Showing papers by "Abbasali Karimi published in 2008"

Co-deposition process of RF-Sputtering and RF-PECVD of copper/carbon nanocomposite films

Abstract: Nanoparticle copper/carbon composite films were prepared by co-deposition of RF-Sputtering and RF-PECVD method from acetylene gas and copper target. We investigate deposition process in the region where by changing pressure, the process converts to physical sputtering mode in constant power regime and at a critical pressure between 1.5 to 3 Pa. The estimated value of mean ion energy at this critical point of pressure is close to threshold energy of physical sputtering of copper atoms by acetylene ions. By utilizing this property and by setting initial pressure from 1.3 to 6.6 Pa, nanoparticles copper/carbon composite films were grown with different copper content. The Copper content of our films was obtained by Rutherford Back Scattering (RBS) and it varied from 2% to 97%. The copper content of the surface was obtained by X-ray Photoelectron Spectroscopy (XPS). The results of XPS at different stages of the growth and copper oxidization confirm our suggested mechanism of deposition. Atomic force microscopy (AFM) image and X-ray diffraction (XRD) indicated that copper nanoparticles were formed in our films.

Factors affecting postoperative morbidity and mortality in isolated coronary artery bypass graft surgery.

Abstract: Purpose This study was conducted to investigate predictors of mortality before and after isolated coronary artery bypass grafting (CABG).

Concomitant carotid endarterectomy and coronary artery bypass grafting versus staged carotid stenting followed by coronary artery bypass grafting.

Abstract: AIM Significant carotid stenosis (>or=70%) in patients undergoing coronary artery bypass grafting (CABG) can increase the risk of perioperative cerebral vascular accident (CVA). In this study, we compared the results of two common operative strategies: concomitant carotid endarterectomy and CABG versus carotid stenting and CABG. METHODS This cohort study was conducted from January 2001 to September 2006. Significant carotid artery stenosis was detected in patients who were candidates for CABG at the Tehran Heart Center. The stenosis was detected by carotid Doppler screening and was confirmed by magnetic resonance angiography. Reluctant patients or those with previous major CVA, significant bilateral carotid stenosis and intracranial lesions were excluded. Patients were divided into 2 groups. Group A underwent concomitant carotid endarterectomy and CABG (n=19), while carotid stenting and CABG were done in group B (n=28). RESULTS The mean age in group A was 67.37+/-7.09 years and 65.57+/-8.13 years in group B. The mean hospital stay (days) was 18.68+/-7.95 in group A and 26.35+/-77.04 in group B (P=0.01). The median charge was dollars 252.79 in group A and dollars 2206.66 in group B (P <0.0001). There was a significant difference in frequency of hypotension and bradycardia between the 2 groups (P <0.05). There were 2 cases of in-hospital mortality in each group (10.5% and 7.1%, respectively). Two postoperative strokes occurred in group A and 3 in group B (10.5% and 10.7%, respectively). CONCLUSION Concomitant carotid endarterectomy and CABG is as safe as carotid stenting and CABG, with fewer neurologic events and less hypotension, bradycardia, cost and shorter hospital stay.

Coronary artery bypass grafting in patients with low ejection fraction: the effect of intra-aortic balloon pump insertion on early outcome.

Abstract: Background: Survival benefit with intra-aortic balloon pump (IABP) insertion for coronary artery bypass grafting (CABG) patients with left ventricular dysfunction is controversial. The aim of this study was to assess the early results of CABG that predict 30-day mortality and prolonged length of hospital stay (LOS) after isolated CABG and the role of IABP application as a main predictor in patients with an ejection fraction (EF) of 30% or less. Materials and Methods: Eight hundred and thirty-three patients who underwent isolated CABG with EF ≤ 30% were entered and compared with 10881 patients with EF > 30% as the control group. Demographic and clinical characteristics and postoperative complications were considered. Data were analyzed using the student's t-test and chi-square test for univariate analysis and the analysis of covariance and logistic regression for multivariate analysis. Results: The thirty-day mortality rate (1.6% vs. 0.7%, P P P = 0.002) and prolonged LOS ( P = 0.009). Also, urinary tract infection, prolonged ventilation, and renal failure as postoperative complications were statistically more in the group with the application of IABP. Conclusion: Low ejection fraction can positively affect thirty-day mortality and prolonged LOS and ICU stay in patients who undergo CABG. In these patients, IABP insertion is a strong predictor for early complication and mortality.

