Pulmonary arterial changes in patients with ventricular septal defects and severe pulmonary hypertension
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Pulmonary hypertension in patients with ventricular septal defects (VSD) shows structural changes primarily in small arteries. Post-surgery, lung biopsy findings like Heath-Edwards grade predict pressure changes better than catheterization data.
Area of Science:
- Cardiology
- Pulmonary Medicine
- Pediatric Surgery
Background:
- Ventricular septal defect (VSD) can lead to severe pulmonary artery hypertension (PAH).
- Understanding the structural basis of PAH in VSD is crucial for surgical outcomes.
- PAH is defined by elevated pulmonary artery systolic pressure and pulmonary vascular resistance.
Purpose of the Study:
- To correlate morphologic and morphometric data from open-lung biopsy with hemodynamic measurements in patients with VSD and severe PAH.
- To identify predictors of postoperative pulmonary artery pressure changes after VSD closure.
Main Methods:
- Open-lung biopsy for structural and morphometric analysis.
- Cardiac catheterization for hemodynamic measurements (pulmonary artery pressure, pulmonary vascular resistance, flow ratios).
- Correlation analysis between structural and hemodynamic data; analysis of postoperative pressure changes after VSD closure.
Main Results:
- Pulmonary-to-systemic flow and resistance ratios correlated significantly with structural findings.
- Pulmonary artery pressure and resistance did not correlate with specific structural features.
- Increased external diameter of respiratory bronchiolar arteries indicates distal arterial bed changes.
- Heath-Edwards grade and arterial density predicted postoperative pulmonary artery pressure changes after VSD closure.
Conclusions:
- Structural changes in pulmonary hypertension associated with VSD are most significant in the distal small arteries.
- Lung biopsy findings, particularly Heath-Edwards grade and arterial density, are better predictors of postoperative hemodynamic improvement than pre-operative catheterization data in VSD patients.
Abstract:
In 25 patients, aged eight months to 31 years, with ventricular septal defect (VSD; isolated in 15, the others with atrial septal defect, PDA, coarctation or patent ductus arteriosus + coarctation), each with severe pulmonary artery hypertension (pulmonary artery systolic pressure [Ppa] at least 75% of systemic and an elevated pulmonary vascular resistance), we related morphologic and morphometric data from open-lung biopsy to hemodynamic measurements obtained at cardiac catheterization during the same hospital admission. Of the hemodynamic features measured, only the ratios of pulmonary-to-systemic flow and pulmonary-to-systemic resistance correlated significantly with structure. Neither pulmonary artery pressure (Ppa) nor pulmonary vascular resistance correlated significantly with any structural feature studied. The increased external diameter of respiratory bronchiolar arteries in those with the more advanced Heath-Edwards grades reflects dilatation and suggests that it is in the small arteries of the distal arterial bed that the changes of pulmonary hypertension are most significant. Neither age nor body weight correlated significantly with the degree of structural or hemodynamic abnormality. In the ten patients who underwent VSD closure, Ppa was measured postoperatively. The Heath-Edwards grade (no more than one grade-III lesion) and arterial density (at least one-half that normal for age) were the best correlates of the difference between preoperative Ppa and Ppa immediately after corrective surgery. The presurgical catheterization data, including pulmonary resistance and the resistance ratio, did not correlate significantly with change in Ppa following VSD closure.(ABSTRACT TRUNCATED AT 250 WORDS)