Publications by authors named "Kan N Hor"

49 Publications

Feature-tracking cardiovascular magnetic resonance as a novel technique for the assessment of mechanical dyssynchrony.

Int J Cardiol 2014 Jul 9;175(1):120-5. Epub 2014 May 9.

Department of Cardiology, The Queen Elizabeth Hospital Birmingham, Mindelsohn Way, Edgbaston, Birmingham, B15 2WB, United Kingdom; Centre for Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom. Electronic address:

Background: Myocardial tagging using cardiovascular magnetic resonance (CMR) is the gold-standard for the assessment of myocardial mechanics. Feature-tracking cardiovascular magnetic resonance (FT-CMR) has been validated against myocardial tagging. We explore the potential of FT-CMR in the assessment of mechanical dyssynchrony, with reference to patients with cardiomyopathy and healthy controls.

Methods: Healthy controls (n=55, age: 42.9 ± 13 yrs, LVEF: 70 ± 5%, QRS: 88 ± 9 ms) and patients with cardiomyopathy (n=108, age: 64.7 ± 12 yrs, LVEF: 29 ± 6%, QRS: 147 ± 29 ms) underwent FT-CMR for the assessment of the circumferential (CURE) and radial (RURE) uniformity ratio estimate based on myocardial strain (both CURE and RURE: 0 to 1; 1=perfect synchrony)

Results: CURE (0.79 ± 0.14 vs. 0.97 ± 0.02) and RURE (0.71 ± 0.14 vs. 0.91 ± 0.04) were lower in patients with cardiomyopathy than in healthy controls (both p<0.0001). CURE (area under the receiver-operator characteristic curve [AUC]: 0.96), RURE (AUC: 0.96) and an average of these (CURE:RUREAVG, AUC: 0.98) had an excellent ability to discriminate between patients with cardiomyopathy and controls (sensitivity 90%; specificity 98% at a cut-off of 0.89). The time taken for semi-automatically tracking myocardial borders was 5.9 ± 1.4 min.

Conclusion: Dyssynchrony measures derived from FT-CMR, such as CURE and RURE, provide almost absolute discrimination between patients with cardiomyopathy and healthy controls. The rapid acquisition of these measures, which does not require specialized CMR sequences, has potential for the assessment of mechanical dyssynchrony in clinical practice.
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http://dx.doi.org/10.1016/j.ijcard.2014.04.268DOI Listing
July 2014

Prevalence and distribution of late gadolinium enhancement in a large population of patients with Duchenne muscular dystrophy: effect of age and left ventricular systolic function.

J Cardiovasc Magn Reson 2013 Dec 21;15:107. Epub 2013 Dec 21.

Nationwide Children's Hospital, Columbus, OH, USA.

Background: Duchenne muscular dystrophy (DMD), an X-linked disorder affects approximately 1 in 5000 males, is universally associated with heart disease. We previously identified myocardial disease by late gadolinium enhancement (LGE) in DMD subjects at various stages of disease, but the true prevalence is unclear. Cardiovascular magnetic resonance (CMR) is well established for both assessment of ventricular function and myocardial fibrosis by LGE. We sought to establish i) prevalence and distribution of LGE in a large DMD population and ii) relationship among LGE, age, LVEF by CMR and current living status.

Methods: Current living status, demographic and CMR data including ventricular volumes, LVEF and LGE from 314 DMD patients undergoing evaluation at a single large tertiary referral center were analyzed.

Results: 113 of 314 (36%) of DMD subjects showed LGE positivity with prevalence increasing from 17% of patients <10 years to 34% of those aged 10-15 years and 59% of those >15 years-old. Patients with LVEF ≥55% were LGE positive in 30% of cases; this increased to 84% for LVEF <55%. LGE was more prevalent in the free wall (531/1243, 42.7%) vs. septal segments (30/565, 5.3%). Patients with septal involvement were significantly older and had lower LVEF than those with isolated free wall LGE. Ten percent (11/113) patients who had LGE died 10.8 months after CMR. Only one patient from the LGE negative group died. Patients who died had higher heart rate, larger left ventricular volume and mass, greater number of positive LGE segment and increase incident of septal LGE compared to those who remained alive.

Conclusion: In DMD patients, LGE occurs early, is progressive and increases with both age and decreasing LVEF. Segmentally, the incidence of the number of positive LGE segments increase with age and lower LVEF. Older patients and those who died during the study period had more septal LGE involvement. The current studies suggest that the time course and distribution of LGE-positivity may be an important clinical biomarker to aid in the management of DMD-associated cardiac disease.
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http://dx.doi.org/10.1186/1532-429X-15-107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3896985PMC
December 2013

Comparison of area-length method by echocardiography versus full-volume quantification by cardiac magnetic resonance imaging for the assessment of left atrial volumes in children, adolescents, and young adults.

