Gerard R. Martin

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.

Strategies for Implementing Screening for Critical Congenital Heart Disease

BACKGROUND: Although newborn screening for critical congenital heart disease (CCHD) was recommended by the US Health and Human Services Secretarys Advisory Committee on Heritable Disorders in Newborns and Children to promote early detection, it was deemed by the Secretary of the HHS as not ready for adoption pending an implementation plan from HHS agencies. OBJECTIVE: To develop strategies for the implementation of safe, effective, and efficient screening. METHODS: A work group was convened with members selected by the Secretarys Advisory Committee on Heritable Disorders in Newborns and Children, the American Academy of Pediatrics, the American College of Cardiology Foundation, and the American Heart Association. RESULTS: On the basis of published and unpublished data, the work group made recommendations for a standardized approach to screening and diagnostic follow-up. Key issues for future research and evaluation were identified. CONCLUSIONS: The work-group members found sufficient evidence to begin screening for low blood oxygen saturation through the use of pulse-oximetry monitoring to detect CCHD in well-infant and intermediate care nurseries. Research is needed regarding screening in special populations (eg, at high altitude) and to evaluate service infrastructure and delivery strategies (eg, telemedicine) for nurseries without on-site echocardiography. Public health agencies will have an important role in quality assurance and surveillance. Central to the effectiveness of screening will be the development of a national technical assistance center to coordinate implementation and evaluation of newborn screening for CCHD.

Diagnosis and management of fetal cardiac tumors: a multicenter experience and review of published reports☆

OBJECTIVES We sought to determine the prevalence and natural history of cardiac tumors in patients referred for fetal echocardiography. BACKGROUND Cardiac tumors are rare; the prevalence, reported from autopsy studies of patients of all ages, varies from 0.0017% to 0.28%. Despite many case reports, the prevalence and natural history of fetal cardiac tumors are unclear. METHODS Fourteen thousand fetal echocardiograms recorded over an 8-year period in seven centers were available for retrospective review. Medical records and echocardiograms were studied to determine the reason for referral, family history of tuberous sclerosis, prenatal and postnatal course and tumor description and type. RESULTS Cardiac tumors were present in 19 pregnancies (0.14%). Gestational age at diagnosis ranged from 21 to 38 weeks. The most common indication for referral was a mass on an obstetric ultrasound study. The tumors were singular in 10 patients and multiple in 9. Tumor size ranged from 0.4 x 0.4 to 3.5 x 4 cm, and the majority of tumors were not hemodynamically significant. There were 17 patients with rhabdomyomas, 1 with a fibroma and 1 with an atrial hemangioma. Tuberous sclerosis complex was diagnosed in 10 patients. Partial or complete tumor regression was seen in eight patients; tumors were unchanged in five; and three required operation. CONCLUSIONS Fetal cardiac tumors, a rare condition, are often benign. The majority of tumors are rhabdomyomas, but not all fetuses with rhabdomyoma have tuberous sclerosis.

Oxygen consumption and cardiovascular function in children during profound intraoperative normovolemic hemodilution.

The clinically acceptable limit of acute normovolemic, normothermic hemodilution, a standard procedure in scoliosis surgery, is not yet well defined.Eight ASA class I patients undergoing idiopathic scoliosis correction were administered a standard anesthetic with 100% oxygen and controlled ventilation. Hemodilution was accomplished by exchanging whole blood for 5% albumin in 0.9% saline. Blood gases, acid-base status, and circulatory variables were recorded prior to and after hemodilution, and every 30 min throughout surgery. The impact of hemodilution was judged by mixed venous oxygen saturation which was maintained at > or=to60%, while intravascular volume was maintained with the 5% albumin solution. Reinfusion of the autologous blood was completed by the end of surgery. In the eight controlled cases in which normovolemic hemodilution was studied, hemoglobin levels decreased from 10.0 +/- 1.6 g/dL to 3.0 +/- 0.8 g/dL. Mixed venous oxygen saturation decreased from 90.8% +/- 5.4% to 72.3% +/- 7.8%. Oxygen extraction ratio increased from 17.3% +/- 6.2% to 44.4% +/- 5.9%. Oxygen delivery decreased from 532.1 +/- 138.1 mL centered dot min-1 centered dot m-2 to 260.2 +/- 57.1 mL centered dot min-1 centered dot m-2, while global oxygen consumption did not decrease and plasma lactate did not appreciably increase. Central venous pressure increased and peripheral resistance decreased during hemodilution. Cardiac index increased, heart rate remained essentially constant, and left ventricular stroke work index did not decrease significantly. No patients suffered clinically adverse outcomes. Global oxygen transport and myocardial work can be maintained at extreme normovolemic anemia. Our evidence suggests that stages of normovolemic hemodilution more severe than previously reported may be clinically acceptable for young, healthy patients during normocarbic anesthesia. (Anesth Analg 1995;80:219-25)

