Yazar "Aygul, Nazif" seçeneğine göre listele
Listeleniyor 1 - 10 / 10
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Assessment of exercise stress testing with artificial neural network in determining coronary artery disease and predicting lesion localization(PERGAMON-ELSEVIER SCIENCE LTD, 2009) Babaoglu, Ismail; Baykan, Omer Kaan; Aygul, Nazif; Ozdemir, Kurtulus; Bayrak, MehmetThe aim of this study is to show the artificial neural network (ANN) on determination of coronary artery disease existence and localization of lesion based upon exercise stress testing (EST) data. EST and coronary angiography were performed on 330 patients. The data studied acquiring 27 verifying features was normalized employing z-score method. To select training and test data, 10-fold cross-validation methods were involved and multi-layered perceptron neural network was employed for the classification. The interpretation of EST using ANN proved 91%, 73% and 65% diagnostic accuracy for the left main coronary (LMCA), left anterior descending and left circum-flex coronary arteries, respectively. Besides, 69% for the right coronary artery is also predicted. For the LMCA, a 94% negative predictive value (NPV) was obtained. This high percentage of NPV encourages the elimination of LMCA lesions. Some knowledge call also be obtained about lesion localization, besides diagnosing of coronary artery disease by the assessment of EST via ANN. (C) 2007 Elsevier Ltd. All rights reserved.Öğe Combined anterior and inferior ST segment elevation during the exercise stress testing(ELSEVIER IRELAND LTD, 2008) Aygul, Nazif; Ozdemir, Kurtulus; Aydin, Meryem Ulku; Duzenli, Mehmet AkifExercise induced ST elevation, especially in anterior derivations, does localize the ischemic region. We describe a patient who presented with exercise induced ST elevation in both anterior and inferior leads without prior myocardial infarction. Coronary angiography showed a "wrap around LAD" with significant proximal lesion. (C) 2007 Elsevier Ireland Ltd. All rights reserved.Öğe The Comparative Effects of Long-Term Carvedilol versus Bisoprolol Therapy on QT Dispersion in Patients with Chronic Heart Failure(KARGER, 2009) Aygul, Nazif; Ozdemir, Kurtulus; Duzenli, Mehmet Akif; Aygul, Meryem UlkuObjectives: Carvedilol and bisoprolol reduce QT dispersion (QTD) in chronic heart failure (CHF). However, it is unclear whether there is a difference between the effects of the two drugs. The aim of the present study was to compare the long-term effects of carvedilol and bisoprolol on QTD in patients with CHF. Methods: Eighty-one patients with CHF with no previous beta-blocker therapy were included in this prospective study. The patients were randomly allocated to carvedilol or bisoprolol therapy. Left ventricular ejection fraction (LVEF), heart rate (HR), QTD, and corrected QTD (QTcD) were calculated at baseline and at the 6th month of therapy. Results: In comparison to baseline values in both therapy groups, LVEF was significantly improved, and a statistically significant decrease was found in HR ( carvedilol from 76 +/- 12 to 65 +/- 10 beats/min, p < 0.001; bisoprolol from 78 +/- 13 to 65 +/- 8 beats/min, p < 0.001) and QTcD ( carvedilol from 85 +/- 28 to 65 +/- 22 ms, p < 0.001; bisoprolol from 83 8 22 to 61 8 20 ms, p ! 0.001). In our study, carvedilol and bisoprolol were found to have similar effects on LVEF, HR, and QTcD. Conclusions: Carvedilol and bisoprolol decrease HR and QTcD in patients with CHF, and there is no meaningful difference between the two beta-blockers as regards their effects on these parameters. Copyright (c) 2008 S. Karger AG, BaselÖğe Comparison of increased aspirin dose versus combined aspirin plus clopidogrel therapy in patients with diabetes mellitus and coronary heart disease and impaired antiplatelet response to low-dose aspirin(EXCERPTA MEDICA INC-ELSEVIER SCIENCE INC, 2008) Duzenli, Mehmet Akif; Ozdemir, Kurtulus; Aygul, Nazif; Soylu, Ahmet; Tokae, MehmetThe effects