Pediatr Cardiol 2014 Apr 17;35(4):645-51. Epub 2013 Nov 17.

The Heart Institute, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue MLC 2003, Cincinnati, OH, 45229-3039, USA,

Left atrial (LA) size is a known predictor of adverse cardiovascular events. Echocardiography is the modality of choice for the evaluation of atrial size; however, cardiac magnetic resonance imaging (cMRI) remains the "gold standard." We sought to calculate atrial volumes using the area-length method by both echocardiography and cMRI and compare them with area-volume quantification by cMRI. Thiry-eight patients (mean age 20 ± 12 years, 71% male) who underwent cMRI and echocardiography between September 2010 and June 2012 were retrospectively identified. The time interval between the two studies was ≤ 6 months. LA volumes by echocardiogram were estimated using the area-length method: LA volume = (0.85 × area(4ch) × area(2ch))/(shortest atrial length). The atrial length and area were measured in standard apical two-chamber and four-chamber planes. Measured values were indexed to body surface area (BSA). CMRI measurements were obtained from prospectively gated steady-state free precession cine stack images obtained in a standard four-chamber plane. LA volumes were calculated using Simpson's method: LA volume = LA area × (slice thickness + gap) per slice. Slice thickness ranged from 5 to 7 mm with contiguous slices of 5 to 7 mm. The values were indexed to BSA. Statistics were summarized using measures of central tendency. LA volumes by echocardiography were significantly less than those by full-volume cMRI quantification. The mean LA volume by echocardiography and full-volume cMRI were 35 ± 14.5 and 42.4 ± 17.2, respectively (p = 0.05). The mean difference between LA volumes obtained by the two methods was 7.4 ± 10.6. LA volume measured by cMRI using the area-length method closely approximated full-volume assessment by cMRI with mean values of 42.9 ± 17.4 versus 42.4 ± 17.2, respectively (p = 0.91). There were no significant differences in the patient characteristics between the two study modalities. LA volumes as measured by echocardiography using the area-length method consistently underestimated the true volume when compared with cMRI. LA volumes measured using the area-length method by cMRI is an alternative technique for accurately quantifying chamber size and can be useful in decreasing scan time or when full-volume data sets are incomplete.
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http://dx.doi.org/10.1007/s00246-013-0833-yDOI Listing
April 2014

Occult cardiotoxicity in childhood cancer survivors exposed to anthracycline therapy.

Circ Cardiovasc Imaging 2013 Nov 4;6(6):873-80. Epub 2013 Oct 4.

Department of Pediatrics, Division of Pediatric Cardiology and Radiology.

Background: More than 50% of >270 000 childhood cancer survivors in the United States have been treated with anthracyclines and are therefore at risk of developing cardiotoxicity. Cardiac magnetic resonance (CMR) has demonstrated utility to detect diffuse interstitial fibrosis and changes in regional myocardial function. We hypothesized that CMR would identify occult cardiotoxicity characterized by structural and functional myocardial abnormalities in a cohort of asymptomatic pediatric cancer survivors with normal global systolic function.

Methods And Results: Forty-six long-term childhood cancer survivors with a cumulative anthracycline dose ≥200 mg/m(2) and normal systolic function were studied 2.5 to 26.9 years after anthracycline exposure. Subjects underwent transthoracic echocardiography, CMR with routine cine acquisition, tissue characterization, and left ventricular strain analysis using a modified 16-segment model. Extracellular volume was measured in 27 subjects, all of whom were late gadolinium enhancement negative. End-systolic fiber stress was elevated in 45 of 46 subjects. Low average circumferential strain magnitude (εcc) -14.9±1.4; P<0.001, longitudinal strain magnitude (εll) -13.5±1.9; P<0.001, and regional peak circumferential strain were seen in multiple myocardial segments, despite normal global systolic function by transthoracic echocardiography and CMR. The mean T1 values of the myocardium were significantly lower than that of control subjects at 20 minutes (458±69 versus 487±44 milliseconds; P=0.01). Higher mean extracellular volume was observed in female subjects (0.34 versus 0.22; P=0.01).

Conclusions: Asymptomatic postchemotherapy pediatric patients have abnormal myocardial characteristics and strain parameters by CMR despite normal global cardiac function by standard transthoracic echocardiography and CMR measures.
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http://dx.doi.org/10.1161/CIRCIMAGING.113.000798DOI Listing
November 2013

Non-invasive evaluation of energy loss in the pulmonary arteries using 4D phase contrast MR measurement: a proof of concept.