First Database Report on Cardiothoracic Surgery in Tehran Heart Center

Abstract: Background: The use of cardiac surgical database is necessary for evaluating and improving the quality of care. The aim of this report was to provide useful information for surgeons in Iran and other countries for their daily practice. Methods: We analyzed data from 14288 consecutive patients in four different types of procedures, namely isolated coronary artery bypass grafting (CABG), combined CABG and valve (CABG-V), only valve (V), and other adult cardiac surgical operations from 2002 to 2006. Results: The activity load increased from 1765 in 2002 to 3309 surgical operations in 2006 with almost 87.2% of activity being isolated CABG. The mortality rate for CABG was 1%, which decreased from 1.7% to 0.9% over the five years. The mortality rates for CABG-V and V were 5.8% and 4.8% in the last year of the study, respectively. Over the 5 yr period, the proportion of urgent operations increased substantially from 4% to 24.5% (P< 0.0001), causing a reduction in elective operations. The mean length of hospital stay for the entire population was 8.38±5.74 d, which remained almost steady during the study period. Conclusion: This database can serve as a valuable resource of preoperative measurers and surgical outcomes for surgeons and researchers with a view to improving overall surgical performance.

Mortality in open heart surgery with intraaortic balloon pump support.

Abstract: Mechanical circulatory assistance is frequently needed to support the failing heart. The aim of this study was to determine perioperative prognostic factors for hospital mortality in patients undergoing open heart surgery who required intraaortic balloon pump support. Between January 2002 and September 2006, 475 patients received an intraaortic balloon pump perioperatively. Hospital mortality was 21.89%. Risk factors for hospital death identified by multivariate logistic regression analysis were peripheral vascular disease, left main coronary artery disease, postoperative renal failure, postoperative cardiac arrest, and prolonged hospital stay. Minor and major intraaortic balloon pump-related complications were not significant in univariate and multivariate analysis; the incidence was 5.05%. It is suggested that the threshold for using balloon pump support is decreased in high-risk patients undergoing cardiac surgery.

Early mortality predictors in coronary artery bypass grafting patients required intra-aortic balloon pump in perioperative and postoperative periods.

Abstract: Aim. The intra-aortic balloon pump (IABP) is commonly used for decreasing myocardial oxygen demand by systolic unloading in perioperative heart failure. The aim of this study was to determine perioperative prognostic factors for in-hospital mortality in coronary artery bypass grafting patients who received the intraaortic balloon pump. Methods. A total of 271 patients who underwent coronary artery bypass grafting and received intra-aortic balloon pump perioperatively between January 2002 and September 2006 were studied. The preoperative, operative and postoperative risk factors for early death were evaluated. Results. Early mortality rate in the study population was 17.3%. From variables entered into multivariate logistic regression the following parameters were identified as prognostic factors for early death: left main disease, diabetes, postoperative renal failure and cardiac arrest (P<0.05). The minor and major intra-aortic balloon pump related complications were not significant in univariate and multivariate analysis and its rate was 3.6%. Conclusion. According to our study the mortality of IABP group is low compared to other studies, as well as IABP-associated complications. Also it revealed that there is no correlation between IABP-associated complications and early mortality.

