Levent Çetin - Academia.edu (original) (raw)
Papers by Levent Çetin
Tainn, 2005
ABSTRACT In this work the navigation and GPS based trajectory control of an unmanned autonomous v... more ABSTRACT In this work the navigation and GPS based trajectory control of an unmanned autonomous vehicle is introduced. The caterpillar tread like mobile vehicle with duo cycle drive is equipped with a mobile GPS and micro controller. To get accurate position data, a DGPS (Differential GPS) with a local base station is used. In order to let the vehicle to follow a desired trajectory, a reference path is given by using Way Points as GPS data’s to micro controller, which provide the position and orientation control of the vehicle. The instant position and orientation of the vehicle in accordance to an assigned plane coordinate frame are calculated by micro controller from detected latitude and longitude values (land coordinates) of mobile GPS, which receive corrected on line data’s from base station.The duo cycle vehicle is driven with geared DC motors, which are equipped with chained caterpillar tread drives, so that it can have better motion, clambering and tracking performances. Successful navigation and path following results are obtained with several experiments by various control applications
Page 1. A COMPUTER CONTROLLED VISION ORIENTED ROBOT MANIPULATOR FOR CHESS GAME Erol UYAR, Sevket ... more Page 1. A COMPUTER CONTROLLED VISION ORIENTED ROBOT MANIPULATOR FOR CHESS GAME Erol UYAR, Sevket GÜMÜSTEKIN, Sükrü OZAN, Levent ÇETIN Dokuz Eylül University - Faculty of Engineering Department ...
Turkiye Klinikleri Journal of Cardiovascular Surgery, 2001
Bu çalışmanın amacı genç erişkin (40 yaş altı) hastalar ile ileri yaştaki (75 yaş üstü) koroner a... more Bu çalışmanın amacı genç erişkin (40 yaş altı) hastalar ile ileri yaştaki (75 yaş üstü) koroner arter hastalarının CABG sonrası erken ve orta dönem sonuçlarını kıyaslamak ve bu sonuçlar üzerinde etkisi olan faktörleri ortaya koyabilmektir. Materyel ve Metod: Ağustos 1998 ile Ağustos 2000 tarihleri arasında Alkan Hastanesi, Kalp ve Damar Cerrahisi Kliniğinde 1393 koroner bypass ameliyatı yapılmış olup, bunlardan 54'ü 40 yaş altı (grup 1), 42'si ise 75 yaş üstü (grup 2) idi. Grup 1'de ortalama yaş 37.8±2.8, Grup 2' de ise 76.4±2.4 yıldı. Her iki grubun preoperatif, operatif ve post operatif bulguları analiz edildi. Bulgular: Grup 2 ile kıyaslandığında Grup 1'de sigara içiciliği (%77.4'e karşı % 21.4, p<0.001), [son 10 yıldır hiç sigara içmeyen hastalar sigara içmeyen gruba alınmıştır.] hiperlipidemik hasta sayısı (%41.5'e karşı %19.8, p<0.05) ve obez hasta oranı (%28.3'e karşı %0, p<0.001) daha fazlaydı. Grup 2'deki hastalarda ise arteriyel hipertansiyon öyküsü (%57.7'e karşı %17, p<0.05) daha fazlaydı. Grup 2'de ortalama kros klemp zamanı (32.2±17dk'a karşı 24.8±11.1 dk), kardiopulmoner bypass (52.6±21.6 dk'a karşı 40.8±15.4 dk) ve ekstübasyon süreleri (8.6±2.9'e karşı 5.1±2.3 saat) Grup 1 ile kıyaslandığında anlamlı biçimde daha uzundu (p<0.05). Grup 2'de hasta başına anastomoz sayısı (2.7±1'e karşı 2.2±1, p<0.05) daha fazlaydı. Post operatif kardiak aritmi açısından değerlendirildiğinde iki grup arasında istatistiksel fark vardı Summary Objective: The purpose of this study was to evaluate significant factors that affecting early and midterm results of coronary artery surgery in patients aged less than 40 and more than 75 years old. Materials and Methods: Ninty-six Coronary artery bypass operation has been performed in Alkan Hospital between August 1998 and August 2000 in patients aged less than 40 years and moe than 75 years old. Hese patients divided into the two groups. Group I included 54 (mean age 37.8±2.8) patients group II included 42 patients (mean age 76.4±2.4 years). Preoperative and postoperative data in both groups were analyzed.
