Effects of N-Acetylcysteine and N-Acetylcysteine Amide on Erythrocyte Deformability and Oxidative Stress in a Rat Model of Lower Extremity Ischemia-Reperfusion Injury.

N-acetylcysteine (NAC) is an antioxidant which works as a free radical scavenger and antiapoptotic agent. N-acetylcysteine-amide (NACA) is a modified form of NAC containing an amide group instead of a carboxyl group of NAC. Our study aims to investigate the effectiveness of these two substances on erythrocyte deformability and oxidative stress in muscle tissue. Materials and Methods. A total of 24 Wistar albino rats were used in our study. The animals were randomly divided into five groups as control (n: 6), ischemia (n: 6), NAC (n: 6), and NACA (n: 6). In the ischemia, NAC, and NACA groups, 120 min of ischemia and 120 min of reperfusion were achieved by placing nontraumatic vascular clamps across the abdominal aorta. The NAC and NACA groups were administered an injection 30 min before ischemia (100 mg/kg NAC; 100 mg/kg NACA; intravenous). Blood samples were taken from the animals at the end of the ischemic period. The lower extremity gastrocnemius muscle was isolated and stored at -80 degrees to assess the total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) values and was analyzed. Results. The erythrocyte deformability index was found to be statistically significantly lower in rats treated with NAC and NACA before ischemia-reperfusion compared to the groups that received only ischemia-reperfusion. In addition, no statistically significant difference was found between the control group and the NAC and NACA groups. The groups receiving NAC and NACA before ischemia exhibited higher total antioxidative status and lower total oxidative status while the oxidative stress index was also lower. Conclusion. The results of our study demonstrated the protective effects of NAC and NACA on erythrocyte deformability and oxidative damage in skeletal muscle in lower extremity ischemia-reperfusion. NAC and NACA exhibited similar protective effects on oxidative damage and erythrocyte deformability.

Re-do aortic valve replacement: does a previous homograft influence the operative outcome?

BACKGROUND AND AIM OF THE STUDY: Late reoperation for failed aortic homograft is widely regarded as a high-risk procedure. A review is presented of the authors' experience of redo-aortic valve replacement (re-do AVR) examining factors which affect, and whether a previous aortic homograft replacement influences, operative outcome. METHODS: A retrospective review was conducted of consecutive re-do AVR performed at the authors' institution between 1998 and 2002. RESULTS: During the study period, 178 patients (125 males, 53 females; mean age 52.4 years; range: 16-85 years) underwent re-do AVR. The group included first-time (72%), second-time (20%), and more than third-time re-do AVR (8%). Forty-six patients (26%) received a homograft (group I), and 132 (74%) a stented biological/mechanical valve (group II). The two groups were matched for baseline clinical characteristics and operative variables. The type of explanted valve, and preoperative and operative variables, were analyzed using univariate and multivariate models. Primary outcome was defined as 30-day mortality, and secondary outcome as postoperative complications. The overall 30-day mortality was 12.3%, but was much lower (4.5%) for elective isolated and multiple re-do AVR. Univariate analysis showed significant predictors of 30-day mortality to be: age >65 years (p = 0.02); renal dysfunction (p = 0.005); preoperative unstable status (p = 0.03); preoperative NYHA class III/IV dyspnea (p = 0.02); non-elective operation (p = 0.01); preoperative arrhythmia (p = 0.005); history of chronic obstructive pulmonary disease (COPD) (p = 0.002); preoperative cardiogenic shock (p = 0.03); impaired left ventricular ejection fraction (LVEF) <50% (p = 0.04); and other valvular procedure(s) performed simultaneously (p = 0.01). In a multivariate analysis, the only significant predictors of 30-day mortality were impaired LVEF (p = 0.03) and a history of COPD (p = 0.007). Group I patients had a significantly shorter mean hospital stay (10.2+/-5.9 versus 14.1+/-12.5 days; p = 0.009), but there were no significant differences between groups in terms of postoperative complications. CONCLUSION: A previous aortic homograft replacement was not associated with an increased operative risk at the time of re-do AVR. A history was COPD was an important predictor of 30-day mortality, and this finding requires further investigation.

