Ryo Otsuka

Automated Assessment of Left Atrial Function From Time-Left Atrial Volume Curves Using a Novel Speckle Tracking Imaging Method

BACKGROUND Using a novel speckle-tracking imaging method, time-left atrial (LA) volume curves (TLAVCs) can be automatically obtained. The aim of this study was to evaluate whether this method can be used for the measurement of LA function with TLAVCs. METHODS In 10 normal subjects and 20 patients, apical 4-chamber images were obtained. Maximum volume, reservoir volume, conduit volume, booster pump volume, and minimum volume were measured from TLAVCs. The results were compared with those obtained by the manual tracing method on every frame during 1 cardiac cycle. RESULTS There was good agreement between the speckle-tracking imaging and manual methods for maximum LA volume (r = 0.98, P < .001), reservoir volume (r = 0.82, P < .001), conduit volume (r = 0.87, P < .001), booster pump volume (r = 0.80, P < .001), and minimum volume (r = 0.98, P < .001). The time to obtain TLAVCs was significantly shorter with the speckle-tracking imaging method (64 +/- 22 seconds) than with the manual method (22 +/- 4 minutes). CONCLUSION TLAVCs obtained using the speckle-tracking imaging method can be used for the rapid and noninvasive automated quantitation of LA function.

Noninvasive coronary flow velocity reserve measurement in the posterior descending coronary artery for detecting coronary stenosis in the right coronary artery using contrast-enhanced transthoracic Doppler echocardiography.

Background: Coronary flow velocity reserve (CFVR) measurement by transthoracic Doppler echocardiography (TTDE) has been found to be useful for assessing left anterior descending coronary artery (LAD) stenosis. However, this method has been restricted only for the LAD. The purpose of this study was to detect severe right coronary artery (RCA) stenosis by CFVR measurement using contrast‐enhanced TTDE. Methods: In 60 consecutive patients with angina pectoris (mean (SD) age: 60 (11), 18 women), coronary flow velocities in the RCA were recorded in the postero‐descending coronary artery by contrast‐enhanced TTDE at rest and during hyperemia induced by intravenous infusion of adenosine triphosphate (140 mcg/ml/kg). CFVR was calculated as the ratio of hyperemic to basal peak and mean diastolic flow velocity. CFVR measurements by TTDE were compared with the results of coronary angiography performed within 1 week. Results: Coronary flow velocity was successfully recorded in 49 (82%) of the 60 patients with contrast agent. CFVR (mean (SD)) was 1.4 (0.4) in patients with, and 2.6 (0.6) in patients without significant stenosis in the RCA (%diameter stenosis > 75%, P < 0.001). Using the cutoff value 2.0 for CFVR in the RCA, its sensitivity and specificity in detecting significant stenosis in the RCA were 88% and 91%, respectively. Conclusion: CFVR measurement in the postero‐descending coronary artery by contrast enhanced TTDE is a new, noninvasive method to detect significant stenosis in the RCA. (ECHOCARDIOGRAPHY, Volume 21, April 2004)

Clinical utility of new real time three-dimensional transthoracic echocardiography in assessment of mitral valve prolapse.

Background: Noninvasive and accurate assessment of mitral valve anatomy has become integral in the presurgical evaluation of patients with mitral valve prolapse (MVP). Recently developed real time three‐dimensional (RT3D) ultrasound allows online acquisition, rendering, and can provide accurate information on cardiac structures. We sought to evaluate the feasibility of RT3D for the assessment of MVP segments when compared with transesophageal echocardiography (TEE) and intraoperative findings. Methods: We examined 42 patients with MVP using RT3D, two‐dimensional (2D) transthoracic echocardiography (TTE) and TEE. For RT3D analysis, cropping planes were used to slice the 3D volume on line to visualize the prolapsed segments of the mitral valve leaflets. The mitral valve was divided into six segments based on the American Society of Echocardiographys recommendations. Two experienced cardiologists evaluated echocardiographic images. Results: Adequate RT3D images of the mitral valve were acquired in 40 out of 42 patients. The sensitivity and specificity of RT3D for defining prolapsed segments when compared with TEE were 95% and 99%, respectively (anterior leaflet: 96% and 99%, posterior leaflets: 93% and 100%, respectively). The sensitivity and specificity of TTE were 93% and 97%, respectively (anterior leaflet: 96% and 98%, posterior leaflets: 90% and 97%, respectively). Interobserver agreement for RT3D (Kappa 0.95, 95% confidence interval [CI] 0.91–1.00) was significantly greater than for TTE (Kappa 0.85, 95% CI 0.78–0.93) (P < 0.05). The elapsed time for completion of RT3D (14.4 ± 2.8 min) was shorter than for TEE (26.4 ± 4.7 min, P < 0.0001) and TTE (19.0 ± 3.1 min, P< 0.0001). Conclusions: RT3D is fast, accurate, and highly reproducible for assessing MVP.

