Suprasternal M-mode echocardiography of the right pulmonary artery as a model for investigation of pulmonary hemodynamics in essential hypertension.

The right pulmonary artery (RPA) dimensions of 85 asymptomatic mild or moderate hypertension (HT) patients, divided into 6 subgroups according to the left ventricular (LV) mass index (125g/m2 BSA) left atrial (LA) dimension index (2.2cm/m2 BSA), and 40 normal subjects were studied utilizing suprasternal M-mode echocardiography in order to examine the consistency of the elevated PA pressure in essential HT and to understand its pathogenesis. The RPA dimension at late diastole, at the end of the right ventricular isovolumic contraction, and at systole in the subgroup of HT without LV hypertrophy and LA enlargement was significantly increased compared with those of the normal group (18.4 +/- 2.8 vs 16.2 +/- 2.3mm, 19.6 +/- 3.0 vs 17.2 +/- 1.3mm, 22.5 +/- 2.5 vs 20.8 +/- 1.9mm, p less than 0.05, respectively) and varied in close correlation with systolic and diastolic BP and the dimension of the aorta. The dimensions in the other 5 subgroups were the same and were not further affected by the LV mass and LA dimension. The above results suggest that elevated systemic BP per se is associated with the dilation of the RPA supposedly caused by increased PA resistance, besides the backward effect of the increased LV and/or LA pressure which may affect the increase of PA pressure.