Metallic Surface Treatment Using Electrochemical Polishing Decreases Thrombogenicity and Neointimal Hyperplasia of Coronary Stents

An abundant healing response resulting in a more pronounced neointimal hyperplasia compared to conventional balloon angioplasty remains the most important clinical problem after coronary stent implantation. In the present study the potential beneficial effect of metal surface treatment using electrochemical polishing on stent thrombogenicity and neointimal hyperplasia was evaluated in a rat A‐ V model and a porcine coronary model. An electrochemical polishing system was developed to improve surface characteristics of stainless steel stents. Topographic scanning of the stent surface using a profilometer type Taylor Holson Form Taylsurf 120L showed a significant effect on R, (arithmetic mean of the roughness height) (0.14 vs 0.04 μm: P < 0.001) and R_t (maximum rouhgness height between a peak and a valley for the sampling length) (1.44 vs 0.43 μm: P < 0.001). Thrombogenicity of polished stents (n = 6) was compared to nonpolished stents (n = 5) in a rat A ‐ V shunt model using ¹²⁵I fibrinogen and ⁵¹Cr‐labeled platelets. Total clot weight after 30 minutes was significantly lower in the polished stents (32.1 + 2.8 vs 18.1 + 4.4: P < 0.001). Also ¹²⁵I fibrinogen deposition was significantly lower in the polished stents (1.30 + 0.07 vs 0.66 + 0.04: P < 0.001). Platelet deposition, however, was not significantly reduced (12.7 + 3.4 vs 9.87 + 1.9, NS). Subsequently, the effect of electrochemical polishing on neointimal hyperplasia was evaluated in a porcine coronary model. Polished (n =10) and nonpolished stents (n =10) were randomly implanted in the right coronary artery of healthy pigs. Neointimal hyperplasia was significantly decreased in the polished stents (0.6 + 0.28 vs 0.9 + 0.34 mm²: P <0.01). Electrochemical polishing oj coronary stents results in decreased thrombogenicity and neointimal hyperplasia after stent implantation in different animal models.     

Growth after ventricular septal defect repair: does defect size matter? A 10‐year experience

Aim: To evaluate whether the ventricular septal defect (VSD) size, along with the degree of preoperative growth impairment and age at repair, may influence postoperative growth, and if VSD size can be useful to identify children at risk for preoperative failure to thrive. Methods: Sixty‐eight children submitted to VSD repair in a Brazilian tertiary‐care institution were evaluated. Weight and height measurements were converted to Z‐scores. Ventricular septal defect size was normalized by dividing it by the aortic root diameter (VSD/Ao ratio). Results: Twenty‐six patients (38%) had significantly low weight‐for‐height, 10 patients (15%) had significantly low height‐for‐age and 13 patients (19%) had both conditions at repair. Catch‐up growth occurred in 82% of patients for weight‐for‐age, in 75% of patients for height‐for‐age and in 89% of patients for weight‐for‐height. Weight‐for‐height Z‐scores at surgery were significantly lower in patients who underwent repair before 9 months of age. The VSD/Ao ratio did not associate with any other data. On multivariate analysis, weight‐for‐age Z‐scores and age at surgery were independent predictors of long‐term weight and height respectively. Conclusion: The VSD/Ao ratio was not a good predictor of preoperative failure to thrive. Most patients had preoperative growth impairment and presented catch‐up growth after repair. Preoperative growth status and age at surgery influenced long‐term growth.     

Serum Amino Acid Concentrations in Patients Receiving Total Parenteral Nutrition with an Amino Acid Plus Dextrose Mixture

The results of monitoring the serum amino acid concentrations during three infusion regimens using a 5:4 mixture of 70% glucose and the synthetic L-amino acid solution, Synthamin 17 (Travasol) are reported. Twelve stabilized patients received continuous total parenteral nutrition (TPN), eight of whom were subsequently placed on a second regimen of cyclical feeding. A separate group of five patients was infused with amino acids, both with and without simultaneous glucose. The serum amino acid concentrations indicated that the supply of valine, leucine, isoleucine, lysine, and histidine, and the synthesis of taurine from the infused methionine was suboptimal, particularly if the period of TPN was prolonged. The synthesis of tyrosine from phenylalanine appeared to be inversely proportional to the infusion rate of the TPN mixture, in particular the glucose component, resulting in depressed tyrosine and increased phenylalanine concentrations in serum during continuous iv nutrition. Cyclical infusions, on the other hand, permitted the tyrosine and phenylalanine concentrations to return to normal during the noninfusion stage of the cycle. Amino acid measurements enabled us to design an amino acids additive mixture which normalized the serum concentrations in three long-term home parenteral nutrition patients. As a result of these investigations serum amino acid measurements are used routinely to monitor the efficacy of TPN and accommodate any specific amino acid requirements of individual patients. (Journal of Parenteral and Enteral Nutrition 8: 535–541, 1984)     

Hub Colonization as the Initial Step in an Outbreak of Catheter-Related Sepsis Due to Coagulase Negative Staphylococci during Parenteral Nutrition

A prospective study was carried out to determine the pathogenesis of coagulase negative staphylococci catheter-related sepsis during parenteral nutrition. Forty-three catheters were cultured by semiquantitative and quantitative methods. The skin around the puncture site was cultured at the time of catheter removal and three segments of the catheter were cultured apart: the hub, the proximal subcutaneous segment, and the tip. Skin cultures were negative (89%) or yielded different coagulase negative staphylococci from those recovered in catheter and/or blood. Seventeen catheters were the source of sepsis. In 15 cases an infected hub was associated with an infected tip. In two cases the hub was negative (one sepsis due to mixture contamination and the other due to hematogenous seeding of the catheter tip). Sixteen cases of sepsis were due to coagulase negative staphylococci. Staphylococcus epidermidis has been the species most commonly isolated, followed by Staphylococcus haemolyticus, Staphylococcus saprophyticus, and Staphylococcus hominis. In our patients most catheter sepsis have their origin in an infected hub and are not due to migration of skin bacteria along catheter subcutaneous tunnel. (Journal of Parenternal and Enteral Nutrition 8:668–672, 1984)     

Energy and mineral utilization from a peptide-based elemental diet and a polymeric enteral diet given to ileostomists in the early postoperative course

Small intestinal absorption was studied in 12 patients receiving enteral nutrition in the immediate postoperative period after colorectal surgery including construction of an ileostomy. Seven patients were given a peptide-based, low osmolality elementary diet and five patients were given a polymeric diet. Comparisons between the intake and ileal excretion showed on both diets a high utilization of energy, fat, and nitrogen as well as of calcium, phosphorus, magnesium, zinc, and iron. From a nutritional point of view a polymeric diet could thus replace an elementary diet in the immediate postoperative course.