Biomed Eng Online 2013 Sep 23;12:93. Epub 2013 Sep 23.

Mechanical Engineering, School of Dynamics Systems, University of Cincinnati, 593 Rhodes Hall, ML 0072, Cincinnati, OH 45221, USA.

Background: The repair surgery of congenital heart disease (CHD) associated with the right ventricular (RV)-pulmonary artery (PA) pathophysiology often left patients with critical post-operative lesions, leading to regurgitation and obstruction in the PAs. These lesions need longitudinal (with time) assessment for monitoring the RV function, in order for patients to have appropriate treatment before irreversible RV dysfunction occurs. In this research, we computed energy loss in the branch PAs using blood flow and pressure drop data obtained from 4D phase contrast (PC) MRI, to non-invasively quantify the RV-PA pathophysiology.

Methods: 4D PC MRI was acquired for a CHD patient with abnormal RV-PA physiology, including pulmonary regurgitation and PA stenosis, and a subject with normal RV-PA physiology. The blood velocity, flow rate, and pressure drop data, obtained from 4D PC MRI, were used to compute and compare the energy loss values between the patient and normal subjects.

Results: The pressure drop in the branch PAs for the patient was -1.3 mmHg/s and -0.2 mmHg/s for the RPA and LPA, respectively, and was larger (one order of magnitude) than that for the control. Similarly, the total energy loss in the branch PAs for the patient, -96.9 mJ/s and -16.4 mJ/s, for the RPA and LPA, respectively, was larger than that for the control.

Conclusions: The amount of energy loss in the pulmonary blood flow for the patient was considerably larger than the normal subject due to PA regurgitation and PA stenosis. Thus, we believe that the status of RV-PA pathophysiology for CHD patients can be evaluated non-invasively using energy loss endpoint.
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http://dx.doi.org/10.1186/1475-925X-12-93DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3849381PMC
September 2013

Left ventricular noncompaction in Duchenne muscular dystrophy.

J Cardiovasc Magn Reson 2013 Aug 1;15:67. Epub 2013 Aug 1.

Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.

Background: Left ventricular noncompaction (LVNC) describes deep trabeculations in the left ventricular (LV) endocardium and a thinned epicardium. LVNC is seen both as a primary cardiomyopathy and as a secondary finding in other syndromes affecting the myocardium such as neuromuscular disorders. The objective of this study is to define the prevalence of LVNC in the Duchenne Muscular Dystrophy (DMD) population and characterize its relationship to global LV function.

Methods: Cardiac magnetic resonance (CMR) was used to assess ventricular morphology and function in 151 subjects: DMD with ejection fraction (EF) > 55% (n = 66), DMD with EF < 55% (n = 30), primary LVNC (n = 15) and normal controls (n = 40). The non-compacted to compacted (NC/C) ratio was measured in each of the 16 standard myocardial segments. LVNC was defined as a diastolic NC/C ratio > 2.3 for any segment.

Results: LVNC criteria were met by 27/96 DMD patients (prevalence of 28%): 11 had an EF > 55% (prevalence of 16.7%), and 16 had an EF < 55% (prevalence of 53.3%). The median maximum NC/C ratio was 1.8 for DMD with EF > 55%, 2.46 for DMD with EF < 55%, 1.54 for the normal subjects, and 3.69 for primary LVNC patients. Longitudinal data for 78 of the DMD boys demonstrated a mean rate of change in NC/C ratio per year of +0.36.

Conclusion: The high prevalence of LVNC in DMD is associated with decreased LV systolic function that develops over time and may represent muscular degeneration versus compensatory remodeling.
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http://dx.doi.org/10.1186/1532-429X-15-67DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3750745PMC
August 2013

Abnormal circumferential strain is present in young Duchenne muscular dystrophy patients.

Pediatr Cardiol 2013 Jun 29;34(5):1159-65. Epub 2013 Jan 29.

Division of Pediatric Cardiology, The Heart Institute, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, MLC 2003, Cincinnati, OH 45229-3039, USA.

