Nee Scze Khoo

Diffuse myocardial fibrosis by T1-mapping in children with subclinical anthracycline cardiotoxicity: relationship to exercise capacity, cumulative dose and remodeling

BackgroundThe late cardiotoxic effects of anthracycline chemotherapy influence morbidity and mortality in the growing population of childhood cancer survivors. Even with lower anthracycline doses, evidence of adverse cardiac remodeling and reduced exercise capacity exist. We aim to examine the relationship between cardiac structure, function and cardiovascular magnetic resonance (CMR) tissue characteristics with chemotherapy dose and exercise capacity in childhood cancer survivors.MethodsThirty patients (15 ± 3 years), at least 2 years following anthracycline treatment, underwent CMR, echocardiography, and cardiopulmonary exercise testing (peak VO2). CMR measured ventricular function, mass, T1 and T2 values, and myocardial extracellular volume fraction, ECV, a measure of diffuse fibrosis based on changes in myocardial T1 values pre- and post-gadolinium. Cardiac function was also assessed with conventional and speckle tracking echocardiography.ResultsPatients had normal LVEF (59 ± 7%) but peak VO2 was 17% lower than age-predicted normal values and were correlated with anthracycline dose (r = −0.49). Increased ECV correlated with decreased mass/volume ratio (r = −0.64), decreased LV wall thickness/height ratio (r = −0.72), lower peak VO2(r = −0.52), and higher cumulative dose (r = 0.40). Echocardiographic measures of systolic and diastolic function were reduced compared to normal values (p < 0.01), but had no relation to ECV, peak VO2 or cumulative dose.ConclusionsMyocardial T1 and ECV were found to be early tissue markers of ventricular remodeling that may represent diffuse fibrosis in children with normal ejection fraction post anthracycline therapy, and are related to cumulative dose, exercise capacity and myocardial wall thinning.

Novel insights into RV adaptation and function in hypoplastic left heart syndrome between the first 2 stages of surgical palliation.

OBJECTIVES This study sought to examine the changes in ventricular function of hypoplastic left heart syndrome (HLHS) between the first 2 stages of surgical palliation. BACKGROUND The mortality risk between first and second stages of surgical palliation in HLHS remains high. Right ventricular (RV) dysfunction predicts mortality. Postulated mechanisms include a maladaptive contraction pattern, myocardial ischemia, or contraction asynchrony. Speckle tracking imaging allows accurate measurement of myocardial deformation without geometric assumptions. METHODS Prospective echocardiography pre-Norwood and pre-bidirectional cavopulmonary anastomosis (BCPA) examinations were performed in 20 HLHS patients, with comparisons made between stages. Measurements of ventricular function included: longitudinal/circumferential strain ratio, reflecting changes in contraction pattern; post-systolic strain index, a potential marker of myocardial ischemia; and mechanical dyssynchrony index. Relationships between echocardiographic variables and magnetic resonance imaging RV parameters before BCPA were examined. RESULTS Before BCPA, myocardial contractility estimated by isovolumic acceleration and strain rate was reduced, paralleled by an increased in post-systolic strain index (p < 0.01). Right ventricular longitudinal/circumferential strain ratio decreased, becoming similar to a left ventricle-like contraction pattern, and this correlated with decreased mechanical dyssynchrony index (r = 0.65, p < 0.01), magnetic resonance imaging RV end-diastolic volume (r = 0.65, p < 0.05) and mass (r = 0.71, p < 0.01). Ventricular strain (r = -0.72, p < 0.01), strain rate (r = -0.85, p < 0.001), and mechanical dyssynchrony index (r = -0.73, p < 0.01) correlated linearly with magnetic resonance imaging-derived RV ejection fraction. CONCLUSIONS Reduced RV contractility occurred before BCPA. RV with a left ventricle-like contraction pattern was associated with improved contraction synchrony as well as a reduction in RV size and mass in HLHS. The finding of increased post-systolic strain index before BCPA is novel and its potential link with myocardial ischemia warrants further investigation. RV strain, strain rate, and contraction synchrony measured by speckle tracking imaging correlated closely with ventricular function and might be useful for monitoring ventricular function in HLHS.

