Mitochondrial transplantation preserves myocardial function and viability in pediatric and neonatal pig hearts donated after circulatory death

OBJECTIVE

Mitochondrial transplantation has been shown to preserve myocardial function and viability in adult porcine hearts donated after circulatory death (DCD) . Herein, we investigate the efficacy of mitochondrial transplantation for the preservation of myocardial function and viability in neonatal and pediatric porcine DCD heart donation.

METHODS

Circulatory death was induced in neonatal and pediatric Yorkshire pigs by cessation of mechanical ventilation. Hearts underwent 20 or 36 minutes of warm ischemia time (WIT), 10 minutes of cold cardioplegic arrest, and then were harvested for ex situ heart perfusion (ESHP). Following 15 minutes of ESHP, hearts received either vehicle (VEH) or vehicle containing isolated autologous mitochondria (MITO). A sham nonischemic group (SHAM) did not undergo WIT, mimicking donation after brain death heart procurement. Hearts underwent 2 hours each of unloaded and loaded ESHP perfusion.

RESULTS

Following 4 hours of ESHP perfusion, left ventricle developed pressure, dP/dt max, and fractional shortening were significantly decreased (P < .001) in DCD hearts receiving VEH compared with SHAM hearts. In contrast, DCD hearts receiving MITO exhibited significantly preserved left ventricle developed pressure, dP/dt max, and fractional shortening (P < .001 each vs VEH, not significant vs SHAM). Infarct size was significantly decreased in DCD hearts receiving MITO as compared with VEH (P < .001). Pediatric DCD hearts subjected to extended WIT demonstrated significantly preserved fractional shortening and significantly decreased infarct size with MITO (P < .01 each vs VEH).

CONCLUSIONS

Mitochondrial transplantation in neonatal and pediatric pig DCD heart donation significantly enhances the preservation of myocardial function and viability and mitigates against damage secondary to extended WIT.

Comparison of Thromboelastography Devices TEG®6S Point of Care Device vs. TEG®5000 in Pediatric Patients Undergoing Cardiac Surgery

Thromboelastography (TEG) can predict bleeding in pediatric patients undergoing cardiac surgery. We hypothesized that results obtained from TEG^®5000 correlate with the new point-of-care TEG^®6S system and that TEG^®6S rewarming maximum amplitude (MA) is associated with surrogate endpoints for perioperative bleeding in pediatric patients who underwent complex cardiac surgery. We describe a retrospective study of pediatric (≤18 years) patients who underwent complex cardiac surgery on cardiopulmonary bypass. Citrate whole-blood samples were used to compared TEG^®5000 vs.TEG^®6S and TEG^®6S-FLEV (with fibrinogen measurement) vs. Clauss-fibrinogen methods. TEG^®6S parameters obtained during rewarming were compared to the surrogate endpoints for perioperative bleeding using linear regression analysis. Among 100 patients, 225 TEG^®5000 vs.TEG^®6S comparisons and 54 TEG^®6S-FLEV were analyzed. Good correlation was observed for all parameters comparing TEG^®5000 to TEG^®6S and TEG^®6S-FLEV to the Clauss-fibrinogen method (Pearson r ≥ .7). Similar to rewarming TEG^®5000 MA, rewarming TEG^®6S MA was the only parameter independently associated with risk for perioperative bleeding (median [interquartile range {IQR}] in bleeding vs. nonbleeding patients: 35 [29, 48] vs. 37 [32, 55]; p = .02). A platelet transfusion calculator was developed based on TEG^®6S results by determining the relationship between platelet transfusion volume (mL/kg) and percent change in MA using linear regression analysis. TEG^®6S is a good alternative point-of-care method to analyze a patient's coagulation profile and it is comparable to TEG^®5000 in pediatric patients undergoing cardiac surgery on cardiopulmonary bypass. Lower TEG^®6S MA during rewarming is associated with increased risk for perioperative bleeding. TEG analysis during rewarming may be useful in customizing platelet transfusion therapy by reducing the risk of bleeding while minimizing excessive blood product transfusions.