of therapy with aspirin 300 mg/day and with combined aspirin 100 mg/day plus clopidogrel 75 mg/day on platelet function were compared in patients with diabetes mellitus and coronary artery disease and impaired antiplatelet responses to aspirin 100 mg/day. The study population consisted of 151 outpatients with type 11 diabetes mellitus and coronary artery disease who were taking aspirin 100 mg/day. Of the 151 patients, a subgroup of subjects with impaired aspirin response were selected on the basis of the results of platelet aggregometry. Nonresponsiveness to aspirin was defined as mean aggregation >= 69% with 3 mu mol/L adenosine diphosphate and mean aggregation >= 70% with 2 mu mol/L collagen. Aspirin semiresponders were defined as meeting I but not both of these criteria. Nonresponders and semiresponders were randomized equally to aspirin 300 mg/day and aspirin 100 mg/day plus clopidogrel 75 mg/day, and aggregation tests were repeated after 2 weeks. Sixty of the 151 patients with diabetes (40%) were found to respond to aspirin inadequately. Platelet aggregation induced by adenosine diphosphate and collagen decreased significantly after aspirin 300 mg/day or combined therapy. Combined treatment was found to have a stronger inhibitory effect on platelet aggregation induced by adenosine diphosphate than aspirin 300 mg/day (p = 0.002). Impaired aspirin response was resolved by increasing the aspirin dose or adding clopidogrel to aspirin (p < 0.0001 for each). However, desired platelet inhibition was achieved in significantly more patients by combined treatment than by aspirin 300 mg/day (p < 0.05). In conclusion, aspirin 100 mg/day does not inhibit platelet function adequately in a significant number of patients with diabetes mellitus and coronary artery disease. Increasing the aspirin dose to 300 mg/day or adding clopidogrel to aspirin can provide adequate platelet inhibition in a significant number of those patients with impaired responses to low-dose aspirin. (C) 2008 Elsevier Inc. All rights reserved.Öğe Comparison of myocardial performance index obtained either by conventional echocardiography or tissue Doppler echocardiography in healthy subjects and patients with heart failure(SPRINGER, 2009) Duzenli, Mehmet Akif; Ozdemir, Kurtulus; Aygul, Nazif; Soylu, Ahmet; Aygul, Meryem Ulku; Goek, HasanThis study was planned to investigate the normal reference values of myocardial performance index (MPI) obtained by tissue Doppler echocardiography (TDE) and the agreement between MPI measured by TDE and conventional MPI measured by pulsed-wave Doppler (PWD) in healthy subjects and patients with heart failure (HF). Two hundred and three patients with HF and 190 healthy subjects were enrolled in this study. Isovolumic contraction and relaxation time (ICT and IRT) and ejection time (ET) were measured from mitral inflow and left ventricular (LV) outflow. Tissue Doppler echocardiography recordings were obtained at the septal, lateral, inferior, and anterior of the mitral annulus and same time intervals were measured. Myocardial performance index was calculated. The functional capacity of the patients with HF was determined according to New York Heart Association classification. TDE-MPI values were higher than conventional PWD-MPI values in both groups (53% +/- 8% vs 48% +/- 11%, P < 0.0001 in the healthy subjects; 84% +/- 21% vs 72% +/- 19%, P < 0.0001 in the patients with HF). Moderate agreement was found between PWD-MPI and LV mean TDE-MPI in both groups. In identifying patients with moderately or severely decreased LV ejection fraction, TDE-MPI had higher cutoff values than conventional PWD-MPI, and TDE-MPI had higher specificity, sensitivity, negative predictive value, and diagnostic accuracy. In patients with HF, TDE-MPI had a stronger correlation with LV ejection fraction and functional capacity than did PWD-MPI. TDE-MPI is an alternative to conventional PWD-MPI in assessment of cardiac function. However, the higher MPI cutoff points should be considered when this method is used for the evaluation of cardiac function.