Comparison of histopathologic effects of carnitine and ascorbic acid on reperfusion injury.

OBJECTIVE: Reperfusion injury can be seen after acute arterial occlusion, acute myocardial infarctus and during open heart surgery and vascular surgery. Protective effects of ascorbic acid and carnitine on reperfusion damage were tested and compared using histopathologic examination on ischemia model in the rabbit hind limb. METHODS: Four groups (each containing ten animals) were used. In group I (G1), only anesthesia was administered and a biopsy was taken from the soleus muscle after 6 h. In group II (G2), group III (G3), and group IV (G4), after induction of anesthesia, arterial blood circulation of right posterior extremity was blocked by a tourniquet proximally. After four hours of ischemia, just before releasing of tourniquet, physiologic saline solution, sodium ascorbate (Redoxan) and L-carnitine (Carnitine) were administered intravenously to G2, G3 and G4, respectively. Following 2 h of reperfusion, biopsies were taken from soleus muscles. All of the biopsy slides were observed under the light microscope from the aspect of six different histopathologic criteria (loss of striation, nuclear centralisation, formation of ring and/or splitting, changing on diameters of muscle fibers, necrosis and minimal fibrosis) of ischemic muscle. RESULTS: Ischemic change criteria were seen less frequency in both vitamin C and carnitine groups compared to the control and placebo groups. However, this protective effect was statistically significant only for the aspect of segmental necrosis, centralization of nuclei and diameter change parameters in G3 and in G4. When G3 and G4 were compared, the differences on protective effects were significant only from the aspect of fibrosis (P<0.001) and changing on diameter of the fibers (P<0.001). CONCLUSIONS: Both sodium ascorbate and carnitine are effective on reducing the reperfusion injury in skeletal muscle. But when we compared these two agents to each other, we found that carnitine seems a little more protective on our experimental model.

Sternal closure with resorbable synthetic loop suture material in children.

PURPOSE: The reliability of poly-p-dioxanone (PDS) suture for sternal closure was tested on 264 consecutive sternotomies in the authors' department from April 1987 to May 1998. METHODS: The reason for sternotomy was tetralogy of Fallot in 65 cases (24.6%), ventricular septal defect (VSD) in 38 cases (14.4%), atrial septal defect (ASD) in 77 cases (29.2%), ASD + VSD in 23 (8.7%), mitral valve replacement in 22 cases (8.3%), aortic valve replacement in 10 cases (3.8%), and other cardiac disorders in 29 cases (11.0%). RESULTS: Sternal wound infection, sternal dehiscence, and mediastinitis occurred in 1.5% of patients (4 of 264). The overall hospital mortality rate related to the mediastinitis was 1.1% (3 of 264) in the early postoperative period. CONCLUSION: This absorbable suture and our different technique are a safe alternative to standard sternotomy closure after pediatric open cardiac surgery.

The use of a stentless porcine bioprosthesis to repair an ascending aortic aneurysm in combination with aortic valve regurgitation.

Over the years, many surgical methods have evolved for the treatment of ascending aortic aneurysm in combination with aortic valve regurgitation; however, precise guidelines for optimal surgical techniques for varying presentations have not been defined. We describe the use of a stentless porcine bioprosthesis (Medtronic Freestyle) in a patient with an ascending aortic aneurysm and aortic regurgitation. We used the complete root replacement method, and anastomosed a Dacron graft (Hemashield) between the bioprosthetic valve and the native aorta to replace the distal part of the aneurysm.

Effect of partial oxygen supply on mitochondrial electron transport system during complete cardiac ischemia.

During complete ischemia we assessed myocardial utilization of the small amount of oxygen available. We also determined whether blood cardioplegia has any advantage over crystalloid cardioplegia in this setting. Patients with preserved left ventricular myocardial function and without anterolateral wall infarct or aneurysm were included to the study. Intermittent cold blood and crystalloid cardioplegia were used in 10 patients (group BC) and 9 patients (group CC), respectively. From myocardial biopsies, obtained before and after ischemia, complete electron transport system (ETS) enzyme activities (NDH, SDH, NCCR, SCCR, and COX) and lactate content were analyzed. Biochemical and hemodynamic analyses also were done. Myocardial and blood temperatures were monitored. Ischemic time was longer in group CC (p < 0.05). There were no important differences in biochemical and hemodynamic variables between the two groups. In addition, there was no difference in NDH and SDH activities as well as COX/SCCR and COX/RS-NCCR ratios between the two groups before and after ischemia. After Ischemia, RS-NCCR in group CC and SCCR and COX activities in both groups were lower than the control. For all enzymes, activity change ratios were not different between groups. Myocardial lactate content was increased in both groups after ischemia. However, the increase in group BC was less (p < 0.01). Based on our findings, we believe that the superiority of blood cardioplegia over crystalloid cardioplegia does not depend on oxygen content, but on other factors such as buffering and free oxygen radical scavenger effects among others. However, with the warm and continuous blood cardioplegia technique, oxygen content might be more important.

A no-touch technique for calcified ascending aorta during coronary artery surgery.

Despite improvements in cardiovascular surgery techniques over the years, the incidence of neurologic complications has not declined, and stroke remains a possible (and devastating) sequela to coronary artery surgery. In this report, we describe a moderate hypothermic fibrillatory arrest technique that avoids cross-clamping or otherwise touching the aorta; use of the internal thoracic arteries and the right gastroepiploic artery provides optimum revascularization and minimizes the risk of cerebrovascular accident. Over a 1-year period, we used the technique in 21 patients who had heavy calcifications of the ascending aorta. No hemodynamic problems, lower-limb ischemia, or neurologic complications were seen. Only 1 patient underwent reoperation (for bleeding), and another--whose revascularization was incomplete--had a high postoperative level of myocardial creatine kinase MB isoenzyme and a new Q wave, but no hemodynamic deterioration. This technique seems reasonable, because it appears to provide good myocardial protection and to reduce neurologic complications, without comprising myocardial revascularization.

Ultrasonic decalcification of calcified valve and annulus during heart valve replacement.

A heavily calcified heart valve annulus increases the likelihood of sequelae after prosthetic valve replacement. Such sequelae include cerebral embolism, paravalvular leakage, valvular dysfunction, rhythm disturbance, hemolysis, communication of the heart chambers, and rupture of the posterior wall of the left ventricle. From January 1991 through June 1994, we performed heart valve replacement on 30 patients, using an ultrasonic surgical aspirator to remove calcific deposits. We placed aortic valve prostheses in 12 patients, mitral valve prostheses in 13 patients, and both aortic and mitral prostheses in 5 patients, after ultrasonic débridement of calcified annuli. All patients were re-examined 6 months after surgery: echocardiographic study showed no paravalvular leakage or valve-related complications. In our experience, ultrasonic decalcification of the annulus is superior to traditional methods. We advocate the use of ultrasonic débridement as an adjunctive tool in calcified heart valve replacement.