Serial Assessment of Right Ventricular Volume and Function in Surgically Palliated Hypoplastic Left Heart Syndrome Using Real-Time Transthoracic Three-Dimensional Echocardiography

BACKGROUND Right ventricular (RV) failure is a major cause of morbidity and mortality in patients with hypoplastic left heart syndrome (HLHS), but the longitudinal course of RV volumes through staged palliation (SP) has not been previously investigated. The aim of this study was to evaluate RV volume and function longitudinally through SP of HLHS using real-time three-dimensional echocardiography. METHODS A total of 18 subjects with HLHS were prospectively studied at four time points from diagnosis through stage 2 (SP2). Real-time three-dimensional echocardiographic full-volume data sets were acquired in high-frame rate mode with electrocardiographic gating. Volumetric and functional analyses were performed using a semiautomatic contour detection algorithm. Eighteen age-matched and sex-matched normal infants (aged 0-6 months) were studied at comparable time points as controls. RESULTS Presurgical examinations (pre-stage 1 [SP1]; n = 18) were performed at a mean age of 4 days, post-SP1 examinations (n = 17) at a mean age of 20 days, pre-SP2 examinations (n = 14) at a mean age of 4.6 months, and post-SP2 examinations (n = 14) at a mean age of 5.5 months, constituting a total of 63 examinations. The mean values of RV end-diastolic volume indexed to body surface area (EDVi) at the four time points were 87 ± 30, 104 ± 39, 112 ± 34, and 102 ± 35 mL/m(2), respectively. There was an increase in EDVi (P = .024) from pre-SP1 to post-SP1 but no significant change between post-SP1 and pre-SP2. The decrease in EDVi after SP2 did not reach statistical significance. Mean RV ejection fractions (EFs) were 50 ± 5%, 45 ± 5%, 46 ± 5%, and 38 ± 4%, respectively. There was a trend toward decreasing EF throughout SP, with statistically significant decreases from pre-SP1 to post-SP1 (P = .003) and from pre-SP2 to post-SP2 (P < .001). In normal infants, the mean RV EDVi was 50 ± 10 mL/m(2) (approximately half that of patients with HLHS), and the mean EF was 51 ± 3%. There was good interobserver agreement for EDVi, end-systolic volume indexed to body surface area, and EF. CONCLUSIONS Real-time three-dimensional echocardiography is a reproducible means for evaluating RV volumes and EFs in patients with HLHS. Indexed RV diastolic volume remains stable to slightly increased, and RV EF deteriorates as the first two stages of surgical palliation are accomplished. The findings of this study highlight the adverse physiology of HLHS, which deteriorates even among early survivors despite SP.

Severe left heart obstruction with retrograde arch flow influences fetal cerebral and placental blood flow

Decreased middle cerebral artery (MCA) pulsatility index (PI) is a marker of fetal brain‐sparing in placental insufficiency and it is also found in fetuses with severe congenital heart disease. This study sought to explore the impact of anatomical subtypes in fetal heart disease on MCA‐PI and head growth.

Measurements of changes in left ventricular volume, strain, and twist during isovolumic relaxation using MRI

Left ventricular (LV) active relaxation begins before aortic valve closure and is largely completed during isovolumic relaxation (IVR), before mitral valve opening. During IVR, despite closed mitral and aortic valves, indirect assessments of LV volume have suggested volume increases during this period. The aim of this study is to measure LV volume throughout IVR and to determine the sources of any volume changes. For 10 healthy individuals (26.0 + or - 3.8 yr), magnetic resonance imaging was used to measure time courses of LV volume, principal myocardial strains (circumferential, longitudinal, radial), and LV twist. Mitral leaflet motion was observed using echocardiography. During IVR, LV volume measurements showed an apparent increase of 4.6 + or - 1.5 ml (5.0 + or - 2.0% of the early filling volume change), the LV untwisted by 4.5 + or - 1.9 degrees (36.6 + or - 18.0% of peak systolic twist), and changes in circumferential, longitudinal, and radial strains were +0.87 + or - 0.64%, +0.93 + or - 0.57%, and -1.46 + or - 1.66% (4.2 + or - 3.3%, 5.9 + or - 3.3%, and 5.3 + or - 7.5% of peak systolic strains), respectively. The apparent changes in volume correlated (P < 0.01) with changes in circumferential, longitudinal, and radial strains (r = 0.86, 0.69, and -0.37, respectively) and untwisting (r = 0.83). The closed mitral valve leaflets were observed to descend into the LV throughout IVR in all subjects in apical four- and three-chamber and parasternal long-axis views by 6.0 + or - 3.3, 5.1 + or - 2.4, and 2.1 + or - 5.0 mm, respectively. In conclusion, LV relaxation during IVR is associated with changes in principal strains and untwisting, which are all correlated with an apparent increase in LV volume. Since closed mitral and aortic valves ensure true isovolumic conditions, the apparent volume change likely reflects expansion of the LV myocardium and the inward bowing of the closed mitral leaflets toward the LV interior.

