Border Medicine: The Pediatric Cardiology Perspective.

Pediatric cardiology and cardiovascular surgery have witnessed significant advancements over the last two decades. In spite of this progress, congenital heart disease (CHD) still remains as one of the major causes of death in infants and young children in the United States. Many patient-related and patient-independent factors influence the outcomes in patients with CHD, one of which is the geographical location. In the US-Mexico border, management and outcomes of patients with CHD are further complicated by additional problems stemming from complex interplay between two different health systems, and socioeconomic disparities. In this article, the authors evaluate the various interplaying factors and describe the difficulties facing the practicing pediatric cardiologists in a US-Mexico border city.

Establishment of Myocardial Strain Measurement Data in Pediatric Patients Without Structural Heart Disease: A Single Center Study.

Accurate assessment of LV systolic function remains a challenge, especially in the pediatric population. Myocardial strain measurement by 2D speckle tracking echocardiography (2DSTE) is a relatively new modality for assessment of regional and global myocardial wall motion. This study aims to establish the normative value among various pediatric age groups at a large pediatric tertiary care institution and to describe the challenges encountered in establishing such strain data. Transthoracic echocardiograms were acquired in 121 healthy children (age 0-21 years) and were retrospectively analyzed. The global longitudinal strain (GLS) was obtained by 2D speckle tracking using Philips Epiq7® and QLAB post processing software. The normative value for left ventricular GLS (%) obtained in our study was - 20.8 ± 2.3 (< 1 year); - 21.4 ± 2.2 (1-4 years); - 19.6 ± 2.4 (5-9 years); - 19.4 ± 2.6 (10-14 years); - 18.9 ± 3.0 (15-21 years). There was a statistically significant difference in GLS between the different age groups. The BMI (kg/m2) of assessed subjects were 14.6 ± 2.3 (< 1 year); 16.3 ± 1.5 (1-4 years); 16.7 ± 2.3 (5-9 years); 21.3 ± 4.6 (10-14 years); 23.9 ± 5.9 (15-21 years). There was no significant difference in GLS by gender or by BMI found in our study. We present our experience with establishment of normative values of 2DSTE in our pediatric echocardiography lab. This study shows that age is the major determinant of variation in peak GLS in healthy subjects, emphasizing the importance of establishment of normative data among various age groups in pediatrics.

Comparison of echocardiographic changes in children with primary hypertension and hypertension due to mild to moderate chronic kidney disease.

BACKGROUND: Chronic systemic hypertension has a well-known association with increased cardiovascular morbidity and mortality. One of the most important target organs affected in systemic hypertension is the heart. In addition, chronic kidney disease (CKD) further increases the mortality from cardiovascular disease. The aim of this study was to evaluate the differences in the cardiovascular changes in pediatric patients with primary hypertension (pHTN) vs. those with secondary hypertension from chronic kidney disease (CKD-HTN). METHODS: This was a retrospective chart review of patients with CKD-HTN and pHTN. The medical records were reviewed for anthropometric data, biochemical assessment of renal function, and for cardiovascular changes on echocardiogram. RESULTS: Twenty-three patients with pHTN and 29 patients with CKD-HTN were included in the study. There were no differences in age, gender, weight, height, body mass index, and blood pressure between the 2 groups. There was a high prevalence of left ventricular diastolic dysfunction among both the groups (CKD-HTN 25 vs. pHTN 26%). Reduced mitral valve inflow Doppler E/A ratio, a marker of left ventricular diastolic dysfunction in echocardiogram, was more pronounced in CKD-HTN patents, in comparison to those with pHTN (p = 0.042). Also, diastolic function worsened with declining glomerular filtration rate in patients with CKD-HTN. Similarly, patients with CKD-HTN had a larger aortic root dimension when compared to patients with pHTN (p = 0.049). CONCLUSIONS: The prevalence of left ventricular diastolic dysfunction is similar in patients with pHTN and CKD-HTN. Patients with CKD-HTN appear to have more severe diastolic dysfunction and larger aortic root dimensions.

Emerging trends in the prenatal diagnosis of complex CHD and its influence on infant mortality in this cohort.

BACKGROUND: Fetal echocardiography is the main modality of prenatal diagnosis of CHD. This study was done to describe the trends and benefits associated with prenatal diagnosis of complex CHD at a tertiary care centre. METHODS: Retrospective chart review of patients with complex CHD over an 18-year period was performed. Rates of prenatal detection along with early and late infant mortality outcomes were studied. RESULTS: Of 381 complex CHD patients born during the study period, 68.8% were diagnosed prenatally. Prenatal detection rate increased during the study period from low-50s in the first quarter to mid-80s in the last quarter (p=0.001). Rate of detection of conotruncal anomalies increased over the study period. No infant mortality benefit was noted with prenatal detection. CONCLUSIONS: Improved obstetrical screening indications and techniques have contributed to higher proportions of prenatal diagnosis of complex CHD. However, prenatal diagnosis did not confer survival benefits in infancy in our study.

