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Biomedical subjects

Selami Dogan

Publications and source records attributed to Selami Dogan.

At least 19 recordsLinked to original sources
PubMed2006

Facilitating coronary artery evaluation in MDCT using a 3D automatic vessel segmentation tool.

The purpose of this study was to investigate a 3D coronary artery segmentation algorithm using 16-row MDCT data sets. Fifty patients underwent cardiac CT (Sensation 16, Siemens) and coronary angiography. Automatic and manual detection of coronary artery stenosis was performed. A 3D coronary artery segmentation algorithm (Fraunhofer Institute for Computer Graphics, Darmstadt) was used for automatic evaluation. All significant stenoses (>50%) in vessels >1.5 mm in diameter were protocoled. Each detection tool was used by one reader who was blinded to the results of the other detection method and the results of coronary angiography. Sensitivity and specificity were determined for automatic and manual detection as well as was the time for both CT-based evaluation methods. The overall sensitivity and specificity of the automatic and manual approach were 93.1 vs. 95.83% and 86.1 vs. 81.9%. The time required for automatic evaluation was significantly shorter than with the manual approach, i.e., 246.04+/-43.17 s for the automatic approach and 526.88+/-45.71 s for the manual approach (P<0.0001). In 94% of the coronary artery branches, automatic detection required less time than the manual approach. Automatic coronary vessel evaluation is feasible. It reduces the time required for cardiac CT evaluation with similar sensitivity and specificity as well as facilitates the evaluation of MDCT coronary angiography in a standardized fashion.

Aged↗
PubMed2006

Does totally endoscopic access for off-pump cardiac surgery influence the incidence of postoperative atrial fibrillation in coronary artery bypass grafting? A preliminary report.

BACKGROUND: The occurrence rate of atrial fibrillation (AF) after coronary artery bypass grafting, quoted in the literature, is wide ranging from 5% to over 40%. It is speculated that, off-pump coronary artery bypass grafting (OPCAB) and also minimally invasive cardiac surgery reduces the incidence of postoperative AF due to reduced trauma, ischemia, and inflammation. Current data, however, do not clearly answer the question, whether the incidence of postoperative AF is reduced in using minimally invasive techniques, ideally resulting in the combination of both small access and off-pump surgery. The aim of this study was to evaluate the incidence of postoperative AF in patients undergoing totally endoscopic off-pump coronary artery bypass grafting (TECAB). METHODS: A retrospective analysis of 72 patients undergoing myocardial revascularization was performed. Early postoperative incidence of AF was compared between three groups of patients: 24 after conventional coronary artery bypass grafting (CABG), 24 after OPCAB, and 24 after totally endoscopic off-pump CABG. Clinical profile of the patients, including factors having potential influence on postoperative AF was matched for groups. RESULTS: Postoperative AF occurred in 25% of the patients in the CABG group, in 16% of the patients in the OPCAB group, and in 16% of the patients in the TECAB group. This difference has no statistical significance. Risk factors and incidence of postoperative complications were comparable in all groups excepting the number of distal anastomoses. There was a statistical significance between CABG group and TECAB group. CONCLUSION: Avoiding cardiopulmonary bypass and minimizing surgical trauma did not reduce the incidence of postoperative AF in this patient collective. It remains an attractive hypothesis that postoperative AF is reduced by off-pump myocardial revascularisation and minimizing surgical trauma but more robust data are required.

Aged↗
PubMed2006

Two hundred forty minimally invasive mitral operations through right minithoracotomy.

