Myung-Ki Seo

Influence of ZnO evaporation on the microwave dielectric properties of La(Zn12Ti12)O3

Microwave dielectric properties of the complex perovskite compound La(Zn12Ti12)O3 (LZT) and the effect of ZnO evaporation on the quality factor were examined. The results show that ZnO evaporation was related with the increase in quality factor. The comparison between weight loss and XRD data shows that defects were induced in the samples sintered in air. To investigate the correlation between quality factor and ZnO evaporation, samples sintered in both air and a ZnO atmosphere were examined. The characterization techniques used for this investigation were XRD and TEM. Samples sintered in a ZnO atmosphere have lower quality factor than those sintered in air. The results were compared to the previously reported case of Ba(Zn13Ta23)O3. The variation of quality factor of LZT samples sintered in a ZnO atmosphere was not related to the degree of cation ordering, lattice distortion and second phase.

Safety and efficacy of a novel hyperaemic agent, intracoronary nicorandil, for invasive physiological assessments in the cardiac catheterization laboratory.

AIMS Maximal hyperaemia is a key element of invasive physiological studies and adenosine is the most commonly used agent. However, infusion of adenosine requires additional venous access and can cause chest discomfort, bronchial hyper-reactivity, and atrioventricular conduction block. The aim of this study was to evaluate the feasibility and efficacy of intracoronary (IC) nicorandil as a novel hyperaemic agent for invasive physiological studies. METHODS AND RESULTS We enrolled 210 patients who underwent fractional flow reserve (FFR) measurement. Hyperaemic efficacy of the following methods was compared: IC bolus injection of adenosine; intravenous (i.v.) infusion of adenosine (140 μg/kg/min); and IC bolus of nicorandil (1 and 2 mg). In 70 patients, the index of microcirculatory resistance was also measured. Hyperaemic efficacy of IC nicorandil 2 mg was non-inferior to that of i.v. adenosine infusion (FFR: 0.82 ± 0.10 vs. 0.82 ± 0.10; P for non-inferiority < 0.001). There was a strong correlation between FFRs measured by i.v. adenosine and IC nicorandil (R² = 0.934). Nicorandil produced fewer changes in blood pressure, heart rate and PR interval, and less chest pain than adenosine (all P-values < 0.05). Atrioventricular block occurred in 12 patients with IC adenosine, 4 patients with i.v. adenosine and none with IC nicorandil. The index of microcirculatory resistance was 18.3 ± 8.7 with i.v. adenosine and 17.2 ± 7.6 with IC nicorandil (P = 0.126). CONCLUSION This study suggests that IC bolus injection of nicorandil is a simple, safe, and effective way to induce steady-state hyperaemia for invasive physiological evaluations. Clinicaltrials.gov number: NCT01331902.

Comparison of Hyperemic Efficacy Between Central and Peripheral Venous Adenosine Infusion for Fractional Flow Reserve Measurement

Background— Maximal hyperemia is a prerequisite for the accurate measurement of fractional flow reserve (FFR). Although continuous infusion of adenosine via the femoral vein is considered to be the gold standard, this requires an additional invasive procedure for femoral vein access and is difficult to use during transradial coronary catheterization. We performed this prospective study to evaluate the feasibility and efficacy of peripheral intravenous infusion of adenosine for FFR measurement. Methods and Results— Seventy-one patients were prospectively enrolled, and FFR was measured using a 0.014-inch coronary pressure wire. Hyperemic efficacy of adenosine was compared among intracoronary bolus injection and continuous IV infusion (140 &mgr;g/min/kg) via the femoral and via the forearm vein. In 20 patients, hyperemic mean transit time and index of microcirculatory resistance were also measured. Mean FFR after bolus administration of adenosine was 0.81±0.10. As compared with femoral vein infusion (FFR: 0.80±0.10), hyperemic efficacy of forearm vein infusion of adenosine (FFR: 0.80±0.11) was not inferior (P for noninferiority=0.01). The number of functionally significant stenoses (FFR <0.75) was also not different between the 2 methods (femoral vein versus forearm vein; 17 (25.0%) versus 17 (25.0%), P=1.0). Both hyperemic mean transit time and index of microcirculatory resistance were not different between the 2 routes of adenosine infusion. Additional bolus injection of adenosine during IV infusion did not improve the hyperemic efficacy but increased the risk of atrioventricular block. Conclusions— This study suggests that continuous intravenous infusion of adenosine via the forearm vein is a convenient and effective way to induce steady-state hyperemia for invasive physiological measurements. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01070420.