The Assessment of Atrial Function in Single Ventricle Hearts from Birth to Fontan: A Speckle-Tracking Study by Using Strain and Strain Rate

BACKGROUND Single ventricle (SV) exercise performance is impaired and limited by reduced ventricular preload reserve. The atrium modulates ventricular filling, and enhancement of atrial compliance can increase cardiac performance. We aimed to study atrial mechanics in SV hearts across staged surgical palliation compared with healthy children by using novel speckle-tracking echocardiography techniques. METHODS A cross-sectional study of 81 patients with SV (1 day to 6.5 years) at 4 stages of surgical palliation (presurgery, 22; prebidirectional cavopulmonary anastomosis, 23; pre-Fontan, 22; post-Fontan, 14). The dominant atrium was assessed with speckle-tracking echocardiography for active (εact), conduit (εcon), and reservoir (εres) strain; strain rate (SR); and εact/εres ratio before each stage of surgical palliation. Findings were compared with the left atrium of 51 healthy children (1 day to 5.5 years). RESULTS Single ventricle atrial size was increased (P < .01), and atrial εres was decreased (P < .01) compared with healthy controls. SV atrial εcon (P < .01) and SRcon (P < .0001) was decreased, increased εact persisted (P < .05), and εact/εres was increased (P < .001) between surgical stages. Although the expected maturational trend of increasing εcon, decreasing εact, and εact/εres occurred in SV, they lagged behind healthy maturational changes (P < .0001). CONCLUSION Single ventricle atrium is dilated, has deceased compliance, decreased early diastolic emptying, and increased reliance on active atrial contraction for ventricular filling. This deviates from normal early childhood maturational changes and appears to parallel those of an atrium facing early ventricular diastolic dysfunction.

Tricuspid Regurgitation in Hypoplastic Left Heart Syndrome Mechanistic Insights From 3-Dimensional Echocardiography and Relationship With Outcomes

Background—Our purpose was to test the following hypotheses: (1) patients with hypoplastic left heart syndrome who develop significant tricuspid regurgitation (TR) or require tricuspid valve (TV) surgery in the medium term have detectable TV abnormalities by 3-dimensional echocardiography (3DE) prestage 1 palliation and (2) TR is associated with reduced survival and increased TV intervention. Methods and Results—Infants were prospectively studied with 3DE and 2DE prestage 1 and followed up for the end points of TR, TV surgery, transplantation, or death. From prestage 1 3DE, spatial coordinates of TV annulus and leaflets were extracted; annulus size, leaflet area, prolapse volume, tethering volume, bending angle, and papillary muscle angle were measured. TR was assessed prestage 1 and at latest follow-up. Of 70 patients, 62 (88.6%) had mild or less TR and 8 (11.4%) had moderate or greater TR prestage 1. Prestage 1 tethering volume correlated to leaflet area (r=0.736; P<0.001), annulus area (r=0.651; P<0.001), right ventricular end-diastolic area (r=0.347; P=0.003), fractional area change (r=−0.387; P<0.001), and TR grade (r=0.447; P<0.001). At follow-up, 46 (65.7%) had mild or less TR (group A) and 24 (34.3%) had moderate or greater TR (group B). Prestage 1 3DE showed greater TV tethering volume and flatter annulus in group B. Survival was better in group A. Conclusions—Increased TV tethering volume and flatter bending angle prestage 1 palliation is associated with TV failure at medium-term follow-up. Increased prestage 1 tethering is related to having larger TV annulus, larger leaflet area, larger right ventricular size, and reduced systolic function. TR progression results in increased TV intervention and decreased survival.Background— Our purpose was to test the following hypotheses: (1) patients with hypoplastic left heart syndrome who develop significant tricuspid regurgitation (TR) or require tricuspid valve (TV) surgery in the medium term have detectable TV abnormalities by 3-dimensional echocardiography (3DE) prestage 1 palliation and (2) TR is associated with reduced survival and increased TV intervention. Methods and Results— Infants were prospectively studied with 3DE and 2DE prestage 1 and followed up for the end points of TR, TV surgery, transplantation, or death. From prestage 1 3DE, spatial coordinates of TV annulus and leaflets were extracted; annulus size, leaflet area, prolapse volume, tethering volume, bending angle, and papillary muscle angle were measured. TR was assessed prestage 1 and at latest follow-up. Of 70 patients, 62 (88.6%) had mild or less TR and 8 (11.4%) had moderate or greater TR prestage 1. Prestage 1 tethering volume correlated to leaflet area ( r =0.736; P <0.001), annulus area ( r =0.651; P <0.001), right ventricular end-diastolic area ( r =0.347; P =0.003), fractional area change ( r =−0.387; P <0.001), and TR grade ( r =0.447; P <0.001). At follow-up, 46 (65.7%) had mild or less TR (group A) and 24 (34.3%) had moderate or greater TR (group B). Prestage 1 3DE showed greater TV tethering volume and flatter annulus in group B. Survival was better in group A. Conclusions— Increased TV tethering volume and flatter bending angle prestage 1 palliation is associated with TV failure at medium-term follow-up. Increased prestage 1 tethering is related to having larger TV annulus, larger leaflet area, larger right ventricular size, and reduced systolic function. TR progression results in increased TV intervention and decreased survival.

