The neural crest origin of the aortopulmonary septum has led us to investigate the septum for a special function, and we designed the present study to assess the alteration, if any, in the dimensions of the aortopulmonary septum in hypertension. The dimensions of the aortopulmonary septum were measured by echocardiography in 36 hypertensive and 36 age- and sex-matched normotensive subjects. Echocardiographic examination included measurement of the cross-sectional area of the aortopulmonary septum with standard two-dimensional views from the parasternal windows. Standardization of this dimension with appropriate cardiac measurements such as aortic and internal left ventricular diameters was also performed to provide growth-independent estimates of septal size. The average area of the septum in the hypertensive group was 2.18+/-30.391 cm(2), significantly lower than that in the normotensive group (2.370+/-0.415 cm(2)). There were also significant differences in the area of the aortopulmonary septum between the groups when the values were standardized with internal left ventricular diameters. In conclusion, these data confirm that the aortopulmonary septum is smaller in hypertensive than in normotensive humans. This difference might be the result of a possible function of the aortopulmonary septum in blood pressure regulation.