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.

Dystrophin-deficient cardiomyopathy in mouse: Expression of Nox4 and Lox are associated with fibrosis and altered functional parameters in the heart

Duchenne muscular dystrophy (DMD; dystrophin-deficiency) causes dilated cardiomyopathy in the second decade of life in affected males. We studied the dystrophin-deficient mouse heart (mdx) using high-frequency echocardiography, histomorphometry, and gene expression profiling. Heart dysfunction was prominent at 9-10months of age and showed significantly increased LV internal diameter (end systole) and decreased posterior wall thickness. This cardiomyopathy was associated with a 30% decrease in shortening fraction. Histologically, there was a 10-fold increase in connective tissue volume (fibrosis). mRNA profiling with RT-PCR validation showed activation of key pro-fibrotic genes, including Nox4 and Lox. The Nox gene family expression differed in mdx heart and skeletal muscle, where Nox2 was specifically induced in skeletal muscle while Nox4 was specifically induced in heart. This is the first report of an altered profibrotic gene expression profile in cardiac tissue of dystrophic mice showing echocardiographic evidence of cardiomyopathy.

Improved pulmonary outcome after exogenous surfactant therapy for respiratory failure in term infants requiring extracorporeal membrane oxygenation

A blinded, randomized, controlled study was designed to test whether multiple-dose surfactant therapy would improve pulmonary outcome in term infants with respiratory failure, resulting in a shortened period of extracorporeal membrane oxygenation (ECMO). Infants > or = 34 weeks of gestational age in severe respiratory failure and receiving ECMO were stratified by diagnosis and then randomly assigned to the treatment or the control group. Four doses of modified bovine lung surfactant extract (beractant) were administered to the surfactant group (n = 28), and an equal volume of air was administered to the control group (n = 28). Lung compliance was initially low in both groups; after treatment, values were higher with time in the surfactant group (F = 5.40, p = 0.026). The ECMO treatment period was significantly shorter in the surfactant group (mean +/- SD: 107 +/- 33 hours vs 139 +/- 54 hours for the control group; U = 232, p = 0.023). Tracheal aspirate concentrations of surfactant protein A were low in both groups, and then increased steadily to a higher level in the surfactant group (F = 2.58, p = 0.04). The overall incidence of complications after ECMO was decreased in the surfactant group (18% vs 46% for the control group; chi-square value = 5.004, p = 0.025). Radiographic scores, echocardiographic findings, incidence of intracranial or pulmonary hemorrhage and bronchopulmonary dysplasia, time to extubation, duration of oxygen therapy, and duration of hospitalization did not differ between the two groups. Beractant in this population improved pulmonary mechanics, increased surfactant protein A content in tracheal aspirate, decreased time on ECMO duration, and reduced disease complications.