Sequestration of Midazolam, Fentanyl, and Morphine by an Ex Vivo Cardiopulmonary Bypass Circuit

Cardiopulmonary bypass (CPB) circuits can significantly sequester intravenous anesthetics. Adsorption of medications by our institution's standard circuit (Terumo CAPIOX FX05 oxygenator; noncoated polyvinylchloride tubing) has not been described. We prepared ex vivo CPB circuits with and without oxygenators. Medication combinations studied included midazolam (0.5 mg), fentanyl (50 µg), midazolam (0.5 mg) with morphine (0.5 mg), and midazolam (0.5 mg) with fentanyl (50 µg). Medications were administered after obtaining baseline samples. Samples were drawn at 2, 5, 15, 30, 60, 120, and 180 minutes, and analyzed for concentration of injected medications. Midazolam demonstrated no sequestration after 180 minutes. Fentanyl concentration at 180 minutes was lower with an oxygenator (52.7 ± 12.5 vs. 110.9 ± 12.0 ng/ml, P = 0.00432). More fentanyl was found in solution after 180 minutes when given with midazolam compared to fentanyl given alone in the presence of an oxygenator (101 ± 22.3 vs. 52.7 ± 12.5 ng/ml, P = 0.044). Less midazolam was present after 180 minutes when given with morphine compared to midazolam given alone in the absence of an oxygenator (1264.9 ± 425.6 vs. 2124 ± 254 ng/ml, P = 0.037). We successfully characterized the adsorption of various combinations of midazolam, fentanyl, and morphine to our CPB circuit, showing that fentanyl and midazolam behave differently based on other medications present.

Initial experience with del Nido cardioplegia solution at a Pediatric and Congenital Cardiac Surgery Program in Brazil

OBJECTIVE

The aim of this study was to evaluate outcome measures between our standard multidose cardioplegia protocol and a del Nido cardioplegia protocol in congenital heart surgery patients.

METHODS

Retrospective single-center study including 250 consecutive patients that received del Nido cardioplegia (DN group) with a mandatory reperfusion period of 30% of cross clamp time and 250 patients that received a modified St. Thomas' solution (ST group). Groups were matched by age, weight, gender, and Risk Adjustment for Congenital Heart Surgery (RACHS-1) scores. Preoperative hematocrit and oxygen saturation were also recorded. Outcomes analyzed were the vasoactive inotropic score (VIS), lactate, ventilation time, ventricular dysfunction with low cardiac output syndrome (LCOS), intensive care unit (ICU) length of stay (LOS), hospital LOS, bypass and aortic cross-clamp times, and in-hospital mortality.

RESULTS

Both groups were comparable demographically. Statistically significant differences (p ⩽ 0.05) were noted for cardiac dysfunction with LCOS, hematocrit at end of surgery (p = 0.0038), VIS on ICU admission and at end of surgery (p = 0.0111), and ICU LOS (p = 0.00118) with patients in the DN group having more desirable values for those parameters. Other outcome measures did not reach statistical significance.

CONCLUSION

In our congenital cardiac surgery population, del Nido cardioplegia strategy was associated with less ventricular dysfunction with LCOS, a lower VIS and decreased ICU LOS compared with patients that received our standard myocardial protection using a modified St. Thomas' solution. Despite the limitation of this study, including its retrospective nature and cohort size, these data supported our transition to incorporate del Nido cardioplegia solution with a mandatory reperfusion period as the preferred myocardial protection method in our program.

Mitochondrial transplantation for myocardial protection in ex-situ‒perfused hearts donated after circulatory death

BACKGROUND

Donation after circulatory death (DCD) offers an additional source of cardiac allografts, potentially allowing expansion of the donor pool, but is limited owing to the effects of ischemia. In this study, we investigated the efficacy of mitochondrial transplantation to enhance myocardial function of DCD hearts.

