James S. Tweddell

Prospective Trial of a Pediatric Ventricular Assist Device

BACKGROUND Options for mechanical circulatory support as a bridge to heart transplantation in children with severe heart failure are limited. METHODS We conducted a prospective, single-group trial of a ventricular assist device designed specifically for children as a bridge to heart transplantation. Patients 16 years of age or younger were divided into two cohorts according to body-surface area (cohort 1, <0.7 m(2); cohort 2, 0.7 to <1.5 m(2)), with 24 patients in each group. Survival in the two cohorts receiving mechanical support (with data censored at the time of transplantation or weaning from the device owing to recovery) was compared with survival in two propensity-score-matched historical control groups (one for each cohort) undergoing extracorporeal membrane oxygenation (ECMO). RESULTS For participants in cohort 1, the median survival time had not been reached at 174 days, whereas in the matched ECMO group, the median survival was 13 days (P<0.001 by the log-rank test). For participants in cohort 2 and the matched ECMO group, the median survival was 144 days and 10 days, respectively (P<0.001 by the log-rank test). Serious adverse events in cohort 1 and cohort 2 included major bleeding (in 42% and 50% of patients, respectively), infection (in 63% and 50%), and stroke (in 29% and 29%). CONCLUSIONS Our trial showed that survival rates were significantly higher with the ventricular assist device than with ECMO. Serious adverse events, including infection, stroke, and bleeding, occurred in a majority of study participants. (Funded by Berlin Heart and the Food and Drug Administration Office of Orphan Product Development; ClinicalTrials.gov number, NCT00583661.).

Hypoplastic Left Heart Syndrome : Current Considerations and Expectations

In the recent era, no congenital heart defect has undergone a more dramatic change in diagnostic approach, management, and outcomes than hypoplastic left heart syndrome (HLHS). During this time, survival to the age of 5 years (including Fontan) has ranged from 50% to 69%, but current expectations are that 70% of newborns born today with HLHS may reach adulthood. Although the 3-stage treatment approach to HLHS is now well founded, there is significant variation among centers. In this white paper, we present the current state of the art in our understanding and treatment of HLHS during the stages of care: 1) pre-Stage I: fetal and neonatal assessment and management; 2) Stage I: perioperative care, interstage monitoring, and management strategies; 3) Stage II: surgeries; 4) Stage III: Fontan surgery; and 5) long-term follow-up. Issues surrounding the genetics of HLHS, developmental outcomes, and quality of life are addressed in addition to the many other considerations for caring for this group of complex patients.

Home surveillance program prevents interstage mortality after the Norwood procedure

OBJECTIVE To determine whether early identification of physiologic variances associated with interstage death would reduce mortality, we developed a home surveillance program. METHODS Patients discharged before initiation of home surveillance (group A, n = 63) were compared with patients discharged with an infant scale and pulse oximeter (group B, n = 24). Parents maintained a daily log of weight and arterial oxygen saturation according to pulse oximetry and were instructed to contact their physician in case of an arterial oxygen saturation less than 70% according to pulse oximetry, an acute weight loss of more than 30 g in 24 hours, or failure to gain at least 20 g during a 3-day period. RESULTS Interstage mortality among infants surviving to discharge was 15.8% (n = 9/57) in group A and 0% (n = 0/24) in group B (P =.039). Surveillance criteria were breached for 13 of 24 group B patients: 12 patients with decreased arterial oxygen saturation according to pulse oximetry with or without poor weight gain and 1 patient with poor weight gain alone. These 13 patients underwent bidirectional superior cavopulmonary connection (stage 2 palliation) at an earlier age, 3.7 +/- 1.1 months of age versus 5.2 +/- 2.0 months for patients with an uncomplicated interstage course (P =.028). A growth curve was generated and showed reduced growth velocity between 4 and 5 months of age, with a plateau in growth beyond 5 months of age. CONCLUSION Daily home surveillance of arterial oxygen saturation according to pulse oximetry and weight selected patients at increased risk of interstage death, permitting timely intervention, primarily with early stage 2 palliation, and was associated with improved interstage survival. Diminished growth identified 4 to 5 months after the Norwood procedure brings into question the value of delaying stage 2 palliation beyond 5 months of age.

