Tatsunori Taniguchi

Usefulness of transient elastography for noninvasive and reliable estimation of right-sided filling pressure in heart failure.

Accurate noninvasive assessment of right atrial pressure (RAP) is important for volume management in patients with heart failure (HF). Transient elastography is a noninvasive and reliable method to assess liver stiffness (LS). We investigated the value of LS for evaluation of RAP in patients with HF without structural liver disease. We measured LS using transient elastography (Fibroscan) in 31 patients undergoing right-sided cardiac catheterization (test group). The relation between LS and RAP found in the test group was used to derive the best-fit model to predict RAP. The applicability of the model was then tested in a validation group of 49 additional patients. There was an excellent correlation between LS and RAP in the test group (r = 0.95, p <0.0001; RAP = -5.8 + 6.7 × ln [LS]). Natural log transformation (ln) of LS provided the regression equation to predict RAP. When the equation model derived from the test group was applied to the validation group, predicted RAP correlated excellently with actual RAP (r = 0.90, p <0.0001). The receiver operating characteristic curve analyses in the test group showed that LS favorably compared with echocardiography for detecting RAP >10 mm Hg (area under the curve 0.958 vs 0.800, respectively, p = 0.047). In the validation group, LS with a cut-off value of 10.6 kPa for identifying RAP >10 mm Hg had a higher sensitivity and accuracy (p = 0.046 and p = 0.049, respectively) than echocardiography. In conclusion, LS may offer an accurate noninvasive diagnostic method to assess RAP in patients with HF.

Successful catheter ablation to accessory atrioventricular pathway as cardiac resynchronization therapy in a patient with dilated cardiomyopathy

A 55-year-old man was admitted to our hospital for further examination of the abnormalities of chest X-ray and electrocardiogram. He was diagnosed with type B Wolff-Parkinson-White syndrome concomitant with dilated cardiomyopathy. Despite the medical therapy using enalapril and carvedilol for 20 months, his cardiac performance and brain natriuretic peptide (BNP) were not so improved. Because asynchronous septal motion caused by pre-excitation through a right-sided accessory pathway (AP) might deteriorate his cardiac performance, catheter ablation to the AP was performed. Successful procedure after 17 months improved left ventricular (LV) contraction, reduced LV volume, and decreased mitral regurgitation and BNP.

Impact of Body Size on Inferior Vena Cava Parameters for Estimating Right Atrial Pressure: A Need for Standardization?

BACKGROUND Inferior vena cava (IVC) diameter and its respiratory change, as determined using echocardiography, are commonly used to assess right atrial pressure (RAP). Despite the widespread use of the IVC approach for RAP assessment, the relations among body surface area (BSA), IVC diameter, and respirophasic change remain unclear. The aim of this study was to investigate the impact of BSA on IVC parameters for predicting elevated RAP. METHODS Ninety consecutive patients undergoing right-heart catheterization or central venous catheter insertion were prospectively included. To investigate the impact of BSA on IVC parameters, patients were divided into higher and lower BSA groups by comparing individual BSA measurements with the median value. Optimal cutoff points of IVC parameters for detecting RAP of ≥ 10 mm Hg were defined using receiver operating characteristic curves. RESULTS The median RAP and BSA were 8 mm Hg (range, 1-25 mm Hg) and 1.61 m(2) (range, 1.23-2.22 m(2)), respectively. In all patients, the optimal cutoff point for maximal IVC diameter (IVCDmax) and IVC collapsibility for the detection of RAP ≥ 10 mm Hg were 20 mm and 49.0%, respectively. The optimal cutoff point of IVCDmax for predicting RAP of ≥ 10 mm Hg was significantly larger in patients with higher BSAs than in those with lower BSAs (21 vs 17 mm, P = .0342). No differences in collapsibility indices were detected between the two groups. IVCDmax was larger in men (19 ± 5 vs 17 ± 5 mm in women, P = .0347) and weakly correlated with BSA (r = 0.35, P = .0007), whereas no relation was found between IVCDmax and age. However, the partial correlation coefficient of the entire cohort demonstrated that only BSA was still associated with IVCDmax after adjusting for age and gender (partial correlation coefficient = 0.32, P = .0020). CONCLUSIONS Body size, measured as BSA, is important to consider when IVC diameter is used to assess RAP. The optimal cutoff point of IVCDmax was 21 mm for patients with larger BSAs and 17 mm for those with smaller BSAs. However, the cutoff point of IVC collapsibility was not influenced by the difference of BSA.

