Comparison of Acceptable Noise Levels Using Korean and Non-Semantic Speech Signals in Normal Hearing Subjects / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The acceptable noise level (ANL) test measures the maximum noise level that a subject can tolerate while following speech. Given the limited investigation of ANL across different languages, this study aimed to compare ANLs using both Korean semantic speech and non-semantic speech signals (reversed Korean speech and international speech test signal, ISTS) in normal-hearing subjects. SUBJECTS AND METHOD: Twenty-five subjects with normal hearing (9 males, 16 females, with the mean age of 28.5±3.15 years) were included in the study. ANLs were obtained using three speech materials (Korean speech, reversed Korean speech, and ISTS) as the target speech material and an eight-talker babble noise as the competing background noise. RESULTS: Generally, the inter-subject variability was large. The ANLs did not differ statistically regardless of the type of speech signal. CONCLUSION: The ANLs seemed to be unaffected by the meaningfulness or semantic contents of the target speech, at least in normal-hearing adults. Thus, non-meaningful speech signals or non-semantic material can be considered as the target signal for the implementation of ANL test.

Fetal hematopoietic stem cells express MFG-E8 during mouse embryogenesis

The milk fat globule-EGF-factor 8 protein (MFG-E8) has been identified in various tissues, where it has an important role in intercellular interactions, cellular migration, and neovascularization. Previous studies showed that MFG-E8 is expressed in different cell types under normal and pathophysiological conditions, but its expression in hematopoietic stem cells (HSCs) during hematopoiesis has not been reported. In the present study, we investigated MFG-E8 expression in multiple hematopoietic tissues at different stages of mouse embryogenesis. Using immunohistochemistry, we showed that MFG-E8 was specifically expressed in CD34+ HSCs at all hematopoietic sites, including the yolk sac, aorta-gonad-mesonephros region, placenta and fetal liver, during embryogenesis. Fluorescence-activated cell sorting and polymerase chain reaction analyses demonstrated that CD34+ cells, purified from the fetal liver, expressed additional HSC markers, c-Kit and Sca-1, and that these CD34+ cells, but not CD34- cells, highly expressed MFG-E8. We also found that MFG-E8 was not expressed in HSCs in adult mouse bone marrow, and that its expression was confined to F4/80+ macrophages. Together, this study demonstrates, for the first time, that MFG-8 is expressed in fetal HSC populations, and that MFG-E8 may have a role in embryonic hematopoiesis.

A Case of Incus Vibroplasty: Postoperative Changes in Residual Hearing

In patients with mild to severe hearing loss, conventional hearing aids offer limited benefits and several problems with feedback and cosmesis. Middle ear implants are a feasible option for patients with moderate to severe hearing loss who are unable to achieve adequate benefit from or cannot tolerate hearing aids for various reasons. Here we present a case of middle ear implant surgery using Vibrant Soundbridge with incus vibroplasty technique, and describe the hearing changes during postoperative follow-up.

CD8+ T-cell Activation in Mice Injected with a Plasmid DNA Vaccine Encoding AMA-1 of the Reemerging Korean Plasmodium vivax

Relatively little has been studied on the AMA-1 vaccine against Plasmodium vivax and on the plasmid DNA vaccine encoding P. vivax AMA-1 (PvAMA-1). In the present study, a plasmid DNA vaccine encoding AMA-1 of the reemerging Korean P. vivax has been constructed and a preliminary study was done on its cellular immunogenicity to recipient BALB/c mice. The PvAMA-1 gene was cloned and expressed in the plasmid vector UBpcAMA-1, and a protein band of approximately 56.8 kDa was obtained from the transfected COS7 cells. BALB/c mice were immunized intramuscularly or using a gene gun 4 times with the vaccine, and the proportions of splenic T-cell subsets were examined by fluorocytometry at week 2 after the last injection. The spleen cells from intramuscularly injected mice revealed no significant changes in the proportions of CD8+ T-cells and CD4+ T-cells. However, in mice immunized using a gene gun, significantly higher (P<0.05) proportions of CD8+ cells were observed compared to UB vector-injected control mice. The results indicated that cellular immunogenicity of the plasmid DNA vaccine encoding AMA-1 of the reemerging Korean P. vivax was weak when it was injected intramuscularly; however, a promising effect was observed using the gene gun injection technique.

