Approach to congenital heart diseases (acyanotic): Clinical sciences

Acyanotic congenital heart disease refers to structural heart lesions that do not cause significant blood oxygen desaturation or cyanosis. It's crucial to identify acyanotic congenital heart lesions promptly in order to treat any complications, like shock or heart failure.

If a pediatric patient presents with chief concern suggesting acyanotic congenital heart disease, first perform an ABCDE assessment. If the patient is unstable, stabilize the airway, breathing, and circulation. You may even need to intubate and mechanically ventilate your patient. Next, obtain IV access, and consider starting IV fluids.

Begin continuous vital sign monitoring, including blood pressure, heart rate, and oxygen saturation. Finally, if needed, provide supplemental oxygen. Once you’ve initiated acute management, perform a focused history and physical examination.

Then obtain pulse oximetry measurements in the right hand, which measures preductal saturation; and the feet, which measures post-ductal saturations. These measurements allow you to compare oxygenation of the systemic circulation before and after the ductus arteriosus inserts into the aorta.

Unstable infants often present around 2 weeks of age, as the ductus arteriosus begins to close, with symptoms like poor feeding, lethargy, and respiratory distress. Additionally, there may have been a prenatal ultrasound showing a heart defect.

Exam findings include signs of shock, like gray, cool, mottled skin. You might also find weak pulses in all 4 extremities, or the femoral pulses might be absent.

On auscultation, many patients will have an audible S3, and some will have a murmur. On pulse oximetry, preductal saturations may be higher than postductal saturations.

This suggests that deoxygenated blood is being shunted from the pulmonary artery to the aorta, through an open ductus arteriosus, and the lower extremities might appear cyanotic.

This is called differential cyanosis and suggests the presence of critical congenital heart disease.

These findings should immediately make you consider lesions associated with critical left ventricular outflow tract obstruction, such as critical aortic stenosis or critical coarctation of the aorta.

Start an infusion of prostaglandin E1, or PGE1, to keep the ductus arteriosus open and restore systemic circulation.

Here’s a high-yield fact! PGE1 provides a life-saving bridge to surgery in newborns with ductal-dependent lesions by promoting systemic and pulmonary mixing or by improving systemic or pulmonary circulation. Avoid giving PGE1 to infants with increased pulmonary blood flow, since it can exacerbate pulmonary overcirculation.

Now that you’ve started PGE1, order an echocardiogram or echo to evaluate the heart and great vessels.

If echo reveals severe aortic valve stenosis, with or without left ventricular hypertrophy, diagnose critical aortic stenosis.

On the other hand, echo may show a hypoplastic aortic arch, possibly with abnormal aortic valve morphology and post-stenotic dilatation.

In some cases, it may demonstrate complete discontinuity of the arch between the ascending and descending aorta, indicating an interrupted aortic arch, which is the most severe form of coarctation. In either case, diagnose critical coarctation of the aorta.

Here’s a clinical pearl! Critical left ventricular outflow obstruction is commonly mistaken for sepsis, since both conditions can present with shock and similar clinical manifestations. Remember to check femoral pulses, and consider left ventricular outflow obstruction whenever a newborn presents with shock.

Now that we’ve discussed unstable patients, let’s go back and discuss stable ones. Start by obtaining a focused history and physical exam, and pulse oximetry measurements in the right hand and feet.

History usually reveals abnormal prenatal ultrasound findings suggesting a congenital heart lesion. Depending on the lesion, many patients are asymptomatic, but others may experience poor weight gain, difficulty feeding, or fatigue.

As for the physical exam, your patient will not appear cyanotic, but you may detect a heart murmur and notice signs of heart failure, like tachypnea and hepatomegaly.

Finally, pulse oximetry will reveal oxygen saturations above 90% in the right hand and the feet. With these findings, consider acyanotic congenital heart disease. Next order an echo, and assess the pulmonary blood flow.

First let's discuss patients with normal or decreased pulmonary blood flow.

If it’s normal or decreased, consider obstructive lesions like non-critical coarctation of the aorta, aortic stenosis, and pulmonary stenosis.

Let’s start with non-critical coarctation of the aorta, which is frequently identified in childhood or adolescence. Symptoms are often absent, but some children experience epistaxis or leg pain with exercise.

Physical exam commonly reveals upper extremity hypertension, with a blood pressure gradient of more than 20 mm mercury between the upper and lower extremities.

Additionally, you’ll probably find diminished lower extremity pulses with a radial-femoral delay, and there might be a harsh systolic murmur at the left sternal border that radiates to the back.

Echo typically reveals juxtaductal coarctation of the aorta, often with left ventricular hypertrophy, which confirms non-critical coarctation of the aorta.

Next up is aortic stenosis. Patients with mild-to-moderate stenosis are usually asymptomatic, while those with severe stenosis can develop exertional chest pain, dyspnea, or fatigue.

Physical exam reveals a systolic murmur at the right upper sternal border that is softer with a Valsalva maneuver. There could also be a palpable thrill or a systolic ejection click.

Echo will demonstrate valvular, subvalvular, or supravalvular aortic stenosis and you may notice a bicuspid aortic valve as well as left ventricular hypertrophy. These findings confirm aortic stenosis.

Here’s another clinical pearl! Supravalvular aortic stenosis is commonly seen in association with Williams syndrome, so be sure to look for phenotypic features of this condition, including a full face, broad forehead, rounded cheeks, and a depressed nasal bridge with anteversion of the nares.

Finally, let’s discuss pulmonary stenosis. If the stenosis is mild or moderate, patients are usually asymptomatic, but if it’s severe, patients may report fatigue, exertional dyspnea, or even syncope.