BACKGROUND: This study reports of our 7-year experience with minimally invasive mitral valve operations using the transthoracic clamp technique, reviewing morbidity and mortality as well as echocardiographic follow-up results. METHODS: Between 1997 and 2004, 241 patients (121 male; aged 56 +/- 14 years) underwent minimally invasive mitral valve surgery through right thoracotomy using the transthoracic clamp technique. Reconstructions were done in 199 patients, and 42 valves were replaced. Mean length of incision was 7.0 +/- 1.2 cm. Mean preoperative New York Heart Association functional class was 2.6 +/- 0.9. RESULTS: Thirty-day mortality was 3.3% (n = 8). Operating, bypass, and cross-clamp times averaged 241 +/- 52, 142 +/- 40, and 84 +/- 26 minutes, respectively. Seven patients (2.9%) had conversion to sternotomy. Nine patients (3.7%) underwent reexploration for bleeding. Mean intensive care unit and hospital stay were 18 hours and 8.1 days, respectively. Mean follow-up was 30 +/- 18 months (range, 3 to 76). Echocardiographic follow-up documented persistently competent valve function in all but 6 patients who had grade III regurgitation. Five of them underwent mitral valve re-reconstruction and 1 underwent transplantation. At 76 months, freedom from nontrivial recurrent mitral regurgitation and reoperation were 92.3% and 96.2%, respectively. Actuarial survival at 76 months, including early mortality, was 90.7%. Thoracic wounds were free from infection in all patients. CONCLUSIONS: This study demonstrates that the direct vision, transthoracic clamp technique for minimally invasive mitral valve surgery is reproducible with low mortality and morbidity rates. It results in excellent cosmesis and abolished the risk of thoracic wound infection. Results are comparable to midterm outcomes of conventional operations.

Adolescent↗
PubMed2006

Seven years' experience with suture annuloplasty for mitral valve repair.

OBJECTIVE: Our early experience with the mural annulus shortening suture procedure for mitral valve repair showed superior hemodynamic performance over ring annuloplasty. The aim of this study was to assess the durability of the mural annulus shortening suture procedure and evaluate our 7-year experience regarding valve function, hemodynamic performance, and clinical outcome. METHODS: Between 1996 and 2003, 222 elective consecutive patients (58.1% males; age, 59 +/- 14 years) underwent simple or complex mitral valve repair. Minimal invasive reconstruction was performed in 150 patients. For correction of annular dilatation, we used double-running 2-0 polytetrafluoroethylene sutures to reinforce the posterior circumference of the annulus. Patients were investigated prospectively by means of transthoracic echocardiography before discharge and 1 and 5 years after the operation. The mean follow up was 32 +/- 21 months (range 1-77 months). RESULTS: The operative mortality was 3.1%. Hemodynamic performance at 1 and 5 years showed low mean transvalvular gradients (2.1 +/- 0.9 and 2.0 +/- 0.8 mm Hg, respectively) and a calculated mitral valve orifice area of 3.3 +/- 0.9 cm2 and 3.1 +/- 0.6 cm2, respectively, with progressive annular dilatation from 31.2 +/- 3 mm to 33.9 +/- 4 mm at 1 year and 35.7 +/- 4 mm at 5 years (P < .01). Clinical status improved from New York Heart Association class 3.0 +/- 0.4 to 0.6 +/- 0.8 at 1 year and 0.8 +/- 0.8 at 5 years. Freedom form nontrivial residual mitral regurgitation was 82.3%, freedom from reoperation was 95.1% and actuarial survival was 87.2%, all at 77 months. CONCLUSIONS: The midterm results show satisfactory hemodynamic performance and clinical improvement. Valve competence and reoperation rates are comparable with those of other reports. Durability of the mural annulus shortening suture procedure for mitral valve repair is questioned because progressive annular redilatation occurs.

Female↗
PubMed2006

Navigation-based needle puncture of a cadaver using a hybrid tracking navigational system.

PURPOSE: The purpose of this study was to determine the puncture accuracy of a navigational system, Medarpa, in a soft tissue environment using augmented overlay imaging. MATERIALS AND METHODS: Medarpa is an optical electromagnetic tracking system, which allows tracking of instruments, the radiologist's head position, and the transparent display. The display superimposes a computed tomography scan of a cadaver chest on a human cadaver in real time. In group A, needle puncture was performed using the Medarpa system. Three targets located inside the cadaver chest were selected. In group B, the same targets were used to perform standard computed tomography-guided puncture using a single-slice technique. A total of 42 punctures were performed in each group. Postpuncture computed tomography scans were made to verify needle tip positions. RESULTS: Mean deviation from targets was 8.42 mm +/- 1.78 mm for group A and 8.90 mm +/- 1.71 mm for group B. No significant difference was found between group A and B in any target (P > 0.05). No significant difference was found between the targets of the same group (P > 0.05). Procedural time for 42 punctures was 160 minutes in group A versus 289 minutes in group B (P < 0.05). CONCLUSION: Needle puncture in a soft tissue environment using the navigational system Medarpa can be reliably performed and matches the accuracy achieved by a computed tomography-guided puncture technique.

