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The effect of pressure afterload due to aortic coarctation on left ventricular function in children
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background:

Coarctation of the aorta (CoA) is a congenital heart disease which represents a narrowing of the proximal descending aorta, hence increasing pressure afterload to the left ventricle (LV). Conventional treatment of native CoA is surgical repair, however potential recurrence or other related complications e.g. aortic rupture, heart failure and cerebrovascular events are common. Thus, lifelong follow-up of these patients is required. Echocardiography is the most patient’s friendly method to evaluate CoA and in particular its effect on LV function. Moreover, the novel speckle tracking echocardiography (STE) is an important method to assess subclinical LV dysfunction, a technique that promises better evaluation of LV function in these patients.

The aims of this thesis were to review the literature on LV function in children with CoA using myocardial deformation imaging technologies, hence, to better understand the current knowledge and vagueness of the scientific evidence. We also aimed to study the effect of early CoA repair on the structure and function of LV and ascending aorta. In addition, we wished to establish in a meta-analysis format normal values of speckle tracking derived strain and strain rate values.

Methods:

Study 1. We have systematically searched the PubMed, and studies that fulfilled the inclusion criteria were critically analyzed and presented on a narrative form.

Study 2 and 3. In addition to conventional echocardiographic measures of LV and ascending aorta, we measured longitudinal strain and strain rate of the LV using a vendor independent software, TomTec. We have also measured the aorto-septal angle (AoSA). Data was compared with normal healthy controls.

Study 4. Electronic databases were systematically searched and suitable studies were meta analyzed using Comprehensive meta-analysis version 3 software.

Results:

Study 1. In 7/4945 included articles, 123 and 76 patients with congenital aortic stenosis (CAS) and CoA were reported, respectively. Normal conventional LV function, with subclinical myocardial dysfunction were reported in all studies before intervention. After intervention, a consistent improvement of myocardial deformation parameters was documented, even though not reaching normal values.

Study 2. In 21 patients with CoA, LV function significantly improved after intervention (p <0.001), however normal values were not reached even at medium-term follow-up (p = 0.002). Medium-term longitudinal strain correlated with pre intervention LV ejection faction (EF) (r = 0.58, p = 0.006). Medium-term subnormal values were more frequently associated with Bicuspid aortic valve (BAV) (33.3% vs. 66.6%; p <0.05).

Study 3. AoSA was abnormally wide before intervention, in particular at peak ejection in the descending aorta (p <0.0001), and correlated with CoA pressure gradient. After intervention, AoSA normalized and significantly correlated with the increase of LV cavity function and overall LV deformation parameters.

Study 4. In a meta-analysis of 28/282 studies including 1192 subjects, strain and strain rate values were established. Longitudinal strain normal mean values varied from -12.9 to -26.5 (mean, -20.5; 95 % CI, -20.0 to -21.0). Normal mean values of circumferential strain varied from -10.5 to -27.0 (mean, -22.06; 95 % CI, -21.5 to -22.5). Radial strain normal mean values varied from 24.9 to 62.1 (mean, 45.4; 95 % CI, 43.0 to 47.8). Meta-regression showed LV end-diastolic diameter as a significant determinant of variation of longitudinal strain. Longitudinal systolic strain rate was significantly determined by age and radial strain was influenced by the type of vendor used.

Conclusion:

The systematic review showed subclinical LV dysfunction in children with CoA before and after correction. However, since most of the patients were operated at an older age and had preserved LV EF, the effect of early intervention on LV function was only speculated. Our children with CoA who were operated at an earlier age showed LV subclinical dysfunction even at medium- term after intervention while the AoSA returned to normal shortly after intervention. Lower longitudinal strain values were found in patients with LV dysfunction (LV EF <50%) before intervention and BAV. Finally, normal range values for strain and strain rate have been established and seem to be influenced by patients’ age, LV end-diastolic diameter and vendor used.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet , 2016. , 97 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1864
Keyword [en]
Coarctation of the aorta, congenital aortic stenosis, left ventricle, myocardial deformation imaging, speckle tracking echocardiography, longitudinal strain, aorto-septal angle, children
National Category
Cardiac and Cardiovascular Systems
Research subject
Cardiology
Identifiers
URN: urn:nbn:se:umu:diva-128126ISBN: 978-91-7601-615-2OAI: oai:DiVA.org:umu-128126DiVA: diva2:1049236
Public defence
2016-12-21, Hörsal D Unod T 9, Umeå, 09:00 (English)
Opponent
Supervisors
Available from: 2016-11-30 Created: 2016-11-24 Last updated: 2016-11-29Bibliographically approved
List of papers
1. Left ventricular response to pressure afterload in children: aortic stenosis and coarctation A systematic review of the current evidence
Open this publication in new window or tab >>Left ventricular response to pressure afterload in children: aortic stenosis and coarctation A systematic review of the current evidence
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2015 (English)In: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 178, 203-209 p.Article, review/survey (Refereed) Published
Abstract [en]

Congenital aortic stenosis (CAS) and Coarctation of Aorta (CoA) represent two forms of pressure afterload that affect the left ventricle (LV), hence require regular echocardiographic monitoring. Subclinical dysfunction of the LV exists even in asymptomatic patients with preserved left ventricular ejection fraction (EF), implying low sensitivity of EF in predicting optimum time for intervention. In this article we review patterns of LV myocardial deformation before and after correction of CAS and CoA in infants, children and adolescents, showing their important role in monitoring the course of LV dysfunction. A systematic search using PubMed was performed and suitable studies are presented on a narrative form. Normal EF and/or fractional shortening (FS), with subclinical myocardial dysfunction are reported in all studies before intervention. The short-term results, after intervention, were related to the type of procedure, with no improvement or further deterioration related to surgery but immediate improvement after balloon intervention. Long term follow-up showed further improvement but still subnormal function. Thus correction of CAS and CoA before irreversible LV dysfunction is vital, and requires longitudinal studies in order to identify the most accurate parameter for function prognostication. Until then, conventional echocardiographic parameters together with myocardial velocities and deformation parameters should continue to provide follow-up reproducible measures of ventricular function.

