Table 1.

Cardiac function and shunt changes in persistent pulmonary hypertension of the newborn (see figure 1)

Parameter	Normal	Mild-to-moderate PPHN	Severe PPHN
RV afterload	Normal	↑	↑↑↑
RV contractility	Normal	↑↑ with RV hypertrophy	↓↓ (uncoupling) with RV dilation
RV diastolic function	Normal	Normal / ↓	↓↓*
Septal position	Bulging to the right	Midline	Bulging to the left
PFO shunt	Left-to-right	Bidirectional or right-to-left	Right-to-left (or left-to-right with LV dysfunction)**
PDA shunt (if open)	Left-to-right	Bidirectional or right-to-left	Right-to-left (or closing ductus)
LV preload	Normal	Normal / ↓	Normal / ↓
Systemic blood pressure	Normal	Normal / ↓	↓↓↓↓

^*In the presence of moderate to severe PPHN, RV diastolic function (lusitropy) is significantly reduced. In such states, it is important to avoid chronotropic agents (which will exacerbate diastolic dysfunction) and use agents which specifically target diastolic function (e.g. milrinone).

^**In some patients with severe PPHN, a bidirectional atrial shunt or a left-to-right shunt may be observed even in the absence of LV dysfunction.¹²