Congenital heart defects: Clinical

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Congenital heart defects: Clinical

USMLE® Step 2 questions

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USMLE® Step 2 style questions USMLE

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A 5-day-old female neonate is evaluated in the nursery for a heart murmur. She was born at 36-weeks gestational age to a 27-year-old, gravida 2 para 2, mother via an uncomplicated vaginal delivery. Family history is notable for atrial fibrillation in her father. Vitals are within normal limits. Cardiac examination reveals a holosystolic machine-like murmur best heard in the left infraclavicular region. Pulmonary and abdominal examinations are noncontributory. An echocardiogram is performed which confirms the patient’s diagnosis. Which of the following is the next best step in the management of this patient? 


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Congenital heart defects are usually divided into two categories based on the presence or absence of cyanosis, as well as by how it sounds on cardiac auscultation.

Acyanotic defects cause left to right shunting, and include four conditions: ventricular septal defect or VSD, atrial septal defect or ASD, patent ductus arteriosus or PDA, and coarctation.

Cyanotic defects present right to left shunting, and include five conditions: tetralogy, transposition, truncus arteriosus, total anomalous pulmonary venous return, and hypoplastic left heart syndrome.

Usually the diagnosis is then confirmed by echocardiography.

An ECG should be performed as part of the initial work-up.

Chest x-ray is important when there’s suspicion of heart failure, and, sometimes a CT or MRI are done if the diagnosis is inconclusive.

Rarely, cardiac catheterisation with angiography is used if the diagnosis remains uncertain after non-invasive studies.

Regarding infective endocarditis prophylaxis, it is recommended for high risk individuals: those with a cyanotic congenital heart disease that has not been fully repaired; a congenital heart defect that's been completely repaired with prosthetic material or a device for the first six months after the repair procedure; repaired anomalies with residual defects, such as persisting leaks or abnormal flow.

Most heart defects can also be detected prenatally by standard obstetric ultrasound examination. However, small ventricular septal defects or atrial septal defects, minor valve lesions, partial anomalous pulmonary venous connection, and coronary artery anomalies are often not detected prenatally.

The optimal gestational age for screening for structural fetal cardiac anomalies is 18 to 22 weeks of gestation, although in some cases it can be done as early as 10 weeks of gestation.

In the first two days of life, a pulse oximetry saturation less than 90% in the right hand or either foot requires urgent echocardiography.

If the saturation is 90% to 95% in either location or if there’s a saturation difference greater than 3% between the right hand and either foot, the test should be repeated hourly, and it’s positive three times, then echocardiography should be done.


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