Impact of prenatal diagnosis of complex congenital heart disease on neonatal and infant morbidity and mortality.

OBJECTIVES: The objective of this study was to analyze the benefits associated with prenatal diagnosis of complex congenital heart disease (CHD) on preoperative morbidity, 30-day and 1-year mortality in this population. METHOD: This was a retrospective review of patients with complex CHD born at our tertiary care center over a 10-year period. Date analysis using Student t test and chi-square test. RESULTS: The overall rate of prenatal detection of complex CHD was 68.1%. A steady increase in the number of complex CHD diagnosed prenatally was noted during the study period. The prenatal diagnosis of complex CHD was associated with significant reduction in the incidence of the following preoperative parameters: antibiotic use, mechanical ventilation, inotropic support, hepatic and renal dysfunction, and acidosis. These beneficial effects were more significant in ductal-dependent cardiac anomalies. However, there were no neonatal and infant survival benefits in association with prenatal diagnosis. CONCLUSION: Prenatal diagnosis of complex CHD leads to improved preoperative morbidity, especially in patients with ductal-dependent cardiac anomalies. No survival benefits were noted with prenatal diagnosis of complex CHD.

Sinus node dysfunction masquerading as complete atrioventricular block in the setting of atrial parasystole after heart transplantation.

Heart transplantation is the gold standard for treatment of end stage heart failure. Atrial parasystole (AP), defined as the presence of an additional dissociated atrial pacemaker on a surface electrocardiogram, has been described to be seen after heart transplantation using biatrial surgical technique. AP may pose a challenge in diagnosing underlying rhythm disturbances in these patients. Here, we report a rare phenomenon of junctional escape rhythm with sinus node dysfunction, mimicking as complete atrioventricular block due to the presence of an AP, in a heart transplant recipient.

Association of left atrial pressure with left atrial volume and N-terminal prohormone brain natriuretic peptide in children with cardiomyopathy.

BACKGROUND: Enlargement of the left atrium is a non-invasive marker of diastolic dysfunction of the left ventricle, a determinant of prognosis in children with cardiomyopathy. Similarly, N-terminal prohormone brain natriuretic peptide is a useful marker in the management of children with cardiomyopathy and heart failure. The aim of this study is to evaluate the association of left atrial pressures with left atrial volume and N-terminal prohormone brain natriuretic peptide in children with cardiomyopathy. METHODS: This was a retrospective study reviewing the medical records of patients <18 years of age, who were diagnosed with cardiomyopathy or acute myocarditis with eventual development of cardiomyopathy. Left atrial volume by transthoracic echocardiogram and pulmonary capillary wedge pressure, a surrogate of left atrial pressure, obtained by means of cardiac catheterisation were analysed. In addition, N-terminal prohormone brain natriuretic peptide levels obtained at the time of the cardiac catheterisation were also reviewed. Statistical analysis was performed to evaluate the association of left atrial pressures with left atrial volume and N-terminal prohormone brain natriuretic peptide levels. RESULTS: There was a linear correlation of left atrial pressure estimated in the cardiac catheterisation with indexed left atrial volume (r=0.63; p<0.001) and left atrial volume z-scores (r=0.59; p<0.001). We found no statistically significant association between the left atrial pressure and N-terminal prohormone brain natriuretic peptide levels. CONCLUSIONS: Left atrial volume measured non-invasively by echocardiography can be used as a surrogate for left atrial pressure in assessing diastolic dysfunction of the left ventricle in children with cardiomyopathy. The larger the size of the left atrium, worse is the diastolic function of the left ventricle.

Rapid Involution of Large Cardiac Rhabdomyomas With Everolimus Therapy.

Rhabdomyoma of the fetal heart is a rare disease accounting for about 1% of all fetal cardiac structural anomalies. They are often found in association with tuberous sclerosis complex. Large cardiac rhabdomyomas can compromise the cardiac function. We report a case of multiple large rhabdomyomas of the right and left ventricles, affecting the cardiac function, which was successfully treated with the chemotherapeutic and immunosuppressive medication everolimus, in a neonate with genetically confirmed tuberous sclerosis complex with multisystem manifestations. There was rapid involution of the tumors in response to everolimus therapy in this infant.

Acute Myocardial Injury in Association with Metformin Toxicity.

Metformin is one of the most commonly used oral hypoglycemic agents in the treatment of type 2 diabetes mellitus. Toxicity related to accidental or intentional ingestion of metformin is well reported in the pediatric literature. We report a case of transient acute myocardial injury documented by biochemical and electrophysiological evidences in an adolescent male who presented with intentional ingestion of a large dose of metformin. To our knowledge, this is the first such case of documented reversible myocardial injury in relation to metformin toxicity to be reported in the pediatric literature.