Percutaneous Coronary Intervention versus Coronary Artery Bypass Grafting for Patients with Multivessel Coronary Artery Disease: The Korean Multicenter Revascularization Registry(KORR)

BACKGROUND AND OBJECTIVE: Despite many multicenter trials on percutaneous coronary intervention (PCI), versus coronary artery bypass surgery (CABG), in multivessel coronary artery disease (MVCAD), the most appropriate treatment remains a matter of debate. Moreover, studies comparing the 2 strategies in eastern society are rare. The aim of this study was to assess the relative merits of PCI and CABG in MVCAD in the post-stent era. SUBJECTS AND METHODS: Patients, with MVCAD, indicated for revascularization were enrolled from 9 centers in Korea. Out of the 3,279 patients in the registry, 2102 (CABG 609 patients, PCI 1,493 patients) were selected for a comparison of their outcomes, after a statistical adjustments for the disparity for 6 independent risk factors, for the prognosis between the two groups. RESULTS: There was no significantly different in the 3 year survival rates between PCI and CABG groups. In the diabetic patients, the 3-year mortality rate in PCI group was 1.6-fold higher than in the CABG group, although it was not statistically significant (PCI 19.8%, CABG 12.5%, p=0.24). The incidence of cerebrovascular events (CVE) was higher in the CABG group. The thirty-day death rate, myocardial infarction or CVE were higher in the CABG group (PCI 1.3%, CABG 4.2%, p<0.001). Both the long and short-term revascularization rates were higher in PCI group compared to CABG group. CONCLUSION: Our Korean registry demonstrated a comparable survival rate between the PCI and CABG groups. A PCI was associated with a lower early morbidity, but with a greater need for repeated revascularization compared to a CABG.

Clinical significance of reciprocal ST segment depression in acute myocardial infarction: Analysis based on the time interval from the onset of symptoms / 대한내과학회지

BACKGROUND: To investigate the clinical significance of reciprocal ST segment depression on the presenting electrocardiogram (ECG) in patients with acute myocardial infarction (MI), in particular, this study focuses whether there is any difference according to the time interval between the onset of symptoms and initial ECG. METHODS: ECG findings in 198 patients with acute MI were retrospectively reviewed. The patients were classified into 4 subgroups based on the infarct region and reciprocal ST depression. The clinical data and angiographic finding were compared in each region. We also explored whether any differences could be recognized according to the time interval. RESULTS: Of 78 anterior MI, 16 (21%) showed a reciprocal ST depression and 62 (80%) did not. Of 120 inferior MI, 50 (41%) displayed a reciprocal ST depression and 70 (59%) did not. In each region, a reciprocal ST depression made no difference between the two groups. However, when divided by the time interval, a reciprocal ST depression more than 4 hours after MI predicted a high incidence of multivessel disease [anterior MI 5/6 (83%), 10/12 (83%): p<0.05 for each]. CONCLUSION: There was a high incidence of multivessel disease when a reciprocal ST segment depression continued for more than 4 hours after MI. The meaning of a reciprocal ST depression can be interpreted differently according to the duration after MI.

Endothelial Dysfunction in Patients with Exaggerated Blood Pressure Response during Exercise Test

BACKGROUND AND OBJECTIVES: The diagnostic and prognostic importance of exaggerated blood pressure response to exercise is controversial. Endothelial dysfunction has been demonstrated in patients with atherosclerosis and risk factors for coronary artery disease, but there is a lack of information in patients with exercise hypertension. Thus, we designed this study to evaluate the endothelial function in patients with exaggerated blood pressure response during exercise. SUBJECTS AND METHODS: Exercise hypertension is defined as a systolic blood pressure >or= 210 mmHg in men, and >or=190 mmHg in female, during Treadmill tests. Using a high resolution ultrasound technique, the endothelial function of the brachial artery, in patients with exercise hypertension (n=25), and control subjects (n=25), were investigated. RESULTS: Endothelial-dependent vasodilation were impaired in patients with exercise hypertension (7.77+/-5.14 vs. 2.81+/-2.29%, p<0.05). On univariate analysis, the extent of vasodilation was significantly correlated with age (r=0.43, p<0.05) and systolic blood pressure (r=0.39, p<0.05). CONCLUSION: We conclude that patients with exercise hypertension have impaired endothelium-dependent vasodilation. Exercise hypertension is a finding, which may, by itself, raise concern when interpreted as an exercise test. This study also supports the concept that endothelial dysfunction may play a role in exercise hypertension.

