Rate of increase in serum lactate level risk-stratifies infants after surgery for congenital heart disease

ObjectiveIncreased blood lactate levels reflect tissue oxygen debt and might be indicative of low cardiac output. We hypothesized that the rate of increase in serum lactate would be an ideal marker to discriminate between infants at high and low risk of a poor outcome after surgical repair of congenital heart disease using cardiopulmonary bypass.MethodsIn the present prospective, observational study in a pediatric cardiac intensive care unit, infants (aged <12 months) undergoing cardiac surgery had serial whole blood lactate levels measured with every arterial blood gas drawn for the first 24 postoperative hours. The composite poor outcome included death, the need for extracorporeal support, and dialysis.ResultsThe lactate levels were measured in 231 infants; 19 infants (8.2%) had a poor outcome. A lactate increase rate of 0.6 mmol/L/h had very good discriminatory ability (area under the curve [AUC], 0.89) with a sensitivity of 90%, specificity of 84%, positive predictive value (PPV) of 34%, and negative predictive value (NPV) of 99%. Similar results were obtained for subgroups stratified by 1- or 2-ventricle heart disease and risk adjustment for congenital heart surgery (RACHS-1) score. In neonates (age <30 days) with single-ventricle physiology (n = 43, poor outcome = 8), a lactate increase of 0.6 mmol/L/h had near perfect discriminatory ability (AUC 0.99) with a sensitivity of 100%, specificity of 51%, PPV of 32%, and NPV of 100%. In 2-ventricle neonates (n = 43, poor outcome = 5), a lactate increase of 0.6 mmol/L/h also had near perfect discriminatory ability (AUC, 0.99), with a sensitivity of 100%, specificity of 90%, PPV of 56%, and NPV of 100%.ConclusionsThe postoperative lactate increase rate allows discrimination between infants at high and low risk of morbidity and mortality after congenital heart disease surgery, and the lactate level can be followed serially for the treatment response

Early Surgical Morbidity and Mortality in Adults with Congenital Heart Disease: The University of Michigan Experience

Objectives.  To review early surgical outcomes in a contemporary series of adults with congenital heart disease (CHD) undergoing cardiac operations at the University of Michigan, and to investigate possible preoperative and intraoperative risk factors for morbidity and mortality. Methods.  A retrospective medical record review was performed for all patients ≥18 years of age who underwent open heart operations by a pediatric cardiothoracic surgeon at the University of Michigan Congenital Heart Center between January 1, 1998 and December 31, 2004. Records from a cohort of pediatric patients ages 1–17 years were matched to a subset of the adult patients by surgical procedure and date of operation. Results.  In total, 243 cardiac surgical operations were performed in 234 adult patients with CHD. Overall mortality was 4.7% (11/234). The incidence of major postoperative complications was 10% (23/234) with a 19% (45/23) minor complication rate. The most common postoperative complication was atrial arrhythmias in 10.8% (25/234). The presence of preoperative lung or liver disease, prolonged cardiopulmonary bypass and aortic cross clamp times, and postoperative elevated inotropic score and serum lactates were significant predictors of mortality in adults. There was no difference between the adult and pediatric cohorts in terms of mortality and morbidity. Conclusions.  The postoperative course in adults following surgery for CHD is generally uncomplicated and early survival should be expected. Certain risk factors for increased mortality in this patient population may include preoperative presence of chronic lung or liver dysfunction, prolonged cardiopulmonary bypass and aortic cross-clamp times, and postoperative elevated inotropic score and serum lactate levels.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75596/1/j.1747-0803.2008.00170.x.pd

Perceptions of 24/7 In‐house Attending Coverage on Fellow Education and Autonomy in a Pediatric Cardiothoracic Intensive Care Unit