Unilateral lung agenesis, hiatal hernia and atrioventricular septal defect: a rare combination of congenital anomalies.

Unilateral lung agenesis is a relatively rare congenital anomaly with a reported incidence of 1 in 15 000 births. It is frequently associated with other congenital malformations. Some of the sequelae of lung agenesis are potentially life-threatening. Here, we report a case of left lung agenesis in association with hiatal hernia and atrioventricular septal defect, a rare combination of anomalies which have not been described previously in the literature.

Infantile Onset Hypertrophic Cardiomyopathy Secondary to PRKAG2 Gene Mutation is Associated with Poor Prognosis.

Hypertrophic cardiomyopathy (HCM) is the second most prevalent form of cardiomyopathy in children. The etiology of the HCM is heterogeneous, so is the age of onset of symptoms. The HCM associated with metabolic disorders and genetic syndromes presents early in childhood. There are very few case reports of early-onset infantile HCM secondary to the PRKAG2 gene. Here, we report a case of HCM in a neonate diagnosed prenatally and eventually diagnosed with a missense mutation in the PRKAG2 gene.

Incidence and factors influencing the spontaneous closure of Fontan fenestration.

INTRODUCTION: The Fontan operation is the final stage of single ventricle palliation in patients with complex congenital heart disease. Fenestration in the Fontan conduit, providing an atrial level right to left shunt, has been shown to reduce early postoperative morbidity. However, there is limited data on the long-term fate of this fenestration. The aim of this study is to define the rate of spontaneous closure of the fenestration in the Fontan conduit and factors predictive of the fate of the fenestration. METHODS: This was a retrospective study reviewing the medical records of the patients who underwent fenestrated Fontan operation at our center. Preoperative, intraoperative and postoperative variables including the status of the Fontan fenestration were extracted and analyzed. RESULTS: Of 67 patients included in the study, 15 (22%) had spontaneous closure of the fenestration. Of the remaining 52 patients, 11 (20%) had procedural closure of this fenestration (10 via cardiac catheterization and 1 via surgery) at a median duration of 3 months after the Fontan operation. Patients with higher preoperative pulmonary vascular resistance and a history of postoperative systemic venous thromboembolism had higher likelihood of having persistence of the fenestration with P value of .045 and .037, respectively. CONCLUSIONS: The rate of spontaneous closure of the Fontan fenestration was 22% in our study. Elevated preoperative pulmonary vascular resistance and history of systemic venous thromboembolism are predictive of persistent Fontan fenestration.

Klinefelter Syndrome in Association with Tetralogy of Fallot and Congenital Diaphragmatic Hernia.

Klinefelter syndrome (KS) is the most common sex chromosomal aneuploidy in males. Major cardiovascular and diaphragmatic anomalies are uncommon in this syndrome. Here we report an infant with KS who had tetralogy of Fallot and congenital diaphragmatic hernia, all of which were identified prenatally and managed successfully after birth. Microarray analysis did not reveal any deletions or duplications other than the additional X-chromosome, to account for the additional abnormalities in this infant. To the authors' knowledge, this is the first such report of major cardiac and diaphragm anomaly occurring together, in an infant with KS.

Lack of Association of ST-T Wave Abnormalities to Congenital Heart Disease in Neonates.

BACKGROUND: ST-T wave (STTW) abnormalities have been described in 20-40% of normal newborns. We sought to describe the associations of these Electrocardiogram (ECG) abnormalities to perinatal course and congenital heart disease (CHD). METHODS: A retrospective chart review was performed on all neonatal ECGs between January 2008 and March 2013 identified from electronic medical records. Electronic medical records were reviewed for perinatal course and maternal medical conditions. Neonates <37 weeks gestation, >3 days age, requiring hemodynamic support in the first 3 days, with oxygen saturation <90% on room air, or with arrhythmias and significant abnormalities of axis and voltage were excluded from the analysis. ST segment elevation or depression of >2 mm in at least one lead and flat or inverted T waves in at least one lead except aVR were considered abnormal. Statistical relationships were explored between STTW abnormalities, perinatal variables and CHD. RESULTS: ECGs were performed on 1043 neonates, of which 664 were included. STTW abnormalities were found in 236 (35.5%) neonates. T wave abnormalities were identified in 191 (28.7%), ST segment abnormalities in 77 (11.6%) and both on 32 (4.8%) neonates. No relationship was found between the ECG abnormalities and perinatal variables, except maternal cefazolin administration during labor. Noncritical CHD was diagnosed by echocardiography in 59/84; STTW abnormalities were seen in 17/59 (29%) patients with and 9/25 (34%) without noncritical CHD, P = .6. CONCLUSION: STTW abnormalities on ECG are commonly found in 35.5% of normal neonates and do not predict noncritical CHD.