Ju Hwan Lee

Intravascular ultrasound guided recanalization of stumpless chronic total occlusion

BACKGROUND The recanalization success rate of blunt and vague stump (stumpless) CTO lesions, especially those with a side branch arising from the occlusion, has been significantly lower than that of tapered stump CTO lesions. Intravascular ultrasound (IVUS) may be useful to identify the occlusion point and may facilitate the passage of guide-wires. We evaluated the clinical feasibility of the IVUS-guided wiring technique for stumpless CTO lesions. METHODS Thirty-one consecutive patients (7 women; mean age: 61.0 ± 8.9 years) with 32 lesions were enrolled. The IVUS catheter was introduced into the side branch and it was withdrawn from the side branch to find the entry point of the occlusion, trying to engage another stiffer guide-wire on the occlusion point with the help of real-time IVUS imaging. RESULTS The left anterior descending artery was the most common target-lesion location (22 lesions [69%]). CTO lesions were successfully reopened in 26 lesions (81%). IVUS guidance allowed confident navigation of the stiff guide-wires. The entry point could not be identified in one, and full guide-wire passage was impossible in 4 with the IVUS guidance; TIMI 3 flow could not be achieved even after stent deployment in 1. Although procedure-related complications developed in 8 lesions (25%), no events were serious. Emergent operation was not needed and death or fatal myocardial infarction did not develop during or after the procedures. CONCLUSIONS The IVUS-guided wiring technique is useful and safe for the recanalization of stumpless CTO lesions and might be a valuable tool for the recanalization of complex CTO lesions.

Electrocardiography patterns and the role of the electrocardiography score for risk stratification in acute pulmonary embolism.

Background and Objectives Data on the usefulness of a combination of different electrocardiography (ECG) abnormalities in risk stratification of patients with acute pulmonary embolism (PE) are limited. We thus investigated 12-lead ECG patterns in acute PE to evaluate the role of the ECG score in risk stratification of patients with acute PE. Subjects and Methods One hundred twenty-five consecutive patients (63±14 years, 56 men) with acute PE who were admitted to Kyungpook National University Hospital between November 2001 and January 2008 were included. We analyzed ECG patterns and calculated the ECG score in all patients. We evaluated right ventricular systolic pressure (RVSP) (n=75) and RV hypokinesia (n=80) using echocardiography for risk stratification of acute PE patients. Results Among several ECG findings, sinus tachycardia and inverted T waves in V1-4 (39%) were observed most frequently. The mean ECG score and RVSP were 7.36±6.32 and 49±21 mmHg, respectively. The ECG score correlated with RVSP (r=0.277, p=0.016). The patients were divided into two groups {high ECG-score group (n=38): ECG score >12 and low ECG-score group (n=87): ECG score ≤12} based on the ECG score, with the maximum area under the curve. RV hypokinesia was observed more frequently in the high ECG-score group than in the low ECG-score group (p=0.006). Multivariate analysis revealed that a high ECG score was an independent predictor of high RVSP and RV hypokinesia. Conclusion Sinus tachycardia and inverted T waves in V1-4 were commonly observed in acute PE. Moreover, the ECG score is a useful tool in risk stratification of patients with acute PE.

The impact of circadian variation on 12-month mortality in patients with acute myocardial infarction.

Background and Objectives Although circadian variation in the onset of acute myocardial infarction (AMI) has been reported in a number of studies, not much is known about the impact of circadian variation on 12-month mortality. The aim of this study was to investigate the impact of circadian variation on 12-month mortality in patients with AMI. Subjects and Methods Eight hundred ninety two patients (mean age 67±12; 66.1% men) with AMI who visited Kyungpook National University Hospital from November 2005 to December 2007 were included in this study. Patients were divided into groups based on four 6-hours intervals: overnight (00:00-05:59); morning (06:00-11:59); afternoon (12:00-17:59) and evening (18:00-23:59). Results Kaplan-Meier survival curves showed 12-month mortality rates of 9.6%, 9.1%, 12.1%, and 16.7% in the overnight, morning, afternoon, evening-onset groups, respectively (p=0.012). Compared with the morning-onset AMI group, the serum creatinine levels (p=0.002), frequency of Killip class ≥3 (p=0.004), and prescription rate of diuretics (p=0.011) were significantly higher in the evening-onset AMI group, while the left ventricular ejection fraction (p=0.012) was significantly lower. The proportion of patients who arrived in the emergency room during routine duty hours was significantly lower in evening-onset groups irrespective of the presence or absence of ST-segment elevation (p<0.001). According to univariate analysis, the 12-month mortality rate in the evening group was significantly higher compared to the morning group (hazard ratio 1.998, 95% confidence interval 1.196 to 3.338, p=0.008). Conclusion Patients with evening-onset AMI had poorer baseline clinical characteristics, and this might affect the circadian impact on 12-month mortality. Further studies are needed to clarify the role of circadian variation on the long-term outcome of AMI.