Keyword
Congenital aortic stenosis, Coarctation of aorta, Left ventricle, Myocardial deformation imaging
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:umu:diva-98834 (URN)10.1016/j.ijcard.2014.10.089 (DOI)000345697300053 ()25464254 (PubMedID)
Available from: 2015-03-16 Created: 2015-01-27 Last updated: 2016-11-24Bibliographically approved
2. Persistent reduced myocardial deformation in neonates after CoA repair
Open this publication in new window or tab >>Persistent reduced myocardial deformation in neonates after CoA repair
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2016 (English)In: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 221, no 15, 886-891 p.Article in journal (Refereed) Published
Abstract [en]

INTRODUCTION: Surgical repair of coarctation of the aorta (CoA) is a safe procedure in children, however the condition is known for its potential recurrence and other related complications. The available evidence shows abnormal intrinsic properties of the aorta in CoA, thus suggesting additional effect, even after CoA repair, on left ventricular (LV) function. Accordingly, we sought to obtain a better understanding of LV myocardial mechanics in very early-corrected CoA using two-dimensional STE.

METHODS AND RESULTS: We retrospectively studied 21 patients with corrected CoA at a median age of 9 (2-53) days at three time points: 1) just before intervention, 2) at short-term follow-up and 3) at medium-term follow-up after intervention and compared them with normal values. Speckle tracking analysis was conducted via vendor independent software, Tomtec. After intervention, LV function significantly improved (from -12.8±3.9 to -16.7±1.7; p<0.001), however normal values were not reached even at medium term follow-up (-18.3±1.7 vs. -20±1.6; p=0.002). Medium term longitudinal strain correlated with pre intervention EF (r=0.58, p=0.006). Moreover, medium term subnormal values were more frequently associated with bicuspid aortic valve (33.3% vs. 66.6%; p<0.05).

CONCLUSION: LV myocardial function in neonates with CoA can be feasibly evaluated and followed up by speckle tracking echocardiography. LV subendocardial dysfunction however, remains in early infancy coarctation long after repair. Long-term follow-up through adulthood using myocardial deformation measurements should shed light on the natural history and consequences of this anomaly.

Place, publisher, year, edition, pages
Elsevier, 2016
Keyword
Coarctation of the aorta, Speckle tracking echocardiography, Longitudinal strain, Neonates, Children
National Category
Pediatrics Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:umu:diva-126952 (URN)10.1016/j.ijcard.2016.07.114 (DOI)000384692600169 ()27434366 (PubMedID)
Available from: 2016-10-24 Created: 2016-10-24 Last updated: 2016-11-24Bibliographically approved
3. Coarctation repair normalizes left ventricular function and aorto-septal angle in neonates
Open this publication in new window or tab >>Coarctation repair normalizes left ventricular function and aorto-septal angle in neonates
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(English)In: Congenital Heart Disease, ISSN 1747-079X, E-ISSN 1747-0803Article in journal (Refereed) In press
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:umu:diva-128146 (URN)
Available from: 2016-11-24 Created: 2016-11-24 Last updated: 2016-11-24
4. Normal ranges of left ventricular strain in children: a meta-analysis
Open this publication in new window or tab >>Normal ranges of left ventricular strain in children: a meta-analysis
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2015 (English)In: Cardiovascular Ultrasound, ISSN 1476-7120, E-ISSN 1476-7120, Vol. 13, 37Article, review/survey (Refereed) Published
Abstract [en]

Aims: The definition of normal values of two-dimensional speckle-tracking echocardiography derived left ventricular (LV) deformation parameters, is of critical importance for the routine application of this modality in children. The objectives of this study were to perform a meta-analysis of normal ranges for longitudinal, circumferential and radial strain/strain rate values and to identify confounders that may contribute to differences in reported measures. Methods and Results: A systematic search was conducted. Studies describing normal healthy subjects and observational studies that used control groups as a comparison were included. Data were combined using a random-effect model. Effects of demographic, clinical and equipment variables were assessed through meta-regression. The search identified 1,192 subjects form 28 articles. Longitudinal strain (LS) normal mean values varied from -12.9 to -26.5 (mean, -20.5; 95 % CI, -20.0 to -21.0). Normal mean values of circumferential strain (CS) varied from -10.5 to -27.0 (mean, -22.06; 95 % CI, -21.5 to -22.5). Radial strain (RS) normal mean values varied from 24.9 to 62.1 (mean, 45.4; 95 % CI, 43.0 to 47.8). Meta-regression showed LV end diastolic diameter as a significant determinant of variation for LS. Longitudinal systolic strain rate (LSRs) was significantly determined by the age and RS by the type of vendor used. Conclusion: Variations among different normal ranges were dependent on the vendor used, LV end-diastolic diameter and age. Vendor-independent software for analyzing myocardial deformation in children, using images from different vendors would be the ideal solution for strain measurements or else using the same system for patient's follow up.

Keyword
Strain, Echocardiography, Children, Left ventricle
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:umu:diva-107851 (URN)10.1186/s12947-015-0029-0 (DOI)000359041400001 ()26250696 (PubMedID)
Available from: 2015-10-13 Created: 2015-08-28 Last updated: 2016-11-24Bibliographically approved

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