Advances in management of non-cardiac issues in Duchenne muscular dystrophy (DMD) have improved such that DMD-associated cardiac disease has become the leading cause of death for such patients. Cardiac dysfunction measured by standard transthoracic echocardiographic methods, e.g., fractional shortening (FS) and ejection fraction (EF), is rarely present during the first decade of life. The current study used transthoracic echocardiogram (TTE) to assess strain (ε), an indicator of regional ventricular function, in young DMD patients. A retrospective review of the TTE database was performed. TTE results from DMD patients <8 years (n = 63) performed during 2009 to 2010 were compared with TTE results from an unaffected control group (n = 61). Feature tracking analysis software was used to measure total circumferential strain (ε cc) as well as segmental ε cc based on the American Society of Echocardiography 16-segment model. Although there were no differences in FS, the absolute value for left-ventricular (LV) ε cc at the mid-chamber level was decreased in DMD (-21.7 % ± 3.8 % vs. -19.8 % ± 4.2 %, p < 0.01; unaffected vs. DMD). Segmental ε(cc) was similarly affected in the anteroseptal segment (-23.0 % ± 6.1 % vs. -18.9 % ± 7.0 %, p = 0.001; controls vs. DMD), the inferior segment (-20.7 % ± 5.16 % vs. -17.7 % ± 6.1 %, p = 0.003; controls vs. DMD), and the inferolateral segment (-18.3 % ± 6.2 % vs. -15.9 % ± 6.7 %, p = 0.04; controls vs. DMD). In the present study we demonstrate both total and segmental LV ε cc (anteroseptal, inferior, and inferolateral segments) abnormalities at the mid-chamber level in a large group of young DMD patients with normal FS. These novel findings substantiate that the disease process is present and results in abnormal myocardial function before standard measures detect global dysfunction.
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http://dx.doi.org/10.1007/s00246-012-0622-zDOI Listing
June 2013

Growth hormone treatment in boys with Duchenne muscular dystrophy and glucocorticoid-induced growth failure.

Neuromuscul Disord 2012 Dec 8;22(12):1046-56. Epub 2012 Sep 8.

Division of Endocrinology, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH 45229, USA.

This study evaluated efficacy and safety of growth hormone treatment in Duchenne muscular dystrophy boys with glucocorticoid-induced growth failure. We reviewed 39 consecutive boys (average age 11.5 years; 32 ambulatory) treated with growth hormone for 1 year during a four-year period. Boys were on long-term daily deflazacort or prednisone (mean duration 5 ± 2.2 years; dosing regimen prednisone 0.75 mg/kg/day equivalent). Primary outcomes were growth velocity and height-for-age z-scores (height SD) at 1 year. Height velocity increased from 1.3 ± 0.2 to 5.2 ± 0.4 cm/year on growth hormone (p<0.0001). Pre-growth hormone decline in height SD (-0.5 ± 0.2SD/year) stabilized at height SD -2.9 ± 0.2 on growth hormone (p<0.0001). The rate of weight gain was unchanged, at 2.8 ± 0.6 kg/year pre-growth hormone and 2.6 ± 0.7 kg/year at 1 year. Motor function decline was similar pre-growth hormone and at 1 year. Cardiopulmonary function was unchanged. Three experienced side effects. In this first comprehensive report of growth hormone in Duchenne muscular dystrophy, growth hormone improved growth at 1 year, without detrimental effects observed on neuromuscular and cardiopulmonary function.
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http://dx.doi.org/10.1016/j.nmd.2012.07.009DOI Listing
December 2012

Partial anomalous pulmonary venous return is common in Turner syndrome.

J Pediatr Endocrinol Metab 2012 ;25(5-6):435-40

Division of Endocrinology, Cincinnati Children's Hospital, Cincinnati, OH, USA.

Background: Cardiovascular disease affects >50% of Turner syndrome (TS) patients. With newer imaging modalities, this prevalence increases and the spectrum of recognized anomalies broadens.

Objective: To determine the prevalence and hemodynamic significance of partial anomalous pulmonary venous return (PAPVR) in adolescents and young adults with TS using transthoracic echocardiogram (TTE) and cardiac magnetic resonance (CMR), and to study the association with phenotype.

Methods: The records of 39 young TS patients who had received TTE and CMR were reviewed.

Results: PAPVR was diagnosed in seven (18%) patients; six were newly diagnosed by CMR after normal TTE. In one subject, PAPVR was associated with right ventricular enlargement and a pulmonic blood flow (Qp) to systemic blood flow (Qs) ratio of 1.9:1.0, necessitating surgical repair. In other subjects with and without PAPVR, Qp:Qs and the right ventricle to left ventricle end-diastolic volume ratio were statistically different. Other clinical features were not predictive of PAPVR.

Conclusions: The prevalence of PAPVR is high in TS, and it may be hemodynamically significant. Diagnosis by TTE can be difficult. Appropriate screening and management are indicated.
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http://dx.doi.org/10.1515/jpem-2012-0046DOI Listing
September 2012

Effects of steroids and angiotensin converting enzyme inhibition on circumferential strain in boys with Duchenne muscular dystrophy: a cross-sectional and longitudinal study utilizing cardiovascular magnetic resonance.

J Cardiovasc Magn Reson 2011 Oct 19;13:60. Epub 2011 Oct 19.

The Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.

