Cyanosis is a bluish discoloration of the skin, a sign that the underlying blood is not carrying enough oxygen. When this appears in one part of the body but not another, it is known as differential cyanosis. Reverse differential cyanosis is a less common pattern where the upper parts of the body appear blue, while the lower parts do not. This presentation points toward specific structural issues within a newborn’s heart and major blood vessels.
The Underlying Physiology
The blood flow pattern causing reverse differential cyanosis is rooted in a newborn’s circulatory system. Before birth, a fetus has a blood vessel called the ductus arteriosus, connecting the aorta and the pulmonary artery. This vessel is meant to close shortly after birth, but when it remains open, it is called a patent ductus arteriosus (PDA). A PDA is a required component for this condition to develop.
In some heart defects, severe pulmonary hypertension (extremely high pressure in the pulmonary artery) can cause a “right-to-left shunt.” This forces deoxygenated blood from the pulmonary artery, through the PDA, and into the aorta. In the circumstances causing the “reverse” pattern, this deoxygenated blood is directed into the aorta before the arteries that supply the arms and head. This altered route delivers oxygen-poor blood to the upper limbs, while the lower body receives more oxygenated blood.
Visual Identification and Contrast
The most direct way to identify reverse differential cyanosis is through visual examination. The defining sign is a clear difference in skin color between the upper and lower body. An infant with this condition will exhibit a bluish tint in the fingers, hands, and upper chest. In contrast, the infant’s feet, toes, and legs will appear pink and well-perfused.
This presentation is the direct opposite of standard differential cyanosis, where a newborn has a pink upper body and blue lower extremities. The term “reverse” highlights this inverted pattern, which signals to clinicians a different set of underlying cardiac anomalies.
Observing this specific distribution of cyanosis is an important clinical clue. It points away from the causes of typical cyanosis and toward more complex structural heart problems. The clear demarcation between the blue upper body and pink lower body prompts a specific diagnostic path.
Associated Medical Conditions
Specific congenital heart defects are the root cause. The primary condition associated with reverse differential cyanosis is Transposition of the Great Arteries (TGA). In TGA, the aorta and the pulmonary artery are switched, with the aorta arising from the right ventricle and the pulmonary artery from the left.
For this pattern to manifest in an infant with TGA, a patent ductus arteriosus (PDA) and severe pulmonary hypertension must also be present. The switched arteries cause deoxygenated blood to be pumped to the body while oxygenated blood is cycled to the lungs. The PDA allows for necessary blood mixing, but when combined with high pulmonary pressure, it creates the flow pattern causing blueness in the upper limbs.
Other, rarer congenital heart issues can also result in this sign. One such condition is a type of total anomalous pulmonary venous connection (TAPVC), where veins from the lungs connect to the wrong place. In some cases of supracardiac TAPVC, blood flow dynamics can create the reverse cyanosis pattern, though TGA is the most frequent cause.
Diagnosis and Management
Diagnosis begins with pulse oximetry, a non-invasive test that measures blood oxygen saturation. To detect reverse differential cyanosis, readings are taken from an upper extremity (the right hand) and a lower extremity (a foot). A diagnosis is suggested if oxygen saturation is significantly lower in the hand than in the foot.
While pulse oximetry can identify the pattern, an echocardiogram is the definitive diagnostic tool. This heart ultrasound allows doctors to visualize its structure, assess blood flow, and confirm the presence of TGA or another underlying defect. This detailed imaging provides a complete picture of the cardiovascular anomaly.
Management focuses on stabilizing the infant before correcting the defect. The immediate goal is to keep the ductus arteriosus open using a medication called prostaglandin, as this may be the only path for some oxygenated blood to circulate. Once stable, the infant requires surgery, such as an arterial switch operation for TGA, to correct the anatomical problem.