Beneficial effect of short term intake of red wine polyphenols on coronary microcirculation in patients with coronary artery disease

Previous studies have shown the antioxidant effects of polyphenols in red wine.1–4 An acute effect of red wine on the coronary microcirculation has been shown in healthy volunteers, although neither white wine nor vodka had an acute effect on coronary microcirculation in that study.5 Thus, we hypothesised that the coronary microcirculation can be improved by a daily intake of red wine polyphenols without alcohol. In addition, this effect may be seen not only in the healthy person but also in the patient with coronary artery disease (CAD). Recent advances in transthoracic Doppler echocardiography (TTDE) have enabled non-invasive assessment of coronary flow velocity reserve (CFVR) in the clinical setting.6,7 This non-invasive technique has made serial assessment of CFVR after daily intake of red wine polyphenols possible even in patients with CAD. The purpose of this study was to evaluate the short term effect of taking red wine polyphenols on the coronary microcirculation by using TTDE to assess patients with CAD. Ten male patients with angiographically documented CAD were recruited for this study (mean (SD) age 61 (7) years, body mass index 28.5 (5.2) kg/cm2) in New York, USA and Osaka, Japan from October 2000 to March 2002. Exclusion criteria were as follows: (1) anterior myocardial infarction (MI); (2) significant stenosis (> 50%) in the left anterior descending coronary artery; (3) recent MI (< 6 months); (4) severely disturbed cardiac function (ejection fraction < 40%); (5) uncontrolled hypertension (systolic …

Effects of Ultrasonic Exposure Parameters on Myocardial Lesions Induced by High-Intensity Focused Ultrasound

Objective. This study evaluated variables relevant to creating myocardial lesions using high‐intensity focused ultrasound (HIFU). Without an effective means of tracking heart motion, lesion formation in the moving ventricle can be accomplished by intermittent delivery of HIFU energy synchronized by electrocardiographic triggering. In anticipation of future clinical applications, multiple lesions were created by brief HIFU pulses in calf myocardial tissue ex vivo. Methods. Experiments used f‐number 1.1 spherical cap HIFU transducers operating near 5 MHz with in situ spatial average intensities of 13 and 7.4 kW/cm2 at corresponding depths of 10 and 25 mm in the tissue. The distance from the HIFU transducer to the tissue surface was measured with a 7.5‐MHz A‐mode transducer coaxial and confocal with the HIFU transducer. After exposures, fresh, unstained tissue was dissected to measure visible lesion length and width. Lesion dimensions were plotted as functions of pulse parameters, cardiac structure, tissue temperature, and focal depth. Results. Lesion size in ex vivo tissue depended strongly on the total exposure time but did not depend strongly on pulse duration. Lesion width depended strongly on the pulse‐to‐pulse interval, and lesion width and length depended strongly on the initial tissue temperature. Conclusions. High‐intensity focused ultrasound creates well‐demarcated lesions in ex vivo cardiac muscle without damaging intervening or distal tissue. These initial studies suggest that HIFU offers an effective, noninvasive method for ablating myocardial tissues to treat several important cardiac diseases.

Long-acting calcium channel antagonist pranidipine prevents ventricular remodeling after myocardial infarction in rats

