BACKGROUND: Acute @entity1062 ( @entity1062 ) is considered mandatory in the diagnostic work-up of @entity1 with @entity120 ( @entity120 ). We studied the relation between the acute absolute arterial vasodilatation and the severity of vascular remodeling estimated by intravascular ultrasound (IVUS) in @entity1 with idiopathic @entity120 . METHODS: Simultaneous right heart catheterization and IVUS of the pulmonary artery (PA) were performed both in basal conditions and during short-term intravenous @entity4770 infusion in nineteen idiopathic @entity120 @entity1 . Pulmonary vascular resistance (PVRi) and capacitance indexes ( @entity64 volume/pulse pressure, Cp), were calculated. Local pulsatility was estimated by IVUS (IVUSp) (systolic-diastolic lumen area/diastolic lumen area 100; sA-dA/dA) and PA stiffness was assessed by the elastic modulus (E: pulse pressure/IVUSp). RESULTS: @entity4770 infusion (11  2ng/kg/min) determined a real vasodilatation (increment of dA>10%) in six @entity1 . This vasodilation group presented on average significantly higher cardiac index, @entity64 volume index and Cp, and lower PVRi and IVUSp (P<0.05), with a lower E (P=0.08). Three @entity1 were responders according to the actual criteria, but only one showed a real vasodilator response. Baseline E below the median value ( <=190mm Hg) was able to differentiate @entity1 with an acute vasodilator response (sensibility 83%, specificity 73%, area under ROC 0.81; P<0.05). Neither E nor vasodilator response is correlated with delta mean PA pressure and PVRi. CONCLUSIONS: @entity1 with higher IVUSp and lesser E displayed an absolute PA vasodilation during @entity1062 with @entity4770 . The @entity1 with a positive @entity1062 according to actual criteria do not necessarily have a real vasodilatation on intravascular ultrasound.

Acute absolute vasodilatation is associated with a lower vascular wall stiffness in XXXX .

@entity1 :: ('9606', 'Species') :: ['Patients', 'patients'] @entity64 :: ('MESH:D020521', 'Disease') :: ['stroke'] @entity120 :: ('MESH:D006976', 'Disease') :: ['PAH', 'pulmonary arterial hypertension'] @entity4770 :: ('MESH:D011464', 'Chemical') :: ['epoprostenol', 'Epoprostenol'] @entity1062 :: ('MESH:D013736', 'Disease') :: ['VT', 'vasoreactivity testing']
@entity120 :: (MESH:D006976,Disease) :: ['pulmonary arterial hypertension']