Radiofrequency Catheter Ablation of Atrioventricular Nodal Re-entrant Tachycardia in a Patient with Dextrocardia Associated with Atrial Septal Defect

It is known that tachyarrhythmias in patients with congenital heart defects have a potentially high impact on quality of life, morbidity and mortality. Conventional treatment with antiarrhythmic drugs may have untoward results including recurrence of tachyarrhythmia and its adverse effects. Therefore, radiofrequency catheter ablation is increasingly used for the treatment of supraventricular tachycardias in patients with congenital heart diseases, although abnormal anatomy and atypical conduction systems have the potential to complicate catheter ablation procedures. This report describes our experience with the successful radiofrequency catheter ablation of atrio-ventricular nodal reentrant tachycardia (AVNRT) in a patient with dextrocardia with situs solitus (isolated dextrocardia).

Echocardiographic and Clinical Factors Affecting Normalization of LV Systolic Function in Patients with Cardiomyopathy

BACKGROUND: During clinical practice we found that left ventricular systolic function(LVSF) has been normalized in some patients with cardiomyopathy. We investigated the echocardiographic and clinical factors affecting normalization of LVSF in these patients. METHOD: The patients with LV systolic dysfunction(EF or =55%) in FUE were defined to Group 1(mean age 57+/-16, male 21, female 29, mean follow-up 18+/-6 month) and another consecutive 50 patients with sustained decreased LVSF(EF<40%) and no increment of EF over 10% in FUE were defined to Group 2(mean age 56+/-14, male 32, female 18, mean follow-up 20+/-6 month). RESULTS: By univariate analysis, significant factors affecting normalization of LVSF were female sex, non-smoker, first experience of dyspnea, absence of bundle branch block in ECG, end-diastolic dimension of LV(LVEDD), end-diastolic volume of LV(LVEDV), LA size, less sphericity, presence of pericardial effusion, peak and end systolic wall stress. By multivariate analysis, LVEDD(Group 1: 61+/-7, Group 2: 71+/-7mm, p<0.001), LVEDV(Group 1: 139+/-59, Group 2: 190+/-51ml, p<0.01), absence of bundle branch block in ECG and 1st attack of symptom were significant. By Receiver operating characteristics curve analysis, area under curve of LVEDD and LVEDV were 0.859(95%CI: 0.775-0.920) and 0.805(95%CI: 0.681-0.896), respectively. LVEDD< or =64mm predicted normalization of LVSF with a sensitivity 76% and a specificity 86%. CONCLUSION: Determination of cardiac dimension and volume by echocardiography is very important to predicting normalization of LV systolic function in primary myocardial disease. And this results suggest that myocardial structural integrity may be important for recovery of LV function in clinical setting.

Relation Between Vascular Resistance and Intimal Thickness in Patients with Coronary Artery Disease

BACKGROUND: The intimal thickening of coronary artery was understood as an early process in the beginning of atherosclerosis. However, the implication of intimal thickening as a morphologic change of coronary artery disease, on the coronary vascular hemodynamics has not been explored. METHODS: To evaluate the effect of intimal thickening on the coronary vascular hemodynamics, we studied the extent of intimal thickening on intravascular ultrasound(IVUS) and the coronary vascular flow and resistance by using Doppler wire in left anterior descending coronary arteries after successful intervention in 40 patients(29 males, mean age 55+/-9 years) with coronary artery disease. Mean intimal index and mean lumen cross sectional area were determined by IVUS and coronary flow average peak velocity was obtained by using Doppler wire before and after intracoronary adenosine in distal artery to the stenosis. Coronary flow velocity reserve(CFR), volumetric coronary blood flow(CBF) and coronary vascular resistance index(CVRI) were calculated. Hyperemic pressure-to-flow ratio(hyperemic mean aortic pressure/hyperemic volumetric coronary blood flow), ie, an index of minimal coronary vascular resistance(mCVR), was further derived. RESULTS: Intimal index(mean 20.0+/-8.3%) was significantly correlated with CVRI(mean 0.33+/-0.14, r=.37, p=.02) and mCVR(mean 0.81+/-0.40mmHg/ml/min, r=.36, p=.02). However, there was no correlation with CBF and CFR. CONCLUSION: The CVRI and mCVR(hyperemic pressure to flow ratio), the indices coronary microvascular resistance, were significantly related to the degree of intimal thickness of coronary artery. The extent of intimal thickness of coronary artery on IVUS study may be related to microvascular integrity.

