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Midterm results after arterial switch operation for transposition of the great arteries: a single centre experience
Popov Aron Frederik,Tirilomis Theodor,Giesler Michael,Oguz Coskun Kasim
Journal of Cardiothoracic Surgery , 2012, DOI: 10.1186/1749-8090-7-83
Abstract: Background The arterial switch operation (ASO) has become the surgical approach of choice for d-transposition of the great arteries (d-TGA). There is, however an increased incidence of midterm and longterm adverse sequelae in some survivors. In order to evaluate operative risk and midterm outcome in this population, we reviewed patients who underwent ASO for TGA at our centre. Methods In this retrospective study 52 consecutive patients with TGA who underwent ASO between 04/1991 and 12/1999 were included. To analyze the predictors for mortality and adverse events (coronary stenoses, distortion of the pulmonary arteries, dilatation of the neoaortic root, and aortic regurgitation), a multivariate analysis was performed. The follow-up time was ranged from 1–10 years (mean 5 years, cumulative 260 patient-years). Results All over mortality rate was 15.4% and was only observed in the early postoperative period till 1994. The predictors for poor operative survival were low APGAR-score, older age at surgery, and necessity of associated surgical procedures. Late re-operations were necessary in 6 patients (13.6%) and included a pulmonary artery patch enlargement due to supravalvular stenosis (n = 3), coronary revascularisation due to coronary stenosis in a coronary anatomy type E, aortic valve replacement due to neoaortic valve regurgitation (n = 2), and patch-plasty of a pulmonary vein due to obstruction (n = 1). The dilatation of neoaortic root was not observed in the follow up. Conclusions ASO remains the procedure of choice for TGA with acceptable early and late outcome in terms of overall survival and freedom of reoperation. Although ASO is often complex and may be associated with morbidity, most patients survived without major complications even in a small centre.
Unified Analysis of Transmit Antenna Selection/Space-Time Block Coding with Receive Selection and Combining over Nakagami-m Fading Channels in the Presence of Feedback Errors
Ahmet Faruk Coskun,Oguz Kucur
Mathematics , 2012,
Abstract: Examining the effect of imperfect transmit antenna selection (TAS) caused by the feedback link errors on the performance of hybrid TAS/space-time block coding (STBC) with selection combining (SC) (i.e., joint transmit and receive antenna selection (TRAS)/STBC) and TAS/STBC (with receive maximal-ratio combining (MRC)-like combining structure) over Nakagami-m fading channels is the main objective of this paper. Under ideal channel estimation and delay-free feedback assumptions, statistical expressions and several performance metrics related to the post-processing signal-to-noise ratio (SNR) are derived for a unified system model concerning both joint TRAS/STBC and TAS/STBC schemes. Exact analytical expressions for outage probability and bit/symbol error rates (BER/SER) of binary and M-ary modulations are presented in order to provide an extensive examination on the capacity and error performance of the unified system that experiences feedback errors. Also, the asymptotic diversity order analysis, which shows that the diversity order of the investigated schemes is lower bounded by the diversity order provided by STBC transmission itself, is included in the paper. Moreover, all theoretical results are validated by performing Monte Carlo simulations.