Turkiye Klinikleri Journal of Cardiology, 2000
Mersin Universitesi Tip Fakultesi Dergisi, Dec 3, 2012
OZET Atriyal septal defektler (ASD) adolesan ve yetiskinlerde en sik gorulen konjenital kalp hast... more OZET Atriyal septal defektler (ASD) adolesan ve yetiskinlerde en sik gorulen konjenital kalp hastaligidir (% 10-15). Medikal tedaviyle izlenen hastalarda ortalama olum yasi 50 civarindadir ve en sik mortalite nedenleri kalp yetmezligi, pulmoner ve sistemik embolidir. Ileri yastaki Izole sekundum tip ASD'ler de cerrahi tedavi guvenle yapilabilir. 1985-1997 yillari arasinda toplam 202 adet 35 yas uzerinde izole sekundum atriyal septal defektli hasta, Turkiye Yuksek Ihtisas Hastanesi Kalp ve Damar Cerrahisi Klinigi'nde ameliyat edilmistir ve erken-gec donem sonuclari retrospektif sekilde incelenmistir. Hastane (erken) mortalite % 2.9'dur. Takip periyodunda ise gec mortalite 3 hasta ile % 2.5'tir. Hastalarin %96'sina ulasilabilmis ve ortalama 64±42.8 ay takip edilmislerdir. Hastalarin ameliyat sonrasi ortalama fonksiyonel kapasiteleri (NYHA) sinif 1.25±0.2 olarak bulunmustur. Kardiyotorasik oran preoperatif ortalama %63.3±3 iken, postoperatif olarak 57±2'ye, pulmoner arter basinclari ise 46.3±13 mmHg iken postoperatif olarak 30.9±4.4 mmHg gerilemistir. Izole sekundum ASD ileri yasta da guvenle onarilmaktadir. Cerrahi tedaviyle hasta cesitli komplikasyonlardan korunmus, yasam kalitesi arttirilmis ve gec donem yasam beklentisi normal populasyona yaklasmis olur. Ancak izole sekundum ASD tanili ileri yastaki hasta grubu, genc yasta ameliyat edilenlere oranla mortalite ve morbidite acisindan daha cok risk tasir. Anahtar Kelimeler: Sekundum Tip ASD, Cerrahi tedavi, Ileri yas SUMMARY EARLY AND LATE RESULTS IN LATE SURGICAL CLOSURE OF ATRIAL SEPTAL DEFECTS Atrial septal defect (ASD) is the most common congenital cardiac anomaly found in adults. The onset of serious symptoms is apperent in yhe fourty decade and these increaser gradually. Heart failure, pulmonary and systemic embolies are the most common causes of death in medically treated patients. Betvveen 1985 and 1997, a total number of 202 patients who were in the range of 35 and 68 years of age (mean 46.6±5.5 years) underwent surggery for secundum isolated type of ASD in cardiovascular surgery clinic of Turkiye Yuksek ihtisas Hospital. Our surgical experience of ASD repair in patients above 35 years of age is reported regarding early and late term results. Hospital mortality was 2.9%. In the late follow-up period, 3 patients died, giving a late mortality of 2.5%. Long-term follow-up was available in 96% of the patient population and the total follow-up was 1001 Per patient year (mean 64±42.8 months). Postoperative mean functional capacity was 1.25+0.2, pulmonary artery measure was 30.9±4.4 mmHg while they were respectively 2.1+0.5 and 46.3±13 mmHg in the preoperative period. In our experience, surgigal closure of ASD in adults was found to be successful and with low morbidity in patients with pulmonary hypertension and congestive heart failure. Key Words: Secundum type ASD, Surgical treatment, Older age
Artificial Intelligence and Neural Networks, 2006
Page 1. FA Savacı (Ed.): TAINN 2005, LNAI 3949, pp. 2431, 2006. © Springer-Verlag Berlin Heidelb... more Page 1. FA Savacı (Ed.): TAINN 2005, LNAI 3949, pp. 2431, 2006. © Springer-Verlag Berlin Heidelberg 2006 Navigation and GPS Based Path Control of an Autonomous Vehicle Erol Uyar, Levent Çetin, and Aytaç Gören Dokuz ...
Cellulose, 2015
In this article, the effects of graphene loading (0.1, 0.2, 0.3 wt%) on both the electromechanica... more In this article, the effects of graphene loading (0.1, 0.2, 0.3 wt%) on both the electromechanical and mechanical properties of carboxymethylcellulose (CMC)-based actuators were investigated. CMC-based graphene-loaded actuators were prepared by using 1-butyl-3-methylimidazolium bromide. The synthesized graphene-loaded actuators were characterized by Fourier transform infrared, X-ray diffraction analysis, thermogravimetric analysis, scanning electron microscopy, and tensile tests. Electromechanical properties of the actuators were obtained under DC excitation voltages of 1, 3, 5, and 7 V with a laser displacement sensor. According to the obtained results, the ultimate tensile strength of CMC-based actuators containing 0.3 wt% graphene was higher than that of unloaded actuators by approximately 72.8 %. In addition, the Young's modulus value of the graphene-loaded actuators increased continuously with increasing graphene content. Under a DC excitation voltage of 5 V, the maximum tip displacement of 0.2 wt% graphene-loaded actuators increased by about 15 % compared to unloaded actuators.
Texas Heart Institute journal / from the Texas Heart Institute of St. Luke's Episcopal Hospital, Texas Children's Hospital, 2012
Arteriovenous fistulae have a substantial impact on systemic hemodynamics, but their effect on ca... more Arteriovenous fistulae have a substantial impact on systemic hemodynamics, but their effect on cardiopulmonary bypass is not well understood. The left-to-right shunting of blood through an arteriovenous fistula can create flow problems during cardiopulmonary bypass. We present the case of a 59-year-old man with end-stage renal disease who underwent coronary artery bypass grafting. During surgery, a large brachiocephalic arteriovenous fistula provided excessive venous return to the heart, compromising the myocardial protection offered by cardiopulmonary bypass. We modified the venous cannulation from a 2-stage single cannula to a bicaval cannula and were then able to achieve cardioplegic arrest and myocardial protection with no further problems.
