Normal pulmonary vascular resistance and left ventricular hypertrophy in young infants with bronchopulmonary dysplasia: an echocardiographic and pathologic study.

To evaluate the cardiac anatomy and functional hemodynamics in young infants with chronic lung disease, nine patients, aged 2 to 7 months, with a clinical diagnosis of bronchopulmonary dysplasia (BPD) underwent echocardiographic examination. All infants required supplemental O2 (mean FIO2 35%) to maintain adequate systemic oxygenation (Pao2 greater than 50 mm Hg). None of the infants had evidence of a patent ductus arteriosus at the time of examination. Echocardiographic measurements of left and right ventricular systolic time intervals revealed normal systolic time interval ratios suggesting pulmonary vascular resistances. However, echocardiographic evidence of left ventricular hypertrophy was found in eight of the nine infants, while right ventricular anterior wall thickness and right ventricular diastolic dimensions were not increased. Two infants died; marked left ventricular hypertrophy was noted at the time of postmortem examination while the right ventricular wall thickness was normal. The findings of left ventricular hypertrophy led to a retrospective review of autopsy material of seven patients who died with BPD over the past year. In six of seven cases examined, left ventricular posterior wall thickening was noted (range 7 to 11 mm); while the right ventricular wall thickness was normal (range 2 to 5 mm). These data suggest that (1) as assessed by echocardiography, the pulmonary vascular resistance is not significantly elevated in young infants with BPD, and (2) a hypertrophic left ventricle evolves which may assume importance in the pathogenesis of pulmonary edema in BPD, though the precise etiology remains undetermined.