Increased common atrioventricular valve tenting is a risk factor for progression to severe regurgitation in patients with a single ventricle with unbalanced atrioventricular septal defect

OBJECTIVE Significant atrioventricular valve regurgitation (AVVR) increases mortality in patients with unbalanced atrioventricular septal defects (uAVSDs) and a single ventricle. We tested the hypothesis that abnormal leaflet tethering is associated with progressive AVVR in patients with a single ventricle with uAVSD. METHODS We retrospectively reviewed the initial presentation and prebidirectional cavopulmonary anastamosis echocardiograms of 46 consecutive patients with uAVSD with single ventricle palliation. AVVR was graded as moderate to severe if the sum of vena contracta width to dominant valve annulus ratio was ≥ 0.33. We measured tenting height, annular to leaflet angle and annular diameter, indexed to patient size where appropriate. Multivariate analysis of variables to predict progressive AVVR was performed. RESULTS At follow-up of 3.3 ± 2.4 years, 24 patients had mild AVVR (Group A) and 22 had moderate to severe AVVR. Overall mortality was 6%, whereas 10 had valve repair/replacement surgery. Of 22 patients with severe AVVR at follow-up, 9 had severe AVVR at initial presentation (Group B), whereas 13 had mild AVVR at presentation but developed severe AVVR at their prebidirectional cavopulmonary anastamosis echocardiogram (Group C). Group A patients had a smaller tenting height at initial presentation compared with patients in Group B and Group C, and also had early progressive reduction of indexed tenting height (P < .01). An absolute tenting height >6 mm (odds ratio, 6.6; 95% confidence interval, 1.1-39.0; P = .03) at the initial echocardiogram was identified as an independent predictor of subsequent severe AVVR. CONCLUSIONS Early leaflet tethering is predictive of subsequent AVVR in patients with a single ventricle with uAVSD. Patients with competent AVV had progressive reduction in the degree of leaflet tethering, whereas patients with AVVR did not. This may represent an important adaptive process to maintain valve competency in uAVSD.

Tricuspid Regurgitation In Hypoplastic Left Heart Syndrome: Mechanistic Insights On Tricuspid Valve Tethering And Relationship With Outcomes