The Journal of cardiovascular surgery
In this study, we present a single center experience with Bicarbon bileaflet valve in 307 patient... more In this study, we present a single center experience with Bicarbon bileaflet valve in 307 patients with rheumatic heart disease. Between August 1998 and September 2000, 307 patients underwent heart valve replacement using the Bicarbon bileaflet valve (Sorin Biomedica, Saluggia, Italy) with an average age of 47.19+/-13.21 years (range 14 to 80 years), consisting of 147 males and 160 females at Alkan Hospital, Cardiovascular Surgery Department. Aortic valve replacement (AVR) was performed in 77 patients, mitral valve replacement (MVR) in 156 patients and double valve replacement (DVR) in 74 patients. The early mortality rate was 3.3% (10/307) and there was no late mortality. The actuarial survival rate, including hospital mortality, was 96.74+/-1.01% for the whole group, 96.5+/-1.5% for the MVR group, 97.4+/-1.8% for the AVR group and 97.3+/-1.9% for the DVR group at 35 months. One patient had obstructive valve thrombosis with MVR. The 35 months actuarial freedom from valve thrombosis...
Cellulose, 2015
Electroactive behavior of carboxymethylcellulose (CMC)-based actuators was investigated in this s... more Electroactive behavior of carboxymethylcellulose (CMC)-based actuators was investigated in this study. CMC-based films were firstly fabricated by using 1-butyl-3-methylimidazolium bromide. Characterization studies of the CMC films were conducted by using Fourier transform infrared, X-ray diffraction analysis, thermogravimetric analysis, scanning electron microscopy, and tensile testing. CMC-based actuator films were produced by gold coating on both surfaces of CMC-based films. Polyethylene glycol (PEG) at different loadings (1, 1.5 and 2 g) was used to improve electroactive behavior of CMC based actuators. Maximum tip displacements were obtained under DC excitation voltages of 1, 3, 5 and 7 V. CMC based actuator loaded with 1.5 g PEG exhibited the largest tip displacement among other actuators for each excitation voltage. The PEG loading did not lead to considerable differences in tensile strength of CMC-based films. However, Young's modulus decreased with PEG loading.
Interactive CardioVascular and Thoracic Surgery, 2013
The aim of this study was to compare additive and logistic European System for Cardiac Operative ... more The aim of this study was to compare additive and logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE), EuroSCORE II and the Society of Thoracic Surgeons (STS) models in calculating mortality risk in a Turkish cardiac surgical population. METHODS: The current patient population consisted of 428 patients who underwent isolated coronary artery bypass grafting (CABG) between 2004 and 2012, extracted from the TurkoSCORE database. Observed and predicted mortalities were compared for the additive/logistic EuroSCORE, EuroSCORE II and STS risk calculator. The area under the receiver operating characteristics curve (AUC) values were calculated for these models to compare predictive power. RESULTS: The mean patient age was 74.5 ± 3.9 years at the time of surgery, and 35.0% were female. For the entire cohort, actual hospital mortality was 7.9% (n = 34; 95% confidence interval [CI] 5.4-10.5). However, the additive EuroSCORE-predicted mortality was 6.4% (P = 0.23 vs observed; 95% CI 6.2-6.6), logistic EuroSCORE-predicted mortality was 7.9% (P = 0.98 vs observed; 95% CI 7.3-8.6), EuroSCORE II-predicted mortality was 1.7% (P = 0.00 vs observed; 95% CI 1.6-1.8) and STS predicted mortality was 5.8% (P = 0.10 vs observed; 95% CI 5.4-6.2). The mean predictive performance of the analysed models for the entire cohort was fair, with 0.7 (95% CI 0.60-0.79). AUC values for additive EuroSCORE, logistic EuroSCORE, EuroSCORE II and STS risk calculator were 0.70 (95% CI 0.60-0.79), 0.70 (95% CI 0.59-0.80), 0.72 (95% CI 0.62-0.81) and 0.62 (95% CI 0.51-0.73), respectively. CONCLUSIONS: EuroSCORE II significantly underestimated mortality risk for Turkish cardiac patients, whereas additive and logistic EuroSCORE and STS risk calculators were well calibrated.
Diagnostic and Interventional Radiology, 2012
We aimed to present our clinical experience with the renal artery catheterization (RAC) technique... more We aimed to present our clinical experience with the renal artery catheterization (RAC) technique, which reduces the volume of intra-arterial contrast media (ICM) used during endovascular aortic repair (EVAR), and describe the short-term results of this technique. MATERIALS AND METHODS We retrospectively evaluated 16 patients (15 males and one female) who underwent EVAR between March 2011 and February 2012 using the RAC technique for an abdominal aortic aneurysm. A Simmons-1 catheter was preferred for renal artery cannulation. The mean age of the patients at the time of treatment was 70 years (range, 61-82 years). Fifteen cases were fusiform aneurysms, and one case was a saccular aneurysm. Creatinine and estimated glomerular filtration rate (eGFR) values were recorded before the procedure and during the first 72 hours postprocedure. RESULTS Bifurcated stent grafts were implanted with 100% procedural success using the RAC technique. The inferiorly positioned renal artery was cannulated with a Simmons-1 catheter in the first five patients, and was maintained at the level of the renal artery orifice in the remaining patients. The mean volume of the ICM used was 47 mL (range, 23-83 mL). The creatinine and eGFR values were not significantly different between the pre-and postoperative periods (P > 0.05). CONCLUSION Reducing the volume of ICM used during EVAR is critical for protecting renal function. The RAC technique is a safe and effective method in appropriate patients when performed by experienced clinicians.
