Age-Dependent Echocardiographic and Pathologic Findings in a Rat Model with Duchenne Muscular Dystrophy Generated by CRISPR/Cas9 Genome Editing.

Duchenne muscular dystrophy (DMD) is X-linked recessive myopathy caused by mutations in the dystrophin gene. Although conventional treatments have improved their prognosis, inevitable progressive cardiomyopathy is still the leading cause of death in patients with DMD. To explore novel therapeutic options, a suitable animal model with heart involvement has been warranted.We have generated a rat model with an out-of-frame mutation in the dystrophin gene using CRISPR/Cas9 genome editing (DMD rats). The aim of this study was to evaluate their cardiac functions and pathologies to provide baseline data for future experiments developing treatment options for DMD.In comparison with age-matched wild rats, 6-month-old DMD rats showed no significant differences by echocardiographic evaluations. However, 10-month-old DMD rats showed significant deterioration in left ventricular (LV) fractional shortening (P = 0.024), and in tissue Doppler peak systolic velocity (Sa) at the LV lateral wall (P = 0.041) as well as at the right ventricular (RV) free-wall (P = 0.004). These functional findings were consistent with the fibrotic distributions by histological analysis.Although the cardiac phenotype was milder than anticipated, DMD rats showed similar distributions and progression of heart involvement to those of patients with DMD. This animal may be a useful model with which to develop effective drugs and to understand the underlying mechanisms of progressive heart failure in patients with DMD.

High Prevalence of Left Ventricular Non-Compaction and Its Effect on Chemotherapy-Related Cardiac Dysfunction in Patients With Hematological Diseases.

BACKGROUND: Recent progress in chemotherapy has prolonged the survival of patients with hematological diseases, but has also increased the number of patients with chemotherapy-related cardiac dysfunction (CTRCD). However, the causes of individual variations and risk factors for CTRCD have yet to be fully elucidated.Methods and Results:Consecutive echocardiograms of 371 patients were retrospectively evaluated for the presence of left ventricular (LV) non-compaction (LVNC). Individual LV ejection fraction (LVEF) outcome estimates were made using bivariate linear regression with log-transformed duration Akaike information criterion (AIC) model fitting. The prevalence of LVNC was 6-fold higher in patients with hematological diseases than in those with non-hematological diseases (12% vs. 2%; risk ratio 6.1; 95% confidence interval [CI] 2.0, 18.2). Among patients with hematological diseases, the ratio of myeloid diseases was significantly higher in the group with LVNC (P=0.031). Deterioration of LVEF was more severe in patients with than without LVNC (-14.4 percentage points/year [95% CI -21.0, -7.9] vs. -4.6 percentage points/year [95% CI -6.8, -2.4], respectively), even after multivariate adjustment for baseline LVEF, background disease distributions, cumulative anthracycline dose, and other baseline factors. CONCLUSIONS: LVNC is relatively prevalent in patients with hematological diseases (particularly myeloid diseases) and can be one of the major risk factors for CTRCD. Detailed cardiac evaluations including LVNC are recommended for patients undergoing chemotherapy.

Nimura lecture: why are you evaluating RV function in patients with pulmonary arterial hypertension?

LV is a pressure-generating pump which endures pressure overload, while RV is a flow-generating pump intolerant of pressure overload. Therefore, RV pump function (but not RV myocardial contractility) can easily fail in face of severe pulmonary arterial hypertension (PH) because of increased afterload. Available indexes of RV function are load dependent and incapable of accurately reflecting RV myocardial contractility. Animal RV in which myocardium is damaged extensively by either soldering iron or coronary occlusion can work well without causing systemic congestion or decreased SV. In clinical settings, evaluation of pre-treatment RV function in patients with PH has limited value in predicting prognosis. Furthermore, in virtually all patients with PH after successful lung transplantation, RV function has been reported to improve indicating that deteriorated RV function in patients with PH is due to an increase in RV afterload, but not to decreased RV myocardial contractility. In view of these facts, evaluation of RV function seems hardly useful in patients with PH.

Errata: Therapeutic Strategy for Heart Failure in Becker Muscular Dystrophy.

An error appeared in the article titled "Therapeutic Strategy for Heart Failure in Becker Muscular Dystrophy" by Koichi Kimura, Hiroyuki Morita, Akinori Nakamura, Katsu Takenaka, Masao Daimon (Vol. 57, No. 5, 527-529, 2016). The name of the last author on page 527 and the back cover should be "Masao Daimon" and not "Daimon Masao".

Utility of Cystatin C for Estimating Glomerular Filtration Rate in Patients With Muscular Dystrophy.

