Original article
Inhaled Nitroglycerin Versus Inhaled Milrinone in Children with Congenital Heart Disease Suffering from Pulmonary Artery Hypertension

https://doi.org/10.1053/j.jvca.2009.10.024Get rights and content

Objective

The aim of the present study was to compare the acute effects of inhaled milrinone and inhaled nitroglycerin on pulmonary and systemic hemodynamics in children with acyanotic congenital heart disease (left-to-right shunt) and pulmonary artery hypertension.

Setting

Catheterization laboratory of a tertiary care hospital.

Participants

Thirty-five children below the age of 12 years who were suffering from acyanotic congenital heart disease with left-to-right intracardiac shunt and pulmonary artery hypertension (mean PA pressure > 30 mmHg).

Intervention

Right-heart catheterization was done using an end-hole balloon wedge pressure catheter. Baseline pulmonary and systemic hemodynamic parameters were recorded for all patients while breathing room air. All patients then underwent pulmonary vasodilator testing with 100% oxygen. Following this, patients were randomized into two groups and received either inhaled milrinone (group M, n = 18) or inhaled nitroglycerin (group N, n = 17) in a 50% air-oxygen mixture. Oximetry data were used to calculate systemic and pulmonary cardiac output based on Fick's principle.

Results

Systolic, diastolic, and mean pulmonary artery pressures decreased significantly in both the groups after drug nebulization, while there were no significant changes in systemic pressures. The percentage decrease from baseline in systolic (5.2% v 8.6%, p = 0.43), diastolic (19.5% v 16.8%, p = 0.19) and mean (14.9% v14.5%, p = 0.29) pulmonary artery pressures were comparable in both groups. The pulmonary vascular resistance index (PVRI) decreased from 9.0 ± 3.9 to 2.9 ± 1.7 Wood Units (WU)/m2 in group M (p < 0.001) and from 8.6 ± 3.8 to 3.2 ± 3.3 WU/m2 in group N (p < 0.001). The fall in pulmonary artery pressures after drug nebulization in both groups was comparable to the fall seen with 100% oxygen.

Conclusion

Both milrinone and nitroglycerin when given via the inhaled route significantly decrease systolic, diastolic and mean pulmonary artery pressures as well as PVRI without significant effects on systemic hemodynamics. Both the drugs given via inhaled route therefore can offer a good therapeutic choice and can help decrease the high inspired oxygen concentrations needed to treat pulmonary artery hypertensive episodes in perioperative settings.

Section snippets

Materials and Methods

After approval from the institute's ethics committee and written informed consent from the parents, 40 children (age < 12 years) with acyanotic CHD (left-to-right intracardiac shunt) with moderate or severe PAH (defined by mean PAP > 30 mmHg) were enrolled in the study. Patients with associated mitral valve disease, severe pulmonary or tricuspid regurgitation, obstructive lesions, severe left ventricular dysfunction, and those already receiving vasodilator treatments were excluded from the

Results

The demographics and the clinical diagnosis of the patients receiving milrinone (group M, n = 18) and nitroglycerin (group N, n = 17) were similar (Table 1). Hemodynamic variables in group M and group N are shown in Table 2, Table 3, respectively. After drug nebulization or treatment with oxygen, both groups did not reveal any significant changes in heart rate, systolic, diastolic and mean systemic arterial pressures, RAPs and PCWP while compared with their baseline values. However, the

Discussion

The results of this study demonstrated that in patients with congenital heart disease and pulmonary artery hypertension, both inhaled milrinone and inhaled nitroglycerin led to significant decreases in systolic, diastolic, and mean pulmonary artery pressures. The drugs also cause a decrease in PVRI and SVRI, but the effect on SVRI is small compared with the effect on PVRI, highlighting a more selective effect on pulmonary vasculature when given through the inhaled route. These acute changes

Conclusion

Both milrinone and nitroglycerin given via the inhaled route significantly decrease systolic, diastolic and mean PAPs as well as PVRI without significant effects on systemic hemodynamics. Both drugs given via the inhaled route offer a good therapeutic choice to address pulmonary artery hypertensive episodes in perioperative settings. Additional studies are needed to define the optimal dosing range for both drugs via the inhalation route to treat children with severe pulmonary artery

Acknowledgment

The authors thank M. Kalaivani, PhD, scientist, for her assistance in the statistical analysis of the data.

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