Background—Our purpose was to test the following hypotheses: (1) patients with hypoplastic left heart syndrome who develop significant tricuspid regurgitation (TR) or require tricuspid valve (TV) surgery in the medium term have detectable TV abnormalities by 3-dimensional echocardiography (3DE) prestage 1 palliation and (2) TR is associated with reduced survival and increased TV intervention. Methods and Results—Infants were prospectively studied with 3DE and 2DE prestage 1 and followed up for the end points of TR, TV surgery, transplantation, or death. From prestage 1 3DE, spatial coordinates of TV annulus and leaflets were extracted; annulus size, leaflet area, prolapse volume, tethering volume, bending angle, and papillary muscle angle were measured. TR was assessed prestage 1 and at latest follow-up. Of 70 patients, 62 (88.6%) had mild or less TR and 8 (11.4%) had moderate or greater TR prestage 1. Prestage 1 tethering volume correlated to leaflet area (r=0.736; P<0.001), annulus area (r=0.651; P<0.001), right ventricular end-diastolic area (r=0.347; P=0.003), fractional area change (r=−0.387; P<0.001), and TR grade (r=0.447; P<0.001). At follow-up, 46 (65.7%) had mild or less TR (group A) and 24 (34.3%) had moderate or greater TR (group B). Prestage 1 3DE showed greater TV tethering volume and flatter annulus in group B. Survival was better in group A. Conclusions—Increased TV tethering volume and flatter bending angle prestage 1 palliation is associated with TV failure at medium-term follow-up. Increased prestage 1 tethering is related to having larger TV annulus, larger leaflet area, larger right ventricular size, and reduced systolic function. TR progression results in increased TV intervention and decreased survival.Background— Our purpose was to test the following hypotheses: (1) patients with hypoplastic left heart syndrome who develop significant tricuspid regurgitation (TR) or require tricuspid valve (TV) surgery in the medium term have detectable TV abnormalities by 3-dimensional echocardiography (3DE) prestage 1 palliation and (2) TR is associated with reduced survival and increased TV intervention. Methods and Results— Infants were prospectively studied with 3DE and 2DE prestage 1 and followed up for the end points of TR, TV surgery, transplantation, or death. From prestage 1 3DE, spatial coordinates of TV annulus and leaflets were extracted; annulus size, leaflet area, prolapse volume, tethering volume, bending angle, and papillary muscle angle were measured. TR was assessed prestage 1 and at latest follow-up. Of 70 patients, 62 (88.6%) had mild or less TR and 8 (11.4%) had moderate or greater TR prestage 1. Prestage 1 tethering volume correlated to leaflet area ( r =0.736; P <0.001), annulus area ( r =0.651; P <0.001), right ventricular end-diastolic area ( r =0.347; P =0.003), fractional area change ( r =−0.387; P <0.001), and TR grade ( r =0.447; P <0.001). At follow-up, 46 (65.7%) had mild or less TR (group A) and 24 (34.3%) had moderate or greater TR (group B). Prestage 1 3DE showed greater TV tethering volume and flatter annulus in group B. Survival was better in group A. Conclusions— Increased TV tethering volume and flatter bending angle prestage 1 palliation is associated with TV failure at medium-term follow-up. Increased prestage 1 tethering is related to having larger TV annulus, larger leaflet area, larger right ventricular size, and reduced systolic function. TR progression results in increased TV intervention and decreased survival.

Right Atrial Dysfunction in the Fetus with Severely Regurgitant Tricuspid Valve Disease: A Potential Source of Cardiovascular Compromise

Background: In severe right heart obstruction (RHO), redistribution of cardiac output to the left ventricle (LV) is well tolerated by the fetal circulation. Although the same should be true of severely regurgitant tricuspid valve disease (rTVD) with reduced or no output from the right ventricle, affected fetuses more frequently develop hydrops or suffer intrauterine demise. We hypothesized that right atrium (RA) function is altered in rTVD but not in RHO, which could contribute to differences in outcomes. Methods: Multi‐institutional retrospective review of fetal echocardiograms performed over a 10‐year period on fetuses with rTVD (Ebsteins anomaly, tricuspid valve dysplasia) or RHO (pulmonary atresia/intact ventricular septum, tricuspid atresia) and a healthy fetal control group. Offline velocity vector imaging and Doppler measurements of RA size and function and LV function were made. Results: Thirty‐four fetuses with rTVD, 40 with RHO, and 79 controls were compared. The rTVD fetuses had the largest RA size and lowest RA expansion index, fractional area of change, and RA indexed filling and emptying rates compared with fetuses with RHO and controls. The rTVD fetuses had the shortest LV ejection time and increased Tei index with a normal LV ejection fraction. RA dilation (odds ratio, 1.27; 95% CI, 1.05–1.54) and reduced indexed emptying rate (odds ratio, 2.49; 95% CI, 1.07–5.81) were associated with fetal or neonatal demise. Conclusions: Fetal rTVD is characterized by more severe RA dilation and dysfunction compared with fetal RHO and control groups. RA dysfunction may be an important contributor to reduced ventricular filling and output, potentially playing a critical role in the worsened outcomes observed in fetal rTVD. HighlightsThis is the first study to examine intrinsic right atrial function using velocity vector imaging in fetuses with and without right heart disease.Fetuses with regurgitant tricuspid valve disease, including Ebsteins anomaly and tricuspid valve dysplasia, have evidence of impaired right atrial function characterized by increased global size, decreased emptying fraction and reservoir function, and reduced indexed emptying and filling rates.Impaired right atrial function in fetuses with regurgitant tricuspid valve disease may compromise fetal cardiac output, potentially contributing to the higher rate of poor outcomes in this population.