Medical Journal of Babylon

ORIGINAL ARTICLE
Year
: 2018  |  Volume : 15  |  Issue : 3  |  Page : 227--230

Interventricular mechanical dyssynchrony in dilated cardiomyopathy and its relation with left ventricular systolic dysfunction


Ahlam Kadhim Abbood1, Haider Jabar Al-Ghizzi2, Wissam S Tajuldin3,  
1 Department of Physiology, University of Babylon, College of Medicine, Babylon, Hillah, Iraq
2 Department of Internal Medicine, University of Babylon, College of Medicine, Babylon, Hillah, Iraq
3 Shaheed Al-Mihrab Center for Cardiac Catheterization, Babylon, Hillah, Iraq

Correspondence Address:
Ahlam Kadhim Abbood
Department of Physiology, College of Medicine, University of Babylon, Babylon, Hillah
Iraq

Abstract

Background: Heart failure (HF) is a major problem worldwide, and despite the optimal medical treatment, still it carries high mortality. Ventricular dyssynchrony among patient with HF portends poor prognosis. Aim of the Study: The aim is to evaluate the prevalence of interventricular dyssynchrony in patients with dilated cardiomyopathy (DCM) patients and its relation to underlying etiology and the severity of systolic dysfunction. Materials and Methods: Fifty-eight patients with ischemic and nonischemic cardiomyopathy (ICM and NCM) were included in this study. Inclusion criteria include Type II–IV New York Heart Association patients with ejection fraction (EF) <35%. Mechanical dyssynchrony (interventricular dyssynchrony) was assessed by pulsed Doppler. Assessment of left ventricular (LV) systolic function was by EF and stroke volume. Evaluation of the prevalence of mechanical indices in DCM and their relation to underlying etiology and severity of LV systolic dysfunction was done. Results: The prevalence of interventricular dyssynchrony was more in NCM than ICM. There was a nonsignificant negative correlation between this dyssynchrony and LV systolic parameters. Conclusion: Mechanical dyssynchrony indices were affected by the underlying etiology and severity of LV systolic dysfunction associated with the existence of the mechanical dyssynchrony.



How to cite this article:
Abbood AK, Al-Ghizzi HJ, Tajuldin WS. Interventricular mechanical dyssynchrony in dilated cardiomyopathy and its relation with left ventricular systolic dysfunction.Med J Babylon 2018;15:227-230


How to cite this URL:
Abbood AK, Al-Ghizzi HJ, Tajuldin WS. Interventricular mechanical dyssynchrony in dilated cardiomyopathy and its relation with left ventricular systolic dysfunction. Med J Babylon [serial online] 2018 [cited 2019 Sep 16 ];15:227-230
Available from: http://www.medjbabylon.org/text.asp?2018/15/3/227/242069


Full Text



 Introduction



One of the major problems that affect about 10% of the population (with age >65 years) is heart failure (HF).[1] Despite considerable progress in the medical treatment of HF, morbidity and mortality are still high with a bad prognosis in the presence of conduction abnormality.[2] This conduction abnormality leads to dyssynchrony, which is a common finding in severe HF patients.[3],[4],[5] Ventricular dyssynchrony among patients with HF portends poor prognosis [6] Ventricular dyssynchrony in these patients with HF, as a result of the left bundle branch block or interventricular conduction delays, leads to irregular ventricular activation which causes irregular wall motion with filling reduction [7] and reduction in cardiac output.[8]

 Materials and Methods



This study was performed in Marjan teaching hospital in Hilla city–Babylon province. From December 12, 2017, to April 25, 2018, 58 patients with ischemic and nonischemic cardiomyopathy (ICM and NCM), with mean age (63 ± 6, 52 ± 10.2, respectively), were recruited from Shaheed Al-Mihrab for cardiac catheterization and Marjan teaching hospital, after having their signed consent and approval from Ethical Committee at Babylon College of Medicine. Inclusion criteria include ICM and NCM patients with New York Heart Association functional Class II/IV HF and left ventricular (LV) ejection fraction (EF) ≤35%. ICM and NCM dilated cardiomyopathy (DCM) patients were categorized according to history (such as previous myocardial infarction, percutaneous transluminal coronary angioplasty, and coronary artery bypass graft surgery), electrocardiography (ECG) findings, echocardiographic study (distinguishing features of an ICM include a relatively greater degree of regional heterogeneity of systolic function often with areas of frank scar or aneurysm formation, and when either area of scar conforming to a well-defined coronary territory or LV aneurysm is noted, the likelihood of an ICM etiology is high).[9] Angiographic finding was recorded if coronary artery disease was defined as ≥50% stenosis of the left main coronary artery or ≥70% stenosis of one or more of the three major epicardial arteries.[10]

These patients were divided into two groups according to QRS width – patients with QRS duration ≥120 ms and those with QRS duration <120 ms.