Biopsy, Needle↗
PubMed2006

Perioperative biventricular pacing leads to improvement of hemodynamics in patients with reduced left-ventricular function--interim results.

BACKGROUND: Cardiac resynchronization therapy (CRT) has been introduced as a new therapeutic modality in patients with chronic heart failure. However, most studies have investigated the hemodynamic effects in congestive, but not postoperative heart failure. OBJECTIVE: The following study investigates hemodynamic effects of perioperative temporary biventricular pacing in patients undergoing open heart surgery. In 54 patients one left and one right ventricular epicardial wire was placed during open heart operations. Hemodynamic parameters were measured immediately after the operation and 6 as well as 24 hours postoperatively. Transesophageal echocardiography was performed 1 hour postoperatively. RESULTS: Of the 54 patients (59.2%), 32 responded to biventricular pacing with an increase in cardiac output; in these patients synchronized ventricular contraction could be verified echocardiographically. This hemodynamic benefit persisted 6 hours and 24 hours postoperatively. The remaining 22 patients did not show any hemodynamic improvement from biventricular stimulation. CONCLUSION: Biventricular pacing leads to significant rise in cardiac output in approximately 59% of patients with severely reduced left ventricular function and widened QRS complexes. Further studies are necessary to define clearly the clinical characteristics of patients who show remodeling by CRT.

Aged↗
PubMed2006

Multi-detector row CT coronary angiography: influence of reconstruction technique and heart rate on image quality.

PURPOSE: To prospectively evaluate to what extent image quality in 16-detector row computed tomographic (CT) coronary angiography is a function of the heart rate and the image reconstruction technique used. MATERIALS AND METHODS: A total of 70 patients (49 men, 21 women; mean age, 59.1 years +/- 5.8 [standard deviation]) consecutively underwent multi-detector row CT coronary angiography; 49 patients additionally underwent coronary angiography. Image reconstruction was based on both relative and absolute timing. A total of 20 equidistant relative and absolute image reconstructed intervals were assessed by applying a four-step grading scale. Cluster and discrimination analysis, Spearman correlation analysis, and Wilcoxon and chi2 tests were used for statistical analysis. Institutional review board approval and written informed consent were obtained. RESULTS: Though significantly (P < .001) better image quality was observed for image reconstruction based on absolute timing and in patients with lower heart rates, influence on diagnostic accuracy was not significant. Irrespective of the reconstruction technique used, best image quality was observed in patients with a low heart rate for middiastolic reconstruction intervals (starting points: 61% of R-R interval [range, 40%-75%] and 599.3 msec after R [range, 450-840 msec]) and in patients with a high heart rate for end-systolic or early-diastolic intervals (starting points: 27.3% of R-R interval [range, 10%-45%] and 202.3 msec after R [range, 82-336 msec]). With regard to the vessel section and reconstruction technique, cutoff heart rates of the intervals were 64.0-68.5 beats per minute. Patients with stenoses of more than 50% were identified with 86% sensitivity and specificity, and there was no significant difference between relative and absolute timing (P = .99). CONCLUSION: In multi-detector row CT coronary angiography, image quality depends on the choice of a suited reconstruction interval. In patients with high heart rates, the best image quality can be obtained with end-systolic and early-diastolic intervals; in patients with low heart rates, the best results are achieved with middiastolic intervals.

Adult↗
PubMed2005

Echocardiographic assessment in minimally invasive mitral valve surgery.