Impact of Loading Condition on the 2D Speckle Tracking–Derived Left Ventricular Dyssynchrony Index in Nonischemic Dilated Cardiomyopathy

Background—The effects of left ventricular (LV) loading conditions on LV dyssynchrony have not been elucidated. We modified LV loading conditions to reveal their effects on echocardiography-derived LV dyssynchrony index (LVdys) in patients with documented nonischemic dilated cardiomyopathy. Methods and Results—Thirty-seven patients were consecutively enrolled. After baseline measurements, pneumatic compression of the lower extremities (Pcom) was used to increase LV afterload. Subsequently, sublingual nitroglycerin (SL-NG) was administered to modify preload. Conventional echocardiographic parameters, LVdys (by speckle-tracking radial strain analysis) and LV end-systolic wall stress (LV-ESWS), were calculated under each condition. LVdys-6 (defined as the maximal difference in time-to-peak radial strain between 6 myocardial segments) and LV-ESWS increased under Pcom (for LVdys-6, 159±117 at baseline versus 239±140 ms under Pcom, P<0.05; for LV-ESWS, 191±63 versus 228±80 g/m2, P<0.05) After SL-NG application, both parameters decreased significantly (for LVdys-6, 239±140 under Pcom versus 147±103 ms after SL-NG, P<0.05; for LV-ESWS, 228±80 under Pcom versus 189±67 g/m2 after SL-NG, P<0.05). When the presence of LV dyssynchrony was defined as the absolute difference in time-to-peak radial strain between the anteroseptal and posterior segments (LVdys-2), the results were unchanged. Using 130 ms as a cutoff value, the proportion of patients with LV dyssynchrony changed significantly (29.7% at baseline, 45.9% under Pcom, and 35.1% after SL-NG). When the presence of LV dyssynchrony was defined as standard deviation of the time to peak radial strain for 6 segments (LVdys-SD), the results were same. LVdys and LV-ESWS showed a modest but significant association with each other (r=0.47, P<0.001 for LVdys-6; r=0.41, P<0.001 for LVdys-2; r=0.46, P<0.001 for LVdys-SD). Conclusions—To the best of our knowledge, the present study provides the first evidence of a significant association between LVdys and LV loading status, reflective of a dynamic nature of LVdys. Accordingly, LV loading conditions should be taken into account when echocardiographic LVdys is used for clinical decision-making of selecting candidates for cardiac resynchronization therapy or when it is used as a surrogate marker of prognosis.

Synchronicity of LV Contraction as a Determinant of LV Twist Mechanics: Serial Speckle-Tracking Analyses in WPW Syndrome Before and After Radiofrequency Catheter Ablation

OBJECTIVES This study set out to investigate the isolated impact of synchronous patterns of left ventricular (LV) contraction (i.e., LV synchronicity) on LV twist behavior. BACKGROUND Although the relationships between LV loading status/LV contractility and twist are well-established, no data are available regarding the relation between LV twist and LV synchronicity, without any interference by changes in LV pre-load, afterload, and contractility. Serial assessment of patients with Wolff-Parkinson-White syndrome before and after radiofrequency catheter ablation (RFCA) allows this to be explored. METHOD Of the 40 Wolff-Parkinson-White patients initially screened, 34 were enrolled. Two-dimensional and Doppler echocardiography along with speckle tracking-derived LV twist mechanics, apical-basal rotation delay, and left ventricular dyssynchrony index (LVdys) were obtained before and after RFCA. The LVdys was defined as the maximal delay in time-to-peak radial strain of different LV segments at the papillary muscle level. RESULTS Overall, no significant changes were demonstrated in LV volumes, systolic and diastolic function, and end-systolic wall stress before versus after RFCA. After RFCA, median value of LVdys was attenuated from 33.5 (interquartile range [IQR]: 14.0 to 84.3) to 14.0 (IQR: 11.5 to 21.8) (p = 0.002), which was accompanied by a reduction in apical-basal rotation delay from 9.7% (IQR: 3.5 to 23.7) to 3.3% (IQR: 1.3 to 8.0) (p = 0.004). In contrast, LV twist increased from 14.2° (IQR: 9.1° to 18.4°) before to 19.7° (IQR: 15.0° to 22.6°) after RFCA (p = 0.002). Delta LV twist pre- to post-RFCA displayed a significant inverse correlation with changes in apical-basal rotation delay (r = -0.42, p = 0.01) and Delta LVdys (r = -0.39, p = 0.02). CONCLUSIONS The LV synchronous contraction is significantly related to LV twist.

Assessment of the Efficacy and Tolerability of 2 Formulations of Atorvastatin in Korean Adults With Hypercholesterolemia: A Multicenter, Prospective, Open-Label, Randomized Trial

