar left ventricular pacing is unrelated to myocardial flow and metabolism

474 Role of regional mechanical dyssynchrony as determinant of functional mitral regurgitation in patients with left ventricular systolic dysfunction

474 Role of regional mechanical dyssynchrony as determinant of functional mitral regurgitation in patients with left ventricular systolic dysfunction

Global and regional parameters of dyssynchrony in ischemic and nonischemic cardiomyopathy

In this study, color tissue Doppler imaging was used to assess global and regional mechanical dyssynchrony in patients with ischemic cardiomyopathy and those with idiopathic dilated cardiomyopathy. Potential differences in the area of latest mechanical activation could have practical implications regarding lead positioning and the success rate of biventricular pacemaker implantation.