BACKGROUND: Due to limited exposure, removal of intracavitary air and visual assessment of cardiac function during minimally invasive procedures are not always possible. We analysed the utility of intraoperative transesophageal echocardiography (TEE) and postoperative transthoracic echocardiographic (TTE) in minimally invasive mitral valve (MV) procedures. MATERIAL/METHODS: We evaluated data from 163 consecutive patients undergoing isolated minimally invasive MV replacement (n=40) or repair (n=123) via small right anterolateral thoracotomy (121 complex mitral procedures). Cardioplegic arrest was achieved using either endoaortic (n=23) or transthoracic aortic clamp (n=140). In addition to preoperative TTE, TEE was used intraoperatively before and after cardiopulmonary bypass (CPB). Postoperative TTE was performed to monitor valve function at 3 and 12 months, and at 5-year follow-up. RESULTS: Pre-CPB TEE was useful to assess valve dysfunction and assist in placement of the arterial and venous cannulas. During CPB, placement and positioning of the endoclamp were guided effectively in all but 4 patients, in whom recurrent balloon migration necessitated secondary transthoracic aortic clamping. TEE detected one acute retrograde aortic dissection and one circumflex artery occlusion. After 18.7+/-10.6 months follow-up, all patients except three improved symptomatically and had consistently good valve function. CONCLUSIONS: Intraoperative TEE is essential for minimally invasive MV surgery, because it allows immediate control of valve function before and after surgery. It is useful to detect unexpected complications requiring immediate remedy. Postoperative echocardiographic results show that minimally invasive MV surgery is a good alternative to conventional surgery even in complex MV repairs.

Adolescent↗
PubMed2005

Accuracy of biopsy needle navigation using the Medarpa system--computed tomography reality superimposed on the site of intervention.

The aim of this work was to determine the accuracy of a new navigational system, Medarpa, with a transparent display superimposing computed tomography (CT) reality on the site of intervention. Medarpa uses an optical and an electromagnetic tracking system which allows tracking of instruments, the radiologist and the transparent display. The display superimposes a CT view of a phantom chest on a phantom chest model, in real time. In group A, needle positioning was performed using the Medarpa system. Three targets (diameter 1.5 mm) located inside the phantom were punctured. In group B, the same targets were used to perform standard CT-guided puncturing using the single-slice technique. The same needles were used in both groups (15 G, 15 cm). A total of 42 punctures were performed in each group. Post puncture, CT scans were made to verify needle tip positions. The mean deviation from the needle tip to the targets was 6.65+/-1.61 mm for group A (range 3.54-9.51 mm) and 7.05+/-1.33 mm for group B (range 4.10-9.45 mm). No significant difference was found between group A and group B for any target (p>0.05). No significant difference was found between the targets of the same group (p>0.05). The accuracy in needle puncturing using the augmented reality system, Medarpa, matches the accuracy achieved by CT-guided puncturing technique.

Biopsy, Needle↗
PubMed2005

Minimally invasive port access versus conventional mitral valve surgery: prospective randomized study.

BACKGROUND: We compared the port access mitral valve surgery with the conventional procedure through median sternotomy in a prospective randomized study. METHODS: Forty elective patients with mitral valve disease were prospectively randomized to undergo minimally invasive (group I) or conventional (group II) mitral valve operation. The patients of group I had limited access through right small anterior thoracotomy and a femorofemoral cardiopulmonary bypass system using the endoclamp technique. To assess the efficiency and safety of the procedure, intraoperative and postoperative clinical data and markers of myocardial, cerebral, and lower limb ischemia were collected. Pulmonary function tests were performed to compare the preservation of pulmonary function. Neuropsychological tests were conducted for quantification of neurological and cognitive disorders. RESULTS: Mitral valve reconstructions were performed in 28 patients (70%) in both groups. Intraoperative procedure-associated problems were experienced in 9 patients (45%) in group I, and 6 of them (30%) had to be converted to direct transthoracic aortic clamping. Markers of myocardial and cerebral damage as well as pulmonary and neuropsychological tests did not show statistically significant difference between groups. CONCLUSIONS: The minimally invasive port access technique for mitral valve surgery can be done with similar clinical safety as procedures through median sternotomy. The problems with endoclamping have forced us to change our practice to the more simple and economic transthoracic aortic clamping technique.

Cardiopulmonary Bypass↗
PubMed2005

Comparison of three anesthetic techniques for off-pump coronary artery bypass grafting: general anesthesia, combined general and high thoracic epidural anesthesia, or high thoracic epidural anesthesia alone.