Results of the probe technique for transatrial repair of tetralogy of Fallot.

OBJECTIVE: Total correction of classical tetralogy of Fallot (TOF) by transatrial approach has become a standard procedure in the goal to minimize structural damage to the pulmonary pump. The most critical point in transatrial repair of TOF is infundibular dissection. Right atrial approach provides better surgical exposure for parietal extension of the infundibular septum when compared to the right ventricular approach. However it is not always easy to determine the localization and amount of muscle bundles to be resected and this surgical maneuver requires experience. METHODS: Nineteen patients who had repair of isolated TOF using this technique from 1993 to 2001 were reviewed. The mean age of patients were 5 +/- 2 years. Transatrial-transpulmonary approach were performed for all patients. To make easier the infundibular muscle bundles resection and to determine the localization and amount of muscle bundle to be resected, we placed a Hegar dilator into the right ventricle through pulmonary arteriotomy. The muscle bundles between the dilator and the anterior leaflet annulus of the tricuspid valve were totally excised until the intraventricular part of the dilator and pulmonary annulus became completely visible. The area between the Hegar dilator and the margins of the ventricular septal defect (VSD) was left untouched. None of the patients had transannular patch. To improve exposure, tricuspid valve detachment was performed in 11 patients. All patients were followed-up in our clinic every 6 months using echocardiography. RESULTS: There were no early or late deaths, and no reoperation for residual VSD or residual right ventricle (RV) outflow obstruction. All patients were in NYHA Class I. RV on the echocardiography was spared late dilatation and had a good late functional status. Eighteen patients had no or mild pulmonary regurgitation. One patient who had undergone tricuspid anterior leaflet detachment showed mild tricuspid insufficiency. CONCLUSION: On the basis of hemodynamic outcomes, this procedure for elective repair of TOF in selected cases shows excellent early and mid-term results.

The results of probe technique for transatrial repair of tetralogy of Fallot.

OBJECTIVE: Total correction of classic tetralogy of Fallot (TOF) by transatrial approach has become a standard procedure with a principal theoretical aim of minimizing structural damage to the pulmonary pump. The most critical point in transatrial repair of TOF is infundibular dissection. Right atrial approach provides better surgical exposure for parietal extension of the infundibular septum when compared to a right ventricular approach. However, it is not always easy to determine the localization and amount of muscle bundles to be resected and this surgical maneuver requires experience. METHODS: Nineteen patients were reviewed who had repair of isolated TOF by this technique from 1993 to 2001. The mean age of patients was 5 +/- 2 years. Transatrial-transpulmonary approach was performed for all patients. To make the infundibular muscle-bundle resection easier and to determine the localization and amount of muscle bundle to be resected, we placed a Hegar dilator into the right ventricle through pulmonary arteriotomy. The muscle bundles between the dilator and the anterior leaflet annulus of the tricuspid valve were totally excised until the intraventricular part of the dilator and pulmonary annulus became completely visible. The area between the Hegar dilator and the margins of the ventricular septal defect (VSD) was left untouched. None of the patients had transannular patch. Tricuspid valve detachment in order to improve the exposure was done in 11 patients. All patients were followed up in our clinic at regular six-month intervals by echocardiography. RESULTS: There was no early or late mortality nor reoperation for residual VSD or residual right ventricle (RV) outflow obstruction. All patients were in NYHA class I. RV on the echocardiography was spared late dilatation and had a good late functional status. Eighteen patients had no or mild pulmonary regurgitation. One patient who had undergone tricuspid anterior leaflet detachment showed mild tricuspid insufficiency. CONCLUSIONS: On the basis of hemodynamic outcomes, this procedure for elective repair of TOF in selected cases gives excellent early and mid-term results.