Background: Steroid use has prolonged ambulation in Duchenne muscular dystrophy (DMD) and combined with advances in respiratory care overall management has improved such that cardiac manifestations have become the major cause of death. Unfortunately, there is no consensus for DMD-associated cardiac disease management. Our purpose was to assess effects of steroid use alone or in combination with angiotensin converting enzyme inhibitors (ACEI) or angiotension receptor blocker (ARB) on cardiovascular magnetic resonance (CMR) derived circumferential strain (εcc).

Methods: We used CMR to assess effects of corticosteroids alone (Group A) or in combination with ACEI or ARB (Group B) on heart rate (HR), left ventricular ejection fraction (LVEF), mass (LVM), end diastolic volume (LVEDV) and circumferential strain (εcc) in a cohort of 171 DMD patients >5 years of age. Treatment decisions were made independently by physicians at both our institution and referral centers and not based on CMR results.

Results: Patients in Group A (114 studies) were younger than those in Group B (92 studies)(10 ± 2.4 vs. 12.4 ± 3.2 years, p < 0.0001), but HR, LVEF, LVEDV and LVM were not different. Although εcc magnitude was lower in Group B than Group A (-13.8 ± 1.9 vs. -12.8 ± 2.0, p = 0.0004), age correction using covariance analysis eliminated this effect. In a subset of patients who underwent serial CMR exams with an inter-study time of ~15 months, εcc worsened regardless of treatment group.

Conclusions: These results support the need for prospective clinical trials to identify more effective treatment regimens for DMD associated cardiac disease.
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http://dx.doi.org/10.1186/1532-429X-13-60DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3207955PMC
October 2011

Magnetic resonance derived myocardial strain assessment using feature tracking.

J Vis Exp 2011 Feb 12(48). Epub 2011 Feb 12.

The Heart Institute, Cincinnati Children Hospital Medical Center (CCHMC), USA.

Purpose: An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that strain is a more sensitive and earlier marker for contractile dysfunction than the frequently used parameter EF. Current technologies for CMR are time consuming and difficult to implement in clinical practice. Feature tracking is a technology that can lead to more automatization and robustness of quantitative analysis of medical images with less time consumption than comparable methods.

Methods: An automatic or manual input in a single phase serves as an initialization from which the system starts to track the displacement of individual patterns representing anatomical structures over time. The specialty of this method is that the images do not need to be manipulated in any way beforehand like e.g. tagging of CMR images.

Results: The method is very well suited for tracking muscular tissue and with this allowing quantitative elaboration of myocardium and also blood flow.

Conclusions: This new method offers a robust and time saving procedure to quantify myocardial tissue and blood with displacement, velocity and deformation parameters on regular sequences of CMR imaging. It therefore can be implemented in clinical practice.
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http://dx.doi.org/10.3791/2356DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3074463PMC
February 2011

Presence of mechanical dyssynchrony in Duchenne muscular dystrophy.

J Cardiovasc Magn Reson 2011 Feb 2;13:12. Epub 2011 Feb 2.

The Heart and Vascular Center, The Christ Hospital, Cincinnati, Ohio, USA.

Background: Cardiac dysfunction in boys with Duchenne muscular dystrophy (DMD) is a leading cause of death. Cardiac resynchronization therapy (CRT) has been shown to dramatically decrease mortality in eligible adult population with congestive heart failure. We hypothesized that mechanical dyssynchrony is present in DMD patients and that cardiovascular magnetic resonance (CMR) may predict CRT efficacy.

Methods: DMD patients (n = 236) were stratified into 4 groups based on age, diagnosis of DMD, left ventricular (LV) ejection fraction (EF), and presence of myocardial fibrosis defined as positive late gadolinum enhancement (LGE) compared to normal controls (n = 77). Dyssynchrony indices were calculated based on timing of CMR derived circumferential strain (ecc). The calculated indices included cross-correlation delay (XCD), uniformity of strain (US), regional vector of variance (RVV), time to maximum strain (TTMS) and standard deviation (SD) of TTMS. Abnormal XCD value was defined as > normal + 2SD. US, RVV, TTMS and SD were calculated for patients with abnormal XCD.

Results: There was overall low prevalence of circumferential dyssynchrony in the entire DMD population; it increased to 17.1% for patients with abnormal EF and to 31.2% in the most advanced stage (abnormal EF with fibrosis). All but one DMD patient with mechanical dyssynchrony exhibited normal QRS duration suggesting absence of electrical dyssynchrony. The calculated US and RVV values (0.91 ± 0.09, 1.34 ± 0.48) indicate disperse rather than clustered dyssynchrony.

