A newborn boy is delivered by cesarean delivery at 39 weeks gestation to a 26-year-old woman, gravida 1 para 1, with gestational diabetes mellitus. First-trimester laboratory testing was normal, and second-trimester ultrasound showed no anomalies. At 28 weeks gestation, oral glucose tolerance testing indicated hyperglycemia, for which the patient initiated dietary modification and exercise. At 34 weeks gestation, maternal fasting blood sugars were consistently 100 mg/dL. She was started on subcutaneous insulin therapy but was frequently hyperglycemic. Other than prenatal vitamins, the patient's mother did not take any medications and did not use tobacco, alcohol, or illicit drugs. The infant's birthweight is 3.99 kg (8.8 lb). Temperature is 36.8 C (98.2 F), blood pressure is 70/40 mm Hg, pulse is 150/min, and respirations are 62/min. Pulse oximetry on room air is 92% in the right upper extremity and 93% in the left lower extremity. Examination shows a nondysmorphic infant with mild tachypnea, nasal flaring, and retractions. Auscultation reveals a heart murmur, but breath sounds are clear. Chest radiograph reveals mild pulmonary congestion.
An echocardiogram in this neonate would most likely show which of the following findings?

Question

A newborn boy is delivered by cesarean delivery at 39 weeks gestation to a 26-year-old woman, gravida 1 para 1, with gestational diabetes mellitus.  First-trimester laboratory testing was normal, and second-trimester ultrasound showed no anomalies.  At 28 weeks gestation, oral glucose tolerance testing indicated hyperglycemia, for which the patient initiated dietary modification and exercise.  At 34 weeks gestation, maternal fasting blood sugars were consistently >100 mg/dL.  She was started on subcutaneous insulin therapy but was frequently hyperglycemic.  Other than prenatal vitamins, the patient's mother did not take any medications and did not use tobacco, alcohol, or illicit drugs.  The infant's birthweight is 3.99 kg (8.8 lb).  Temperature is 36.8 C (98.2 F), blood pressure is 70/40 mm Hg, pulse is 150/min, and respirations are 62/min.  Pulse oximetry on room air is 92% in the right upper extremity and 93% in the left lower extremity.  Examination shows a nondysmorphic infant with mild tachypnea, nasal flaring, and retractions.  Auscultation reveals a heart murmur, but breath sounds are clear.  Chest radiograph reveals mild pulmonary congestion. 
An echocardiogram in this neonate would most likely show which of the following findings?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c117_6905_8f63_b385e77750eb_MD0005_00 This newborn with respiratory distress (tachypnea, nasal flaring, retractions) and a heart murmur likely has transient hypertrophic cardiomyopathy, a cardiac anomaly found in infants of mothers with gestational diabetes. This disease occurs in the late second to early third trimesters due to fetal hyperinsulinemia in response to maternal and fetal hyperglycemia. Insulin triggers glycogen synthesis, and excess glycogen and fat are deposited within the myocardium, particularly the interventricular septum. Increased oxidative stress of the interventricular septum may contribute to this selective thickening. A hypertrophic interventricular septum is usually asymptomatic; however, if left ventricular outflow is obstructed, manifestations of congestive heart failure may occur. In infants, these can include respiratory distress, tachycardia, and hypoxia (as seen in this patient), as well as failure to thrive. Despite the presence of pulmonary edema, crackles may not be auscultated. Pulmonary congestion and cardiomegaly may be evident on chest radiograph, and echocardiography confirms the diagnosis. Although transient tachypnea of the newborn is a common cause of tachypnea and respiratory distress, this patient's murmur makes cardiogenic pulmonary edema due to transient hypertrophic cardiomyopathy the most likely etiology. Poorly controlled gestational diabetes mellitus carries numerous additional risks for the infant, including macrosomia, hypocalcemia, hypoglycemia, hyperviscosity due to polycythemia, and respiratory difficulties. Most of these adverse effects can be avoided with strict glycemic control throughout pregnancy (ideal fasting blood glucose ≤95 mg/dL). (Choice A) Ebstein anomaly is characterized by atrialization of the right ventricle due to a malformed tricuspid valve. Severely affected newborns present with tricuspid regurgitation and cyanosis. Although some infants have mild symptoms, this diagnosis is unlikely in this patient who had a normal second-trimester ultrasound. (Choice C) Hypoplastic left ventricle (ie, hypoplastic left heart syndrome) is an embryologic malformation that occurs early in the first trimester in infants of mothers with pregestational diabetes. It presents with cyanosis, and the structural abnormality is often recognized on second-trimester ultrasound. (Choice D) Coarctation, or narrowing of the aorta, is typically associated with Turner syndrome rather than prenatal maternal hyperglycemia. Neonates with severe coarctation have weak femoral pulses and decreased postductal oxygen saturation. Aortic arch indentation ("3 sign") is seen on radiography. (Choice E) Congenital pulmonary valve stenosis, characterized by an obstruction of the pulmonary valve, is typically associated with Noonan syndrome. Right ventricular outflow tract obstruction may result in cyanosis if right-to-left shunting occurs. Educational objective: Infants born to mothers with diabetes and poor glycemic control during pregnancy are at increased risk for transient hypertrophic cardiomyopathy with a thickened interventricular septum due to excess glycogen deposition in the fetal myocardium. Tachypnea and respiratory distress may be early signs of congestive heart failure. References: Neonates of diabetic mothers: the starting point for developing novel therapeutic approaches to ischemic heart and brain? (http://www.ncbi.nlm.nih.gov/pubmed/27959282) Myocardial hypertrophy and dysfunction in maternal diabetes. (http://www.ncbi.nlm.nih.gov/pubmed/22445568)

A Newborn Boy Is Delivered by Cesarean Delivery at 39