Atsuko Muranaka

Left Ventricular Hypertrophy Causes Different Changes in Longitudinal, Radial, and Circumferential Mechanics in Patients with Hypertension: A Two-Dimensional Speckle Tracking Study

BACKGROUND Systolic reserve is an important compensatory mechanism against increasing afterload. Although longitudinal systolic dysfunction with preserved ejection fraction has been reported in hypertensive hearts, radial and circumferential function has not been fully examined. The aim of this study was to investigate three-directional systolic function and its relationships with left ventricular geometry in asymptomatic hypertensive patients using two-dimensional speckle-tracking imaging. METHODS Echocardiographic evaluations were performed in 74 hypertensive patients and 55 age-matched control subjects. RESULTS Longitudinal strain was significantly reduced in the hypertrophy groups compared with that in control subjects (concentric, -15.1 ± 4.0%; eccentric, -15.9 ± 4.4%; control, -18.9 ± 3.3%; P < .05). Conversely, radial strain was significantly higher in the normal geometry group than in control subjects (53.8 ± 19.4% vs 40.3 ± 15.1%, P < .05). However, this augmentation was attenuated in the other geometries. CONCLUSION Hypertrophic remodeling attenuates compensatory augmentation of radial systolic function and is associated with latent longitudinal systolic dysfunction.

Elevation of circulating fatty acid-binding protein 4 is independently associated with left ventricular diastolic dysfunction in a general population

BackgroundFatty acid-binding protein 4 (FABP4) is expressed in both adipocytes and macrophages. Recent studies have shown secretion of FABP4 from adipocytes and association of elevated serum FABP4 level with obesity, insulin resistance, hypertension, and atherosclerosis. However, little is known about role of FABP4 in cardiac function.MethodsFrom the database of the Tanno-Sobetsu Study, data for 190 subjects (male/female: 82/108) who were not treated with any medication and underwent echocardiography in 2011 or 2012 were retrieved for analyses of relationships between serum FABP4 concentration, metabolic markers and parameters of echocardiography.ResultsSerum FABP4 level was positively correlated with age, body mass index (BMI), blood pressure (BP), LDL cholesterol, HOMA-R and mean left ventricular (LV) wall thickness (LVWT, males: r = 0.315, females: r = 0.401, p < 0.01) and was negatively correlated with HDL cholesterol, estimated glomerular filtration rate (eGFR) and peak myocardial velocity during early diastole (e’; males: r = −0.434, females: r = −0.353, p < 0.01), an index of LV diastolic function. However, no significant correlation was found between FABP4 level and LV end-diastolic dimension, LV ejection fraction or LV mass index. There were significant correlations of e’ with age, BMI, BP, eGFR, brain natriuretic peptide (BNP), FABP4, metabolic markers and LVWT. Multivariate regression analysis adjusted by HOMA-R, BMI, eGFR, BNP or LVWT in addition to age, gender and BP revealed that serum FABP4 concentration was independently correlated with e’.ConclusionsElevation of circulating FABP4 may contribute to LV diastolic dysfunction in a general population.

Quantitative Measurement of Circumferential Carotid Arterial Strain by Two‐Dimensional Speckle Tracking Imaging in Healthy Subjects

Background: Two‐dimensional speckle tracking imaging (2DS) enables quantitative measurement of left ventricular strain. However, application of 2DS for measurement of circumferential carotid arterial strain (CAS) is not fully elucidated. We investigated the feasibility and reproducibility of measuring CAS by 2DS and determinants of CAS in healthy subjects. Methods: Fifty‐one healthy subjects (20 men and 31 women) with a mean age of 29 ± 11 years were enrolled. Ultrasound examination of bilateral common carotid arteries (CCAs) was performed and short axial views were recorded. The mean intima‐media thickness (IMT) of bilateral CCAs was measured using semiautomated edge‐detection software. Bilateral peak CAS at systole and time to peak CAS in each region were measured by 2DS. Stiffness parameter β of bilateral CCAs was measured and bilateral cardio‐ankle vascular index (CAVI) was recorded. Intraobserver and interobserver variabilities for mean CAS were calculated in 15 subjects. Results: Of the 612 regions, 577 (94%) had adequate waveforms for measurement of CAS. The mean value of CAS was 6.7 ± 2.1%. Required time for CAS analysis was 128 ± 12 seconds per subject. Multiple regression analysis identified age (P < 0.001) and pulse pressure (P < 0.05) as independent significant determinants of mean CAS. Corrected CAS, which was calculated as mean CAS/pulse pressure, correlated with age, mean IMT, and stiffness parameter β and systolic pressure (P < 0.001), age (P < 0.01), and stiffness parameter β (P = 0.02) were identified as independent significant determinants of corrected CAS. Coefficient of variance (CV) of intraobserver and interobserver variabilities for mean CAS were 8.8% and 5.9%, respectively. Conclusions: 2DS in the CCAs is simply and quickly performed with high feasibility and excellent reproducibility. In healthy subjects, age and pulse pressure are the most important determinants of mean CAS. (Echocardiography 2011;28:899‐906)

Inter-vendor variability of left ventricular volumes and strains determined by three-dimensional speckle tracking echocardiography.

