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Relation between plasma nitrate and mean pulmonary arterial pressure in ventricular septal defect
J Takaya1, M Teraguchi, S Nogi
1Department of Paediatrics, Kansai Medical University, Osaka, Japan.
Background:
Nitric oxide (NO) is known to modulate myocardial contraction and coronary tone, and its inhalation reduces pulmonary vascular resistance in patients with pulmonary hypertension.
Objectives:
To evaluate the pathophysiological role of NO in patients with a ventricular septal defect (VSD).
Patients:
Twenty-nine children with VSD, nine of whom had undergone VSD closure surgery, and 14 patients with Kawasaki disease. The mean age of the VSD patients was 3.1 years (range, 2 months to 9 years).
Methods:
Using high performance liquid chromatography, nitrate (a more stable NO oxidation product) was measured in plasma specimens of the patients undergoing cardiac catheterisation.
Results:
Nitrate concentrations in the pulmonary artery bore a significant relation to mean pulmonary artery pressure, pulmonary to systemic systolic pressure ratio, and pulmonary to systemic flow ratio.
Conclusions:
The concentration of nitrate was in proportion to the increment in intravascular or cardiac pressure, indicating that endogenous NO is upregulated as a compensatory homeostatic attempt to reduce pulmonary pressure and blood flow.