[A loud second heart sound]. / Een luide tweede harttoon.

When a loud second heart sound is heard in a child, the possibility of pulmonary hypertension must be borne in mind. The second heart sound is also loud in patients with congenitally corrected transposition (CGT) because of the anterior position of the aortic valve. Therefore, it is difficult to distinguish the relatively rare isolated CGT from cardiac disease with high pressure in the pulmonary artery. We discuss this diagnostic problem on the basis of a two year old boy with a loud second heart sound.