Correlations between Coronary Flow Reserve and the Presence of Viable Myocardium after Acute Anterior Myocardial Infarction

BACKGROUND: Coronary flow reserve (CFR) was defined as the ability to increase coronary blood flow maximally in response to demand. The presence of viable myocardium in an infarcted zone indicates the presence of an intact microvasculature. We hypothesized that coronary flow reserve, which assesses the microcirculation, might be associated with the presence of viable myocardium. METHODS: Thirty seven patients with acute anterior myocardial infarction (mean age 55+/-10, 25 males) were enrolled and abnormal 127 segments were analyzed. Dobutamine stress echocard-iography (5 to 20 g/kg/min) was performed before coronary angiography (6+/-3 days after acute myocardial infarction (AMI)). Coronary flow reserve in infarct-related artery was measured at distal site to lesion immediately after successful angioplasty (7+/-2 days after AMI, with residual stenosis less than 20%) by using intracoronary Doppler flow wire. And follow-up 2-dimentional transthoracic echocardiography was performed in 26 patients during 333+/-161 (range of 109-780) days after acute myocardial infarction. Improvement of wall motion at least one segment by one more grade in dobutamine stress echocardiography was defined as contractile reserve. Viable myocardium was defined as the improvement of wall motion in transthoracic echocardiography during follow-up periods. RESULTS: In 26 patients, viable myocardium was detected in 19 patients (73%) and their mean CFR was 1.74+/-0.42, which was significantly increased than 1.16+/-0.14 of CFR of patients without viable myocardium (p<0.001). The agreement of CFR score and presence of viable myocardium in AMI was excellent when CFR was above 1.3 (Area under the curve was 0.906 in receiver operating characteristic (ROC) curve). Sensitivity and specificity to detect viable myocardium in CFR more than 1.3 were 84% & 85% respectively. CONCLUSION: CFR was increased in patients with viable myocardium, and the cut-off value of CFR more than 1.3 was agreed excellently to detect viable myocardium.

Predictors of Arrhythmic Events in Idiopathic Dilated Cardiomyopathy

BACKGROUND AND OBJECTIVES: Previous studies have indicated that idiopathic dilated cardiomyopathy (IDCM) is associated with a high incidence of lethal ventricular arrhythmia and sudden cardiac death (due to arrhythmic events). The objective of this study was to evaluate predictive factors of arrhythmic events in IDCM. SUBJECTS AND METHODS: A total of 174 patients with IDCM were evaluated for the measurement of multiple parameters such as PR interval, QRS duration, rate corrected QT dispersion, bundle branch block, atrial fibrillation, left ventricular end diastolic dimension, ejection fraction, left atrial size, and left ventricular hypertrophy. The patients were divided into 2 groups:group A with and group B without arrhythmic events. RESULTS: Over an observation period of 38+/-19 months, arrhythmic events developed in 39 of the 174 patients (4 VT, 1 VF and 34 sudden cardiac death, 22.4%). In multivariate analysis, only QTDc was found to be an independent predictor of arrhythmic events (RR:1.03, 95% CI:1.01 - 1.04, p108 ms were 43.8% (7/16) and 85.6% (83/97) respectively. The positive predictive value of arrhythmic events in patients with QTDc>108 ms and EF<28% was 66.6% (8/12). CONCLUSION: The extent of repolarization dispersion and LV systolic function was determined to have value as a useful screening test for the prediction of arrhythmic events in IDCM.

