Novel bioresorbable stent coating for drug release in congenital heart disease applications.

A novel double opposed helical poly-l-lactic acid (PLLA) bioresorbable stent has been designed for use in pediatrics. The aim was to test the PLLA stent biocompatibility. The PLLA stent was immersed into whole pig's blood in a closed loop circuit then fibrin and platelet association was assessed via enzyme-linked immunosorbent assay. D-Dimer was valued at 0.2 ± 0.002 ng/mL and P-selectin 0.43 ± 00.01 ng/mL indicating limited association of fibrin and platelets on the stent. To improve biocompatibility by targeting inflammatory cells, dexamethasone was incorporated on PLLA fibers with two coating methods. Both coatings were poly(l-lactide-co-glycolide) acid (PLGA) but one was made porous with sucrose while the other remained nonporous. There was no change in mechanical properties of the fiber with either coating of PLGA polymer. The total amount of dexamethasone released was then determined for each coating. The cumulative drug release for the porous fiber was significantly higher (∼100%) over 8 weeks than the nonporous fiber (40%). Surface examination of the fiber with scanning electron microscopy showed more surface microfracturing in coatings that contain pores. The biocompatibility of this novel stent was demonstrated. Mechanical properties of the fiber were not altered by coating with PLGA polymer. Anti-inflammatory drug release was optimized using a porous PLGA polymer.

Use of del Nido cardioplegia solution and a low-prime recirculating cardioplegia circuit in pediatrics.

The evolution of myocardial protection techniques has been both the source of milestone advancements and controversial debate in cardiac surgery. Our institution has modified a low-prime cardioplegia system (CPS) and adopted a single-dose cardioplegia solution (del Nido cardioplegia) for our congenital heart disease population. The goal of this article is to describe our CPS and outline our myocardial protection protocol. These techniques have allowed us to minimize circuit surface area, operate uninterrupted, and safely protect the myocardium during extended ischemic periods.

The impact of temperature and pump flow rate during selective cerebral perfusion on regional blood flow in piglets.

OBJECTIVE: Ideal temperature and flow rate for selective cerebral perfusion (SCP) are not known. We examined regional organ perfusion in a piglet SCP model. METHODS: Three groups underwent SCP at 30 mL/kg/min at different temperatures (15°C, 25°C, and 32°C) and 4 groups remained at 25°C for SCP at different flow rates (10, 30, 50 and 75 mL/kg/min). Fluorescent microspheres were injected at 5 minutes of normothermic cardiopulmonary bypass (CPB), immediately before SCP, SCP 45 minutes, SCP 90 minutes, and 2 hours after CPB. Brain and lower body organs were collected to examine regional blood flow (RBF, mL/min/g). RESULTS: At 2 hours after CPB, RBF of the 32°C group was higher than that of the 15°C group (P < .05) at the caudate nucleus and hippocampus; RBF of the 32°C group was higher than that of the 25°C and 15°C groups (P < .05) at the neocortex. No significant difference in RBF was observed among any of the 25°C groups at different flow rates. Also, there was no significant difference between the RBF to the left and right sides of brain in either the temperature or flow rate groups. RBF did significantly increase with temperature in the liver and quadriceps during SCP (P < .05). At the kidney, RBF at SCP 90 minutes was significantly higher than that at SCP 45 minutes when all temperature groups were combined (P < .05). CONCLUSIONS: SCP at 32°C provides higher brain RBF 2 hours after CPB. Increasing SCP flow rate does not increase RBF significantly at 25°C. Higher temperature during SCP results in improved RBF to the liver and quadriceps.

Cerebral near-infrared spectroscopy during cardiopulmonary bypass predicts superior vena cava oxygen saturation.

OBJECTIVE: Cerebral and flank near-infrared spectroscopy are used to monitor tissue oxygenation during cardiopulmonary bypass in pediatric patients. We sought to validate these noninvasive measurements as predictors of oxygen saturation in the superior and inferior venae cavae during cardiopulmonary bypass. METHODS: Eight patients underwent elective repair of congenital heart defects with bicaval cannulation. Ultrasonic flow probes and oximetric catheters were placed in the superior and inferior venae cavae limbs of the perfusion circuit. Cerebral and flank near-infrared spectroscopy and 12 additional variables were recorded each minute on cardiopulmonary bypass. Relationships between these variables and superior and inferior venae cavae oxygen saturation were analyzed by linear mixed modeling. The regression of superior vena cava oxygen saturation by current cerebral near-infrared spectroscopy and 1-minute lag cerebral near-infrared spectroscopy, which are equivalent to the regression of the superior vena cava saturation by the current cerebral near-infrared spectroscopy and the 1-minute change in cerebral near-infrared spectroscopy, were used to assess cerebral near-infrared spectroscopy as a trend monitor. RESULTS: The mean number of observation time points per patient was 86 (median 72, range 34-194) for 690 total observations. The root mean square percentage error was 6.39% for the prediction model of superior vena cava saturation by single-factor cerebral near-infrared spectroscopy. The root mean square percentage error was 10.8% for the prediction model of inferior vena cava saturation by single-factor flank near-infrared spectroscopy. CONCLUSIONS: Cerebral near-infrared spectroscopy accurately predicts superior vena cava oxygen saturation and changes in superior vena cava oxygen saturation on cardiopulmonary bypass. The relationship between flank near-infrared spectroscopy and inferior vena cava saturation is not as strong.

Departmental use of perfusion crisis management drills: 2002 survey results.

Serious complications during the performance of cardiopulmonary bypass (CPB) are an infrequent event. However, when potentially fatal technical complications, such as oxygenator or pump failure, do occur, it necessitates a swift and well-co-ordinated response. Periodic performances of drills that simulate various CPB crises are a way to improve individual perfusionist proficiency during disaster situations. The purpose of this study is to determine the utilization of crisis management drills in perfusion departments. Every open-heart program listed by the American Hospital Association in the New England states (Maine, Massachusetts, Rhode Island, Vermont, New Hampshire, Connecticut) and New York were contacted by telephone. Of the 61 contacted, 59 participated for a response rate of 97%. Demographically, the survey represents 312 perfusionists and 47 227 cases annually. While 97% of the perfusion departments believed that regular practice and performance of crisis management drills would improve individual proficiency, only 17% of the programs mandated that their perfusionists perform crisis management drills as a matter of departmental policy. Reasons expressed for not having a formal written policy regarding performance crisis management drills were as follows: left up to the individuals to maintain proficiency 19 (39%), not motivated 11 (22%), confident of proficiency 9 (19%), no time 8 (17%), dubious value 1 (2%), and cost prohibitive 1 (2%). While it is nearly universally accepted that periodically practicing perfusion crisis management drills in a 'wet lab' environment would improve proficiency, only a minority of perfusion teams deem this a high enough priority to make it a matter of formal departmental policy.