Bridging children of all sizes to cardiac transplantation: The initial multicenter North American experience with the Berlin Heart EXCOR ventricular assist device

BACKGROUND Beginning in 2000 and accelerating in 2004, the Berlin Heart EXCOR (Berlin Heart Inc Woodlands, TX) became the first pediatric-specific ventricular assist device (VAD) applied throughout North America for children of all sizes. This retrospective study analyzed the initial Berlin Heart EXCOR pediatric experience as a bridge to transplantation. METHODS Between June 2000 and May 2007, 97 EXCOR VADs were implanted in North America at 29 different institutions. The analysis is limited to 73 patients (75%) from 17 institutions, for which retrospective data were available. RESULTS Median age and weight at VAD implant were 2.1 years (range, 12 days-17.8 years) and 11 kg (range, 3-87.6 kg), respectively. The primary diagnoses were dilated cardiomyopathy in 42 (58%), congenital heart disease in 19 (26%), myocarditis in 7 (10%), and other cardiomyopathies in 5 (7%). Pre-implant clinical condition was critical cardiogenic shock in 38 (52%), progressive decline in 33 (45%), or other in 2 (3%). Extracorporeal membrane oxygenation was used as a bridge to EXCOR in 22 patients (30%). Device selection was left VAD (LVAD) in 42 (57%) and biventricular assist devices (BiVAD) in 31 (43%). The EXCOR bridged 51 patients (70%) to transplant and 5 (7%) to recovery. Mortality on the EXCOR was 23% (n = 17) overall, including 35% (11 of 31) in BiVAD vs 14% (6 of 42) in LVAD patients (p = 0.003). Multivariate analysis showed younger age and BiVAD support were significant risk factors for death while on the EXCOR. CONCLUSIONS This limited but large preliminary North American experience with the Berlin Heart EXCOR VAD as a bridge to cardiac transplantation for children of all ages and sizes points to the feasibility of this approach. The prospective investigational device evaluation trial presently underway will further characterize the safety and efficacy of the EXCOR as a bridge to pediatric cardiac transplantation.

Phenoxybenzamine improves systemic oxygen delivery after the Norwood procedure

BACKGROUND Achieving adequate systemic oxygen delivery after the Norwood procedure frequently is complicated by excessive pulmonary blood flow at the expense of systemic blood. We hypothesized that phenoxybenzamine could achieve a balanced circulation through reduction of systemic vascular resistance. METHODS In this prospective, nonrandomized study, oximetric catheters were placed in the superior vena cava for continuous monitoring of systemic venous oxygen saturation. Postoperative hemodynamic variables were compared between 7 control patients and 8 patients who received phenoxybenzamine. RESULTS The hospital survival rate was 93% (14 of 15 patients). Improvements in postoperative hemodynamics in the phenoxybenzamine group included a higher systemic venous oxygen saturation, a narrower arteriovenous oxygen content difference, a lower ratio of pulmonary to systemic flow, and a lower indexed systemic vascular resistance. In the phenoxybenzamine group, mean arterial blood pressure was related directly to systemic oxygen delivery, in contrast to the control group, where mean arterial pressure was related directly to indexed systemic vascular resistance and the ratio of pulmonary to systemic circulation. CONCLUSIONS Continuous postoperative monitoring of systemic venous oxygen saturation in a patient who has undergone the Norwood procedure provides early identification of low systemic oxygen delivery and an elevated ratio of pulmonary to systemic circulation. In this pilot study, phenoxybenzamine appeared to improve systemic oxygen delivery during the early postoperative period after the Norwood procedure. Further studies are indicated to confirm these results.