BACKGROUND A manufacturer of atorvastatin is seeking marketing approval in Korea of a generic product for adult patients with primary hypercholesterolemia. OBJECTIVE The objective of this study was to compare the efficacy and tolerability of a new generic formulation of atorvastatin (test) with those of an original formulation of atorvastatin (reference) to satisfy regulatory requirements for marketing of the generic product in Korea. METHODS Patients enrolled were aged 20 to 79 years with documented primary hypercholesterolemia who did not respond adequately to therapeutic lifestyle changes and with a LDL-C level >100 mg/dL from a high-risk group of coronary artery disease patients. Eligible patients were randomized to receive 1 of the 2 formulations of atorvastatin 20 mg per day for 8 weeks. The primary end point was the percent change in LDL-C level from baseline to week 8. Secondary end points included the percent change in total cholesterol, triglycerides, HDL-C level, apolipoprotein B:apolipoprotein A-I ratio, LDL:HDL ratio, LDL-C particle size, high-sensitivity C-reactive protein from baseline to week 8, and achievement rate of the LDL-C goal. RESULTS A total of 298 patients (141 men and 157 women; 149 patients in each group; mean [SD] age, 62.4 [9.2] in the test group vs 60.3 [8.9] years in the reference group) were included. LDL-C levels were significantly decreased from baseline to week 8 in both groups, and there was no significant difference in the percent change in LDL-C level between groups (-44.0% [17.2%] in the test group, -45.4% [16.9%] in the reference group; P = 0.49). The between-group differences in the percent changes in total cholesterol and triglyceride levels were not statistically significant. In addition, there was no significant difference between the 2 groups in percent changes in HDL-C, apolipoprotein B:apolipoprotein A-I ratio, LDL-C:HDL-C ratio, LDL-C particle size, high-sensitivity C-reactive protein, and the achievement rate of the LDL-C goal. Two (1.3%) patients in the reference group (N = 150) experienced treatment-related serious adverse events (AEs): toxic hepatitis and aggravation of chest pain. Common AEs were cough (4.1%), myalgia (2.1%), and indigestion (1.4%) in the test formulation group and cough (5.3%), creatine kinase elevation (2.7%), and edema (0.7%) in the reference formulation group; however, the differences in overall prevalence of AEs between the 2 treatment groups was not significant (P = 0.88). CONCLUSIONS There were no significant differences observed in the efficacy and tolerability between the test and reference formulations of atorvastatin in these Korean adult patients with primary hypercholesterolemia.

Beneficial Effect of Efonidipine, an L- and T-Type Dual Calcium Channel Blocker, on Heart Rate and Blood Pressure in Patients With Mild-to-Moderate Essential Hypertension

Background and Objectives Efonidipine hydrochloride, an L- and T-type dual calcium channel blocker, is suggested to have a heart rate (HR)-slowing action in addition to a blood pressure (BP)-lowering effect. The aim of this study was to determine the effect of efonidipine on HR and BP in patients with mild-to-moderate hypertension. Subjects and Methods In a multi-center, prospective, open-labeled, single-armed study, we enrolled 53 patients who had mild-to-moderate hypertension {sitting diastolic BP (SiDBP) 90-110 mmHg}. After a 2-week washout, eligible patients were treated with efonidipine (40 mg once daily for 12 weeks). The primary end point was the change in HR from baseline to week 12. The secondary end-point included the change in trough sitting BP and 24-hour mean BP between baseline and week 12. Laboratory and clinical adverse events were monitored at each study visit (4, 8, and 12 weeks). Results Fifty-two patients were included in the intention-to-treat analysis. After 12 weeks of treatment with efonidipine, the resting HR decreased significantly from baseline to week 12 {from 81.5±5.3 to 71.8±9.9 beats/minute (difference, -9.9±9.0 beats/minute), p<0.0001}. The trough BP {sitting systolic blood pressure (SiSBP) and SiDBP} and 24-hour mean BP also decreased significantly (SiSBP: from 144.6±8.2 to 132.9±13.5 mmHg, p<0.0001; SiDBP: from 96.9±5.4 to 88.3±8.6 mmHg, p<0.0001, 24-hour mean systolic BP: from 140.4±13.5 to 133.8±11.6 mmHg, p<0.0001; 24-hour mean diastolic BP: from 91.7±8.7 to 87.5±9.5 mmHg, p<0.0001). Conclusion Efonidipine was effective in controlling both HR and BP in patients with mild-to-moderate hypertension.

Electrocardiographic QRS duration reflects right ventricular remodeling in patients undergoing corrective surgery for isolated tricuspid regurgitation: a comparative study with cardiac magnetic resonance imaging.

The role of electrocardiogram (ECG) is unclear for the longitudinal follow‐up of patients who undergo corrective surgery for isolated severe tricuspid regurgitation (TR).

MECHANISM OF SIDE BRANCH JAILING IN BIFURCATION LESION: PLAQUE OR CARINA SHIFT?

Authors: Ji-Hyun Kim, Bon-Kwon Koo, Myung-Ki Seo, Seung-Jung Park, Kyung Woo Park, Hye-Young Lee, Hyun-Jae Kang, Hyo-Soo Kim, Byung-Hee Oh, Young-Bae Park, Chang-Wook Nam, Seung-Ho Hur, Donghoon Choi, Yangsoo Jang, Joo-Yong Hahn, Hyeon-Cheol Gwon, Myeong-Ho Yoon, SeungJea Tahk, Woo-Young Chung, Young-Seok Cho, Dong-Ju Choi, Sung Jin Oh, Yasuhiro Honda, Peter J. Fitzgerald, William F. Fearon, Seoul National University hospital, Seoul, South Korea, Stanford University Medical center, Stanford, CA