Journal-Cardiovascular Surgery, 2013
Deep venous thrombosis is a common pathology frequently managed conservatively with anticoagulant... more Deep venous thrombosis is a common pathology frequently managed conservatively with anticoagulant therapy alone. Unfortunately, conservative treatment may fail to achieve enough venous flow through recanalization within the thrombus. Here, we present a 38 year old young woman with deep venous thrombosis treated with intravenous catheter mediated thrombolysis with ultrasonographic waves and had a good outcome. Catheter-directed trombolysis and pharmaco-mechanical procedures seem to be effective alternative treatment strategies to resolve symptoms in a shorter period than conventional anticoagulant theraphy. We aimed to emphasize the evolving management of deep venous thrombosis.
Surgery Today, 2014
Patient-prosthesis mismatch (PPM) is defined when the ratio of the effective orifice area of the ... more Patient-prosthesis mismatch (PPM) is defined when the ratio of the effective orifice area of the normally functioning prosthetic valve to the body surface area of the patient is &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.85 cm(2)/m(2). The aim of this study was to assess the measurements of the mean platelet volume (MPV) as an indicator of platelet activation in patients with PPM. A total of 109 patients with isolated aortic valve replacement (AVR) procedures with a mechanical prosthesis and a control group from a normal population of 102 people compatible in terms of age and sex were chosen for the study. The AVR group was subdivided into a PPM group (n = 41) and non-PPM group (n = 68). All patients and control participants underwent echocardiographic examinations, with simultaneous measurements of the serum MPV values. The MPV measurements were significantly higher in the patients with AVR compared to the control group (8.97 ± 0.93 vs. 8.26 ± 0.14, p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). Higher results were also obtained in the patients with PPM compared to the non-PPM group (9.36 ± 0.61 vs. 8.73 ± 1.01, p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). The platelet counts were found to be similar in both groups (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 0.05). We have herein shown that the PPM patients had a significantly higher MPV compared to the patients with AVR without PPM and healthy subjects.
Composites Part B: Engineering, 2015
In this study, graphene nanoplatelets (0.10, 0.25, and 0.50 wt.%) were loaded into cellulose matr... more In this study, graphene nanoplatelets (0.10, 0.25, and 0.50 wt.%) were loaded into cellulose matrix to improve electroactive performance of cellulose-based composite actuators. Firstly, cellulosic films were produced by dissolving microcrystalline cellulose in 1-butyl-3-methylimidazolium chloride. Afterwards, graphene loaded cellulosic films were fabricated and gold leaf was coated on both surfaces of graphene loaded cellulose-based films. The changes in crystallographic properties and chemical functional groups of cellulose were investigated by X-ray diffraction and Fourier transform infrared analyses, respectively. Besides, thermal stability, electrical conductivity, and morphological properties of the films were examined by thermogravimetric analysis, electrical conductivity measurement, and scanning electron microscopy, respectively. The tensile strength and the Young's modulus of the films and actuators were also determined by tensile tests. The electroactive characteristics were analyzed under DC excitation voltages of 3 V, 5 V and 7 V. The time responses were evaluated via proposed experimental data based model. The performances of the actuators were compared in terms of maximum tip displacement, minimum tip displacement and time constant.
Smart Materials and Structures, 2014
The effects of the PWM excitation signal parameters, such as frequency and magnitude, on the Nafi... more The effects of the PWM excitation signal parameters, such as frequency and magnitude, on the Nafion-based ionic polymer metal composite (IPMC) actuator response were found out. The first set of experiments was designed to observe the actuator response when the actuators were biased with constant DC voltages. These experimental results were exploited to build an experimental data based dynamic model. The model and these results were also used as references to evaluate the experimental results in the proceeding experiments. The second set of experiments was designed to observe the actuator response when the DC square wave signals at different frequencies (0 to 1000 Hz) were applied. The third set of experiments was designed to observe the actuator response when the PWM signals at different magnitudes (6, 8 and 10 V) were applied. It is observed that back relaxation reduces with increasing frequency, but after a certain frequency value, it remains approximately constant. It is seen that the input output relationship of the actuators are linear only for a range of PWM signal magnitudes. The observations in both the PWM frequency and the magnitude experiments indicated that the performance of the Nafion-based IPMC actuator could be improved by selecting a magnitude of PWM signals between 6–8 Volts and by selecting a frequency between 400–1000 Hz.
Surgery Today, 2003
Simultaneous coronary artery bypass grafting with a resection of left atrial myxoma has been rare... more Simultaneous coronary artery bypass grafting with a resection of left atrial myxoma has been rarely reported. The ages and the symptoms of patients who have left atrial myxomas and coronary artery disease are similar. In this report, we present our cases of left atrial myxoma with concomitant coronary artery disease who were all treated surgically. Between September 1998 and January 2001, 11 patients were surgically treated after being diagnosed to have left atrial myxoma. Routine coronary angiography was performed on all patients preoperatively. In four patients concomitant coronary artery disease was identified. At surgery we performed coronary artery bypass grafting after a resection of left atrial myxoma in three patients. All patients were weaned from cardiopulmonary bypass without any difficulty. The postoperative course was uneventful. The follow-up period was 17 +/- 10 months (range 3-32 months). All patients were symptom-free and no recurrence of myxoma was detected. Based on our experience, cardiovascular surgeons should be aware of the concomitance of these diseases. It is therefore recommended that coronary angiography should be performed on all patients who present with left atrial myxomas.