BackgroundThe 24/7 in‐house attending coverage is emerging as the standard of care in intensive care units. Implementation costs, workforce feasibility, and patient outcomes resulting from changes in physician staffing are widely debated topics. Understanding the impact of staffing models on the learning environment for medical trainees and faculty is equally warranted, particularly with respect to trainee education and autonomy.ObjectiveThis study aims to elicit the perceptions of pediatric cardiology fellows and attendings toward 24/7 in‐house attending coverage and its effect on fellow education and autonomy.MethodsWe surveyed pediatric cardiology fellows and attendings practicing in the pediatric cardiothoracic intensive care unit (PCTU) of a large, university‐affiliated medical center, using structured Likert response items and open‐ended questions, prior to and following the transition to 24/7 in‐house attending coverage.ResultsAll (100%) trainees and faculty completed all surveys. Both prior to and following transition to 24/7 in‐house attending coverage, all fellows, and the majority of attendings agreed that the overnight call experience benefited fellow education. At baseline, trainees identified limited circumstances in which on‐site attending coverage would be critical. Preimplementation concerns that 24/7 in‐house attending coverage would negatively affect the education of fellows were not reflected following actual implementation of the new staffing policy. However, based upon open‐ended questions, fellow autonomy was affected by the new paradigm, with fellows and attendings reporting decreased “appropriateness” of autonomy after implementation.ConclusionsOur prospective study, showing initial concerns about limiting the learning environment in transitioning to 24/7 in‐house attending coverage did not result in diminished perceptions of the educational experience for our fellows but revealed an expected decrease in fellow autonomy. The study indirectly facilitated open discussions about methods to preserve fellow education and warranted autonomy in our PCTU; however, continued efforts are needed to achieve the optimal balance between supervised training and the transition to autonomous practice.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111990/1/chd12261.pd

Impact of Vitamin C on Endothelial Function and Exercise Capacity in Patients with a Fontan Circulation

Objective.  To evaluate the impact of antioxidant therapy on functional health status in Fontan‐palliated patients. Design.  Prospective, randomized, double‐blind, placebo‐controlled trial. Patients.  Fifty‐three generally asymptomatic Fontan patients. Interventions.  Patients were randomized to receive either high‐dose ascorbic acid (vitamin C) or placebo for 4 weeks. Outcome Measures.  Peripheral vascular function, as measured with endothelium‐dependent digital pulse amplitude testing (EndoPAT), and exercise capacity were assessed before and after study drug treatment. Primary outcome measures included the EndoPAT index and peripheral arterial tonometry (PAT) ratio, both validated markers of vascular function. Secondary outcome measures included peak oxygen consumption and work. Results.  Twenty‐three vitamin C‐ and 21 placebo‐assigned subjects completed the protocol (83%). Median age and time from Fontan completion were 15 (interquartile range [IQR] 11.7–18.2) and 11.9 years (IQR 9.0–15.7), respectively. Right ventricular morphology was dominant in 30 (57%). Outcome measures were similar between groups at baseline. Among all subjects, vitamin C therapy was not associated with a statistical improvement in either primary or secondary outcome measures. In subjects with abnormal vascular function at baseline, compared with placebo, vitamin C therapy more frequently resulted in normalization of the EndoPAT index (45% vs. 17%) and PAT ratio (38% vs. 13%). Conclusions.  Short‐term therapy with vitamin C does not alter endothelial function or exercise capacity in an asymptomatic Fontan population overall. Vitamin C may provide benefit to a subset of Fontan patients with abnormal vascular function.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92126/1/j.1747-0803.2011.00605.x.pd

Ischemic Preconditioning Attenuates Myocardial Apoptosis through Regulation of Hypoxia Inducible Factor-1αand Heat Shock Protein 70

Ischemic preconditioning (IPC) increases expression of several cardioprotective genes and attenuates myocardial dysfunction after ischemia-reperfusion (IR) injury. However, the precise cellular mechanisms by which IPC confers myocardial protection are incompletely understood. We hypothesized that the beneficial effect of IPC in the heart is due to upregulation of two key transcription factors, Hypoxia Inducible Factor-1α (HIF-1α) and Heat Shock Protein 70 (HSP70). In this study, neonatal rat cardiomyoblasts (H9c2 cells) were subjected to IPC (four cycles of 15-min hypoxia/15-min reoxygenation), followed by 12-hr hypoxia-reoxygenation (HR). HIF-1α and HSP70 expression were measured by ELISA and immunoblot. Apoptosis was assessed by DNA fragmentation and caspase-3 activity. The results showed that IPC induced HIF-1α and HSP70 expression and attenuated apoptosis after 12-hr HR. Pretreatment with DMOG, an HIF-1α activator, showed a similar protective effect as IPC. An HIF-1α inhibitor (CAY10585) or HSP70 inhibitor (KNK437) decreased IPC-induced HIF-1α or HSP70 expression, respectively, and abrogated the anti-apoptotic effect of IPC. In summary, IPC is associated with increased HIF-1α and HSP70 expression and a subsequent decreased apoptosis in neonatal cardiomyoblasts exposed to HR. These results suggest that HIF-1α and HSP70play important roles in IPC-induced cardioprotection, and these endogenous transcription factors may provide a novel therapeutic target to prevent myocardial IR injury in vivo

