Table 2. RHC with fluid challenge.

RA pressure tracing	Kussmaul’s sign: abnormal rise in RA pressure during inspiration, reflective of an inability of the RV to handle increased blood volume, which can be due to a non-compliant RV, a non-compliant pericardium (that is, constrictive pericarditis) or significant (typically severe) tricuspid regurgitation.
	On the RV pressure tracing, a dip-and-plateau sign is indicative of either a non-compliant RV or constrictive pericarditis.
	As is the case with the RA pressure tracing, a tall A wave at end-diastole in the RV pressure tracing is a sign of a non-compliant RV.
PA pressure waveform	A wide PA pulse pressure (PA systolic pressure–PA diastolic pressure) is a sign of increased PA stiffness.
	PH is defined as a mean PA pressure ⩾25 mmHg, while PAH is defined as a mean PA pressure ⩾25 mmHg and pulmonary arterial wedge pressure (PAWP) <15 mmHg (along with elevated pulmonary vascular resistance [PVR] >3.0 Wood units). In patients with pulmonary venous hypertension (i.e., PH with PAWP ⩾15 mmHg), an elevated diastolic pulmonary gradient (PA diastolic pressure – PCWP) >7 mmHg is a sign of combined post-capillary and pre-capillary.
Fluid challenge during RHC	If RA pressure is ⩽12 mmHg and PAWP ⩽20 mmHg at rest, we recommend intravenous fluid challenge with 10 cc/kg warmed normal saline, infused over a 10-min period. The RA, PA and PAWP pressure should be measured, along with the cardiac output, immediately after the fluid challenge. Signs that demonstrate inability of the SSc patient to handle a volume load include:
	(1) RA pressure post >PCWP post or ΔRA pressure >ΔPCWP, which are signs of RV dysfunction.
	(2) Increased mean PA pressure post >35 mmHg, increased PVR post >3 Wood units or increased DPG post >7 mmHg, which are indicative of stiff pulmonary vasculature.
	(3) Increased PAWP post >25 mmHg, which is indicative of LV diastolic dysfunction.
	(4) Unchanged or decreased cardiac output post, which is indicative of RV or LV dysfunction.
	(5) Exaggerated dip-and-plateau pattern in the RV pressure tracing, which is a sign of restrictive or constrictive physiology.

Abbreviations: DPG=diastolic pulmonary vascular pressure gradient; LV=left ventricle; PA=pulmonary artery; PAWP=pulmonary arterial wedge pressure; PCWP=pulmonary capillary wedge pressure; PVR=pulmonary vascular resistance; RA=right atrial; RHC=right heart catheterization; RV=right ventricle; SSc=systemic sclerosis.