Prospective echocardiographic diagnosis and surgical repair of anomalous origin of a coronary artery from the opposite sinus with an interarterial course

OBJECTIVES In this study, we sought to describe the mode of presentation, anatomic features, diagnostic techniques, and surgical outcome in a group of patients with anomalous origin of a coronary artery from the opposite sinus with an interarterial course between the great arteries (AOCA). BACKGROUND Anomalous origin of a coronary artery from the opposite sinus with an interarterial course is associated with myocardial ischemia and sudden cardiac death, particularly in adolescents and young adults. METHODS The cardiology database at Childrens Hospital of Wisconsin was reviewed to identify all patients diagnosed with AOCA. RESULTS From September 1997 to August 2002, 10 patients were identified with AOCA; all were children/adolescents (age range, 3 months to 20 years; weight range, 4.7 to 72 kg), and nine were diagnosed prospectively by transthoracic echocardiography (TTE). Symptoms of cardiac ischemia initiated investigation in 4/10 patients at a mean age of 16 +/- 2.8 years; the other six had TTE for suspected congenital heart disease/musculoskeletal chest pain. The left coronary artery originated from the right sinus in six patients, and the right coronary artery originated from the left sinus in four patients. An intramural course of the AOCA within the anterior aortic wall was found in 9/10 patients and was reliably identified by TTE; the other patient had an intramyocardial course of the anomalous coronary. Surgical repair was performed in 8/10 patients at a mean age of 13 +/- 4.7 years. Unroofing of the intramural portion of the AOCA to relocate the ostia in the appropriate sinus was successfully performed in seven patients. All patients status post unroofing were asymptomatic with patent coronary flow by Doppler and normal exercise treadmill testing at a median follow-up interval of 1.5 years. CONCLUSIONS Anomalous origin of a coronary artery from the opposite sinus with an interarterial course is frequently characterized by an intramural course, which can be prospectively identified by TTE. Unroofing the intramural segment without bypass grafting can reliably repair the intramural form of AOCA.

Venous saturation and the anaerobic threshold in neonates after the Norwood procedure for hypoplastic left heart syndrome

BACKGROUND Reduction in oxygen delivery can lead to organ dysfunction and death by cellular hypoxia, detectable by progressive (mixed) venous oxyhemoglobin desaturation until extraction is limited at the anaerobic threshold. We sought to determine the critical level of venous oxygen saturation to maintain aerobic metabolism in neonates after the Norwood procedure (NP) for the hypoplastic left heart syndrome (HLHS). METHODS A prospective perioperative database was maintained for demographic, hemodynamic, and laboratory data. Invasive arterial and atrial pressures, arterial saturation, oximetric superior vena cava (SVC) saturation, and end-tidal CO2 were continuously recorded and logged hourly for the first 48 postoperative hours. Arterial and venous blood gases and cooximetry were obtained at clinically appropriate intervals. SVC saturation was used as an approximation of mixed venous saturation (SvO2). A standard base excess (BE) less than -4 mEq/L (BElo), or a change exceeding -2 mEq/L/h (deltaBElo), were used as indicators of anaerobic metabolism. The relationship between SvO2 and BE was tested by analysis of variance and covariance for repeated measures; the binomial risk of BElo or deltaBElo at SvO2 strata was tested by the likelihood ratio test and logistic regression, with cutoff at p < 0.05. RESULTS Complete data were available in 48 of 51 consecutive patients undergoing NP yielding 2,074 valid separate determinations. BE was strongly related to SvO2 (model R2 = 0.40, p < 0.0001) with minimal change after adjustment for physiologic covariates. The risk of anaerobic metabolism was 4.8% overall, but rose to 29% when SvO2 was 30% or below (p < 0.0001). Survival was 100% at 1 week and 94% at hospital discharge. CONCLUSIONS Analysis of acid-base changes revealed an apparent anaerobic threshold when SvO2 fell below 30%. Clinical management to maintain SvO2 above this threshold yielded low mortality.