Tainn, 2005
ABSTRACT In this work the navigation and GPS based trajectory control of an unmanned autonomous v... more ABSTRACT In this work the navigation and GPS based trajectory control of an unmanned autonomous vehicle is introduced. The caterpillar tread like mobile vehicle with duo cycle drive is equipped with a mobile GPS and micro controller. To get accurate position data, a DGPS (Differential GPS) with a local base station is used. In order to let the vehicle to follow a desired trajectory, a reference path is given by using Way Points as GPS data’s to micro controller, which provide the position and orientation control of the vehicle. The instant position and orientation of the vehicle in accordance to an assigned plane coordinate frame are calculated by micro controller from detected latitude and longitude values (land coordinates) of mobile GPS, which receive corrected on line data’s from base station.The duo cycle vehicle is driven with geared DC motors, which are equipped with chained caterpillar tread drives, so that it can have better motion, clambering and tracking performances. Successful navigation and path following results are obtained with several experiments by various control applications
Page 1. A COMPUTER CONTROLLED VISION ORIENTED ROBOT MANIPULATOR FOR CHESS GAME Erol UYAR, Sevket ... more Page 1. A COMPUTER CONTROLLED VISION ORIENTED ROBOT MANIPULATOR FOR CHESS GAME Erol UYAR, Sevket GÜMÜSTEKIN, Sükrü OZAN, Levent ÇETIN Dokuz Eylül University - Faculty of Engineering Department ...
Turkiye Klinikleri Journal of Cardiovascular Surgery, 2001
Bu çalışmanın amacı genç erişkin (40 yaş altı) hastalar ile ileri yaştaki (75 yaş üstü) koroner a... more Bu çalışmanın amacı genç erişkin (40 yaş altı) hastalar ile ileri yaştaki (75 yaş üstü) koroner arter hastalarının CABG sonrası erken ve orta dönem sonuçlarını kıyaslamak ve bu sonuçlar üzerinde etkisi olan faktörleri ortaya koyabilmektir. Materyel ve Metod: Ağustos 1998 ile Ağustos 2000 tarihleri arasında Alkan Hastanesi, Kalp ve Damar Cerrahisi Kliniğinde 1393 koroner bypass ameliyatı yapılmış olup, bunlardan 54'ü 40 yaş altı (grup 1), 42'si ise 75 yaş üstü (grup 2) idi. Grup 1'de ortalama yaş 37.8±2.8, Grup 2' de ise 76.4±2.4 yıldı. Her iki grubun preoperatif, operatif ve post operatif bulguları analiz edildi. Bulgular: Grup 2 ile kıyaslandığında Grup 1'de sigara içiciliği (%77.4'e karşı % 21.4, p<0.001), [son 10 yıldır hiç sigara içmeyen hastalar sigara içmeyen gruba alınmıştır.] hiperlipidemik hasta sayısı (%41.5'e karşı %19.8, p<0.05) ve obez hasta oranı (%28.3'e karşı %0, p<0.001) daha fazlaydı. Grup 2'deki hastalarda ise arteriyel hipertansiyon öyküsü (%57.7'e karşı %17, p<0.05) daha fazlaydı. Grup 2'de ortalama kros klemp zamanı (32.2±17dk'a karşı 24.8±11.1 dk), kardiopulmoner bypass (52.6±21.6 dk'a karşı 40.8±15.4 dk) ve ekstübasyon süreleri (8.6±2.9'e karşı 5.1±2.3 saat) Grup 1 ile kıyaslandığında anlamlı biçimde daha uzundu (p<0.05). Grup 2'de hasta başına anastomoz sayısı (2.7±1'e karşı 2.2±1, p<0.05) daha fazlaydı. Post operatif kardiak aritmi açısından değerlendirildiğinde iki grup arasında istatistiksel fark vardı Summary Objective: The purpose of this study was to evaluate significant factors that affecting early and midterm results of coronary artery surgery in patients aged less than 40 and more than 75 years old. Materials and Methods: Ninty-six Coronary artery bypass operation has been performed in Alkan Hospital between August 1998 and August 2000 in patients aged less than 40 years and moe than 75 years old. Hese patients divided into the two groups. Group I included 54 (mean age 37.8±2.8) patients group II included 42 patients (mean age 76.4±2.4 years). Preoperative and postoperative data in both groups were analyzed.