Viable myocardium in reperfused acute myocardial infarction: rest and stress first-pass mr imaging

Feasibility of identifying viable myocardium in rest and stress magnetic resonance imaging (MRI) was evaluated using 3 hr occlusion and 30 min reperfusion model of left anterior descending (LAD) coronary artery in 12 felines. At rest MRI, viable myocardium confirmed by 2,3,5-triphenyl tetrazolium chloride (TTC)- staining showed rapid signal intensity (SI) rise followed by gradual decline not significantly different from normal myocardium that the two hyperperfused regions were distinguishable only from the hypoperfused nonviable myocardium. At stress MRI, hyperemia induced perfusion change was most pronounced in normal myocardium with earlier and greater peak enhancement followed by brisk 'washout' phase while minimally augmented enhancement in viable myocardium was still in 'washin' phase. From these findings, it was concluded that viable myocardium is identified in rest and stress MRI as redistributing hypo- perfusion compared to persistent hyper-perfusion of the normal myocardium and the persistent hypo-perfusion of the nonviable myocardium.

Efficacy and Safety of Bevantolol HCl in Treating Essential Hypertension

BACKGROUND: Bevantolol HCl was developed as the first antihypertensive agent that has selective beta1 and alpha1 blocking effects with an additional calcium antagonistic activity. It's expected that antihypertensive effect is comparable to other beta-blockers without any significant adverse effect on lipid and glucose metabolism observed in other drugs, and It has less negative inotropic effect due to peripheral vasodilatation mediated through alpha1 and calcium channel blocking effects. To evaluate the antihypertensive effect and safety of bevantolol HCl, we investigated 73 patients with mild to moderately severe essential hypertension. METHODS: Patients who showed either systolic blood pressure 150-209 mmHg or diastolic pressure 95-119 mmHg, were enrolled in this study. Following placebo period of 2weeks, bevantolol HCl was administered in daily dose of 100-200 mg for 12 weeks. RESULTS: Of the 73 patients, 55 patients who were able to receive bevantolol HCl were observed for the safety and 45 patients who completed this study were evaluated for the antihypertensive effect of the drug. 1) Antihypertensive effect: The mean systolic and diastolic blood pressure significantly decreased from 156.7+/-11.7 mmHg to 144.0+/-16.7 mmHg and from 101.6+/-6.4 mmHg to 93.2+/-9.7 mmHg in two weeks of observation in 37/45 patients (82.2%) and was consistently effective for 12 weeks (p<0.01). Blood pressure under 139/89 mmHg was achieved in 20 out of 45 patients (44.4%). The heart rate also declined from 74.9+/-10.5/min to 69.1+/-14.2/min and the effect lasted for 12 weeks (p<0.01). 2) Safety: Mild adverse effects were observed in 27 out of 55 patients. Only one patient developed a significant bradycardia with heart rate of 40/min, which required withdrawal of the drug. No significant changes in the lipid profiles were observed. CONCLUSION: Bevantolol HCl is highly effective and generally well tolerated with an acceptable safety profile in patients with mild to moderately severe essential hypertension.

Intracoronary thrombosis treated with stent and abciximab in patient with membranous glomerulonephritis

The association of nephrotic syndrome with a hypercoagulable state and vascular thrombosis is well recognized. In all adult series of nephrotics, venous thrombosis are much more common than arterial thrombosis, which has been mainly reported in children. Intracoronary thrombus is among the rarest arterial thromboses. We present a case of acute myocardial infarction in a 39-year-old women with nephrotic syndrome secondary to membranous glomeluronephritis, in which subsequent coronary angiography showed no evidence of atherosclerotic change and thrombotic occlusion in the left main coronary artery which was successfully treated with intracoronary stent and intravenous abciximab.