Prognosis and natural history of drug-related bradycardia.

Background and Objectives The prognosis and natural history of bradycardia related to drugs such as beta-blockers and non-dihydropyridine calcium channel blockers are not well known. Subjects and Methods We retrospectively analyzed 38 consecutive patients (age 69±11, 21 women) with drug-related bradycardia (DRB) between March 2005 and September 2007. A drug-associated etiology for the bradycardia was established based on the medical history and patient response to drug discontinuation. The mean follow-up duration was 18±8 months. Results The initial electrocardiogram (ECG) showed sinus bradycardia (heart rate ≤40/min) in 13 patients, sinus bradycardia with junctional escape beats in 18 patients, and third-degree atrioventricular (AV) block in seven patients. Drug discontinuation was followed by resolution of bradycardia in 60% of patients (n=23). Among them, five (17.8%) patients resumed taking the culprit medication after discharge and none developed bradycardia again. Bradycardia persisted in 10 (26.3%) patients despite drug withdrawal, and a permanent pacemaker was implanted in seven of them. Third-degree AV block, QRS width, and bradycardia requiring temporary transvenous pacing were significantly associated with the bradycardia caused by drugs. Conclusion Beta-blockers were the most common drugs associated with DRB. However, in one quarter of the cases the DRB was not associated with drugs; in these patients permanent pacemaker implantation should be considered.

Gender Differences Among Korean Patients With Coronary Spasm

Background and Objectives The gender differences among Korean patients with coronary spasm have not been defined. We thus determined the gender differences among Korean patients with coronary spasm. Subjects and Methods Patients with chest pain and/or syncope who were admitted to Kyungpook National University Hospital between January 2001 and August 2008 were included. Provocation of coronary vasospasm with intracoronary ergonovine maleate was performed when baseline coronary angiography showed no significant stenosis or there was a strong clinical suspicion of coronary spasm. The clinical characteristics were analyzed from 104 consecutive patients (56±9 years of age; 21 females) who were diagnosed with coronary spasm. Results Female patients were younger (52±7 vs. 57±10 years, p=0.046) with lower rates of smoking and alcohol consumption histories than male patients (19% vs. 65%, p<0.001; and 43% vs. 89%, p<0.001, respectively). The other clinical characteristics were not significantly different, except for the triglyceride levels. Conclusion The majority of patients with coronary spasm were males who were smokers and alcohol consumers. The female patients had lower rates of smoking and alcohol consumption, and they were younger than the male patients. Further studies are needed to investigate the relevance of gender differences in the pathogenesis of coronary spasm.

Impact of Multivessel Coronary Disease With Chronic Total Occlusion on One-Year Mortality in Patients With Acute Myocardial Infarction

Background and Objectives The impact of multivessel coronary disease (MVD) with chronic total occlusion (CTO) on one-year mortality in patients with acute myocardial infarction (AMI) is not clearly known. We investigated the impact of MVD with concurrent CTO lesion on one-year mortality in patients with AMI. Subjects and Methods We studied 1008 consecutive patients who underwent coronary angiography between November 2005 and December 2008 with a diagnosis of AMI. Results Among 1008 patients, 432 patients (43%) had MVD, and 88 patients (8.7%) had CTO lesion. The one-year overall mortality was higher in patients with MVD than in patients with single vessel disease (SVD) (10.2% vs. 5.9%, p=0.012). However, the one-year overall mortality was not significantly higher in patients with CTO lesion than in patients without that lesion (12.5% vs. 7.3%, p=0.080). In multivariate analysis, independent predictors of one-year overall mortality were age older than 65 years {hazard ratio (HR) 2.41, 95% confidence interval (CI): 1.43 to 4.08}, Killip class ≥III (HR 3.59, 95% CI: 2.24 to 5.77), ST-elevation myocardial infarction (HR 2.45, 95% CI: 1.49 to 4.05) and MVD (HR 1.76, 95% CI: 1.07 to 2.89). Conclusion Patients with MVD showed higher one-year mortality than patients with SVD. However, the presence of CTO was not an independent predictor of one-year mortality in this study that included patients with successfully revascularized CTO lesion.