Experiences with surgical treatment of ventricle septal defect as a post infarction complication
Kasim Coskun, Sinan Coskun, Aron Popov, Jose Hinz, Jan Schmitto, Kerstin Bockhorst, Kathrin Stich, Reiner Koerfer
Journal of Cardiothoracic Surgery , 2009, DOI: 10.1186/1749-8090-4-3
Abstract: We analysed retrospectively the hospital records of 41 patients, whose ages range from 48 to 81, and underwent a surgical treatment between 1990 and 2005 because of PVSD.In 22 patients concomitant coronary artery bypass grafting (CAGB) was performed. In 15 patients a residual shunt was found, this required re-op in seven of them. The time interval from infarct to rupture was 8.7 days and from rupture to surgery was 23.1 days. Hospital mortality in PVSD group was 32%. The mortality of urgent repair within 3 days of intractable cardiogenic shock was 100%. The mortality of patients with an anterior VSD and a posterior VSD was 29.6% vs 42.8%, respectively. All patients who underwent the surgical repair later than day 36 survived.Surgical intervention is indicated for a majority of patients with mechanical complications. Cardiogenic shock remains the most important factor that affects the early results. The surgical repair of PVSD should be performed 4–5 weeks after AMI. To improve surgical outcome and hemodynamics the choice of surgical technique and surgical timing as well as preoperative management should be tailored for each patient individually.Post myocardial infarction ventricular septal defect (VSD) is a rare but serious complication, which may result in cardiac wall rupture [1]. Surgical intervention is indicated for a majority of patients. The goal of surgical intervention is to improve the cardiac output and to achieve a hemodynamic stability. Complications of acute myocardial infarction that develop within the first 2 weeks after its onset have been associated with a poor prognosis. Cardiogenic shock as a result of involvement of more than 40% of ventricular mass [2], develops in 10% to 27% of these patients [3]. Relative contraindications for cardiac surgery are EF < 30% at rest myocardium, right ventricular (RV) failure, pulmonary hypertension (PHT), mitral insufficiency 3rd degree (MI) and diffuse coronary artery disease (CAD) without a possibility of reva
Extracorporeal life support in pediatric cardiac dysfunction
Kasim O Coskun, Sinan T Coskun, Aron F Popov, Jose Hinz, Mahmoud El-Arousy, Jan D Schmitto, Deniz Kececioglu, Reiner Koerfer
Journal of Cardiothoracic Surgery , 2010, DOI: 10.1186/1749-8090-5-112
Abstract: A retrospective single-centre cohort study was evaluated in pediatric patients, between 1991 and 2008, that required ECLS. A total of 48 patients received ECLS, of which 23 were male and 25 female. The indications for ECLS included CHD in 32 patients and DCM in 16 patients.The mean age was 1.2 ± 3.9 years for CHD patients and 10.4 ± 5.8 years for DCM patients. Twenty-six patients received ECMO and 22 patients received VAD. A total of 15 patients out of 48 survived, 8 were discharged after myocardial recovery and 7 were discharged after successful heart transplantation. The overall mortality in patients with extracorporeal life support was 68%.Although the use of ECLS shows a significantly high mortality rate it remains the ultimate chance for children. For better results, ECLS should be initiated in the operating room or shortly thereafter. Bridge to heart transplantation should be considered if there is no improvement in cardiac function to avoid irreversible multiorgan failure (MFO).Despite technical improvements in congenital heart surgery, mortality as a result of cardiac dysfunction after corrective surgery remains a serious problem. A total of 1 to 5% of these patients will require some form of mechanical support [1-3]. In addition, children with dilatated cardiomyopathy (DCM) may also require extracorporeal life support (ECLS) due to multiorgan dysfunction if conservative medical treatment is inadequate.In this retrospective single center analyzes we present our experience with both extra corporeal membrane oxygenation (ECMO) and ventricle assist device (VAD) for pediatric patients requiring ECLS at our institution. We reviewed the outcomes of pediatric patients necessitating ECLS after corrective surgery and compared outcomes with pediatric patients necessitating ECLS because of DCM. Our aim is to report the prognosis of children undergoing ECLS and to compare the outcomes of the two main diseases associated with high mortality even in canters with ECLS poss
Daptomycin for treatment of methicillin-resistant Staphylococcus epidermidis saphenectomy wound infection after coronary artery bypass graft operation (CABG): a case report
Jan D Schmitto, Aron F Popov, Samuel T Sossalla, Kasim O Coskun, Suyog A Mokashi, Anton Wintner, Friedrich A Schoendube
Journal of Cardiothoracic Surgery , 2009, DOI: 10.1186/1749-8090-4-47