The efficacy and safety of irbesartan in treating essential hypertension

BACKGROUND: Irbersatan, an orally active antihypertensive agent, effectively reduce blood pressure by directly blocking angiotensin II receptors without any significant adverse effects. The purpose of this study is to evaluate the efficacy and safety of irbesartan in patients with mild to moderate hypertension. METHODS: This study enrolled 83 patients who had diastolic pressure above 95 mmHg and below 110 mmHg on two measurements. Sixty eight patients were administered 150mg of irbesartan, an angiotensin II receptor blocker, daily for four weeks as an initial dosage. If the sitting diastolic pressure was equal to or greater than 90 mmHg after a 4 week treatment period, the dosage was doubled until the end of 8 weeks. Baseline pressures, antihypertensive effect, side effects, laboratory findings were compared before and after treatment. RESULTS: Fourty two patients out of 53 patients having completed this study showed decreased blood pressure equal to or more than 5 mmHg of the sitting diastolic pressure (response rate=79%). Twenty one patients out of 53 patients showed normalized blood pressure below 90 mmHg of the sitting diastolic pressure (normalization rate=40%). The extent of decrease in diastolic and systolic blood pressure after eight week treatment was an average 11.7+/-10.1 mmHg and 16.3+/-18.9 mmHg, respectively (p<0.05). Nineteen ontoward side effects was observed in 17 patients out of 68 patients with medication (frequency of ontoward effects=25%). Only one case with headache was considered to be related to the medication. Abnormal laboratory findings were observed in eight patients, and only one case with elevation of bilirubin and ALT levels was considered to be related to the medication. CONCLUSION: In conclusion, irbesartan is a safe and effective antihypertensive drug in patients with mild to moderate hypertension with tolerable side effects.

Efficacy and Safety of Atorvastatin in Patients with Hypercholesterolemia

BACKGROUND: Previous studies indicated that a recently approved synthetic HMG-CoA reductase inhibitor, atorvastatin, reduces LDL cholesterol and triglyceride. To assess the efficacy on the level of serum LDL cholesterol and other lipoprotein fractions and its safety, we investigated 59 patients for lipid and side effect profile. METHOD: In patients with hypercholesterolemia, who showed 12-hours fasting serum LDL cholesterol>145 mg/dl and or =130 mg/dl were assigned to receive 10 mg dose of atorvastatin once daily for 4weeks. After 4 weeks of drug therapy, serum lipid profile were rechecked, if showed LDL cholesterol level> or =130 mg/dl, assigned to receive 20 mg dose of atorvastatin once daily until 8 weeks. RESULTS: Of the 59 patients were assigned to receive atorvastatin therapy, 52 patients completed the study. Among lipid profiles, total cholesterol, triglyceride, LDL-cholesterol and apolipoprotein B levels showed significant reduction with mean reduction rate of 28%, 13%, 38%, 32% respectively after 4 weeks and 31%, 13%, 41% and 34% respectively after 8 weeks. HDL-Cholesterol and lipoprotein (a) level did not show significant change after 8 weeks of therapy. Nine patients had mild adverse events, such as elevated ALT, epigastric pain, insomnia, thumb pain. postural hypotension, palpitation and constipation. Only three patients of fifty-nine withdrew from the study due to adverse events related to drug treatment. CONCLUSION: The atorvastatin was highly effective and generally well tolerated with an acceptable safety profile in patients with primary hypercholestelemia.

Assessment of coronary artery stenosis with intracoronary Doppler guide wire and modified continuity equation method ; A comparison with dipyridamole stress Thallium-201 SPECT

BACKGROUND: Previous studies of animal and human experiments have shown excellent correlation between true or angiographic stenosis severity and stenosis severity calculated from intracoronary Doppler flow measurements and continuity equation method. However, there remains practical problems to be solved on its clinical application. To minimize these problems, the concept of modified continuity equation method, calculating the percent area stenosis by comparing the maximal in-stenosis flow velocity to the distal reference flow velocity, was introduced and compared with dipyridamole stress thallium-201 SPECT. METHODS: In this prospective study, 102 patients (mean age 57+/-10 years, 69 men, 33 women) with coronary artery stenoses ranging from 23-89% in percent diameter stenosis, who received coronary angiography, dipyridamole stress thallium-201 SPECT, and successful intracoronary flow velocity measurements were included. Modified continuity equation method and distal coronary flow velocity reserve were compared to the result of dipyridamole stress thallium-201 SPECT and quantitative coronary angiography. RESULTS: Measurements of adequate intralesional and stenosis distal flow velocities were successful in 102 out of 106 stenoses (96%). Minimal luminal area and percent area stenosis calculated from modified continuity equation method showed significant correlations with those of quantitative coronary angiography. Modified continuity equation method significantly underestimated the severity of stenosis than quantitative coronary angiography did. The test accuracy in relation to the result of dipyridamole stress thallium-201 SPECT were 91% in modified continuity equation method, 80% in quantitative coronary angiography and 63% in distal coronary flow velocity reserve. CONCLUSION: Application of intracoronary Doppler guide wire and modified continuity equation method appears to provide useful on-site implications for the anatomic and functional assessment of coronary artery stenosis. The modified continuity equation method would be one of the promising concepts for clinical decision making during coronary interventions.