OBJECTIVE: This study compared general anesthesia (GA), combined GA plus thoracic epidural anesthesia (TEA), and TEA alone in patients scheduled for off-pump coronary artery bypass grafting. DESIGN: Prospective, nonrandomized clinical study SETTING: University hospital. PARTICIPANTS: Ninety consenting patients undergoing beating-heart coronary artery revascularization with comparable coronary status and left ventricular function. INTERVENTIONS: GA (n=30) was conducted with propofol, remifentanil, and cisatracurium or combined with TEA (GA+TEA, n=30) or TEA as the sole anesthetic with ropivacaine plus sufentanil (TEA, n=30). MEASUREMENTS AND MAIN RESULTS: Groups were comparable regarding the surgical approaches and the number of anastomoses. Four patients (GA, n=2; GA+TEA, n=2) who required unplanned cardiopulmonary bypass, and 4 patients in the TEA group who underwent unexpected intubation because of pneumothorax (n=2), phrenic nerve palsy, or incomplete analgesia were excluded from further analysis. Intraoperative heart rate decreased significantly with both GA+TEA and TEA. None of the patients with TEA alone was admitted to the intensive care unit, they all were monitored on average for 6 hours postoperatively in the intermediate care unit and allowed to eat and drink as desired on admission. Postoperative pain scores were lower in both groups with TEA. There were no differences among groups in patients overall satisfaction. CONCLUSION: Based on the authors data, all anesthetic techniques were equally safe from the clinicians standpoint. However, GA+TEA appeared to be most comprehensive, allowing for revascularization of any coronary artery, providing good hemodynamic stability and reliable postoperative pain relief. Nonetheless, the actual and potential risks of TEA during cardiac surgery should not be underestimated.

Aged↗
PubMed2005

Closure of atrial and ventricular septal defects should be performed by the surgeon.

Surgeons look back on 57 years of experience in the closure of atrial septal defects (ASDs) and 46 years in the closure of ventricular septal defects (VSDs). The transcatheter approaches to repair ASDs started first in the 1980s and for VSDs 8 years later. This study sought to reveal the surgical features only given by the surgical therapy and the limitation of interventional ASD and VSD closure. A variety of surgical techniques including the minimal invasive techniques for ASD or VSD closure are well described in recent publication with good results. The surgical trend is to improve the cosmetic outcome by minimizing the size of skin incision. The latest robotically assisted technique requires only four stab wound incisions. New techniques and devices have revolutionized the transcatheter technique but could not achieve the surgical ability to close all types of ASD or VSD, control arrhythmias, and correct additional valve disease or malformation. The mortality for interventional and surgical procedures approaches zero in recent publication. The residual shunting after surgical closure of ASD varies from 2% to 7.8% versus 5% to 33% after interventional closure. General complications caused by the surgical procedure are negligible; however, the shortness of hospital stay and the cosmetic appeal is an advantage of interventional ASD closure. There is no scientific comparison of surgical vs. interventional VSD closure yet.

Cardiac Catheterization↗
PubMed2005

Valve opening and closing dynamics after different aortic valve-sparing operations.

BACKGROUND AND AIM OF THE STUDY: Aortic valve resuspension for ascending aortic aneurysm repair is associated with removal of the sinus of Valsalva. This may cause changes in leaflet motion and thus impact on long-term durability. The opening and closing characteristics of the aortic valve leaflets after reimplantation were studied using a published technique and a modification to create a 'neosinus', and the results compared to those of an age-matched control group. METHODS: Between September 1995 and March 2002, 25 patients underwent normal aortic root reconstruction (group A), while in a further 21 patients the modified neosinus technique was used (group B). In both groups, the native valve was preserved and suspended inside a tubular prosthesis, with reimplantation of the coronary arteries. Transthoracic and transesophageal studies of aortic valve dynamics were performed intraoperatively, before hospital discharge, and at one year after surgery in all patients; the data were compared with those from a separate group of 25 matched control individuals (group C). RESULTS: The valve opening velocity was 61.3+/-20.1, 46.3+/-8 and 29.2+/-9.8 cm/s in groups A, B and C, respectively (group A versus B, p = 0.003; A versus C, p <0.0001; B versus C, p <0.0001). Closing velocity was increased to 57.5+/-23 and 43.8+/-7 cm/s in groups A and B, compared to 23.6+/-7 cm/s in group C (A versus B, p = 0.012; A versus C, p <0.0001; B versus C, p = 0.0002). In seven group A patients, the leaflets touched the prosthetic wall during systole. Slow systolic closing displacement (SCD) amounted to 7.3+/-6 % of maximal opening in group A and 12.6+/-5 % in group B (p = 0.05), compared to 21.1+/-8.3% in group C (group A versus group C, p <0.0001; B versus C, p = 0.002). CONCLUSION: Reimplantation of the natural aortic valve in a prosthetic graft causes abnormally high opening and closing speeds, with possibly increased stress. The study results showed lower valve opening and closure dynamics after the creation of a sinus bulge compared to the conventional reimplantation technique. However, mid-term clinical observations showed favorable valve competence for both types of repair. Further long-term follow up is necessary to prove whether more physiological leaflet dynamics lead to improved durability.

