**Core Concept:** Cyanotic heart disease in newborns refers to congenital heart defects that result in decreased oxygenation of blood. A systolic murmur on auscultation indicates increased blood flow through the heart due to a congenital heart defect. Echocardiography helps confirm the diagnosis.

**Why the Correct Answer is Right:** Vasodilators are medications that help improve blood flow and oxygen delivery by dilating blood vessels. In the context of cyanotic heart disease, nitroprusside (Option D) is an appropriate choice because it is a potent and long-lasting vasodilator that can help improve oxygenation by increasing cardiac output and decreasing afterload.

**Why Each Wrong Option is Incorrect:**

A. Nitroglycerin (Option A) is also a vasodilator but has a shorter half-life and does not provide adequate long-term therapy for cyanotic heart disease.

B. Oxygen supplementation (Option B) helps increase oxygen saturation but does not directly address the underlying structural heart defect.

C. Propranolol (Option C) is a beta-blocker used to reduce heart rate and blood pressure, which would be counterproductive in cyanotic heart disease.

**Clinical Pearl:** Cyanotic heart disease often requires timely intervention, such as surgical repair or catheter-based interventions. Vasodilators should be considered as temporary adjuvant therapy to improve oxygenation while awaiting definitive treatment.

**Correct Answer:** D. Nitroprusside (Sodium nitroprusside or Nitroprusside Infusion) is a fast-acting, long-acting, and potent vasodilator that can be used in cases where surgical correction is not feasible or immediate and to improve oxygenation in cyanotic heart disease.