Inter‐vendor discordance in three‐dimensional speckle‐tracking echocardiography (3DS) remains uncharacterized. We aimed to examine inter‐vendor discordance of left ventricular (LV) volumes, and functional parameters and their reproducibilities between two commercially available 3DS systems.

Clinical implications of left atrial function assessed by speckle tracking echocardiography

Left atrial (LA) function has a significant impact on cardiovascular diseases and has been assessed by several noninvasive methods. However, several limitations, including the dependence of image quality, single plane assessment, and time-consuming procedures, have prevented widespread clinical application of the assessment of LA function. Strain imaging using tissue Doppler echocardiography enables quantification of LA function. Recently, two-dimensional speckle tracking echocardiography (2D-STE) has been developed as a noninvasive, simple, and reproducible tool for assessment of LA function in patients with cardiovascular disease. 2D-STE enables detection of early LA dysfunction even before LA morphological changes. LA dysfunction determined by 2D-STE can provide additional prognostic information to conventional echocardiographic parameters in patients with cardiovascular diseases. Hence, 2D-STE appears to be a promising technique for diagnosis and therapeutic decision-making. However, standardization of analysis techniques and software applications of 2D-STE is still lacking. Here, we review recent studies on clinical implications of LA function assessed by 2D-STE and summarize the remaining problems to be solved to improve the clinical utility of this tool.

Clinical impact of myocardial mTORC1 activation in nonischemic dilated cardiomyopathy

BACKGROUND Activity of mTOR complex 1 (mTORC1) has been shown to be up-regulated in animal models of heart failure. Here, we investigated the change and role of mTORC1 in human nonischemic dilated cardiomyopathy (NICM). METHODS Endomyocardial biopsy specimens were obtained from patients with NICM (n=52) and from Brugada syndrome patients with normal LVEF as controls (n=10). The specimens were stained for phospho-ribosomal protein S6 (p-Rps6) and phospho-p70S6K (p-p70S6K), and the area with p-Rps6 signal was used as an index of mTORC1 activity. Using median mTORC1 activity, patients were divided into a high mTORC1 activity (H-mTOR) group and a low mTORC1 activity (L-mTOR) group. RESULTS The ratio of p-Rps6-positive area in biopsy samples was 10-fold larger in patients with NICM than in controls (2.0±2.2% vs. 0.2±0.2%, p<0.01). p-p70S6K signal level was higher in the H-mTOR group than in the L-mTOR group. The proportion of patients with a family history of cardiomyopathy was higher and the proportion of patients on ACE inhibitors or angiotensin receptor blockers was lower in the H-mTOR group than in the L-mTOR group. The p-Rps6-positive area was correlated with extent of myocardial fibrosis (r=0.46, p<0.01). The cardiac event-free survival rate during a 5-year follow-up period tended to be lower in the H-mTOR group than in the L-mTOR group (52.9% vs. 81.6%, P=0.10). CONCLUSION Aberrant activation of mTORC1 in cardiomyocytes was associated with myocardial fibrosis and a trend for worse prognosis in patients with NICM, indicating that persistently activated mTORC1 contributes to progression of human heart failure.

Intervendor Variabilities of Left and Right Ventricular Myocardial Velocities among Three Tissue Doppler Echocardiography Systems

Whether an intervendor discordance of myocardial velocities determined by tissue Doppler echocardiography (TDE) can be generalized remains unclear. We compared intervendor variabilities of left ventricular (LV) and right ventricular (RV) myocardial velocities among three TDE systems.