Adolescent↗
PubMed2004

Current status of robotically assisted coronary revascularization.

This article reviews the current status of totally endoscopic coronary revascularization using telemanipulation systems for robotic assistance. Current challenges in implementing a robotic surgical program are discussed, and application of the technology in both arrested and beating heart procedures is considered.

Cardiac Surgical Procedures↗
PubMed2004

Progress in CT imaging for the cardiac surgeon.

The aim of this article is to critically assess the role of multidetector-row CT (MDCT) in the field of cardiothoracic surgery. In the beginning, a short overview is given about technical aspects such as scan protocols, optimal image reconstruction, image reformation techniques, data evaluation, and data presentation. This is followed by sections about possible indications for cardiothoracic surgery and future prospects for this technology. For the cardiac surgeon, the main benefit of MDCT lies in the combination of large scan-volume coverage, high spatial resolution, proper identification of calcifications, and the simultaneous registration of other thoracic structures. Preoperative applications may include the assessment of cardiac valves, noninvasive evaluation of large thoracic vessels, staging of cardiac tumors, and planning of minimally invasive surgical procedures. After surgery, MDCT examinations particularly facilitate an early identification of severe postoperative complications. MDCT may also be used to assess coronary artery bypass graft patency and to identify transplant-related complications in heart transplant recipients at an early stage. New technological developments such as 64-row MDCT or flat panel computed tomography will further increase the field of possible indications.

Coronary Artery Bypass↗
PubMed2003

Multidetector-row CT: cardiosurgery indications.

This article critically evaluates the role of multidetector-row CT before and after cardiosurgical procedures. In addition, technical aspects, such as scan protocols, optimal image reconstruction intervals, image reformation techniques, and data evaluation, are presented and briefly discussed.

Aortic Valve↗
PubMed2003

Awake coronary artery bypass grafting: utopia or reality?

BACKGROUND: Off-pump coronary artery bypass grafting (OPCAB) was implemented to reduce trauma during surgical coronary revascularization. High thoracic epidural anesthesia further reduced intraoperative stress and postoperative pain. This technique also supports awake coronary artery bypass (ACAB), completely avoiding the drawbacks of mechanical ventilation and general anesthesia in high-risk patients. We compared our first results of the ACAB procedure with the conventional OPCAB operation. METHODS: Thirty-five patients underwent ACAB (group A) with left internal mammary artery to left anterior descending coronary artery grafting using a partial lower ministernotomy (n = 25) or double bypass grafting (n = 9) and even triple vessel coronary artery revascularization (n = 1) through complete median sternotomy. Thirty-four patients (group B), matched for age, sex, and comorbidity with group A, underwent either partial lower ministernotomy (n = 24) or OPCAB by complete sternotomy (n = 10). We recorded clinical outcomes and postoperative visual analog scale pain scores. RESULTS: In group A, 32 patients remained awake throughout the entire procedure. Three patients required secondary intubation because of incomplete analgesia (n = 1) or pneumothorax (n = 2). Patients in group A had a recovery room stay of 6.0 +/- 3.2 hours. In group B, mechanical ventilation was implemented for 4.8 +/- 3.1 hours and intensive care unit stay lasted 12 +/- 6.8 hours. Group A had no in-hospital deaths, compared with 1 death in the conventional OPCAB group. Each group had 1 patient with graft stenosis detected on the predischarge angiogram. Early postoperative pain was significantly less in group A than in group B (visual analog scale of 32 +/- 8 compared with 58 +/- 11, p < 0.0001). CONCLUSIONS: The present data demonstrate the feasibility and safety of surgical coronary revascularization without general anesthesia. Continuation of thoracic epidural analgesia provides better pain control and faster mobilization after such procedures. Surprisingly, the ACAB procedure was well accepted by the patients.

Anesthesia, Epidural↗