A 24-year-old asymptomatic man requested a chest radiograph for routine tuberculosis screening. He did not have difficulty breathing, palpitations, chest pain, or edema. His medical history was significant for scoliosis and Rubinstein-Taybi syndrome, a rare genetic condition that causes short stature, broad thumbs and toes, hirsutism, and often intellectual disabilities.
On examination, his lungs were clear to auscultation. He had a regular heart rate and rhythm with no murmurs. There was no jugular venous distension. The heart sounds were shifted to the right, and the apical impulse was located to the right of the sternum. There were normal pulses in all four extremities. Chest radiography was performed (see accompanying figure).
The answer is A: dextrocardia. Dextrocardia is the most common congenital positional abnormality of the heart, occurring in about one out of 12,000 persons.1,2 Dextrocardia refers to the rightward pointing of the cardiac apex.3,4 The malpositioning of the heart occurs during fetal development. Rubinstein-Taybi syndrome is associated with cardiac abnormalities in 32% of patients.5
Dextrocardia cannot be diagnosed from a single chest radiograph. Further evaluation of cardiac position and anatomy with computed tomography and echocardiography is necessary to confirm the diagnosis. In this patient, cardiac auscultation and palpation raised initial suspicion about cardiac placement. In this case, further evaluation with echocardiography demonstrated dextrocardia. This finding is incidental and not of clinical concern, unless it is associated with other anatomic abnormalities that may compromise functional capability.
Right heart failure causing enlargement of the right heart may present with the cardiac silhouette in the right thorax. The most common cause of right heart failure is left heart failure.6
Situs inversus totalis is a mirror-image arrangement of normal organs. It is caused by an abnormal rotation of the organs during fetal development and is associated with dextrocardia.7 The gastric bubble will appear on the right side.
|Cardiac apex points to the right hemithorax; associated with severe cardiac malformations
|Shifting of the heart into the right hemithorax
|Right heart failure
|Enlargement of the right heart; most commonly caused by left heart failure
|Situs inversus totalis
|Mirror-image arrangement of normal organs; gastric bubble will appear on the right side