Turkiye Klinikleri Journal of Cardiology, 2000
Mersin Universitesi Tip Fakultesi Dergisi, Dec 3, 2012
OZET Atriyal septal defektler (ASD) adolesan ve yetiskinlerde en sik gorulen konjenital kalp hast... more OZET Atriyal septal defektler (ASD) adolesan ve yetiskinlerde en sik gorulen konjenital kalp hastaligidir (% 10-15). Medikal tedaviyle izlenen hastalarda ortalama olum yasi 50 civarindadir ve en sik mortalite nedenleri kalp yetmezligi, pulmoner ve sistemik embolidir. Ileri yastaki Izole sekundum tip ASD'ler de cerrahi tedavi guvenle yapilabilir. 1985-1997 yillari arasinda toplam 202 adet 35 yas uzerinde izole sekundum atriyal septal defektli hasta, Turkiye Yuksek Ihtisas Hastanesi Kalp ve Damar Cerrahisi Klinigi'nde ameliyat edilmistir ve erken-gec donem sonuclari retrospektif sekilde incelenmistir. Hastane (erken) mortalite % 2.9'dur. Takip periyodunda ise gec mortalite 3 hasta ile % 2.5'tir. Hastalarin %96'sina ulasilabilmis ve ortalama 64±42.8 ay takip edilmislerdir. Hastalarin ameliyat sonrasi ortalama fonksiyonel kapasiteleri (NYHA) sinif 1.25±0.2 olarak bulunmustur. Kardiyotorasik oran preoperatif ortalama %63.3±3 iken, postoperatif olarak 57±2'ye, pulmoner arter basinclari ise 46.3±13 mmHg iken postoperatif olarak 30.9±4.4 mmHg gerilemistir. Izole sekundum ASD ileri yasta da guvenle onarilmaktadir. Cerrahi tedaviyle hasta cesitli komplikasyonlardan korunmus, yasam kalitesi arttirilmis ve gec donem yasam beklentisi normal populasyona yaklasmis olur. Ancak izole sekundum ASD tanili ileri yastaki hasta grubu, genc yasta ameliyat edilenlere oranla mortalite ve morbidite acisindan daha cok risk tasir. Anahtar Kelimeler: Sekundum Tip ASD, Cerrahi tedavi, Ileri yas SUMMARY EARLY AND LATE RESULTS IN LATE SURGICAL CLOSURE OF ATRIAL SEPTAL DEFECTS Atrial septal defect (ASD) is the most common congenital cardiac anomaly found in adults. The onset of serious symptoms is apperent in yhe fourty decade and these increaser gradually. Heart failure, pulmonary and systemic embolies are the most common causes of death in medically treated patients. Betvveen 1985 and 1997, a total number of 202 patients who were in the range of 35 and 68 years of age (mean 46.6±5.5 years) underwent surggery for secundum isolated type of ASD in cardiovascular surgery clinic of Turkiye Yuksek ihtisas Hospital. Our surgical experience of ASD repair in patients above 35 years of age is reported regarding early and late term results. Hospital mortality was 2.9%. In the late follow-up period, 3 patients died, giving a late mortality of 2.5%. Long-term follow-up was available in 96% of the patient population and the total follow-up was 1001 Per patient year (mean 64±42.8 months). Postoperative mean functional capacity was 1.25+0.2, pulmonary artery measure was 30.9±4.4 mmHg while they were respectively 2.1+0.5 and 46.3±13 mmHg in the preoperative period. In our experience, surgigal closure of ASD in adults was found to be successful and with low morbidity in patients with pulmonary hypertension and congestive heart failure. Key Words: Secundum type ASD, Surgical treatment, Older age
Artificial Intelligence and Neural Networks, 2006
Page 1. FA Savacı (Ed.): TAINN 2005, LNAI 3949, pp. 2431, 2006. © Springer-Verlag Berlin Heidelb... more Page 1. FA Savacı (Ed.): TAINN 2005, LNAI 3949, pp. 2431, 2006. © Springer-Verlag Berlin Heidelberg 2006 Navigation and GPS Based Path Control of an Autonomous Vehicle Erol Uyar, Levent Çetin, and Aytaç Gören Dokuz ...
Cellulose, 2015
In this article, the effects of graphene loading (0.1, 0.2, 0.3 wt%) on both the electromechanica... more In this article, the effects of graphene loading (0.1, 0.2, 0.3 wt%) on both the electromechanical and mechanical properties of carboxymethylcellulose (CMC)-based actuators were investigated. CMC-based graphene-loaded actuators were prepared by using 1-butyl-3-methylimidazolium bromide. The synthesized graphene-loaded actuators were characterized by Fourier transform infrared, X-ray diffraction analysis, thermogravimetric analysis, scanning electron microscopy, and tensile tests. Electromechanical properties of the actuators were obtained under DC excitation voltages of 1, 3, 5, and 7 V with a laser displacement sensor. According to the obtained results, the ultimate tensile strength of CMC-based actuators containing 0.3 wt% graphene was higher than that of unloaded actuators by approximately 72.8 %. In addition, the Young's modulus value of the graphene-loaded actuators increased continuously with increasing graphene content. Under a DC excitation voltage of 5 V, the maximum tip displacement of 0.2 wt% graphene-loaded actuators increased by about 15 % compared to unloaded actuators.
Texas Heart Institute journal / from the Texas Heart Institute of St. Luke's Episcopal Hospital, Texas Children's Hospital, 2012
Arteriovenous fistulae have a substantial impact on systemic hemodynamics, but their effect on ca... more Arteriovenous fistulae have a substantial impact on systemic hemodynamics, but their effect on cardiopulmonary bypass is not well understood. The left-to-right shunting of blood through an arteriovenous fistula can create flow problems during cardiopulmonary bypass. We present the case of a 59-year-old man with end-stage renal disease who underwent coronary artery bypass grafting. During surgery, a large brachiocephalic arteriovenous fistula provided excessive venous return to the heart, compromising the myocardial protection offered by cardiopulmonary bypass. We modified the venous cannulation from a 2-stage single cannula to a bicaval cannula and were then able to achieve cardioplegic arrest and myocardial protection with no further problems.