The patients underwent complete resting conventional echocardiography by measuring as follows:

The EF by modified Simpson methodLV dimensions and end diastolic volume by parasternal long-axis and apical viewsMeasurement of the diameter of the LV outflow tract (LVOT) by parasternal long-axis view, and tracing aortic flow (apical five-chamber view with applying pulse Doppler on LVOT) to get velocity time integral (VTI). Measurement of the hemodynamic parameters was done according to the following equations:[11]

Stroke volume (SV) = 0.785 × D2 × VTI where D is the LVOT diameter and VTI is the velocity time integral.

Evaluation of mechanical dyssynchrony

Interventricular dyssynchrony can be assessed by measuring the time from the beginning of the QRS complex on the ECG to beginning of the pulmonary and aortic flow (by PW Doppler in parasternal short-axis and apical five-chamber views, respectively). If the difference between the onset of aortic and pulmonary flow is ≥40 ms, this means significant dyssynchrony and this is the cutoff value of interventricular dyssynchrony [12] [Figure 1].{Figure 1}

Statistical analysis

All values are expressed as mean ± standard deviation Data were analyzed by SPSS and Microsoft Excel. Categorical variables were analyzed by Chi-square test. The relation between different variables was done by Pearson's correlation coefficient.[13] P < 0.05 was considered statistically significant.

 Results



The demographic data, ECG, and conventional echocardiographic measurements were presented in [Table 1].{Table 1}

Percentage of interventricular mechanical delay (IVMD) evaluated by the difference between aortic pep and pulmonary pep is 48.2% in total patients (ICM and NCM). It is higher in NCM patients in comparison with ICM (50%, 47%, respectively) [Figure 2].{Figure 2}

Assessment of the association of interventricular dyssynchrony with underlying etiology (NCM versus ICM) was as follows: the Chi-square statistic is 4.228. The P = 039754. This result is significant at P < 0.05.

Correlation study of EF and IVMD of total (ICM and NCM) patients shows significant negative correlation (r = −0.38), at P < 0.05), [Figure 3].{Figure 3}

Correlation study of SV and IVMD of total (ICM and NCM) patients shows nonsignificant negative correlation (r = −0.23), at P < 0.05), [Figure 4].{Figure 4}

 Discussion



This study shows the high prevalence of interventricular dyssynchrony in DCM patients (48.2%) (NCM and ICM: 50% and 47%, respectively). These percentages are close to other studies, such as Anzouan-Kacou et al.,[14] where the prevalence of inter-VD was 47.5% in their study. It was significantly greater in NCM than in ICM, which means that etiology influences interventricular dyssynchrony occurrence, and this agreed with other studies such as Montazeri et al. study in 2011.[15] The relation of interventricular dyssynchrony with LV systolic function (demonstrated by EF and SV) was a negative correlation, and this results match the results of Kerwin et al. study in 2000[16] who concluded that the degree of interventricular dyssynchrony presented a significant negative correlation with the left ventricular ejection fraction (LVEF), but against panel Fauchier et al. 2002[17] who demonstrated an impairment of the cardiac function demonstrated by EF not correlated with interventricular dyssynchrony. The results of this study support the hypothesis that DCM with ventricular conduction delay is associated with significant ventricular contraction abnormalities and one level is the interventricular level.[16] The interventricular dyssynchrony is represented as an asymmetric right ventricular/LV phase pattern, and dyssynchrony at this level is related to the site of bundle branch block. Kerwin et al. 2002[16] concluded that the lowest LVEF, the worse interventricular dyssynchrony. Moreover, the degree of improvement in interventricular synchrony during cardiac resynchronization therapy (CRT) correlated significantly with improvements in LVEF. All these go with our finding of negative relation of this dyssynchrony and severity of LV systolic dysfunction. Cheuk-Man et al. (2010) suggested that interventricular dyssynchrony is the major factor associated with contractile diminishing and is affected by CRT.[18]

DCM is characterized by structural abnormalities of ventricular myocardium, disturbing both ventricular stimulation and mechanical contraction.[19],[20] The electrical stimulation of ventricular parts may be delayed subsequent to the pathological involvement of the ventricular conduction system or due to inhomogeneous spread of excitation wavefronts across the scarred tissue.[21] This alteration in cardiac structure and function results in regions of early and late contraction, which disrupts cardiac contraction and decreases pumping effectiveness.[22]

 Conclusion



The study concluded that mechanical dyssynchrony indices were affected by the underlying etiology and severity of LV systolic dysfunction associated with the existence of the mechanical dyssynchrony.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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