Conclusion: Mechanical dyssynchrony is frequent in boys with end stage DMD-associated cardiac dysfunction. It is associated with normal QRS complex as well as extensive lateral fibrosis. Based on these findings, it is unlikely that this patient population will benefit from CRT.
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http://dx.doi.org/10.1186/1532-429X-13-12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3041675PMC
February 2011

Patterns of left ventricular remodeling in patients with Duchenne Muscular Dystrophy: a cardiac MRI study of ventricular geometry, global function, and strain.

Int J Cardiovasc Imaging 2012 Jan 8;28(1):99-107. Epub 2011 Jan 8.

The Heart and Vascular Center at the Christ Hospital, Cincinnati, OH, USA.

The cardiac disease ubiquitously associated in Duchenne Muscular Dystrophy (DMD) has traditionally been considered a progressive dilated cardiomyopathy (DCM). However, left ventricular (LV) dilatation as measured with cardiac MRI has not been a consistent finding in this population, even as circumferential strain (ε(cc)) declines with advancing disease. We hypothesized that a distinct pattern of changes in LV geometry, during the course of ε(cc) decline, distinguishes DMD associated heart disease from DCM. Using CMR, LV end-diastolic volume (EDV), mass (LVM), ejection fraction, ε(cc) and myocardial delayed enhancement (MDE) were determined in DMD patients and normal control subjects. The LV Remodeling Index (LVRI) was calculated as the ratio of LV Mass to Volume (LVM/EDV). Statistical comparisons between all LV parameters and genotype were also performed. Median LVRI in DMD (n = 127) and control subjects (n = 41) were different (0.75 vs. 0.65, P = 0.0150) but within normal range. Furthermore, the median LVRI in DMD boys with reduced LV systolic function was significantly reduced compared to those with normal LV systolic function (0.64 vs. 0.75, P = 0.0974). However, the presence of MDE was associated with a lower median LVRI (0.57 vs. 0.76, P = 0.0471). Regression analysis showed no significant correlation between ε(cc) and LVRI (r = -0.03). The LVRI of DMD patients is unexpectedly normal and not correlated with ε(cc.) Based on these findings, DMD-associated heart disease exhibits a unique remodeling pattern distinct from DCM.
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http://dx.doi.org/10.1007/s10554-010-9781-2DOI Listing
January 2012

Multimodality assessment of cardiac involvement in Churg-Strauss syndrome patients in clinical remission.

Circ J 2011 3;75(3):649-55. Epub 2010 Dec 3.

Department of Medicine, Jagiellonian University Medical College, Skawi´nska 8, 31-066 Kraków, Poland.

Background: Cardiac involvement in Churg-Strauss syndrome (CSS) is not uncommon, but its frequency varies widely and may depend on the activity of the disease. Therefore, the cardiac involvement in CSS patients in clinical remission was assessed in the present study.

Methods And Results: In 20 CSS patients in remission and 20 sex- and age-matched healthy controls, an ECG stress test, echocardiography, and 24-h ECG Holter monitoring were performed, together with cardiac magnetic resonance imaging (cMRI). Cardiac involvement was present in 90% (18/20) of CSS patients. Left ventricular ejection fraction (LVEF) was on average lower in the CSS group than in controls (P<0.05), with 7 patients showing systolic heart failure (LVEF <50%). cMRI changes included late gadolinium enhancement lesions in the LV in 89% of patients (17/19), present in all layers of the myocardium. Signs of ongoing inflammation (early gadolinium enhancement) and edema (T2-weighted imaging) were present in 6/19 patients. Holter monitoring revealed both supraventricular and ventricular arrhythmias more frequently in CSS patients when compared with controls (P<0.05). Absolute eosinophil count before the initiation of treatment was higher in rhythm disturbances (P<0.05), and inversely correlated with LV systolic function (rho -0.65).

Conclusions: Heart involvement in CSS patients who are in clinical remission is very common. It is characterized not only by fibrosis, but also by an active inflammatory process. The latter finding might influence therapeutic decisions in CSS patients in full clinical remission.
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http://dx.doi.org/10.1253/circj.cj-10-0772DOI Listing
July 2011

Detection of progressive cardiac dysfunction by serial evaluation of circumferential strain in patients with Duchenne muscular dystrophy.

Am J Cardiol 2010 May 30;105(10):1451-5. Epub 2010 Mar 30.

Department of Cardiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.