Emerging concerns regarding heart failure, arrhythmia, and sudden death in patients with muscular dystrophy are of significant clinical importance. On the other hand, little attention has been paid to renal dysfunction because these patients have low serum creatinine levels. Serum cystatin C, unaffected by muscle quantity, is a potentially superior marker for estimating renal function. Here, we present cases with muscular dystrophy in which estimated glomerular filtration rate (GFR) by cystatin C (eGFRcys) provided good agreement with simultaneously measured GFR by inulin renal clearance (differences less than 20%). Sudden death with acute heart failure occurred in a patient with underlying renal dysfunction and elevated BNP. Neurologists and cardiologists should evaluate renal function using GFR with cystatin C in patients with muscular dystrophy.

Evaluation of right ventricle by speckle tracking and conventional echocardiography in rats with right ventricular heart failure.

Speckle tracking echocardiography (STE) has been reported to be a promising technique for evaluating right ventricular (RV) function in the clinical setting. On the other hand, the usefulness of STE for RV evaluation in small animal models has not been clarified, although the rat model is among the most commonly used animal models to develop novel effective treatments against pulmonary hypertension and RV heart failure (HF).We validated the use of STE and conventional echocardiographic variables for evaluating RV functions in a rat model by comparing the echocardiographic values of RVHF rats (n = 12) induced by monocrotaline injection with those of control rats (n = 12).Most conventional echocardiographic variables demonstrated that RVHF rats have significant RV dysfunction. The area under the curve (AUC) values to distinguish RV dysfunction in RVHF rats from normal RV function in control rats using fractional area change (FAC), tricuspid annular plane systolic excursion (TAPSE), RV myocardial performance index (MPI), peak tissue Doppler tricuspid annular velocities at systole (Sa), and at early diastole (Ea) were 0.71, 0.98, 0.79, 0.92, and 0.91, respectively. However, using STE analysis for RV evaluation, limited reproducibility was observed (variability 19-37 %, ICC 0.74-0.88) and the only circumferential strain showed significantly lower absolute values (P = 0.039, AUC = 0.76).To evaluate RV function in rat models, circumferential strain may be useful, however, the reproducibility and diagnostic utility were limited. Conventional echocardiographic variables such as TAPSE, tissue Doppler Sa, and Ea have superior diagnostic utility.

The Speckle Tracking Imaging for the Assessment of Cardiac Resynchronization Therapy (START) study.

BACKGROUND: We sought to identify the feasibility of speckle tracking echocardiography (STE) to predict cardiac resynchronization therapy (CRT) responders in a prospective multicenter study. METHODS AND RESULTS: Patients who were newly implanted with a CRT device were enrolled. Time (T) from QRS to maximum peak radial and circumferential strain (CS) in 6 segments on the left ventricular (LV) short-axis plane, and to the maximum peak of longitudinal strain in 18 segments on 3 apical LV planes was measured (Tmax). In segments with multiple peaks on the time-strain curves, time to the first peak (Tfirst) was also assessed. Difference in T between the earliest and latest segment and standard deviation (SD) of T in each strain component were assessed. CRT responders were defined as having LV end-systolic volume reduction >15% at 6 months after CRT. Clinical outcomes were assessed with a composite endpoint of death from cardiac causes or unplanned hospitalization for heart failure. Among 180 patients, 109 patients were identified as responders. Tfirst-SD of CS >116 ms was selected as the best independent predictor of CRT responders (P<0.001, hazard ratio=9.83, 95% confidence interval 3.78-25.6). In addition, Tfirst-SD of CS was associated with the clinical endpoints. CONCLUSIONS: This prospective multicenter study revealed the high feasibility of dyssynchrony assessment by STE, which may improve the ability to predict CRT responders.

Normal and shear strains of the left ventricle in healthy human subjects measured by two-dimensional speckle tracking echocardiography.

