**Question:** Millard Gubler syndrome includes the following except -

A. Hypoplastic left heart syndrome
B. Hypoplastic right heart syndrome
C. Tetralogy of Fallot
D. Ductus arteriosus

**Core Concept:** Millard Gubler syndrome is a rare congenital heart defect characterized by the combination of hypoplastic left heart syndrome (HLHS), pulmonary atresia, and ventricular septal defect with intact atrioventricular septum. HLHS is a severe form of hypoplastic left heart syndrome, where the left ventricle and its major branches are underdeveloped.

**Why the Correct Answer is Right:** Ductus arteriosus is a temporary coronary artery that connects the aorta to the pulmonary artery, allowing blood flow from the systemic circulation to bypass the pulmonary circulation in the fetus. After birth, the ductus arteriosus undergoes involution, closing off the connection between the aorta and pulmonary artery. In Millard Gubler syndrome, the ductus arteriosus remains patent, allowing sufficient oxygenated blood flow to the body. Therefore, it is not part of the syndrome.

**Why Each Wrong Option is Incorrect:**

A. Hypoplastic left heart syndrome (HLHS) is a crucial component of Millard Gubler syndrome, and thus, it is incorrect.

B. Hypoplastic right heart syndrome is a separate condition characterized by underdevelopment of the right ventricle and its major branches, which is not part of Millard Gubler syndrome.

C. Tetralogy of Fallot is a combination of defects including tetralogy and pulmonary atresia, but not hypoplastic left heart syndrome. It is incorrect because Millard Gubler syndrome comprises hypoplastic left heart syndrome, pulmonary atresia, and ventricular septal defect with intact atrioventricular septum.

**Clinical Pearl:**

Understanding the specific combination of congenital heart defects in Millard Gubler syndrome is essential for accurate diagnosis and management. The presence of ductus arteriosus patency allows for a unique set of symptoms and signs, which can guide clinicians in reaching the correct diagnosis and planning appropriate interventions.