Abstract: Since its first clinical use by Rene Favaloro in the 60's, the great saphenous vein has become the most commonly harvested conduit for revascularization in coronary artery bypass grafting (CABG) [1]. In order to reduce morbidity and improve the recovery time associated with CABG procedures, various techniques have been developed including conventional conduit harvesting, minimally invasive and/or endoscopic harvesting procedures [2]. Still, these surgical techniques are associated with significant complication rates e.g. wound infections, non-infective wound healing disturbances, postoperative pain, etc. [3]. Avoiding and/or reducing these complication rates is of great medical and economic interest. Improvements would result in increased postoperative mobility and quality of life as well as reduced length of hospital stay following surgery resulting large cost savings. Although much research has focused on comparing less invasive and conventional harvest techniques, there is at present no consensus on the areas of postoperative antibiotic drug treatment of saphenectomy wound infections once an infection occurs. Further studies are required to compare treatment methods of saphenectomy wound infections by different antibiotic drugs. Although, Daptomycin has already been proven to be effective in the treatment of bacteremia and endocarditis [4,5] caused by methilin-resistent Staphylococcus aureus [6,7] and several case reports about its effectiveness in the field of cardiac surgery exist in the literature [8], there are still no cases describing the successful treatment of saphenectomy wound infections by Daptomycin.Therefore, in this paper we report the first case of successful treatment of a postoperative wound infection after saphenectomy of the great saphenous vein of the upper left leg with the new antibiotic drug Daptomycin (Cubicin?, Novartis Pharma Corporation, Germany).We report the case of a 68-year old man with severe, diffuse coronary artery disease who pr
Myocardial contractile function in survived neonatal piglets after cardiopulmonary bypass
Theodor Tirilomis, Oliver J Liakopoulos, K Oguz Coskun, Marc Bensch, Aron-Frederik Popov, Jan D Schmitto, Friedrich A Schoendube
Journal of Cardiothoracic Surgery , 2010, DOI: 10.1186/1749-8090-5-98
Abstract: Three indices of left ventricular myocardial contractile function (dP/dt, (dP/dt)/P, and wall thickening) were studied up to 6 hours after CPB in neonatal piglets (CPB group; n = 4). The contractility data were analysed and then compared to the data of newborn piglets who also underwent median thoracotomy and instrumentation for the same time intervals but without CPB (non-CPB group; n = 3).Left ventricular dP/dtmax and (dP/dtmax)/P remained stable in CPB group, while dP/dtmax decreased in non-CPB group 5 hours postoperatively (1761 ± 205 mmHg/s at baseline vs. 1170 ± 205 mmHg/s after 5 h; p < 0.05). However, with regard to dP/dtmax and (dP/dtmax)/P there were no statistically significant differences between the two groups. Comparably, although myocardial thickening decreased in the non-CPB group the differences between the two groups were not statistically significant.The myocardial contractile function in survived neonatal piglets remained stable 6 hours after cardiopulmonary bypass and mild hypothermia probably due to regional hypercontractility.The postoperative course after cardiac surgery in infants and children is in most cases uneventful. However, in some cases hemodynamic deterioration was observed early after surgery. The first characteristic change is regarding systemic blood pressure. The cause may be hypovolemia or reduced cardiac output. In clinical studies a significant reduction of cardiac index and stroke work index started at least two hours after cardiopulmonary bypass [1]. Management of hypovolemia requires infusions to maintain fluid balance. A fall in cardiac index results in inotropic support. Nevertheless, a hemodynamic unstable situation may result in combined treatment with blood, colloid, and crystalloid infusions and use of catecholamines with the goal to prevent further hemodynamic deterioration and to restore adequate organ perfusion.Extracorporeal perfusion, hypothermia, myocardial ischemia, and reperfusion are some of the factors iden
Universal Current-Mode Biquad Employing Dual Output Current Conveyors and MO-CCCA with Grounded Passive Elements  [PDF]
Kasim Karam Abdalla
Circuits and Systems (CS) , 2013, DOI: 10.4236/cs.2013.41013

A new universal multiple input multiple output (MIMO) type current-mode biquad employing two dual output current conveyors (DOCCII), one multiple output current controlled current amplifier (MOCCCA) and four passive grounded elements is proposed which can realize all the five basic filtering functions namely, low-pass (LP), high-pass (HP), band-pass (BP), band-stop (BR) and all-pass (AP) in current mode from the same configuration. The centre frequency\"\" can be set by the passive elements of the circuit and the quality factor Q0 is electronically tunable through bias currents of the MOCCCA. Therefore, the biquad filter has independent tenability for the\"\" and Q0. The active and passive sensitivities of Q0 and\"\" are low. The workability of the new configuration has been demonstrated by PSPICE simulation results based upon a CMOS CCII in0.35μm technology.