BACKGROUND: Animal studies have shown that shear deformation of myocardial sheets in transmural planes of left ventricular (LV) wall is an important mechanism for systolic wall thickening, and normal and shear strains of the LV free wall differ from those of the interventricular septum (IVS). We sought to test whether these also hold for human hearts. METHODS: Thirty healthy volunteers (male 23 and female 7, aged 34 ± 6 years) from Outpatient Department of the University of Tokyo Hospital were included. Echocardiographic images were obtained in the left decubitus position using a commercially available system (Aloka SSD-6500, Japan) equipped with a 3.5-MHz transducer. The ECG was recorded simultaneously. The peak systolic radial normal strain (length change), shear strain (angle change) and time to peak systolic radial normal strain were obtained non-invasively by two-dimensional speckle tracking echocardiography. RESULTS: The peak systolic radial normal strain in both IVS and LV posterior wall (LVPW) showed a trend to increase progressively from the apical level to the basal level, especially at short axis views, and the peak systolic radial normal strain of LVPW was significantly greater than that of IVS at all three levels. The time to peak systolic radial normal strain was the shortest at the basal IVS, and increased progressively from the base to the apical IVS. It gradually increased from the apical to the basal LVPW in sequence, especially at short axis views. The peak of radial normal strain of LVPW occurred much later than the peak of IVS at all three levels. For IVS, the shear deformation was clockwise at basal level, and counterclockwise at mid and apical levels in LV long-axis view. For LVPW, the shear deformations were all counterclockwise in LV long-axis view and increased slightly from base to the apex. LVPW showed larger shear strains than IVS at all three levels. Bland-Altman analysis shows very good agreement between measurements taken by the same observer and by two independent observers. CONCLUSION: "Myocardial sheets" theory also holds true for intact human LV. Moreover, dyssynchrony exists even in healthy human subjects, which should be considered when evaluating the diseased hearts.

Prolonged vortex formation during the ejection period in the left ventricle with low ejection fraction: a study by vector flow mapping.

PURPOSE: Vortex formation in the left ventricle (LV) can be visualized by novel vector flow mapping (VFM) based on color Doppler and speckle tracking data. The aim of this study was to evaluate the impact of a vortex during the ejection period using VFM. SUBJECTS AND METHODS: Color Doppler images were obtained to produce VFM images in 80 subjects (20 normal, 29 with dilated cardiomyopathy, and 31 with old myocardial infarction). The duration of the LV vortex was measured and expressed as the ratio to the ejection time (VTRe). RESULTS: The VTRe showed significant correlations with EDV (ρ = 0.672, p < 0.001), ESV (ρ = 0.772, p < 0.001), EF (ρ = -0.783, p < 0.001), left atrium diameter (LAd) (ρ = 0.302, p = 0.007), stroke volume (ρ = -0.600, p < 0.001), e' (ρ = -0.389, p < 0.001), a' (ρ = -0.314, p = 0.005), s' (ρ = -0.512, p < 0.001), and E/e' (ρ = 0.330, p = 0.003). The diastolic parameters (e', a', E/e', LAd) were not correlated when they were adjusted by EF. CONCLUSIONS: In the normal LV, a vortex existed for only a limited time during the early ejection period. In contrast, the lower the EF was, the longer the vortex remained during systole. Evaluation of vortices by VFM may noninvasively provide novel insights into the pathophysiology of impaired cardiac function.

Prognostic impact of left ventricular noncompaction in patients with Duchenne/Becker muscular dystrophy--prospective multicenter cohort study.

BACKGROUND: The reported prevalence of left ventricular noncompaction (LVNC) varies widely and its prognostic impact remains controversial. We sought to clarify the prevalence and prognostic impact of LVNC in patients with Duchenne/Becker muscular dystrophy (DMD/BMD). METHODS: We evaluated the presence of LNVC in patients with DMD/BMD aged 4-64 years old at the study entry (from July 2007 to December 2008) and prospectively followed-up their subsequent courses (n=186). The study endpoint was all-cause death and the presence of LVNC was blinded until the end of the study (median follow-up: 46 months; interquartile range: 41-48 months). RESULTS: There were no significant differences in baseline characteristics between patients with LVNC (n=35) and control patients without LVNC (n=151), with the exception of LV function. Patients with LVNC showed, in comparison with patients without LVNC, a significant negative correlation between age and LVEF (R=-0.7 vs. R=-0.4) at baseline; and showed a significantly greater decrease in absolute LVEF (-8.6 ± 4.6 vs. -4.3 ± 4.5, p<0.001) during the follow-up. A worse prognosis was observed in patients with LVNC (13/35 died) than in patients without LVNC (22/151 died, Log-rank p<0.001). Multivariate Cox analysis revealed that LVNC is an independent prognostic factor (relative hazard 2.67 [95% CI: 1.19-5.96]). CONCLUSION: LVNC was prevalent in patients with DMD/BMD. The presence of LVNC is significantly associated with a rapid deterioration in LV function and higher mortality. Neurologists and cardiologists should pay more careful attention to the presence of LVNC.

Volumetric and functional assessment of ventricles in pulmonary hypertension on 3-dimensional echocardiography.