Öğe Coronary Arteriovenous Fistula in a Child Presenting with Chest Pain(DERMAN MEDICAL PUBL, 2016) Arslan, Derya; Cimen, Derya; Oran, Bulent; Aygul, NazifCoronary arteriovenous fistula is an incidental finding in 0.1% to 0.2% of coronary angiograms. A 15-year-old famale patient presented with a three years history of chest pain on exertion. Echocardiography was performed previously and a small muscular ventricular septal defect was detected. The electrocardiogram was normal sinus rhythm together with normal axis. On echocardiography, left ventricular function was normal and there was continuous flow into the right ventricle. Therefore, coronary angiography was performed for considering the coronary artery fistula. Coronary artery fistula was observed between the first septal perforating branch of the left anterior descending coronary artery with right ventricle. The patient's clinical follow-up was decided since a significant shunt could not be identified.Öğe The effect of isolated left bundle branch block on the myocardial velocities and myocardial performance index(WILEY, 2008) Duzenli, Mehmet Akif; Ozdemir, Kurtulus; Soylu, Ahmet; Aygul, Nazif; Yazici, Mehmet; Tokac, MehmetObjectives: This study was planned in order to investigate the effect of left bundle branch block (LBBB) on myocardial velocities obtained by tissue Doppler echocardiography (TDE) and myocardial performance index (MPI). Methods: Subjects with LBBB (n = 61) and age-matched healthy subjects (n = 60) were enrolled in the study. Left ventricular (LV) ejection fraction (EF), mitral inflow velocities (E-wave and A-wave), isovolumetric contraction and relaxation time (ICT and IRT), ejection time (ET), and flow propagation velocity (Vp) were measured by conventional echocardiography. Systolic velocity (Sm), early and late diastolic velocities (Em and Am) and time intervals were measured by TDE. MPI was calculated by the formula (ICT + IRT)/ET. Results: LVEF and mitral E/A ratio were similar in both groups. Vp was lower in the LBBB group than in the control group, whereas the E/Em and the E/Vp ratio was higher. LV Sm and Em/Am ratio were lower in LBBB group. Right ventricular Sm and Em/Am ratio were similar in both groups. LV mean and RV MPI were significantly increased in LBBB group. Conclusion: These findings obtained by TDE show that isolated LBBB impairs the ventricular functions. Both of the LV and RV dysfunctions shown by the new parameters may contribute to increased morbidity and mortality in cases with isolated LBBB.Öğe Effects of menopause on the myocardial velocities and myocardial performance index(JAPANESE CIRCULATION SOC, 2007) Duzenli, Mehmet Akif; Ozdemir, Kurtulus; Sokmen, Abdullah; Soylu, Ahmet; Aygul, Nazif; Gezginc, Kazim; Tokac, MehmetBackground Although menopause is known to increase cardiovascular risk and mortality, the effect of menopause on cardiac functions has not been investigated in detail. This study investigates the effect of menopause on cardiac functions by tissue Doppler echocardiography (TDE) and myocardial performance index (MPI). Methods and Results A total of 72 postmenopausal and 71 age-matched premenopausal women were enrolled in the study. After conventional echocardiographic parameters were measured, TDE recordings were obtained at the septal, lateral, anterior and inferior side of the mitral annulus, and tricuspid lateral annulus. Systolic velocity (Sm), early and late diastolic velocities (Em and Am) and time intervals were measured and MPI was calculated. A sequentially symptom-limited exercise stress test was performed. Although left ventricular (LV) ejection fraction and end-diastolic and end-systolic diameter were similar in both groups, LV septum and posterior wall thickness were higher in postmenopausal women. Mitral early inflow velocity and mitral early inflow velocity:mitral late inflow velocity ratio were significantly