The Effect of External Beam Radiation on Neointimal Formation in the Rat Carotid Injury Model

BACKGROUND: Restenosis after successful percutaneous transluminal coronary angioplasty remains a major obstacle to the long-term success of the procedure. Uncontrolled proliferation and extracelluar matrix synthesis in response to mechanical injury are important contributors to this proces. External beam radiation or gamma radiation affects self-renewing tissues by arresting cell division, and therefore limits proliferation by reducing the number of clonal progenitors. The purpose of this study was to determine whether external beam radiation (EBR) could reduce the extent of neointimal formation after balloon injury in the rat carotid injury model and, if it could, to define the minimum effective dose. METHODS: 32 Sprague-Dawley rats (mean weight : 370+/-78g) underwent carotid injury by using 2F Fogarty balloon and EBR with doses ranging from 5 to 20 Gy. Rats were sacrificed after 2 weeks. The arteries were perfusin-fixed in paraformaldehyde. The dose was specified to a depth of 15mm. Histomorphometry was performed to compare external elastic lamina (EEL) area (mm2), lumen area (mm2)and neointimal area (mm2 of the injured segments. RESULTS: EEL area showed no significant difference in each different radiation group. Low dose EBR (5 Gy and 10Gy) had no significant impact on neointimal hyperplasia in rat carotid injury model. However, in high dose group (15Gy and 20Gy) neointimal area was significantly reduced (p<0.01) indicating high dose EBR markedly prevented neointimal hyperplasia. CONCLUSION: Radiation therapy may be an effective adjunctive method for reducing the restenosis rate after successful angioplasty in the rat carotid injury model.

Phasic Coronary Artery Flow Profiles in Patients with Aortic Valve Disease

BACKGROUND: The previous reports have demonstrated that coronary artery flow profiles might change in patients with aortic valve disease. Our objective was to assess phasic coronary artery flow and velocity characteristics and coronary flow reserve in patients with severe aortic vale disease. METHOD: We studied six patients (4 men and 2 women, mean age 61.3+/-6.3 years) with aortic regurgitation and seven patients (3 men and 4 women, mean age 66.3+/-10.3 years) with aortic stenosis. Coronary flow velocity was measured at the proximal portion of left anterior descending artery with 0.014-inch Doppler tipped guide wire and intracoronary injection of adenosine. Nineteen patients (11 men and 8 women, mean age 52+/-9.8 years) with normal coronary artery were served as normal control. Result: The velocity-time integral of systolic coronary flow (SPVi) was significantly higher in patient with severe aortic regurgitation than control (21.1+/-5 vs 9.4+/-3.1, p<0.05, respectively) and ratio of diastlic to systolic the velocity-time integrals (DSiR) was significantly lower in patient with severe aortic regurgitation than control subject (1.5+/-0.5 vs 3.7+/- 0.8 p<0.05, respectively). Patients with severe aortic stenosis had significantly higher velocity-time integral of diastolic coronary flow (DPVi) than control subject (17+/-9.7 vs 8.8+/-3.0 p<0.05, respectively) and slighly higher DSiR than control subject (4.0+/- 2.5 vs 3.7+/-0.8 p<0.05, respectively). Coronary flow reserve was significantly decreased in patient with aortic valve disease compared with control subject (2.1+/-0.8 vs 3.2+/-0.4 p<0.05, respectively). CONCLUSION: Coronary flow reserve decreased significantly in patients with AR and with AS compared with normal control. Coronary blood flow profiles in patients with AR was characterized by systolic flow predominance and reduced diastolic flow whereas patients with AS was a tendency toward decreased systolic flow and increased diastolic flow.