BACKGROUND: Non-invasive assessment of volume and function on the right ventricle (RV) for pulmonary hypertension (PH) is limited. METHODS AND RESULTS: Patients with PH (n=23) underwent 3-dimensional (D) echocardiography (3DECHO), with cardiac magnetic resonance imaging to confirm its precision, and right heart catheterization. On linear regression analysis the RV end-systolic volume index (ESVI) was positively correlated with pulmonary vascular resistance (PVR) and mean pulmonary arterial pressure (mPAP; R=0.42 and 0.46, P=0.03 and 0.03, respectively). The RV end-diastolic volume index (EDVI) was positively correlated with mPAP (R=0.41, P<0.05). The left ventricular (LV) EDVI was inversely correlated with PVR (R=-0.48, P=0.02). The RV ejection fraction was inversely correlated with PVR and mean right atrial pressure (mRAP; R=-0.57, and -0.45, P=0.004, and 0.03, respectively). RVEDVI/LVEDVI and RVESVI/LVESVI (the diastolic and systolic remodeling indices, respectively) had a significantly positive linear relationship with PVR (R=0.67 and 0.55, P=0.0005 and 0.006, respectively), and the former had a significantly positive linear relationship with mRAP (R=0.42, P<0.05). During the recovery process in 1 specific case, the remodeling indices maintained a significant linear relationship with the hemodynamic parameters. CONCLUSIONS: Novel indices provided by 3DECHO may be utilized as alternative indicators of hemodynamic changes in PH patients.

Multiple coronary artery fistulae with biventricular hypertrophy.

Here, we report a case of multiple coronary artery fistulae with biventricular hypertrophy. The initial diagnosis of multiple coronary artery fistulae, draining into the left as well as the right ventricle, was made by standard transthoracic 2-dimensional and Doppler echocardiography. Later, multiple coronary fistulae communicating with the left ventricle through persistent sinusoids were diagnosed by coronary angiography.

Speckle tracking global strain rate E/E' predicts LV filling pressure more accurately than traditional tissue Doppler E/E'.

BACKGROUND: The ratio of early diastolic transmitral flow velocity (E) to tissue Doppler (TD) mitral annular early diastolic velocity (E/E'(VEL-TD)) has been widely used for the noninvasive assessment of LV diastolic filling pressures. However, it has been reported that E/E'(VEL-TD) is not accurate particularly when being applied to patients with advanced heart failure. METHODS: Fifty-six ICU patients with decompensated heart failure underwent simultaneous echocardiography and PCWP measurements. Patients with elevated PCWP (n = 41) were compared with patients normal PCWP (n = 15) as well as age-matched healthy controls (n = 32). In the apical 4-chamber view, the ratio of E to speckle tracking (ST) mitral annular velocity (E/E'(VEL-ST)) and early diastolic global LV longitudinal strain rate (E/E'(SR-ST)) were evaluated as new surrogate markers of elevated PCWP. RESULTS: Correlations with PCWP were observed for speckle tracking derived E/E'(VEL-ST) (r = 0.40,P = 0.002) and E/E'(SR-ST) (r = 0.56, P < 0.001), although the traditional E/E'(VEL-TD) did not show a significant correlation (r = 0.23, P = 0.082). Compared with controls, patients with elevated PCWP had significant increases in all variables. The best cutoff values and diagnostic accuracies for identifying elevated PCWP were E/E'(VEL-TD) >12 (Sensitivity/Specificity/area under the ROC curve: 0.58/0.90/0.78), E/E'(VEL-ST) > 14 (0.60/0.85/0.80), and E/E'(SR-ST) > 93 (0.80/0.88/0.89). CONCLUSION: Speckle tracking derived E/E'(SR-ST) may be a robust surrogate marker of elevated LV filling pressure. In ICU patients, E/E'(SR-ST) showed better correlation with PCWP and higher diagnostic accuracy than the tissue Doppler approach.

Reproducibility and diagnostic accuracy of three-layer speckle tracking echocardiography in a swine chronic ischemia model.

BACKGROUND: The subendocardial myocardium normally has higher systolic strain than the subepicardial myocardium and can be damaged first in face of ischemia. We investigated the reproducibility and feasibility of novel three-layer speckle tracking system and compared the diagnostic accuracy with experienced visual interpretation. METHODS: An ameroid constrictor was placed around the proximal left circumflex (LCX) coronary artery in 19 pigs. Four weeks later, subtotal stenosis was confirmed in all pigs by coronary angiogram. Two dead pigs and three pigs with pathological infarction were excluded. Transthoracic left ventricle (LV) short-axis echocardiograms were recorded at rest before and 4 weeks after the operation. LV posterior wall motion was scored by two experienced doctors and analyzed by the speckle tracking system (n = 14). RESULTS: Strain variables gave reasonable intra/interobserver reproducibility (mean absolute percentage errors = 13/19, intraclass correlation coefficients = 0.97/0.92). All strain variables and visual wall-motion scores changed significantly during stenosis (P < 0.05). Of all variables, endocardial strains, particularly the circumferential strain demonstrated the highest area under curve (AUC), showing better diagnostic accuracy than experienced visual interpretation (sensitivity 0.93 vs. 0.79, specificity 0.93 vs. 0.73, AUC 0.95 vs. 0.77, P < 0.05). CONCLUSION: Three-layer speckle tracking is a feasible and reproducible modality. In particular, endocardial speckle tracking provides incremental value in accurately identifying regional ischemia even in the rest echocardiography.