METHODS

Circulatory death was induced in Yorkshire pigs (40-50 kg, n = 29) by a cessation of mechanical ventilation. After 20 minutes of warm ischemia, cardioplegia was administered. The hearts were then reperfused on an ex-situ blood perfusion system. After 15 minutes of reperfusion, hearts received either vehicle alone (vehicle [VEH], 10 ml; n = 8) or vehicle containing autologous mitochondria (vehicle with mitochondria as a single injection [MT], 5 × 10⁹ in 10 ml, n = 8). Another group of hearts (serial injection of mitochondria [MT_S]; n = 6) received a second injection of mitochondria (5 × 10⁹ in 10 ml) after 2 hours of ex-situ heart perfusion and reperfused for an additional 2 hours. A Sham group (sham hearts; n = 6) did not undergo any warm ischemia.

RESULTS

At the end of 4 hours of reperfusion, MT and MT_S groups showed a significantly increased left ventricle/ventricular peak developed pressure (p = 0.002), maximal left ventricle/ventricular pressure rise (p < 0.001), fractional shortening (p < 0.001), and myocardial oxygen consumption (p = 0.004) compared with VEH. Infarct size was significantly decreased in MT and MT_S groups compared with VEH (p < 0.001). No differences were found in arterial lactate levels among or within groups throughout reperfusion.

CONCLUSIONS

Mitochondrial transplantation significantly preserves myocardial function and oxygen consumption in DCD hearts, thus providing a possible option for expanding the heart donor pool.

Functional Performance of Different Venous Limb Options in Simulated Neonatal/Pediatric Cardiopulmonary Bypass Circuits

OBJECTIVE

Hemodilution is a concern in cardiopulmonary bypass (CPB). Using a smaller dual tubing rather than a single larger inner diameter (ID) tubing in the venous limb to decrease prime volume has been a standard practice. The purpose of this study is to evaluate these tubing options.

METHODS

Four different CPB circuits primed with blood (hematocrit 30%) were investigated. Two setups were used with two circuits for each one. In Setup I, a neonatal oxygenator was connected to dual 3/16" ID venous limbs (Circuit A) or to a single 1/4" ID venous limb (Circuit B); and in Setup II, a pediatric oxygenator was connected to dual 1/4" ID venous limbs (Circuit C) or a single 3/8" ID venous limb (Circuit D). Trials were conducted at arterial flow rates of 500 ml/min up to 1500 ml/min (Setup I) and up to 3000 ml/min (Setup II), at 36°C and 28°C.

RESULTS

Circuit B exhibited a higher venous flow rate than Circuit A, and Circuit D exhibited a higher venous flow rate than Circuit C, at both temperatures. Flow resistance was significantly higher in Circuits A and C than in Circuits B (P<0.001) and D (P<0.001), respectively.

CONCLUSION

A single 1/4" venous limb is better than dual 3/16" venous limbs at all flow rates, up to 1500 ml/min. Moreover, a single 3/8" venous limb is better than dual 1/4" venous limbs, up to 3000 ml/min. Our findings strongly suggest a revision of perfusion practice to include single venous limb circuits for CPB.

The Norwood Stage 1 procedure - conduct of perfusion: 2017 Survey results from NPC-QIC member institutions

Hypoplastic left heart syndrome (HLHS) is a rare and severe congenital cardiac defect. Approximately 1000 infants are born with HLHS in the United States every year. Healthcare collaboratives over the last decade have focused on sharing patient experiences and techniques in an effort to improve outcomes. In 2010, cardiologists and patient families joined together to improve the care of HLHS patients by forming the National Pediatric Cardiology Quality Improvement Collaborative (NPC-QIC). Sixty-six of the approximately 110 institutions caring for patients with HLHS in the United States and Canada are now members of NPC-QIC. In 2017, cardiovascular perfusionists joined the collaborative as another specialty involved in the care of HLHS patients. Perfusionists and cardiac surgeons developed the collaborative’s first conduct of perfusion survey for the Norwood Stage 1 procedure, specifically targeting the provision of cardiopulmonary bypass for patients with HLHS. This manuscript discusses the results of this survey, unveiling a significant variance in the conduct of perfusion for this patient population.

