Effect of Inhaled Iloprost during Off-Medication Time in Patients with Pulmonary Arterial Hypertension

Comparison of acute hemodynamic effects of aerosolized iloprost and inhaled nitric oxide in adult congenital heart disease with severe pulmonary arterial hypertension

OBJECTIVE

To compare the acute hemodynamic effects of aerosolized iloprost and inhaled nitric oxide (NO) in adult congenital heart disease (CHD) patients with severe pulmonary arterial hypertension (PAH).

METHODS

One hundred and eighty five adult CHDs with severe PAH were nonrandomized into two groups (iloprost, n=127; NO, n=58). Various hemodynamic parameters were measured before and after iloprost or NO inhalation.

RESULTS

Iloprost and NO inhalation resulted in significant reductions in pulmonary arterial pressure (from 110.6±21.8 mmHg to 105.5±22.3 mmHg, p<0.05; from 113.1±18.7 mmHg to 107.2±19.9 mmHg, p<0.05, respectively) and pulmonary vascular resistance (PVR) (from 13.4±8.3 Wood units to 9.6±6.4 Wood units, p<0.01; from 13.7±7.1 Wood units to 9.3±4.9 Wood units, p<0.01, respectively) and increases in pulmonary blood flow (from 6.7±3.3 L/min to 9.4±5.8 L/min, p<0.05; from 6.6±3.1 L/min to 9.6±5.9 L/min, p<0.01, respectively) and the Qp/Qs ratio (from 1.5±0.8 to 2.1±1.4, p<0.01; from 1.5±0.8 to 2.0±1.3, p<0.01, respectively). When the effects of inhaled iloprost and NO were compared, similar reductions in pulmonary arterial pressure and pulmonary vascular resistance were observed. Aerosolized iloprost and inhaled nitric oxide (iNO) were generally well tolerated and no patient experienced any side effects during inhalation.

CONCLUSION

Aerosolized iloprost can be effectively and safely used and might be an alternative to NO for testing pulmonary vascular reactivity and treating severe PAH in adult CHD patients.

Inhaled iloprost for the control of pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by an elevated pulmonary arterial pressure and vascular resistance with a poor prognosis. Various pulmonary and extrapulmonary causes are now recognized to exist separately from the idiopathic form of pulmonary hypertension. An imbalance in the presence of vasoconstrictors and vasodilators plays an important role in the pathophysiology of the disease, one example being the lack of prostacyclin. Prostacyclin and its analogues are potent vasodilators with antithrombotic, antiproliferative and anti-inflammatory qualities, all of which are important factors in the pathogenesis of precapillary pulmonary hypertension. Iloprost is a stable prostacyclin analogue available for intravenous and aerosolized application. Due to the severe side effects of intravenous administration, the use of inhaled iloprost has become a mainstay in PAH therapy. However, owing to the necessity for 6 to 9 inhalations a day, oral treatment is often preferred as a first-line therapy. Numerous studies proving the efficacy and safety of inhaled iloprost have been performed. It is therefore available for a first-line therapy for PAH. The combination with endothelin-receptor antagonists or sildenafil has shown encouraging effects. Further studies with larger patient populations will have to demonstrate the use of combination therapy for long-term treatment of pulmonary hypertension.