lower in postmenopausal women compared to premenopausal women. LV Sm, and LV and right ventricular (RV) Em:Am ratios were lower in postmenopausal women. MPI calculated by TDE was significantly increased in postmenopausal women. In addition, exercise duration and metabolic equivalent values were significantly lower in postmenopausal women than in premenopausal women. Conclusions Menopause negatively affects MPI and myocardial velocities, both of which provide more quantitative data about myocardial functions. These findings indicate that the hormonal changes in menopause impair LV systolic and diastolic functions and RV diastolic function.Öğe Influence of menstrual cycle on cardiac performance(ELSEVIER IRELAND LTD, 2007) Zengin, Kadriye; Tokac, Mehmet; Duzenli, Mehmet Akif; Soylu, Ahmet; Aygul, Nazif; Ozdemir, KurtulusObjectives: The purpose of this study was to investigate the relationship between endogen sex hormone levels and myocardial performance in two different phases of menstrual cycle. Background: The relationships between cardiac performance and sex hormone levels in menstrual cycle have not yet been clearly identified. Methods: Twenty-seven women at the age of 19-42 years (mean 24.11 +/- 6.02) with regular menstrual cycles (28-31 days) were enrolled in this study. Cardiac performance was evaluated by tissue Doppler imaging (TDI) derived myocardial performance index (MPI) in the menstrual and the luteal phases of the menstrual cycle. Results: Left ventricular MPI were statistically significant between the menstrual phase and luteal phase of the menstrual cycle (Inferior 0.53 +/not superset of 0.10 versus 0.44 +/not superset of 0.09, P < 0.001; Anterior 0.54 +/not superset of 0.13 versus 0.45 +/not superset of 0.10, P < 0.008; Lateral 0.50 +/not superset of 0.09 versus 0.44 +/not superset of 0.12, P < 0.03; Septum 0.54 +/not superset of 0.07 versus 0.46 +/not superset of 0.10, P < 0.005; Global 0.52 +/not superset of 0.06 versus 0.44 +/not superset of 0.09, P < 0.001). Right ventricle MPI between the two periods was also significantly different (0.49 +/not superset of 0.10 versus 0.42 +/not superset of 0.10, P < 0.01). There was a moderate correlation between estrogen levels and global NIPI (r=0.46, P=0.001), but no correlation was found between progesterone levels and global MPI (r = 0.22, P = NS). Conclusion: We firstly demonstrated that endogen estrogen or progesterone improved the combined systolic and diastolic function in both left and right ventricle during luteal phases of menstrual cycle. Considering the previous studies and our results, estrogen may be responsible for this improvement. (c) 2007 Elsevier Ireland Ltd. All rights reserved.Öğe A NOVEL HYBRID CLASSIFICATION METHOD WITH PARTICLE SWARM OPTIMIZATION AND K-NEAREST NEIGHBOR ALGORITHM FOR DIAGNOSIS OF CORONARY ARTERY DISEASE USING EXERCISE STRESS TEST DATA(ICIC INTERNATIONAL, 2012) Babaoglu, Ismail; Findik, Oguz; Ulker, Erkan; Aygul, NazifThe aim of this study is to investigate the effectiveness of a novel hybrid method, particle swarm optimization with k-nearest neighbor classifier (PSOkNN), on determination of coronary artery disease (CAD) existence upon exercise stress testing (EST) data. The PSOkNN method is composed of two steps. At the first step, one particle which demonstrates the whole samples optimally in training dataset is generated for both healthy and unhealthy patients. Then, at the second one, the class of the test sample is determined according to the distance of the test sample to the generated particles utilizing k-nearest neighbor algorithm. To demonstrate the effectiveness of this novel method, the results of PSOkNN are compared with the classification results of the artificial immune recognition system and k-nearest neighbor algorithm. Besides, reliability of the proposed method on determination of CAD existence upon EST data is examined by using classification accuracy, k-fold cross-validation method and Cohen's kappa coefficient.