High Resolution Cell Positioning Based on a Flow Reduction Mechanism for Enhancing Deformability Mapping

The dispersion of cell deformability mapping is affected not only by the resolution of the sensing system, but also by cell deformability itself. In order to extract the pure deformability characteristics of cells, it is necessary to improve the resolution of cell actuation in the sensing system, particularly in the case of active sensing, where an actuator is essential. This paper proposes a novel concept, a “flow reduction mechanism”, where a flow is generated by a macroactuator placed outside of a microfluidic chip. The flow can be drastically reduced at the cell manipulation point in a microchannel due to the elasticity embedded into the fluid circuit of the microfluidic system. The great advantage of this approach is that we can easily construct a high resolution cell manipulation system by combining a macro-scale actuator and a macro-scale position sensor, even though the resolution of the actuator is larger than the desired resolution for cell manipulation. Focusing on this characteristic, we successfully achieved the cell positioning based on a visual feedback control with a resolution of 240 nm, corresponding to one pixel of the vision system. We show that the utilization of this positioning system contributes to reducing the dispersion coming from the positioning resolution in the cell deformability mapping.

An On-Chip RBC Deformability Checker Significantly Improves Velocity-Deformation Correlation

An on-chip deformability checker is proposed to improve the velocity–deformation correlation for red blood cell (RBC) evaluation. RBC deformability has been found related to human diseases, and can be evaluated based on RBC velocity through a microfluidic constriction as in conventional approaches. The correlation between transit velocity and amount of deformation provides statistical information of RBC deformability. However, such correlations are usually only moderate, or even weak, in practical evaluations due to limited range of RBC deformation. To solve this issue, we implemented three constrictions of different width in the proposed checker, so that three different deformation regions can be applied to RBCs. By considering cell responses from the three regions as a whole, we practically extend the range of cell deformation in the evaluation, and could resolve the issue about the limited range of RBC deformation. RBCs from five volunteer subjects were tested using the proposed checker. The results show that the correlation between cell deformation and transit velocity is significantly improved by the proposed deformability checker. The absolute values of the correlation coefficients are increased from an average of 0.54 to 0.92. The effects of cell size, shape and orientation to the evaluation are discussed according to the experimental results. The proposed checker is expected to be useful for RBC evaluation in medical practices.

Switching from carvedilol to bisoprolol ameliorates adverse effects in heart failure patients with dizziness or hypotension

BACKGROUND Treatment with carvedilol is an established primary therapy for patients with heart failure (HF). However, its most common adverse effects, dizziness and hypotension, often discourage continuation or dosage increase. The aim of this study was to examine whether switching to bisoprolol from carvedilol would help to avoid adverse symptoms and signs related to carvedilol administration. METHODS AND SUBJECTS Data were retrospectively collected from 23 patients with HF [age 57±18 years, left ventricular ejection fraction (LVEF) 33±15%] who could not increase the dosage of carvedilol because of dizziness or hypotension, defined as systolic blood pressure<90 mmHg. Before and immediately after, and 6 months after switching to bisoprolol, we examined symptoms, vital signs, laboratory data, and New York Heart Association functional class. Furthermore, left ventricular (LV) dimension and ejection fraction (EF) were evaluated in 19 patients using echocardiography. RESULTS All 13 patients with dizziness (100%) and 9 of 16 with hypotension (56%) were relieved of adverse symptoms or signs. The mean dose of carvedilol before switching was 5.60±3.43 mg. Immediately after the switch, the mean dose of bisoprolol was 1.84±1.08 mg and then increased to 3.13±1.74 mg after 6 months (p<0.01). At 6-month follow-up examinations, LV function determined by LVEF was significantly improved, which was accompanied by increased exercise tolerance. CONCLUSION Switching from carvedilol to bisoprolol may help with continuation of β-blocker treatment as well as dosage increase in HF patients with adverse symptoms or signs, allowing them to reach the target dose.