The Journal of cardiovascular surgery
In this study, we present a single center experience with Bicarbon bileaflet valve in 307 patient... more In this study, we present a single center experience with Bicarbon bileaflet valve in 307 patients with rheumatic heart disease. Between August 1998 and September 2000, 307 patients underwent heart valve replacement using the Bicarbon bileaflet valve (Sorin Biomedica, Saluggia, Italy) with an average age of 47.19+/-13.21 years (range 14 to 80 years), consisting of 147 males and 160 females at Alkan Hospital, Cardiovascular Surgery Department. Aortic valve replacement (AVR) was performed in 77 patients, mitral valve replacement (MVR) in 156 patients and double valve replacement (DVR) in 74 patients. The early mortality rate was 3.3% (10/307) and there was no late mortality. The actuarial survival rate, including hospital mortality, was 96.74+/-1.01% for the whole group, 96.5+/-1.5% for the MVR group, 97.4+/-1.8% for the AVR group and 97.3+/-1.9% for the DVR group at 35 months. One patient had obstructive valve thrombosis with MVR. The 35 months actuarial freedom from valve thrombosis...
Cellulose, 2015
Electroactive behavior of carboxymethylcellulose (CMC)-based actuators was investigated in this s... more Electroactive behavior of carboxymethylcellulose (CMC)-based actuators was investigated in this study. CMC-based films were firstly fabricated by using 1-butyl-3-methylimidazolium bromide. Characterization studies of the CMC films were conducted by using Fourier transform infrared, X-ray diffraction analysis, thermogravimetric analysis, scanning electron microscopy, and tensile testing. CMC-based actuator films were produced by gold coating on both surfaces of CMC-based films. Polyethylene glycol (PEG) at different loadings (1, 1.5 and 2 g) was used to improve electroactive behavior of CMC based actuators. Maximum tip displacements were obtained under DC excitation voltages of 1, 3, 5 and 7 V. CMC based actuator loaded with 1.5 g PEG exhibited the largest tip displacement among other actuators for each excitation voltage. The PEG loading did not lead to considerable differences in tensile strength of CMC-based films. However, Young's modulus decreased with PEG loading.
Interactive CardioVascular and Thoracic Surgery, 2013
The aim of this study was to compare additive and logistic European System for Cardiac Operative ... more The aim of this study was to compare additive and logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE), EuroSCORE II and the Society of Thoracic Surgeons (STS) models in calculating mortality risk in a Turkish cardiac surgical population. METHODS: The current patient population consisted of 428 patients who underwent isolated coronary artery bypass grafting (CABG) between 2004 and 2012, extracted from the TurkoSCORE database. Observed and predicted mortalities were compared for the additive/logistic EuroSCORE, EuroSCORE II and STS risk calculator. The area under the receiver operating characteristics curve (AUC) values were calculated for these models to compare predictive power. RESULTS: The mean patient age was 74.5 ± 3.9 years at the time of surgery, and 35.0% were female. For the entire cohort, actual hospital mortality was 7.9% (n = 34; 95% confidence interval [CI] 5.4-10.5). However, the additive EuroSCORE-predicted mortality was 6.4% (P = 0.23 vs observed; 95% CI 6.2-6.6), logistic EuroSCORE-predicted mortality was 7.9% (P = 0.98 vs observed; 95% CI 7.3-8.6), EuroSCORE II-predicted mortality was 1.7% (P = 0.00 vs observed; 95% CI 1.6-1.8) and STS predicted mortality was 5.8% (P = 0.10 vs observed; 95% CI 5.4-6.2). The mean predictive performance of the analysed models for the entire cohort was fair, with 0.7 (95% CI 0.60-0.79). AUC values for additive EuroSCORE, logistic EuroSCORE, EuroSCORE II and STS risk calculator were 0.70 (95% CI 0.60-0.79), 0.70 (95% CI 0.59-0.80), 0.72 (95% CI 0.62-0.81) and 0.62 (95% CI 0.51-0.73), respectively. CONCLUSIONS: EuroSCORE II significantly underestimated mortality risk for Turkish cardiac patients, whereas additive and logistic EuroSCORE and STS risk calculators were well calibrated.
Diagnostic and Interventional Radiology, 2012
We aimed to present our clinical experience with the renal artery catheterization (RAC) technique... more We aimed to present our clinical experience with the renal artery catheterization (RAC) technique, which reduces the volume of intra-arterial contrast media (ICM) used during endovascular aortic repair (EVAR), and describe the short-term results of this technique. MATERIALS AND METHODS We retrospectively evaluated 16 patients (15 males and one female) who underwent EVAR between March 2011 and February 2012 using the RAC technique for an abdominal aortic aneurysm. A Simmons-1 catheter was preferred for renal artery cannulation. The mean age of the patients at the time of treatment was 70 years (range, 61-82 years). Fifteen cases were fusiform aneurysms, and one case was a saccular aneurysm. Creatinine and estimated glomerular filtration rate (eGFR) values were recorded before the procedure and during the first 72 hours postprocedure. RESULTS Bifurcated stent grafts were implanted with 100% procedural success using the RAC technique. The inferiorly positioned renal artery was cannulated with a Simmons-1 catheter in the first five patients, and was maintained at the level of the renal artery orifice in the remaining patients. The mean volume of the ICM used was 47 mL (range, 23-83 mL). The creatinine and eGFR values were not significantly different between the pre-and postoperative periods (P > 0.05). CONCLUSION Reducing the volume of ICM used during EVAR is critical for protecting renal function. The RAC technique is a safe and effective method in appropriate patients when performed by experienced clinicians.