Endorsement of Health and Human Services Recommendation for Pulse Oximetry Screening for Critical Congenital Heart Disease

Incorporation of pulse oximetry to the assessment of the newborn infant can enhance detection of critical congenital heart disease (CCHD). Recently, the Secretary of Health and Human Services (HHS) recommended that screening for CCHD be added to the uniform screening panel. The American Academy of Pediatrics (AAP) has been a strong advocate of early detection of CCHD and fully supports the decision of the Secretary of HHS. The AAP has published strategies for the implementation of pulse oximetry screening, which addressed critical issues such as necessary equipment, personnel, and training, and also provided specific recommendations for assessment of saturation by using pulse oximetry as well as appropriate management of a positive screening result. The AAP is committed to the safe and effective implementation of pulse oximetry screening and is working with other advocacy groups and governmental agencies to promote pulse oximetry and to support widespread surveillance for CCHD. Going forward, AAP chapters will partner with state health departments to implement the new screening strategy for CCHD and will work to ensure that there is an adequate system for referral for echocardiographic/pediatric cardiac evaluation after a positive screening result. It is imperative that AAP members engage their respective policy makers in adopting and funding the recommendations made by the Secretary of HHS.

Erythropoietin protects the infant heart against ischemia–reperfusion injury by triggering multiple signaling pathways

Abstract The immediate protective effect of erythropoietin (EPO) against ischemia in heart suggests a role beyond hematopoiesis and the treatment of anemia. We determined the role of JAK/STAT and Ras/Rac/MAPK in the protective effect of EPO against ischemia–reperfusion injury in infant rabbit heart. EPO (1.0 U/ml) administered 15 minutes prior to 30–minutes global ischemia and 35 minutes reperfusion resulted in increased recovery of postischemic ventricular developed pressure in rabbit hearts. EPO exerted its immediate cardioprotective effect via activation of multiple signaling pathways by: 1) phosphorylation and activation of JAK1/2, STAT3 and STAT5A but not of STAT1α and STAT5B, 2) phosphorylation and activation of PI3 kinase and its downstream kinases Akt and Rac, 3) activation of PKCε, Raf, MEK1/2, p42/44 MAPK and p38 MAPK. Pretreatment with Wortmannin abolished EPO–induced Akt activation and phosphorylation. Pretreatment with Chelerythrine followed by EPO treatment resulted in partial inhibition of Raf activation, and abolished PKCε and p38 MAPK activation without any effect on Akt, MEK1/2 and p42/44 MAPK. PD98059 abolished MEK1/2 and p42/44 MAPK activation with no effect on Akt, Raf and p38 MAPK activation. SB203580 inhibited only p38 MAPK activation by EPO. We can conclude EPO increases immediate cardioprotection through the activation of multiple signal transduction pathways.

Fontan Palliation in the Modern Era: Factors Impacting Mortality and Morbidity

BACKGROUND Advances in management of the Fontan patient include interval superior cavopulmonary shunt, total cavopulmonary connection, either lateral tunnel or extracardiac conduit, and the use of a fenestration. Coincident with these improvements, Fontan palliation has been applied to a wider ranger of anatomic subgroups. METHODS A cross-sectional analysis of 256 consecutive patients undergoing a total cavopulmonary connection Fontan after superior cavopulmonary shunt between January 1, 1994, and June 30, 2007 were studied. Fenestration was used selectively. Fontan failure was defined as death, transplant, or takedown. Event-free survival was defined as freedom from death, transplant, Fontan takedown, functional class III to IV, pacemaker, antiarrhythmic medication, protein-losing enteropathy, stroke, or thrombus. RESULTS Survival was 97% +/- 1%, 96% +/- 1%, and 94% +/- 2%, respectively, at 1, 5, and 10 years. Event-free survival was 96% +/- 1%, 87% +/- 3%, and 64% +/- 6%, respectively, at 1, 5, and 10 years. Factors predicting worse event-free survival included longer cross-clamp time (p = 0.003), fenestration (p = 0.014), and longer hospital length of stay (p = 0.016). Ventricular morphology did not predict outcome. Left ventricle (n = 113, 44%) versus right ventricle (n = 142, 56%) failure-free survival (death, transplant, or Fontan takedown) at 10 years was 92% +/- 4% versus 91% +/- 3%, respectively (p = 0.19). Left ventricle versus right ventricle event-free survival at 10 years was 75% +/- 7% versus 67% +/- 9%, respectively (p > 0.1). CONCLUSIONS Survival for patients undergoing a completion Fontan in the current era is excellent, but patients remain at risk for morbid events. In the intermediate follow-up period, we could not identify a difference in outcome between dominant left and right ventricle morphology.