Examining the relationship between triggering activities and the circadian distribution of acute aortic dissection.

Background and Objectives There are limited data examining triggering activities and circadian distribution at the onset of acute aortic dissection (AAD) in the context of diagnostic and anatomical classification. The aim of this study was to further investigate this relationship between triggering activities and circadian distribution at the onset of AAD according to diagnostic and anatomic classification. Subjects and Methods A total of 166 patients with AAD admitted to Kyungpook National University Hospital between July 2001 and June 2009 were included. To assess the influence of diagnostic and anatomical classification, we categorized the patients into intramural hematoma (IMH) group (n=67)/non-IMH group (n=99) and Stanford type A (AAD-A, n=94)/type B (AAD-B, n=72). To evaluate circadian distribution, the day was divided into four 6-hour periods: night (00-06 hours), morning (06-12 hours), afternoon (12-18 hours), and evening (18-00 hours). Results Most (72%) AAD episodes were related to physical (53%) and mental activities (19%), with about one-third occurring during the afternoon, and only 12% occurring at night. No differences in triggering activities or circadian distribution were observed among the groups. Waking hours including morning, afternoon, and evening correlated with triggering activities (p=0.003). These relationships were observed for the non-IMH (p=0.008) and AAD-B (p=0.003) cases. The remaining categories had similar relationships, but did not reach statistical significance. Conclusion Our findings suggest differences in the relationship between triggering activities and the circadian distribution of the onset of AAD according to diagnostic and anatomical classification.

Prediction of improvement in cardiac function by high dose dobutamine stress echocardiography in patients with recent onset idiopathic dilated cardiomyopathy

The prognosis of patients with recent onset idiopathic dilated cardiomyopathy (DCM) is grave and highly variable [1]. Dobutamine stress echocardiography (DSE) has been used to assess contractile reserve in patients with ischemic and idiopathic DCM. Several studies have suggested that contractile reserve assessed by DSE can be of prognostic value inpatientswith idiopathic DCM [2–5]. In this study,we investigated whether contractile reserve on DSE could predict late improvement of cardiac function and had incremental prognostic value for future cardiac events in recent onset idiopathic DCM. Between December 2004 and May 2011, forty-one patients were enrolled in this study. The study population consisted of patients with idiopathic DCMwho had symptom durations of less than 6 months. All study subjects underwent coronary angiography to exclude ischemic heart disease, and endomyocardial biopsies were performed in 35 patients (85%) to exclude reversible causes, such as myocarditis. Patients with chronic kidney disease (estimated glomerular filtration rate b60 ml/min/1.73 m) were also excluded. All patients had a complete echocardiographic study and follow-up echocardiogram was performed after 6 month and 12 month, then when any clinical events occurred. The interval between the time of DSE and last follow-up echocardiogramwas 16±15 months. Dobutamine was infused in 5-min dose increments, starting from 5 μg/kg/min and increasing to 10, 20, 30, and finally, to the maximal dose of 40 μg/kg/min. The infusion was discontinued before the maximal dose was reached if 85% of the maximal predicted heart rate for the age group was achieved, or if symptomatic complex ventricular arrhythmias, defined as the presence of multiform or repetitive ventricular extrasystoles, were observed. Beta-blockers were stopped 48 h before dobutamine testing in all patients taking these agents. The institutional committee of Kyungpook National University Hospital approved the study protocol. Informed consent was obtained in all patients. Cardiac death and hospitalization were combined end-point. The mean age of the patients was 50±14.8 years, and 24 patients (59%)weremale. During themean follow-up period of 30±24 months, 14 patients (34%) experienced cardiac events, and 5 (12%) of them died. Three (7%) of themwere sudden cardiac death, and two (4%) were low cardiac output death. Of the remaining patients, 9 (21%) were rehospitalized due to aggravation of heart failure. During dobutamine infusion, no significant complications occurred. Tenpatientsdidnot reachapeakdoseof dobutamine. Sixpatients reached maximal heart rates before thepeakdose of dobutamine, and in 4patients the test was stopped before the peak dose due to frequent premature complex. The mean value of the maximal dobutamine dose given was 35.6±8.7 μg/kg/min. We investigated the correlation between follow-up LVEFand clinical and echocardiographic parameters (Table 1). The followup LVEF correlated with baseline LVEDV (r=−0.519, p=0.001), LVESV (r=−0.499, p=0.001), LVEDV at peak dose (r=−0.509, p=0.001), LVEFat peakdose (r=0.692, pb0.001), and the changeof LVEF (r=0.515, p=0.001) from baseline to peak dose of dobutamine. Among them, LVEF at the peak dose of dobutamine was the most significant predictor of follow-up LVEF. Follow-up LVEFwas predicted by LVEF at the peak dose of DSE (y=1.033×−0.979, r=0.465, p=0.001). Receiver-operating characteristic analysis was used to determine the optimal cutoff value for predicting cardiac events with respect to the change of LVEF. The optimal change in LVEFwas 9.8%, The Kaplan–Meier survival estimates were stratified according to the results of baseline to peak LVEF variation during dobutamine administration (Fig. 1). The presence of inotropic response after dobutamine infusion, identified in this study as a change of LVEF≥9.8%, showed a significantly better outcome than little inotropic response (pb0.001). In the Cox-proportional hazard model, the change of LVEF from peak to baseline (hazard ratio [HR] 0.834, 95% confidence interval [CI] 0.713–0.976, p=0.024), in addition to age (HR 0.921, 95% CI 0.863– 0.984, p=0.015), log NT-ProBNP (HR 0.261, 95% CI 0.091–0.749, p=0.013), deceleration time (HR 0.964, 95% CI 0.932–0.998, p=0.039) and E/E′ ratio (HR 1.177, 95% CI 1.046–1.325, p=0.007) was also a significant independent predictor of cardiac event (Table 2). Moreover, the LVEF change in DSE had incremental prognostic value to