The present study evaluated progressive cardiac dysfunction using serial circumferential strain (epsilon(cc)) measurements in patients with Duchenne muscular dystrophy (DMD). DMD is characterized by progressive cardiac dysfunction and myocardial fibrosis late in the disease process. We hypothesized that serial epsilon(cc) changes could be detected in individual patients with DMD during a time when the left ventricular ejection fraction (EF) changes are insignificant. Cardiac magnetic resonance imaging data from patients with DMD were evaluated. The left ventricular EF was calculated from steady-state free precession cine images and the composite epsilon(cc) measurement from tagged cine images. The serial epsilon(cc) and EF values for each patient were analyzed using the Wilcoxon sign rank test. Data from 51 patients with DMD (2 studies per patient, mean age at the initial study 11.8 +/- 3.5 years, range 7.4 to 25.4) were analyzed, with a mean interval between cardiac magnetic resonance studies of 15.6 +/- 6.0 months (range 6.2 to 28.1). In the interval between studies, the epsilon(cc) had decreased in all patients with DMD. The average decrease was 1.8 +/- 1.3 (p <0.001). However, the EF had decreased in 33 of the 51 patients and had increased in 18 of the 51 patients. On average, the EF decreased by 2.9 +/- 8.57% (p = NS). In conclusion, in patients with DMD, epsilon(cc) abnormalities indicate progression within a relatively short period when the EF changes were not significant. Serial epsilon(cc) measurements might provide reliable monitoring of the progression of DMD-associated cardiac dysfunction before overt heart failure develops, because it is more sensitive than the EF.
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http://dx.doi.org/10.1016/j.amjcard.2009.12.070DOI Listing
May 2010

Left ventricular T2 distribution in Duchenne muscular dystrophy.

J Cardiovasc Magn Reson 2010 Mar 18;12:14. Epub 2010 Mar 18.

Division of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.

Background: Although previous studies have helped define the natural history of Duchenne muscular dystrophy (DMD)-associated cardiomyopathy, the myocardial pathobiology associated with functional impairment in DMD is not yet known.The objective of this study was to assess the distribution of transverse relaxation time (T2) in the left ventricle (LV) of DMD patients, and to determine the association of myocardial T2 heterogeneity to the severity of cardiac dysfunction. DMD patients (n = 26) and normal control subjects (n = 13) were studied by cardiovascular magnetic resonance (CMR). DMD subject data was stratified based on subject age and LV ejection fraction (EF) into the following groups: A (<12 years old, n = 12); B (>or=12 years old, EF or=12 years old, EF = 55%, n = 6). Controls were also stratified by age into Groups N1 (<12 years, n = 6) and N2 (>12 years, n = 5). LV mid-slice circumferential myocardial strain (epsilon cc) was calculated using tagged CMR imaging. T2 maps of the LV were generated for all subjects using a black blood dual spin echo method at two echo times. The full width at half maximum (FWHM) was calculated from a histogram of LV T2 distribution constructed for each subject.

Results: In DMD subject groups, FWHM of the T2 histogram rose progressively with age and decreasing EF (Group A FWHM= 25.3 +/- 3.8 ms; Group B FWHM= 30.9 +/- 5.3 ms; Group C FWHM= 33.0 +/- 6.4 ms). Further, FWHM was significantly higher in those with reduced circumferential strain (|epsilon cc| 12% (Group A). Group A FWHM was not different from the two normal groups (N1 FWHM = 25.3 +/- 3.5 ms; N2 FWHM= 24.0 +/- 7.3 ms).

Conclusion: Reduced EF and epsilon cc correlates well with increased T2 heterogeneity quantified by FWHM, indicating that subclinical functional impairments could be associated with pre-existing abnormalities in tissue structure in young DMD patients.
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http://dx.doi.org/10.1186/1532-429X-12-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2846924PMC
March 2010

Comparison of magnetic resonance feature tracking for strain calculation with harmonic phase imaging analysis.

JACC Cardiovasc Imaging 2010 Feb;3(2):144-51

Department of Cardiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.

Objectives: To compare a steady-state free precession cine sequence-based technique (feature tracking [FT]) to tagged harmonic phase (HARP) analysis for peak average circumferential myocardial strain (epsilon(cc)) analysis in a large and heterogeneous population of boys with Duchenne muscular dystrophy (DMD).

Background: Current epsilon(cc) assessment techniques require cardiac magnetic resonance-tagged imaging sequences, and their analysis is complex. The FT method can readily be performed on standard cine (steady-state free precession) sequences.

Methods: We compared mid-left ventricular whole-slice epsilon(cc) by the 2 techniques in 191 DMD patients grouped according to age and severity of cardiac dysfunction: group B: DMD patients 10 years and younger with normal ejection fraction (EF); group C: DMD patients older than 10 years with normal EF; group D: DMD patients older than 10 years with reduced EF but negative myocardial delayed enhancement (MDE); group E: DMD patients older than 10 years with reduced EF and positive MDE; and group A: 42 control subjects. Retrospective, offline analysis was performed on matched tagged and steady-state free precession slices.

