**Core Concept**
Inotrope agents are used to increase the contractility of the heart muscle, improving cardiac output in conditions like right heart failure. In the context of pulmonary hypertension, the inotrope agent of choice should be one that does not exacerbate pulmonary vascular resistance, which can worsen the condition.

**Why the Correct Answer is Right**
Milrinone is a phosphodiesterase-3 inhibitor that increases cardiac contractility without significantly increasing afterload or causing vasoconstriction, making it an ideal choice for right heart failure secondary to pulmonary hypertension. It works by increasing cyclic AMP levels within cardiac myocytes, leading to enhanced contractility without significant increases in oxygen demand. This property is particularly beneficial in patients with pulmonary hypertension, as it does not exacerbate the condition.

**Why Each Wrong Option is Incorrect**
**Option A:** Dobutamine, a beta-1 agonist, may increase cardiac contractility but can also increase heart rate and systolic blood pressure, potentially worsening pulmonary hypertension.
**Option B:** Levosimendan, a calcium sensitizer, may have some benefits in heart failure but is not the preferred agent for right heart failure secondary to pulmonary hypertension due to its potential to increase pulmonary vascular resistance.
**Option C:** Digoxin, a cardiac glycoside, increases cardiac contractility but also increases heart rate and can exacerbate pulmonary hypertension.

**Clinical Pearl / High-Yield Fact**
In patients with pulmonary hypertension, inotrope agents that do not increase pulmonary vascular resistance should be used, and Milrinone is a good option due to its unique mechanism of action.

**Correct Answer:** C. Milrinone