Discrete Subvalvular Aortic Stenosis: Severity of Aortic Regurgitation and Rate of Recurrence at Midterm Follow-Up after Surgery

Abstract: Background: Discrete subaortic stenosis (DSS) is a progressive condition. Controversy still rumbles on as to whether the subaortic membrane causes aortic regurgitation (AR) and whether membrane resection reduces AR severity. We investigated the association between the left ventricular outflow tract peak gradient (LVOT-PG) and AR severity preoperatively and changes in AR severity and obstruction recurrence after surgery in DSS patients. Methods: Twenty patients were evaluated before and after surgery for DSS (mean follow-up time: 13.60±9.61 months). The patients were evaluated via transthoracic echocardiography and transesophageal echocardiography, if necessary. The cut-off point for surgery was LVOT-PG ≥50 mmHg or the presence of progressive AR. Results: The mean age of the patients was 28.55±15.23 years, and 35% of them were male. LVOT-PG decreased from a mean of 80.83±42.72 mmHg preoperatively to 19.14±14.03 mmHg postoperatively and to 25.47±16.10 at follow-up. AR was identified in 15 (75%) patients preoperatively: mild in 8 (40%) and moderate in 7 (35%). The postoperative change in AR severity was insignificant. The correlation between preoperative LVOT-PG and the incidence and severity of preoperative AR was not significant. AR severity had no correlation with age. Membrane recurrence occurred in 25% of the patients. Conclusion: Our results indicated no relationship between AR severity and LVOT-PG and the patient’s age. Patient selection for surgery can, therefore, be carried out on the basis of LVOT-PG or AR severity separately. Subaortic resection may reduce AR severity in some patients, but this reduction is not significant. Future studies are required to elucidate whether or not the presence of the AR is an indication for surgery.

Prosthetic Valve Endocarditis: Early Outcome following Medical or Surgical Treatment

Abstract: Background : Prosthetic valve endocarditis (PVE) is an important cause of morbidity and mortality associated with heart valve replacement surgery. The aim of the present study was to describe the early outcome of treatment in patients with PVE in a single center. Methods : The data of all the episodes of PVE registered at our institution between 2002 and 2007 were collected and analyzed retrospectively. The patients were assessed using clinical criteria defined by Durack and colleagues (Duke criteria). The analysis included a detailed study of hospital records. The continuous variables were expressed as mean ± standard deviation, and the discrete variables were presented as percentages. Results: Thirteen patients with PVE were diagnosed and treated at our center during the study period. In all the cases, mechanical prostheses were utilized. The patients' mean age was 46.9±12.8 years . Women made up 53.8% of all the cases. Early PVE was detected in 6 (46.2%) patients, and late PVE occurred in 7 (53.8 %). Eleven (84.6%) patients were treated with intravenous antimicrobial therapy, and the other two (15.4%) required surgical removal and replacement of the infected prosthesis in addition to antibiotic therapy. Blood cultures became positive in 46.2% of the patients. Mortality rate was 15.4% (2 patients). Conclusion: It seems that in selected cases with PVE, i.e. in those who remain clinically stable and respond well to antimicrobial therapy, a cure could be achieved by antimicrobial treatment alone with acceptable morbidity and mortality risk.

Early outcome of concurrent mitral valve replacement and coronary artery bypass grafting

Abstract: Concomitant coronary artery bypass surgery (CABG) in patients undergoing mitral valve replacement (MVR) has been shown to be an important risk factor for hospital mortality. We evaluated preoperative characteristics, postoperative complications, in-hospital mortality rate, and length of stay in hospital for patients undergoing concurrent CABG with MVR. Preoperative and postoperative clinical data from 175 patients undergoing concurrent CABG with MVR operation at Tehran Heart Center from 2002 through 2006 were collected and entered into a database. Information was obtained by clinical and case note review as well as detailed questionnaires to physicians and patients. Mean age of patients was 57.95 ± 10.54 years and 51.4% were male. Mean New York Heart Association (NYHA) score was 2.46 ± 0.84. Among studied patients, 18.3% and 2.9% underwent aortic and tricuspid valve replacement, respectively. In-hospital mortality was 6.9% and 96.0% of patients were hospitalized ≥14 days. History of congestive heart failure (P = 0.027) and postoperative brain stroke (P = 0.004) were independent predictors for in-hospital mortality. Exact considering of congestive heart failure and postoperative brain stroke related to in-hospital mortality in concurrent CABG with MVR operation are necessary.