Clinical Significance of Pulmonary Arterial Capacitance Calculated by Echocardiography in Patients With Advanced Heart Failure

BACKGROUND Advanced left heart failure (HF) often accompanies post-capillary pulmonary hypertension related to RV afterload. Although pulmonary arterial capacitance (PAC), a measure of pulmonary artery compliance, reflects right ventricular (RV) afterload, the clinical utility of PAC obtained by echocardiography (echo-PAC) is not well established in advanced HF.Methods and Results:We performed right heart catheterization in advanced HF patients (n=30), calculating echo-PAC as stroke volume/(tricuspid regurgitation pressure gradient-pulmonary regurgitation pressure gradient). The difference between the echo-PAC and catheter-measured PAC values was insignificant (0.21±0.17 mL/mmHg, P=0.23). Echo-PAC values predicted both pulmonary arterial wedge pressure (PAWP) ≥18 mmHg and pulmonary vascular resistance ≥3 Wood units (P=0.02, area under the curve: 0.88, cutoff value: 1.94 mL/mmHg). Next, we conducted an outcome study with advanced HF patients (n=72). Patients with echo-PAC <1.94 mL/mmHg had more advanced New York Heart Association functional class, higher B-type natriuretic peptide plasma levels, larger RV and lower RV fractional area change than those with echo-PAC ≥1.94 mL/mmHg. They also had a significantly higher rate of ventricular assist device implantation or death, even after adjustment for indices related to HF severity or RV function during a 1-year follow-up period (P<0.01). CONCLUSIONS Decreased PAC as measured by echocardiography, indicating elevated PAWP and RV dysfunction, predicted poorer outcomes in patients with advanced HF.

On-chip RBC deformability checker embedded with vision analyzer

This paper discusses an on-chip Red Blood Cell (RBC) deformability checker with vision analyzer. The system is composed of a PDMS chip including three microfluidic channels, a microscope for appropriately enlarging RBC, and a high-speed vision for observing both the cell size and behaviors in the channel, respectively. We particularly focus on how to analyze the deformability of single cells by the proposed vision analyzer. The analyzer can detect the diameter and velocity of each cell inside and outside the test channel. Based on the information, we can obtain a deformability map which shows the relationship between cell deformation and transit velocity. The results obtained by the proposed vision analyzer are compared to the manual evaluation with a tuning parameter based on gray level control. The comparison results show that the error is less than 5% between vision-based and manual evaluations.

Abdominal admittance helps to predict the amount of fluid accumulation in patients with acute heart failure syndromes