Databases for assessing the outcomes of the treatment of patients with congenital and paediatric cardiac disease - the perspective of cardiology

This review includes a brief discussion, from the perspective of cardiac surgeons, of the rationale for creation and maintenance of multi-institutional databases of outcomes of congenital heart surgery, together with a history of the evolution of such databases, a description of the current state of the art, and a discussion of areas for improvement and future expansion of the concept. Five fundamental areas are reviewed: nomenclature, mechanism of data collection and storage, mechanisms for the evaluation and comparison of the complexity of operations and stratification of risk, mechanisms to ensure the completeness and accuracy of the data, and mechanisms for expansion of the current capabilities of databases to include comparison and sharing of data between medical subspecialties. This review briefly describes several European and North American initiatives related to databases for pediatric and congenital cardiac surgery the Congenital Database of The European Association for Cardio-Thoracic Surgery, the Congenital Database of The Society of Thoracic Surgeons, the Pediatric Cardiac Care Consortium, and the Central Cardiac Audit Database in the United Kingdom. Potential means of approaching the ultimate goal of acquisition of long-term follow-up data, and input of this data over the life of the patient, are also considered.

Reversed shunting across the ductus arteriosus or atrial septum in utero heralds severe congenital heart disease

OBJECTIVES This study was performed to define the significance of Doppler color flow mapping in demonstrating reversal of the direction of the normal physiologic flow across the atrial septum and ductus arteriosus in the human fetus. BACKGROUND Reversal of the physiologic shunting across the ductus arteriosus or atrial septum in utero (i.e., left to right) can be readily identified by Doppler color flow mapping, complemented by pulsed and continuous wave Doppler information. METHODS We reviewed echocardiograms recorded at our three institutions from 1988 to 1993, which displayed reversal of flow by Doppler color flow in 53 fetuses of gestational age 18 weeks to term. The diagnoses were confirmed by postnatal echocardiography, operation or autopsy. Reversal of shunting was consistently associated with severe heart disease. RESULTS Reversed atrial shunting was found with severe left heart obstructive lesions, including 19 with hypoplastic left heart syndrome, 3 with critical aortic stenosis, 2 with double-outlet right ventricle and 1 each with an interrupted aortic arch, atrioventricular septal defect and severe left ventricular dysfunction due to dilated cardiomyopathy. Reversed ductus arteriosus shunting was found with severe right heart obstructive lesions, including nine fetuses with pulmonary atresia, six with severe obstructive tricuspid valve abnormalities, five with severe tetralogy of Fallot, four with Ebsteins anomaly and two with single ventricle and pulmonary stenosis. Associated cardiac lesions were common in both groups. Only 3 of the 15 infants who were delivered alive from the reverse ductus arteriosus shunt group and 4 of 12 from the reverse atrial shunt group still survive. CONCLUSIONS The finding of reversed flow by Doppler color flow mapping during fetal life provides a key to subsequent accurate diagnosis and denotes a spectrum of diseases with a very poor prognosis.

Development of a pediatric cardiology quality improvement collaborative: From inception to implementation. From the joint council on congenital heart disease quality Improvement task force

While clinical outcomes in pediatric cardiac disease have improved in recent years, marked institutional and individual cardiology practice variability exists. Quality improvement science has demonstrated that reducing process variation leads to more favorable outcomes, safer practices, cost savings, and improved operating efficiency. This report describes the process undertaken to develop the first collaborative quality improvement project of the Joint Council on Congenital Heart Disease. The project chosen aims to reduce mortality and improve the quality of life of infants with hypoplastic left heart syndrome during the interstage period between discharge from the Norwood procedure and admission for the bidirectional Glenn procedure. The objective of this special article is to inform the pediatric cardiology and cardiac surgery communities of the project to help ensure that the early work by the project pilot participants will spread to clinicians caring for children with cardiovascular disease. It is anticipated that this project will add to our understanding of care for this challenging group of children with hypoplastic left heart syndrome, identifying clinical care changes with the potential to lead to improvements in outcome. It will also introduce the field of pediatric cardiology to the science of collaborative quality improvement and assist in reducing clinical process variation and improving patient outcomes across centers. Finally, it will establish an ongoing network of pediatric cardiologists and their teams linked through a longitudinal data set and collaboration for improvement and research.