A Case of an Anomalous Hypertrophied Muscle Band in the Left Ventricle

A hypertrophied muscle band (HMB) in the left ventricle (LV), which can be misinterpreted as apical hypertrophic cardiomyopathy, is a rare echocardiographic finding in a patient with normal LV wall thickness. Not only are symptoms produced, but changes in the electrocardiogram (ECG) are limited to the repolarization phase and show no progression even in a large HMB. Hence, we report a case of a 25-year-old woman who visited a local medical clinic due to epigastric discomfort in January 2007. The 24-hour Holter ECG showed multiple premature ventricular complexes. An HMB (3.23 × 10.8 cm) was observed on two-dimensional echocardiography that ran toward the interventricular septum (IVS) across the LV and divided the LV into apical and basal cavities at the apical one-third of the LV. Although LV wall thickness showed normal range, flow acceleration was observed between the HMB and IVS and revealed dagger-shaped with a high pressure gradient up to 30 mmHg in continuous wave Doppler examination. Circumferential band-like myocardial hypertrophy was observed at the LV apex on cardiac magnetic resonance imaging. Myocardial thinning and prominent trabeculae were present from the proximal to distal HMB. However, contractility was normal at the myocardial thinning site, regional wall motion abnormality was not observed in cine images. Focal fatty accumulation was evident at the base of the HMB. Coronary angiography revealed no significant stenosis, whereas left ventriculography showed septation at the apical one-third of the LV. The patient was discharged without any medication.

A measurement system based on capacitance sensors for geometric errors of a miniaturized machine tool

Miniaturized machine tool (mMT) has been presented as a promising technique for machining miniature components due to its advantages such as miniaturized error sources, less heat dissipation and no limitation of the materials. To achieve submicron machining accuracy, geometric errors of a miniaturized machine tool should be accurately identified and compensated. In this paper, a novel multi-degree-of-freedom (DOF) measuring system is proposed for simultaneous measurement of two straightness, roll, yaw and pitch error motions along one moving axis of a miniaturized machining tool. The proposed system consists of five capacitance sensors and a sensing target. Readings of the sensors contain coupled information of all error motions. Based on homogeneous transformation matrix (HTM), the coupled relationships between the readings and error motions are obtained. An error estimation algorithm is developed for calculation of five geometric errors. Simulations are carried out to verify estimation accuracy and robustness of the algorithm