Cardiac sympathetic nervous system in early essential hypertension assessed by 123I-MIBG

Sympathetic overactivity has been noted in Various clinical stages of essential hypertension. The purpose of this study is to investigate I-123-metaiodobenzylguanidine (MIBG) uptake and washout in patients with borderline and mild hypertension. Methods: To assess cardiac sympathetic function in essential hypertension, we performed I-123-MIBG cardiac imaging and echocardiography in 25 normotensive, 25 borderline hypertensive and 24 mildly hypertensive men. Age and body mass index were similar in the three groups. Results: Regarding the echocardiographic variables, the left ventricular mass index (LVMI) was significantly higher in the mildly hypertensive group (125.6 +/- 28.6 g/m(2)) than in the normotensive (99.9 +/- 20.7 g/m(2)) and the borderline hypertensive (110.0 +/- 24.4 g/m(2)) groups (P < 0.001 and P < 0.051 respectively). Regarding the scintigraphic variables, the heart-to-mediastinum (HIM) ratio was significantly tower in the mildly hypertensive group (1.8 +/- 0.3) than in the normotensive (2.1 +/- 0.3) and the borderline hypertensive (2.1 +/- 0.2) groups. in contrast, the washout rate was significantly higher in the mildly hypertensive group (17.6% +/- 10.8%) than in the normotensive (7.0% +/- 4.9%) and the borderline (11.9% +/- 8.9%) hypertensive groups (P < 0.001 and P < 0.02, respectively). In addition, the borderline hypertensive group had a significantly higher washout rate than the normotensive group (P < 0.05). MIBG washout rate had a strong positive correlation with LVMI (r = 0.77, P < 0.0001). In contrast, the H/M ratio had a weak negative correlation with LVMI (r = -0.40, P < 0.0006). Conclusion: During the course of establishment of essential hypertension, the washout Fate becomes higher with the advance of hypertension and with the development of left ventricular hypertrophy. Thus, we suggest a strong relationship between cardiac sympathetic activity and the advance of hypertension at its early stages.