Low renal oximetry correlates with acute kidney injury after infant cardiac surgery

Acute kidney injury (AKI) is a frequent complication after cardiopulmonary bypass surgery during infancy. Standard methods for evaluating renal function are not particularly sensitive nor are proximate indicators of renal dysfunction that allow intervention in real time. Near-infrared spectroscopy (NIRS) is a newer noninvasive technology that continuously evaluates regional oximetry and may correlate with renal injury and adverse outcomes after cardiac surgery in infants. This prospective observational study enrolled 40 infants (age, \u3c12 months) undergoing biventricular repair. Continuous renal oximetry data were collected for the first 48 postoperative hours and correlated with postoperative course, standard laboratory data, and the occurrence of acute renal injury. Subjects with low renal oximetry (below 50% for \u3e2 h) had significantly higher postoperative peak creatinine levels by 48 h (0.8 ± 0.4 vs. 0.52 ± 0.2; p = 0.003) and a higher incidence of AKI (50 vs. 3.1%; p = 0.003) than those with normal renal oximetry. These subjects also required more ventilator days and greater vasoactive support, and they had elevated lactate levels. Prolonged low renal near-infrared oximetry appears to correlate with renal dysfunction, decreased systemic oxygen delivery, and the overall postoperative course in infants with congenital heart disease undergoing biventricular repair. © 2010 Springer Science+Business Media, LLC

Near-infrared spectroscopy: What we know and what we need to know-A systematic review of the congenital heart disease literature

Objectives: Neurologic dysfunction is a problem in patients with congenital heart disease. Near-infrared spectroscopy may provide a real-time window into cerebral oxygenation. Enthusiasm for near-infrared spectroscopy has increased hopes of reducing neurologic dysfunction. However, potential gains need to be evaluated relative to cost before routine implementation. Responding to data in ways that seem intuitively beneficial can be risky when the long-term impact is unknown. Thus, we performed a systematic review of the literature on near-infrared spectroscopy in congenital heart disease. Methods: A literature search from 1950 to April 2007 for near-infrared spectroscopy in congenital heart disease was undertaken. We identified 54 manuscripts and\ 13 reviews. Results: There were 47 case series, 4 randomized trials, and 3 retrospective studies. Two studies had postdischarge follow-up, one incorporating neurologic testing. Neither of these studies demonstrated a benefit. One retrospective study, which included near-infrared spectroscopy and other intraoperative measures of cerebral perfusion, demonstrated a decrease in neurologic dysfunction using this combination of monitors. Three small studies were able to correlate near-infrared spectroscopy with other clinical and radiologic findings. Conclusions: Many centers, and even entire countries, have adopted near-infrared spectroscopy as standard of care. The available data suggest that multimodality monitoring, including near-infrared spectroscopy, may be a useful adjunct. The current literature on the use of near-infrared spectroscopy alone, however, does not demonstrate improvement in neurologic outcome. The data correlating near-infrared spectroscopy findings with indirect measures of neurologic outcome or mortality are limited. Although near-infrared spectroscopy has promise for measuring regional tissue oxygen saturation, the lack of data demonstrating improved outcomes limits the support for widespread implementation. © 2009 The American Association for Thoracic Surgery

Near infrared spectroscopy (NIRS) should not be standard of care for postoperative management

Neurologic dysfunction is a problem in patients with congenital heart disease. Near infrared spectroscopy (NIRS) may provide a real-time window into cerebral oxygenation. Enthusiasm for NIRS has increased in hopes of reducing neurologic dysfunction. However, potential gains need to be evaluated relative to cost and potential detriment of intervention before routine implementation. Responding to data in ways that seem intuitively beneficial can be risky when the long-term impact is unknown. Many centers, and even entire countries, have adopted NIRS as standard of care. Available data suggest that multimodality monitoring, including NIRS, may be a useful adjunct. However, the current literature on the use of NIRS alone does not demonstrate improvement in neurologic outcome. Data correlating NIRS findings with indirect measures of neurologic outcome or mortality are limited. Although NIRS has promise for measuring regional tissue oxygen saturation, the lack of data demonstrating improved outcomes limits the support for wide-spread implementation. © 2010 Elsevier Inc