Serum FABP5 concentration is a potential biomarker for residual risk of atherosclerosis in relation to cholesterol efflux from macrophages

Cholesterol efflux capacity (CEC) from macrophages, the first step in the reverse cholesterol transport pathway, is inversely associated with residual risk for atherosclerotic cardiovascular disease. Fatty acid-binding protein 4 (FABP4) and FABP5 are expressed in both adipocytes and macrophages and play significant roles in the development of insulin resistance and atherosclerosis. Both FABP4 and FABP5 are secreted from cells, and their circulating levels are associated with insulin resistance and atherosclerosis. We investigated the association between CEC and levels of FABP4 and FABP5 in 250 subjects without any medications. CEC was positively correlated with HDL cholesterol level and negatively correlated with concentrations of high-sensitivity C-reactive protein (hsCRP) and FABP5, but not FABP4. Multiple regression analysis demonstrated that FABP5 concentration was an independent predictor of CEC after adjustment of age, gender and levels of HDL cholesterol and hsCRP. In 129 of the 250 subjects who underwent carotid ultrasonography, mean intima-media thickness was negatively correlated with CEC and was positively correlated with concentrations of FABP4 and FABP5. In conclusion, in contrast to FABP4, circulating FABP5 is associated with decreased CEC and carotid atherosclerosis, suggesting that FABP5 level is a regulatory factor of CEC and a potential biomarker for residual risk of atherosclerosis.

Distinct impacts of sleep-disordered breathing on glycemic variability in patients with and without diabetes mellitus

Background Sleep-disordered breathing (SDB) is highly prevalent in patients with diabetes mellitus (DM) and heart failure (HF) and contributes to poor cardiovascular outcomes. Enlarged glycemic variability (GV) is a risk factor of cardiac events independently of average blood glucose level, but the influence of SDB on GV is uncertain. In this study, we examined whether the impact of SDB on GV is modified by the presence of DM with or without HF. Methods and results Two hundred three patients (67.5±14.1 [SD] years old, 132 males) who were admitted to our institute for examination or treatment of DM and/or HF underwent continuous glucose monitoring and polysomnography. Both HbA1c (8.0±2.0 vs. 5.7±0.4%) and mean amplitude of glycemic excursion (MAGE, median: 95.5 vs. 63.5 mg/dl) were significantly higher in a DM group (n = 100) than in a non-DM group (n = 103), but apnea-hypopnea index (AHI: 29.0±22.7 vs. 29.3±21.5) was similar in the two groups. AHI was correlated with log MAGE in the non-DM group but not in the DM group, and multivariate regression analysis revealed that AHI was an independent variable for log MAGE in the non-DM group but not in the DM group. We then divided the non-DM patients into two subgroups according to BNP level (100 pg/ml). AHI was positively correlated with log MAGE (r = 0.74, p<0.001) in the non-DM low-BNP subgroup, but such a correlation was not found in the non-DM high-BNP subgroup. Continuous positive airway pressure (CPAP) reduced MAGE from 75.3 to 53.0 mg/dl in the non-DM group but did not reduce MAGE in the DM group. Conclusion Severity of SDB was associated with higher GV, but DM as well as HF diminished the contribution of SDB to GV. Treatment with CPAP was effective for reduction of GV only in patients without DM.

Soleal vein dilatation assessed by ultrasonography is an independent predictor for deep vein thrombosis after major orthopedic surgery.

BACKGROUND Deep vein thrombosis (DVT) develops after major orthopedic surgery despite the current use of prophylaxis. DVT frequently develops in the soleal vein (SV) and might develop easily at the site of SV dilatation because of blood flow stasis. However, whether preoperative SV dilatation detected by ultrasonography predicts DVT after major orthopedic surgery remains unknown. OBJECTIVE We examined whether SV dilatation detected by preoperative ultrasonography predicts DVT after major orthopedic surgery. METHODS Ultrasonography was performed preoperatively and postoperatively in 243 patients with orthopedic diseases (mean age of 67±13 years, 77% women) who underwent total hip arthroplasty (THA, n=180) or total knee arthroplasty (TKA, n=63). Presence of DVT was diagnosed by ultrasonography and SV diameter ≥10mm was defined as SV dilatation. Patients with preoperative DVT were excluded. RESULTS Sixty-nine patients (28%) developed postoperative DVT. SV dilatation was found in 24 patients (10%), and 16 (67%) of those patients had postoperative DVT. Multivariate logistic regression analysis showed that female gender [odds ratio (OR): 4.09, p=0.004], TKA (OR: 2.52, p=0.011), and SV dilatation (OR: 6.67, p<0.001), but not presence of comorbidities, medications, or plasma d-dimer value, independently predict postoperative DVT. Subgroup analyses according to the operation site showed that female gender (OR: 3.27, p=0.043) and SV dilatation (OR: 3.72, p=0.022) were independent predictors of postoperative DVT in the THA group. SV dilatation (OR: 12.0, p=0.027) was an independent predictor of postoperative DVT also in the TKA group. CONCLUSIONS In addition to gender and TKA, SV dilatation detected by ultrasonography is an independent predictor of DVT after major orthopedic surgery. Determination of SV diameter by ultrasonography before major orthopedic surgery is useful for assessing the risk of postoperative DVT.