Journal-Cardiovascular Surgery, 2013
Deep venous thrombosis is a common pathology frequently managed conservatively with anticoagulant... more Deep venous thrombosis is a common pathology frequently managed conservatively with anticoagulant therapy alone. Unfortunately, conservative treatment may fail to achieve enough venous flow through recanalization within the thrombus. Here, we present a 38 year old young woman with deep venous thrombosis treated with intravenous catheter mediated thrombolysis with ultrasonographic waves and had a good outcome. Catheter-directed trombolysis and pharmaco-mechanical procedures seem to be effective alternative treatment strategies to resolve symptoms in a shorter period than conventional anticoagulant theraphy. We aimed to emphasize the evolving management of deep venous thrombosis.
Surgery Today, 2014
Patient-prosthesis mismatch (PPM) is defined when the ratio of the effective orifice area of the ... more Patient-prosthesis mismatch (PPM) is defined when the ratio of the effective orifice area of the normally functioning prosthetic valve to the body surface area of the patient is &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.85 cm(2)/m(2). The aim of this study was to assess the measurements of the mean platelet volume (MPV) as an indicator of platelet activation in patients with PPM. A total of 109 patients with isolated aortic valve replacement (AVR) procedures with a mechanical prosthesis and a control group from a normal population of 102 people compatible in terms of age and sex were chosen for the study. The AVR group was subdivided into a PPM group (n = 41) and non-PPM group (n = 68). All patients and control participants underwent echocardiographic examinations, with simultaneous measurements of the serum MPV values. The MPV measurements were significantly higher in the patients with AVR compared to the control group (8.97 ± 0.93 vs. 8.26 ± 0.14, p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). Higher results were also obtained in the patients with PPM compared to the non-PPM group (9.36 ± 0.61 vs. 8.73 ± 1.01, p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). The platelet counts were found to be similar in both groups (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 0.05). We have herein shown that the PPM patients had a significantly higher MPV compared to the patients with AVR without PPM and healthy subjects.
Composites Part B: Engineering, 2015
In this study, graphene nanoplatelets (0.10, 0.25, and 0.50 wt.%) were loaded into cellulose matr... more In this study, graphene nanoplatelets (0.10, 0.25, and 0.50 wt.%) were loaded into cellulose matrix to improve electroactive performance of cellulose-based composite actuators. Firstly, cellulosic films were produced by dissolving microcrystalline cellulose in 1-butyl-3-methylimidazolium chloride. Afterwards, graphene loaded cellulosic films were fabricated and gold leaf was coated on both surfaces of graphene loaded cellulose-based films. The changes in crystallographic properties and chemical functional groups of cellulose were investigated by X-ray diffraction and Fourier transform infrared analyses, respectively. Besides, thermal stability, electrical conductivity, and morphological properties of the films were examined by thermogravimetric analysis, electrical conductivity measurement, and scanning electron microscopy, respectively. The tensile strength and the Young's modulus of the films and actuators were also determined by tensile tests. The electroactive characteristics were analyzed under DC excitation voltages of 3 V, 5 V and 7 V. The time responses were evaluated via proposed experimental data based model. The performances of the actuators were compared in terms of maximum tip displacement, minimum tip displacement and time constant.
Smart Materials and Structures, 2014
The effects of the PWM excitation signal parameters, such as frequency and magnitude, on the Nafi... more The effects of the PWM excitation signal parameters, such as frequency and magnitude, on the Nafion-based ionic polymer metal composite (IPMC) actuator response were found out. The first set of experiments was designed to observe the actuator response when the actuators were biased with constant DC voltages. These experimental results were exploited to build an experimental data based dynamic model. The model and these results were also used as references to evaluate the experimental results in the proceeding experiments. The second set of experiments was designed to observe the actuator response when the DC square wave signals at different frequencies (0 to 1000 Hz) were applied. The third set of experiments was designed to observe the actuator response when the PWM signals at different magnitudes (6, 8 and 10 V) were applied. It is observed that back relaxation reduces with increasing frequency, but after a certain frequency value, it remains approximately constant. It is seen that the input output relationship of the actuators are linear only for a range of PWM signal magnitudes. The observations in both the PWM frequency and the magnitude experiments indicated that the performance of the Nafion-based IPMC actuator could be improved by selecting a magnitude of PWM signals between 6–8 Volts and by selecting a frequency between 400–1000 Hz.
Surgery Today, 2003
Simultaneous coronary artery bypass grafting with a resection of left atrial myxoma has been rare... more Simultaneous coronary artery bypass grafting with a resection of left atrial myxoma has been rarely reported. The ages and the symptoms of patients who have left atrial myxomas and coronary artery disease are similar. In this report, we present our cases of left atrial myxoma with concomitant coronary artery disease who were all treated surgically. Between September 1998 and January 2001, 11 patients were surgically treated after being diagnosed to have left atrial myxoma. Routine coronary angiography was performed on all patients preoperatively. In four patients concomitant coronary artery disease was identified. At surgery we performed coronary artery bypass grafting after a resection of left atrial myxoma in three patients. All patients were weaned from cardiopulmonary bypass without any difficulty. The postoperative course was uneventful. The follow-up period was 17 +/- 10 months (range 3-32 months). All patients were symptom-free and no recurrence of myxoma was detected. Based on our experience, cardiovascular surgeons should be aware of the concomitance of these diseases. It is therefore recommended that coronary angiography should be performed on all patients who present with left atrial myxomas.