A red cell preservation strategy reduces postoperative transfusions in pediatric heart surgery patients

BACKGROUND

Blood transfusion has well-documented adverse effects. As part of a blood conservation initiative at our center, we began routine use of cell saver for all congenital heart surgery performed on cardiopulmonary bypass since 2014.

AIMS

This study aimed to compare transfusion rates prior to, and in the first and second year after this initiative. We hypothesized that cell saver use would decrease transfusion requirements in second year after use of the cell saver compared to the pre cell saver group.

METHODS

Consecutive patients under 18 years undergoing congenital heart surgery on cardiopulmonary bypass were retrospectively analyzed as 3 one-year cohorts defined above. We excluded patients who required mechanical support or reoperation at index admission. Baseline characteristics, and use of blood intraoperatively and postoperatively were compared between groups.

RESULTS

The 3 groups had similar baseline characteristics. Blood use was significantly lower in year 2 after cell saver initiation as compared to the pre cell saver group both intra- and postoperatively. The median difference in volume of intraoperative blood transfusion was lower by 138 mL/m² (-266, -10 mL/m² ) in year 2 when compared to the pre cell saver group. Similarly, the proportion of subjects requiring red blood cell transfusion postoperatively on day of surgery was lower by 10% (-15%, -6%).

CONCLUSION

Standardized use of cell saver significantly decreased perioperative blood use in children undergoing cardiac surgery at our center. A risk-adjusted transfusion threshold for children undergoing heart surgery needs to be developed to further decrease exposure to blood products and associated costs.

Comparison of two pediatric cases requiring the use of bivalirudin during cardiopulmonary bypass

Introduction:

Comparison of two pediatric cases at our institution that utilized bivalirudin for anticoagulation on cardiopulmonary bypass (CPB); a bilateral lung transplant (BLT) and a ventricular assist device (VAD) implantation.

Methods:

The same bivalirudin protocol was utilized in both cases with an initial bolus of 1 mg/kg administered by the anesthesia team, a 50 mg bolus in the pump prime at the time of the initial patient bolus and an initial infusion rate of 2.5 mg/kg/h, with titration as needed during CPB to maintain kaolin-activated clotting time (K-ACT) values >400 s.

Results:

The BLT experienced high K-ACT levels (>720 s) for the majority of the case despite decreasing the bivalirudin infusion rate to 0.5 mg/kg/h. The VAD implantation case required the bivalirudin infusion rate to be increased to 5.0 mg/kg/h throughout the case due to low K-ACTs.

Conclusion:

The literature strongly supports a specific infusion rate1–7 (2.5 mg/kg/h) for bivalirudin anticoagulation during extracorporeal circulation. Clinicians must consider the loss of clotting factors and the administration of blood products while adjusting the bivalirudin infusion during bypass. We have now elected to maintain an infusion rate of ≥0.5 mg/kg/h for bivalirudin anticoagulation at our center, based on institutional experience, though consideration for a higher infusion rate for an added margin of safety should be considered. It is imperative to have a well-developed protocol for the management of these cardiopulmonary bypass patients and we offer our one-page timeline of events to help guide other pediatric centers looking to use bivalirudin anticoagulation.