BACKGROUND Predicting fluid volume that needs to be removed in acute heart failure syndromes (AHFS) patients remains challenging. Thoracic admittance (TA), the reciprocal of thoracic impedance measured by bioelectrical impedance, reflects the amount of fluid in the thorax. Abdominal organs play an important role in AHFS as systemic fluid reservoirs. We investigated the relationship between abdominal admittance (AA) at the time of admission for AHFS and net fluid loss (NFL) during hospitalization. METHODS Sixty-two consecutive patients hospitalized for AHFS [age 71±10 years, left ventricular ejection fraction (LVEF) 39±17%] were studied. The admittance values, i.e. the reciprocals of the impedance values, were derived using a BioZ(®) (CardioDynamics, San Diego, CA, USA). The change in weight from admission to discharge was used as a surrogate of amount of NFL. RESULTS At the time of admission, a significant correlation was detected between TA and AA (r=0.46, p=0.0001). TA at admission was significantly correlated with the LV structural variables (end-diastolic dimension and end-systolic dimension), and serum sodium level. AA at admission was significantly correlated with New York Heart Association (NYHA) class and plasma BNP, and also correlated with LVEF and variables related to systemic congestion [minimal inferior vena cava (IVC) diameter and tricuspid regurgitation grade]. Neither TA nor AA values were significantly correlated with weight at admission. During hospitalization, TA and AA declined from 44±8kΩ(-1) to 36±6kΩ(-1) (p<0.0001) and from 74±25kΩ(-1) to 56±17kΩ(-1) (p<0.0001), respectively. Weight fell from 60.1±10.8kg to 54.5±9.4kg (p<0.0001), while NFL was 5.8kg (range, 0.1-17.5kg). In univariate analyses, the admission NYHA class, TA, AA, weight, and IVC diameter correlated with NFL. Multivariate analysis demonstrated that only admission weight [standardized partial regression coefficient (SPRC)=0.596], AA (SPRC=0.529), and NYHA class (SPRC=0.277) were independent predictors of NFL. CONCLUSION Abdominal admittance measurement helps to predict the amount of fluid volume to be removed in patients with AHFS.

EFFECTS OF SWITCHING FROM CARVEDILOL TO BISOPROLOL IN PATIENTS WITH CHRONIC HEART FAILURE

Asrac Caegor: 13. Hear ailure: Therareseaio Numer: 1214-102Auhors: Tatsunori Taniguchi, Yasuhiro Ichibori, Machiko Matsui Kanzaki, Hitoshi Minamiguchi, Isamu Mizote, Tomohito Ohtani, Yoshihiro Asano, Yasushi Sakata, Issei Komuro, Osaka University Graduate School of Medicine, Osaka, JapanBackground: Treame ih careilol has ee esalishe as a rimar hera i aies ih hear failure. Hoeer, aerse smoms or sigs ofe iscourages coiuaio or icreases i osage of his meicaio. We seculae ha sichig o isorolol oul hel aoi aerse smoms a sigs relae o careilol amiisraio.Methods: Daa ere reroseciel collece from 23 aies ih hear failure (age 57±18 ears, NHA 2.±0.7, lef ericular ejecio fracio (LVE) 33±15%) ho coul o icrease heir osage of careilol (5.0±3.43 mg) ecause of aerse smoms (iiess, scoe) or sigs (hoesio: ssolic loo ressure (SB) <90 mmHg). Six mohs afer sichig o isorolol, e chece smoms, ial sigs, laoraor aa a cliical saus (NHA class). urhermore, lef ericular (LV) imesio a coracio ere ealuae i 17 of 23 aies usig echocariograh.Results: All of 13 smomaic aies (100%) a 5 of 10 asmomaic aies (50%) ere reliee of aerse smoms or sigs. The ose of isorolol as icrease from 1.84±1.08 o 3.13±1.74 mg (<0.01). A -moh follo-u examiaios, LV fucio measure LVE as sigiical imroe, accomaie imroeme of exercise olerace.Conclusions: Sichig from careilol o isorolol ma hel ih coiuaio of ʼ-locer reame as ell as osage icrease i aies ih aerse smoms or sigs, alloig hem o reach he arge ose.arameers Baselie mohs alueSB, mmHg 94.1±44.1 109.4±55.1 <0.05HR, m 77.1±38.2 74.±37.2 NSNHA class 2.±1.2 2.4±1.1 <0.05H, mg/l 11.±5.9 12.0±.2 NSCre, mg/l 1.08±0. 1.25±0.78 <0.01BN, g/ml 340.8±417.2 374.9±529.5 NSLVD, mm 59.8±31.5 58.0±31.5 NSLVDs, mm 51.4±27.9 4.2±25.7 <0.01LVE, % 30.3±18.1 39.4±21.8 <0.001