Optical and Morphological Studies of Chemical Bath Deposited Nanocrystalline Cd1-xZnxS Thin Films  [PDF]
Kasim Uthman Isah
Materials Sciences and Applications (MSA) , 2013, DOI: 10.4236/msa.2013.45036

Cadmium Zinc Sulfide, Cd1-xZnxS thin films were deposited by chemical bath deposition technique at bath temperature of 75°C. The morphology of the films was analyzed by scanning electron microscope, the optical constants of the films were estimated from the transmission and reflection spectra of the films in the wavelength range of 300 - 900 nm. The films had a transmittance between 75% and 85% and optical band gap in the range 2.8 - 3.4 eV. The dependence of the refractive index of the films on the wavelength was investigated using the single oscillator model, from which the dispersion parameters were determined. The high frequency dielectric constant εL and the ratio of the carrier concentration to the effective mass N/m* were estimated based on the Spitzer and Fan model. Both εL and N/m* show a decrease in value with increase in Zinc

Daptomycin as a possible new treatment option for surgical management of Methicillin-Resistant Staphylococcus aureus sternal wound infection after cardiac surgery
Aron F Popov, Jan D Schmitto, Theodor Tirilomis, Christian Bireta, Kasim O Coskun, Suyog A Mokashi, Alexander Emmert, Martin Friedrich, Christoph H Wiese, Friedrich A Schoendube
Journal of Cardiothoracic Surgery , 2010, DOI: 10.1186/1749-8090-5-57
Abstract: Sternal wound infection is a severe complication in cardiac surgery despite continuing efforts to improve perioperative conditions. This complication is often associated with significant morbidity and mortality rates of up to 45% [1], with prolonged hospitalization [2] and additional surgical procedures, as well as prolonged antibiotic therapy and its inherent high costs [3]. The most common conventional treatments involve surgical revision, open dressing, closed mediastinal irrigation, debridement, complete sternectomy, or reconstruction with omental or muscleflaps [4]. With the increase of MRSA infection, the accompanying antibiotic therapy has received more attention for treatment of sternal wound infections after cardiac surgery.A 77-year-old female was admitted with coronary artery disease and severe aortic stenosis to the Department of Cardiac Surgery of the University Hospital of Goettingen, Germany in July of 2007. A coronary artery bypass grafting (left anterior descending artery was revascularized by the left internal mammarian artery) and an aortic valve replacement (Cryolife O'Brien? 23 mm, biological) were performed. After an uneventful operation and postoperative course, the patient was discharged home. Three month after discharge, at the initial postoperative visit, physical examination revealed an unstable sternum with purulent drainage (MRSA-positive) from the distal portion of the incision. Subsequently, the patient was hospitalized and started on wide broad spectrum antibiotics (Clindamycin and Rifampicin) in combination with local antiseptic washings. She was urgently taken to the operating room for wound debridement. Once the incision was reopened, frank pus was noted. The wound was irrigated and the sternum was realigned. Her general condition recovered and two months after the operation, the patient was discharged home.One month following this, the patient returned with purulent drainage forming in the distal wound, necessitating hospital read
Myocardial ischemia with left ventricular outflow obstruction
Aron F Popov, Christian Bireta, Jan D Schmitto, Dieter Zenker, Martin Friedrich, Kasim O Coskun, Ralf Seipelt, Gerd G Hanekop, Friedrich A Schoendube
Journal of Cardiothoracic Surgery , 2009, DOI: 10.1186/1749-8090-4-51
Abstract: We are reporting on a 32-year-old patient who had been treated for a prolonged period of time for symptoms of HOCM. However, the diagnosis of a flow acceleration and pressure gradient in the outflow tract had only been made by echocardiography (ECHO) up to that point. In 2004, a 2-chamber pacemaker with a short AV conduction time (70 ms) was implanted for a left precordial repolarization abnormality and to lower the pressure gradient between the ventricle and outflow tract. Freedom from symptoms was not actually achieved with this treatment. In February of this year, the patient was found in a non-responsive state following what had most likely been a period of complete well-being. Emergency cardiovascular resuscitation was not started immediatly, however, and the interval before resuscitation was started was approximately 5 minutes. When the emergency medical services arrived, the patient had no pulse of his own, while the pacemaker continued to work. After a short period of cardiopulmonary reanimation, a status of ventricular fibrillation was reached. At this point, a single defibrillation of 200 joules was applied and spontaneous circulation was established once again. The patient was only taking inadequate gasping breaths; as a result, he was intubated immediately. A low dose of adrenaline was administered due to hypotonic circulation; the patient then became hemodynamically stable. Upon admission to our clinic, cerebral imaging was immediately ordered; this showed no intracerebral bleeding, ischemia or edema. Neuroprotective hypothermia therapy was also immediately introduced for a period of 48 hours. Echocardiography revealed severe left ventricular hypertrophy with normal left ventricular ejection fraction (EF > 60%) and normal dimensions. Additionally, the ECHO exhibited nearly complete obstruction of the the left ventricular outflow tract (LVOT) by the hypertrophied septum including a systolic anterior motion phenomena (SAM) by the anterior leaflet of the m
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