Production Standard and Stability of Compounded Del Nido Cardioplegia Solution

Background: The del Nido cardioplegia solution (dNCS) was originally developed for pediatric cardiac surgery, being now also used for adult patients. Hospital pharmacies frequently resort to internal dNCS production which has led to an increase in the need for validated parameters for compounding and storage. Objective: This report defines in-house production standards, as well as the stability of dNCS under optimal storage conditions. Methods: All ingredients were sterile and United States Pharmacopeia (USP)/National Formulary (NF) certified. All final bags were quarantined at 4°C for quality control, when 3 of 33 weekly bags were randomly assayed for potassium content. Each lot was only released if all 3 samples were within ±5% of target. Stability testing was performed per USP 797 guidance. Over a 6-month period, 4 different lots and 4 bags from each lot of dNCS were assayed. Each bag was assessed for physical and chemical stability while refrigerated at 4°C, at 35°C in an incubator, and at 70°C under 80% relative humidity. A light exposure arm was also set up at 25°C under 150 lumens. Calibrators of lidocaine, mannitol, and gluconate were freshly prepared and assayed with the samples by Liquid chromatography/Mass spectrometry (LC/MS). Results: Lidocaine concentrations averaged 0.117 mg/mL (95.8% of theoretical) at 4°C for 30 days. At 35°C, they decayed by 67% in 30 days, while at 70°C nearly 50% was lost after the first day. A first-order kinetics was observed with an Arrhenius activation energy of 25 kcal/mol. Degradation products identified under stress conditions were absent in the stable product. Conclusions: The dNCS is stable for at least 30 days under 4°C refrigeration in ethylene vinyl acetate (EVA) bags.

Arterial Limb Microemboli during Cardiopulmonary Bypass: Observations from a Congenital Cardiac Surgery Practice

Gaseous microemboli (GME) are known to be delivered to the arterial circulation of patients during cardiopulmonary bypass (CPB). An increased number of GME delivered during adult CPB has been associated with brain injury and postoperative cognitive dysfunction. The GME load in children exposed to CPB and its consequences are not well characterized. We sought to establish a baseline of arterial limb emboli counts during the conduct of CPB for our population of patients requiring surgery for congenital heart disease. We used the emboli detection and counting (EDAC) device to measure GME activity in 103 consecutive patients for which an EDAC machine was available. Emboli counts for GME <40 μ and >40 μ were quantified and indexed to CPB time (minutes) and body surface area (BSA) to account for the variation in patient size and CPB times. Patients of all sizes had a similar embolic burden when indexed to bypass time and BSA. Furthermore, patients of all sizes saw a three-fold increase in the <40 μ embolic burden and a five-fold increase in the >40 μ embolic burden when regular air was noted in the venous line. The use of kinetic venous-assisted drainage did not significantly increase arterial limb GME. Efforts for early identification and mitigation of venous line air are warranted to minimize GME transmission to congenital cardiac surgery patients during CPB.

Bivalirudin Anticoagulation for a Pediatric Patient with Heparin-Induced Thrombocytopenia and Thrombosis Requiring Cardiopulmonary Bypass for Ventricular Assist Device Placement

The direct thrombin inhibitor bivalirudin is an option for anticoagulation in patients with heparin induced thrombocytopenia (HIT) requiring cardiopulmonary bypass (CPB). There are a limited number of reports of pediatric patients in which bivalirudin has been used for anticoagulation for CPB. We present the case of an 11 year old male with acute onset heart failure secondary to idiopathic dilated cardiomyopathy that developed heparin induced thrombocytopenia with thrombosis (HITT). The patient was anticoagulated in the operating room with bivalirudin and placed on CPB for insertion of a HeartWare(®) Ventricular Assist Device (Heartware(®)). Modified techniques were utilized. This included use of the Terumo CDI 500 (Terumo Cardiovascular Systems, Inc.) in-line blood gas monitor which contains a heparin coated arterial shunt sensor. We flushed this sensor with buffered saline preoperatively and noted no significant decrease in platelet count postoperatively. The patient was successfully placed on the ventricular assist device and was subsequently listed for heart transplantation.

A Modified EXIT-to-ECMO with Optional Reservoir Circuit for Use during an EXIT Procedure Requiring Thoracic Surgery

