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 confirms the suspected cardiac abnormality. After the physician explains the condition, the parents express concerns about the prognosis. Which of the following is the most appropriate response to the parents?

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 confirms the suspected cardiac abnormality.  After the physician explains the condition, the parents express concerns about the prognosis.  Which of the following is the most appropriate response to the parents?

Quizplus · Accepted Answer

Explanation: This infant of a mother with gestational diabetes mellitus has transient hypertrophic cardiomyopathy as a result of poor maternal glycemic control during pregnancy. If asymptomatic, no treatment is required. If heart failure symptoms develop, propranolol and appropriate fluid management are indicated. Spontaneous resolution is expected within a few weeks after birth; echocardiogram findings normalize within a year. After birth, the infant is no longer exposed to maternal hyperglycemia, allowing plasma insulin levels to normalize. Excess glycogen within the myocardium is then depleted by normal metabolic processes during periods of fasting. (Choice A) Immediate corrective surgery is required for cyanotic congenital heart abnormalities (eg, tetralogy of Fallot, transposition of the great arteries). Hypertrophic obstructive cardiomyopathy, typically caused by genetically abnormal myocytes rather than by transient hyperinsulinemia, may require a septal myectomy if unresponsive to medical therapy. (Choice B) Insulin is a treatment option for hyperglycemia due to diabetes mellitus; however, infants of mothers with diabetes typically experience hypoglycemia. This occurs because maternal hyperglycemia in utero triggers fetal beta-cell hyperplasia and subsequent hyperinsulinemia. (Choice D) Pacemaker placement is the treatment for arrhythmias (eg, congenital long QT syndrome) and conditions causing heart block (eg, neonatal lupus). Arrhythmias are rare in patients with interventricular septal thickening, and pacemaker placement is not indicated. (Choice E) Prostaglandins maintain the patency of the ductus arteriosus to allow blood flow to the systemic circulation. Prostaglandins are indicated for patients with ductal-dependent lesions (eg, hypoplastic left heart, transposition of the great arteries) and provide immediate symptomatic improvement while awaiting surgery. Educational objective: Hypertrophic cardiomyopathy, with interventricular thickening causing left ventricular outflow tract obstruction, may occur in an infant born to a mother with poorly controlled diabetes. Spontaneous resolution is expected within a few weeks after birth as insulin levels normalize. References: Elevated neonatal insulin-like growth factor I is associated with fetal hypertrophic cardiomyopathy in diabetic women. (http://www.ncbi.nlm.nih.gov/pubmed/24813596)

A Newborn Boy Is Delivered by Cesarean Delivery at 39