SummaryThe purpose of this study was to examine the effects of the long-acting calcium channel antagonist pranidipine on ventricular remodeling, systolic and diastolic cardiac function, circulating humoral factors, and cardiac mRNA expression in myocardial infarcted rats. Myocardial infarction (MI) was produced by ligation of the coronary artery in Wistar rats. Three mg/kg per day of pranidipine was randomly administered to the infarcted rats. Hemodynamic measurements, Doppler echocardiographic examinations, analyses of the plasma levels of humoral factors, and myocardial mRNA expression were performed at 4 weeks after myocardial infarction. Left ventricular end-diastolic pressure (LVEDP) and central venous pressure (CVP) increased to 24.2 ± 1.2mmHg and 5.4 ± 0.6mmHg. Pranidipine reduced LVEDP and CVP to 13.6 ± 1.4mmHg (P < 0.01) and 2.5 ± 0.4mmHg (P < 0.01). The weight of the left and right ventricles in MI was significantly higher than in the sham-operated rats (sham, 2.02 ± 0.04 and 0.47 ± 0.02g/kg; MI, 2.18 ± 0.05 and 0.79 ± 0.04g/kg;P < 0.01). Left ventricular end-diastolic dimension (LVDd) in MI increased to 10.3 ± 0.3mm (P < 0.01) (sham, 6.4 ± 0.3mm). Pranidipine prevented an increase in the weight of the left and right ventricles (2.02 ± 0.04 and 0.6 ± 0.03g/kg,P < 0.01) and LVDd (7.9 ± 0.2mm,P < 0.01 to MI). Plasma renin activity (PRA), and plasma epinephrine, norepinephrine, and dopamine concentrations in MI were higher than those of the sham-operated rats. Pranidipine decreased the PRA and plasma cathecolamine levels of the myocardial infarcted rats to the level of the sham-operated rats. Moreover, the rats in MI showed systolic dysfunction, shown by decreased fractional shortening (sham, 31 ± 2% vs MI, 15 ± 1%;P < 0.01) and diastolic dysfunction shown by the E-wave deceleration rate (sham, 12.8 ± 1.1 m/s2; MI, 32.6 ± 2.1m/s2;P < 0.01). Pranidipine significantly prevented systolic and diastolic dysfunction. The increases in β-myosin heavy chain (MHC), α-skeletal actin, and atrial natriuretic polypeptide mRNAs in the noninfarcted left ventricle and right ventricle at 4 weeks after the myocardial infarction were significantly suppressed by the treatment with pranidipine. On the other hand, depressed α-MHC was restored to normal levels by pranidipine in both regions. In conclusion, pranidipine prevents the left ventricular remodeling process accompanied by systolic and diastolic dysfunction, and inhibits abnormal cardiac gene expression after myocardial infarction.

Comparison of ventricular geometry for two real time 3D ultrasound machines with three dimensional level set

This paper presents new results for segmentation of 3D ultrasound using a robust and smooth segmentation method based on a homogeneity-driven three dimensional level set algorithm. The segmentation was applied to echocardiographic data from healthy volunteers acquired with two 3D ultrasound machines based on matrix-phased array technology. A comparison of ventricular volumes and geometry is performed based on manual and automatic methods of segmentation. Results showed good agreement of the segmentation methods and the ultrasound machines for ventricular geometry and quantitative assessment of cardiac function.

Feasibility of In‐Vivo Cardiac HIFU Ablation

The potential for cardiac applications of HIFU remains largely unexplored. In order to create reproducible lesions in a beating heart, it is necessary to maintain focusing at a certain position within moving myocardial tissue. One technique is to use multiple short HIFU exposures (0.2 s) and to synchronize them with an EKG signal and respiration. In order to investigate the interaction of HIFU exposures and cardiac tissues, a series of in‐vitro experiments was conducted. The left ventricular free wall (LVFW) of calf hearts were cut into 4‐cm cubes, degassed in phosphate buffer saline (PBS), and heated to 37C. Several transducers were employed. Most experiments used a 33‐mm diameter spherical‐cap transducer with focal length of 35 mm, operated at a frequency of 5.075 MHz and a focused intensity of 13 kW/cm2 (in‐situ spatial average over the half‐power points of the focused beam). The transducer was coupled to the LVFW using degassed PBS. First, the effects of pericardial fat, focal depth, and temperature o...

Feasibility of in vivo cardiac HIFU ablation

The potential for cardiac applications of HIFU remains unexamined. In order to create reproducible lesions in a beating heart, it is necessary to maintain focusing at a certain position within moving myocardial tissue. One technique is to use multiple short HIFU exposures (0.2 s) and synchronize them with an EKG signal and respiration. The left ventricular free wall (LVFW) of calf hearts were cut into 4‐cm cubes, degassed in phosphate buffer saline (PBS), and heated to 37 °C. An 80‐mm‐diam spherical‐cap transducer with a focus of 90 mm was operated at a frequency of 4.67 MHz and a nominal focal point intensity of 26.9 kW/cm2. The transducer was coupled to the LVFW using degassed PBS. First, the effect of pericardial fat, focal depth, and temperature on lesion size was individually evaluated. Then the 0.2‐s HIFU exposure was applied 10 to 30 times at 4‐s intervals. The same HIFU transducer was applied to an open‐chest canine LVFW with the same triggering protocol. Dimensions of all lesions were measured...

Intermittent chest pain with marked ST depression after 13 years of aortic valve replacement.

An 80-year-old woman who underwent aortic valve replacement with a 19-mm Medtronic Hall prosthetic valve in 1993 was admitted because of intermittent chest pain. Electrocardiography on admission revealed non-specific changes, but electrocardiography during chest pain revealed significant ST depression. Coronary angiography revealed no significant stenosis. Echocardiography revealed intermittent severe aortic regurgitation and incomplete closure of the prosthetic valve in diastole. An urgent operation was performed, and abnormal pannus formation was observed at the left ventricular side of the prosthetic valve. In this case, intermittent diastolic valvular sticking caused severe aortic regurgitation and induced serious myocardial ischemia.