05 February 2018 by Shine Kumar

Comparison of Intravenous Sildenafil with Inhaled Nitric Oxide in Acute Vasodilator Testing in Patients with Pulmonary Arterial Hypertension


Acute vasodilator testing (AVT) identifies responders in idiopathic pulmonary arterial hypertension (IPAH) and operable shunt lesions. We sought to determine feasibility of intravenous (iv) sildenafil as an alternate agent for inhaled nitric oxide (iNO) in AVT.


Comparison of iv sildenafil with iNO in acute vasodilator testing in patients with PAH

Materials and methods

Patients with PAH undergoing cardiac catheterisation for AVT (June 2015 to October 2017) were prospectively enrolled. Hemodynamic data was obtained at baseline, with iNO 20 parts per million (ppm) and iv sildenafil (0.25 mg/kg for children and 10 mg for adults).


We studied 22 patients (14 females (63.6%), 8 children (36.3%)) with median age 20.5 years (range 2 - 55) and mean body surface area 1.2 ± 0.4 m2. Indications were operability assessment (41%), IPAH (36%) and residual PAH (23%). IV sildenafil compared to iNO from baseline produced more fall in pulmonary artery (PA) pressures (systolic 15.05 ± 16.49 vs 6.18 ± 10.1 mmHg, p <0.01, diastolic 7.64 ± 8.69 vs 2.95 ± 5.9, p <0.01, mean 10.82 ± 10.1 vs 5.36 ± 4.74 mmHg, p <0.01), pulmonary vascular resistance index (pvri) (3.77 ± 3.75 vs 1.03 ± 2.71 Wood units.m2, p <0.01) and ratio to systemic vascular resistance index (pvri: svri) (0.09 ± 0.18 vs 0.01 ± 0.16, p <0.01). Measured variables showed good agreement (intra class correlation) for PA pressures (systolic [0.79], diastolic [0.81], and mean [0.85], p <0.01]), pvri (0.91, p <0.01), pvri: svri ratio (0.86, p < 0.01) and ratios (systolic PA: systolic aortic pressures 0.91, mean PA: mean aortic pressure 0.90, p <0.01).Two patients with positive AVT on iNO met the criteria with iv sildenafil.


The hemodynamic changes caused by iv sildenafil is comparable to iNO, which may be a promising alternative for AVT.

Key Contributors

1Shine Kumar, 2Amitab Sen, 1Abish Sudhakar, 1Krishna Kumar 1 Dept. of Pediatric Cardiology, 2Dept. of Pediatric Cardiac Anesthesia, Pulmonary Hypertension Clinic, AIMS, Amrita University, Kochi, Kerala, India

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