A 34 year old mother with a history of polyhydraminos and premature rupture of membranes presented for an ex utero intrapartum treatment (EXIT) procedure to deliver her 34 week gestation fetus. The fetus had been diagnosed with a large cervical mass which significantly extended into the right chest. The mass compressed and deviated the airway and major neck vessels posteriorly. Imaging also revealed possible tumor involvement with the superior vena cava and right atrium. The plan was for potential extracorporeal membrane oxygenation (ECMO) during the EXIT procedure (EXIT-to-ECMO) and the potential for traditional cardiopulmonary bypass (CPB) for mediastinal tumor resection. A Modified EXIT-To-ECMO with Optional Reservoir (METEOR) circuit was devised to satisfy both therapies. A fetal airway could not be established during the EXIT procedure and so the EXIT-to-ECMO strategy was utilized. The fetus was then delivered and transferred to an adjoining operating room (OR). Traditional cardiopulmonary bypass with a cardiotomy venous reservoir (CVR) was utilized during the establishment of an airway, tumor biopsy and partial resection. The patient was eventually transitioned to our institution's standard ECMO circuit and then transferred to the intensive care unit. The patient was weaned from ECMO on day of life (DOL) eight and had a successful tumor resection on DOL 11. The patient required hospitalization for numerous interventions including cardiac surgery at 4 months of age. She was discharged to home at 5 months of age.

Antibody depletion for the treatment of crossmatch-positive pediatric heart transplant recipients

Sensitization to HLA is a risk factor for adverse outcomes after heart transplantation. Requiring a negative prospective CM results in longer waiting times and increased waitlist mortality. We report outcomes in a cohort of sensitized children who underwent transplant despite a positive CDC CM+ using a protocol of antibody depletion at time of transplant, followed by serial IVIG administration. All patients <21 yrs old who underwent heart transplantation at Boston Children's Hospital from 1/1998 to 1/2011 were included. We compared freedom from allograft loss, allograft rejection, and serious infection between CM+ and CM- recipients. Of 134 patients in the cohort, 33 (25%) were sensitized prior to transplantation and 12 (9%) received a CM+ heart transplant. Serious infection in the first post-transplant year was more prevalent in the CM+ patients compared with CM- patients (50% vs. 16%; p = 0.005), as was HD-AMR (50% vs. 2%; p < 0.001). There was no difference in freedom from allograft loss or any rejection. At our center, children transplanted despite a positive CM had acceptable allograft survival and risk of any rejection, but a higher risk of HD-AMR and serious infection.

A single-center experience with luminal venous cannulae obstruction caused by clot formation during bypass

Our institution experienced two bypass cases from January through December 2011 in which venous return was significantly variable and at times poor. Luminal clot formation in the venous cannulae was found in each case postbypass. These events were captured and monitored through our institution's Non-Routine Event Reporting Program and eventually reported to the Food and Drug Administration (FDA). We began inspecting all venous cannulae postbypass in December 2011. During a subsequent 9-month surveillance period, we documented 33 venous cannulae in 21 patients with luminal clot formation. Only one cannula during this surveillance period required change-out on bypass. The manufacturer eventually identified changes in production that likely caused the clotting events. The manufacturer modified their production methods and began supplying cannulae produced under the new method in September 2012. We have experienced only one clotting event with the new cannulae and in that instance, the metal tip was found to be defective. We recommend inspection of all venous cannulae postbypass with internal, manufacturer, and FDA reporting for those noted to have luminal clot formation.

The addition of a membrane oxygenator to a ventricular assist device in a patient with acute respiratory distress syndrome

A 12-year-old boy with Marfan's syndrome required a biventricular assist device (VAD) after an aortic root replacement. The patient developed acute respiratory distress syndrome and required escalating ventilator support. We hypothesized that the addition of a membrane oxygenator in series with the assist device would improve gas exchange and allow for a more lung-protective ventilator approach. A membrane oxygenator was placed in series with the right VAD resulting in a blood path of right atrium to VAD to oxygenator to pulmonary artery. Circuit function was gauged by monitoring flow and oxygenator pressures and periodic circuit inspections and oxygenator blood gases. Heparin was titrated to maintain unfractionated antifactor Xa levels of .3-.7 IU/mL and partial thromboplastin time of 60-80 seconds. The initial sweep gas supplying the oxygenator was 5 L/min at an F1O2 of 1.0, which achieved a pH > 7.40 and a PF ratio > 250. The pre- and post-oxygenator pressures were 55-60 mmHg and 45-50 mmHg, respectively, and the measured flow at the oxygenator outlet was 2.0-2.2 L/min. The patient was changed from high-frequency oscillatory ventilation to pressure-controlled synchronized intermittent ventilation with pH maintained at 7.35-7.40 and PF ratio > 250. Paralytics were discontinued and the patient's neurologic condition was deemed intact. The patient hemorrhaged after a sternal closure and required transfusions and antifibrinolytics that led to thrombus in the membrane and membrane circuitry, which were replaced without incident. The patient's respiratory status remained stable; however, his overall condition worsened as a result of additional organ dysfunction and septicemia, and he did not survive. The addition of a membrane oxygenator to a VAD is feasible and supplements gas exchange permitting the use of more lung protective ventilation.

