The Assessment of Pulmonary Parenchymal Damage in Congenital Heart Disease using Lung Perfusion Scan

ABSTRACT

PURPOSE: In acyanotic congenital heart disease of children with left to right shunt, 99mTc- Macroaggregate albumin (MAA) was employed to determine the scintigraphic severity of pulmonary parenchymal damage. METHODS: These data of lung perfusion scan using 99mTc-MAA were compared with hemodynamic values obtained from cardiac catheterization. RESULTS: The mean Pulmonary arterial pressure (> or = 30mmHg), total pulmonary resistance (> or = 2 Wood unit) & ratio of pulmonary vascular resistance/systemic resistance (Rp/Rs > or = 0.2) were proportionally related to higher perfusion ratio of upper and lower lung field. The diagnostic values of perfusion ratio of upper & lower field of both lung (cut off value > or = 0.8) for pulmonary hypertension were as follows 60-65% of sensitivity, 75-90% of specificity, 72-86% of positive predictive value & 68-69% of negative predictive value. The mottled perfusion defect was frequently found in patients with pulmonary hypertension (mean pulmonary arterial pressure > or = 30mmHg, Rp > or = 2 Wood unit). The degree of perfusion defect as indicator of severe pulmonary parenchymal damage was utilized clinically as determinator of operability and morbidity for acyanotic shunt lesions perioperatively. CONCLUSION: The scintigraphic severity determined by 99mTc-MAA lung perfusion scan could be valid for evaluating the extent of pulmonary parenchymal damage in acyanotic congenital heart disease complicated by pulmonary hypertension.