Results: For the entire study population (N = 233), mean FT epsilon(cc) values (-13.3 +/- 3.8%) were highly correlated with HARP epsilon(cc) values (-13.6 +/- 3.4%), with a Pearson correlation coefficient of 0.899. The mean epsilon(cc) of DMD patients determined by HARP (-12.52 +/- 2.69%) and FT (-12.16 +/- 3.12%) was not significantly different (p = NS). Similarly, the mean epsilon(cc) of the control subjects by determined HARP (-18.85 +/- 1.86) and FT (-18.81 +/- 1.83) was not significantly different (p = NS). Excellent correlation between the 2 methods was found among subgroups A through E, except there was no significant difference in strain between groups B and C with FT analysis.

Conclusions: FT-based assessment of epsilon(cc) correlates highly with epsilon(cc) derived from tagged images in a large DMD patient population with a wide range of cardiac dysfunction and can be performed without additional imaging.
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http://dx.doi.org/10.1016/j.jcmg.2009.11.006DOI Listing
February 2010

Circumferential strain analysis identifies strata of cardiomyopathy in Duchenne muscular dystrophy: a cardiac magnetic resonance tagging study.

J Am Coll Cardiol 2009 Apr;53(14):1204-10

Department of Cardiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039, USA.

Objectives: This study sought to evaluate the natural history of occult cardiac dysfunction in Duchenne muscular dystrophy (DMD).

Background: Duchenne muscular dystrophy is characterized by progressive cardiac dysfunction and myocardial fibrosis late in the disease process. We hypothesized that left ventricular myocardial peak circumferential strain (epsilon(cc)) would decrease in DMD before global systolic functional abnormalities regardless of age or ventricular ejection fraction (EF).

Methods: We evaluated cardiac magnetic resonance image (MRI) data from 70 DMD patients and 16 aged-matched control subjects. Standard imaging data included steady-state free precession short-axis cine stack images, cine myocardial tagged images, and myocardial delayed enhancement (MDE) (an indicator of myocardial fibrosis) sequences. Analysis was performed with QMASS (Medis Medical Imaging Systems, Leiden, the Netherlands) and HARP (Diagnosoft, Palo Alto, California) software. The DMD patient data were subdivided by age (<10 or >10 years), EF (>55% or <55%), and the presence or absence of MDE.

Results: The DMD patients with normal EF had reduced epsilon(cc) at an early age (<10 years) compared with control subjects (p < 0.01). The DMD patients age >10 years with normal EF had further decline in epsilon(cc) compared with younger DMD patients (p < 0.01). There was further decline in epsilon(cc) with age in patients with reduced EF (p < 0.01) without MDE. The oldest patients, with both reduced EF and positive MDE, exhibited the lowest epsilon(cc). None of the patients had ventricular hypertrophy.

Conclusions: Myocardial strain abnormalities are prevalent in young DMD patients despite normal EF, and these strain values continue to decline with advancing age. Strain analysis in combination with standard MRI and MDE imaging provides a means to stratify DMD cardiomyopathy.
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http://dx.doi.org/10.1016/j.jacc.2008.12.032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2709409PMC
April 2009

The presence of bicuspid aortic valve does not predict ventricular septal defect type.

Am J Med Genet A 2008 Dec;146A(24):3202-5

Division of Cardiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA.

Previous studies have identified an increased incidence of bicuspid aortic valve (BAV) in patients with ventricular septal defect (VSD). Because endocardial cushion remodeling contributes to both the formation of semilunar valves and ventricular septation, we hypothesized that examination of humans with BAV and VSD would identify a specific VSD type. We evaluated VSD type in pediatric patients diagnosed with BAV and VSD (n=82) and compared findings to patients diagnosed with VSD and normal aortic valve morphology (n=429). VSD type was described as conoventricular, muscular, inlet or conoseptal using a clinical taxonomy. Based on the contribution of the outflow tract endocardial cushions to the membranous ventricular septum, we expected patients with BAV to have conoventricular VSD. In both patient groups, conoventricular VSD was most common; however, the prevalence was not significantly different when BAV patients were compared to those with normal aortic valve morphology (67% vs. 57%, P=0.11). The primary finding of this study is that despite a developmental link between semilunar valve formation and ventricular septation during cardiogenesis, there is no clear association between BAV and VSD type. This may be due to phenotypic and genetic heterogeneity of BAV and VSD, other modifying factors as manifested by differences in associated CVM, as well as limitations of the clinical taxonomy of VSD.
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http://dx.doi.org/10.1002/ajmg.a.32609DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2644069PMC
December 2008