Prediction of coronary artery stenosis using strain imaging diastolic index at rest in patients with preserved ejection fraction.

BACKGROUND: Post-ischemic myocardial diastolic stunning persists for a long time after transient ischemia even after systolic function has recovered. We sought to identify coronary artery stenosis in clinical patients using strain imaging diastolic index (SI-DI) at rest. METHODS: We retrospectively examined 85 patients with suspected coronary artery disease and preserved ejection fraction (EF; >50%) who underwent both echocardiography and coronary angiography. Speckle tracking strains were measured in 3 apical views and parasternal left ventricular (LV) short-axis views at the papillary muscle level. LV segments with inadequate image quality and deficit segments in the movie were excluded by the blinded observer. After strain analysis, LV segments were classified into no stenosis (≤ 50%), mild stenosis (51-75%), and severe stenosis (>75%) groups on the bases of the coronary angiogram. RESULTS: SI-DI decreased significantly in severe stenosis segments (p<0.05, ANOVA), but none of the peak strains showed significant difference. The area under the curve for predicting severe stenosis in radial, longitudinal, and transverse SI-DI was 0.72, 0.74, and 0.80, respectively. A cut-off value of 49 for transverse SI-DI can predict LV segments with severe stenosis with sensitivity of 0.79 and specificity of 0.73. A screening cut-off value of 63 for transverse SI-DI shows sensitivity of 0.95 and specificity of 0.50. CONCLUSION: SI-DI at rest is a novel marker in predicting coronary stenosis even in patients with preserved EF. This index can be used to screen patients with suspected coronary artery disease in routine echocardiography and does not require stress provocation.

Value of live 3D transoesophageal echocardiography in the diagnosis of mitral valve lesions.

We experienced a case in which live 3D transoesophageal echocardiography (TEE) was found much more valuable than 2D TEE in assessing mitral lesions in circumferential direction and making surgical plans for mitral valve prolapse.

Paradoxical mineralocorticoid receptor activation and left ventricular diastolic dysfunction under high oxidative stress conditions.

BACKGROUND: Salt status plays a pivotal role in angiotensin-II-induced organ damage by regulating reactive oxygen species status, and it is reported that reactive oxygen species activate mineralocorticoid receptors. METHOD: To clarify the role of reactive oxygen species-related mineralocorticoid receptor activation in angiotensin-II-induced cardiac dysfunction, we examined the effect of the following: salt status; an MR antagonist, eplerenone; and an antioxidant, tempol in angiotensin-II-loaded Sprague-Dawley rats. RESULTS: Angiotensin-II/salt-loading elevated blood pressure, and neither eplerenone nor tempol antagonized the rise in blood pressure significantly. Left ventricular diastolic function was monitored by measuring peak velocity of a mitral early inflow (E), the ratio of mitral early inflow to atrial contraction related flow (E/A), deceleration time of mitral early inflow and -dP/dt, the time constant (T), and filling pressure (left ventricular end-diastolic pressure) by echocardiography or cardiac catheterization. Despite the suppressed serum aldosterone, left ventricular diastolic function was deteriorated with angiotensin II/high salt, but not affected by angiotensin II/low salt. However, angiotensin-II/salt-induced cardiac dysfunction was restored by eplerenone and tempol. Nicotinamide adenine dinucleotide phosphateoxidase-derived superoxide formation was greater in the hearts of the angiotensin II/high-salt rats than of the angiotensin II/low-salt rats. The expression of the Na(+) -H(+) exchanger isoform 1, a target of mineralocorticoid receptor activation, was significantly increased in the angiotensin II/high-salt group. Both tempol and eplerenone inhibited the angiotensin-II/salt-induced upregulation of Na(+) -H(+) exchanger isoform 1. CONCLUSION: These findings demonstrate that mineralocorticoid receptor activation by oxidative stress can cause left ventricular diastolic dysfunction in a rat model of mild hypertension.