Massive air embolism in a Fontan patient

Most institutions performing cardiopulmonary bypass for congenital heart disease patients use an integrated hard shell cardiotomy and venous reservoir attached to an oxygenator. It is of paramount importance that the integrated reservoir be vented so as not to cause pressurization. A pressurized sealed cardiotomy has been reported to occur secondary to issues with vacuum assisted venous drainage systems as well as improper venting in general. We report a case of air embolus caused by retrograde propulsion of air through the venous line secondary to a pressurized cardiotomy reservoir in a patient with Fontan circulation. The mechanism of cardiotomy pressurization is described, and the scenario simulated in a mock circuit.

The Children's Hospital Boston non-routine event reporting program

Several authors have described methods to track perfusion and cardiac surgical morbidity and mortality as well as perfusion accidents. There is currently not a standard definition of a perfusion accident nor is there a standard reporting threshold for events which do not directly cause known morbidity. We propose the term non-routine events (NREs) instead of accidents, and provide a working definition and reporting threshold for such. This paper describes the program which we developed to track perfusion NREs within the Cardiovascular Program at Children's Hospital, Boston. NREs are categorized by type (technique, equipment, or patient-related) and bypass period (pre-cardiopulmonary bypass, bypass, or post-cardiopulmonary). NRE outcomes are also classified by the level of discussion or change in perfusion practice after multidisciplinary review. We have documented during a 44 month interval that 42% (29/69) of reported NREs occur during the bypass period and are equipment related and thus, efforts to improve practice should focus there. We have also seen a generally decreasing incidence of NREs requiring either a change in perfusion practice or a new protocol during this time period. We believe that our regular multidisciplinary meetings to discuss NREs have increased awareness among the entire team about potential problems in the program and that intuitively, it has improved patient safety.

Potassium-channel opener cardioplegia is superior to St. Thomas' solution in the intact animal

BACKGROUND

In isolated hearts, the potassium-channel opener pinacidil is an effective cardioplegic agent. This study tested the hypothesis that pinacidil is superior to St. Thomas' solution in the more clinically relevant intact animal.

METHODS

Sixteen pigs were placed on full cardiopulmonary bypass. Hearts underwent 2 hours of global ischemia (10 degrees to 15 degrees C). Either St. Thomas' or 100 micromol/L pinacidil was administered every 20 minutes (10 mL/kg). Preischemic and postreperfusion slopes of the preload-recruitable stroke work relationship were determined. Changes in myocardial adenine nucleotide levels and cellular ultrastructure were analyzed.

RESULTS

Pinacidil cardioplegia resulted in an insignificant change in the slope of the preload-recruitable stroke work relationship (40.6+/-2.1 mm Hg/mm before ischemia and 36.5+/-3.7 mm Hg/mm after ischemia; p = 0.466). In contrast, St. Thomas' solution resulted in a significant decrease in the slope after reperfusion (34.3+/-5.5 mm Hg/mm and 13.5+/-2.3 mm Hg/mm; p = 0.003). Adenine nucleotide levels, myocardial tissue water, and ultrastructural changes were similar between groups.

CONCLUSIONS

Pinacidil ameliorated myocardial stunning associated with traditional hyperkalemic cardioplegia without causing significant differences in cellular metabolism.