Significant Correlation Between Arterial Velocity Pulse Index And Muscle Sympathetic Nerve Activity In Hypertensive Patients

Introduction: Augmented sympathetic nerve activity (SNA) in hypertension (HT) is regarded as a therapeutic target, but there is few non-invasive markers to evaluate SNA in clinical practice. It is reported to associate with SNA which increased arterial reflected wave plays the important role in disease progression in HT, and it is reported to associate with SNA. Recently, Arterial Velocity Pulse Index (AVI) are developed as an index of arterial reflected waves, however the relationship between AVI and SNA is still uncertain. Methods: Patients with essential HT and matched non-hypertensive control subjects were included in this study. HT was diagnosed as systolic blood pressure (SBP) ≧ 140 mmHg or diastolic blood pressure (DBP) ≧ 90 mmHg. Patients with secondary HT was excluded. AVI was measured from left upper arm by NAS-1000 (Nihon Koden, Japan). SNA was evaluated by direct recording of muscle sympathetic nerve activity (MSNA) from peroneal nerves. Results: 50 HT patients and 50 control subjects were included. Age, SBP and DBP were significantly increased in HT group compared to control (Age 63±14 vs 42±16 years, p<0.001; SBP 144±16 vs 115±9 mmHg, p<0.001; DBP 80±14 vs 67±9 mmHg, p<0.001). MSNA and AVI were significantly increased in HT group compared to control (MSNA 34±10 vs 25±8 bursts/min, p<0.05; AVI 28±9 vs 17±5, p<0.05). In univariate analysis, AVI was significantly correlated with MSNA, age, and SBP in HT group. However, no significant relationship was observed between AVI and MSNA in multivariate analysis. Therefore, HT group was divided into two groups according to their severity (group 1, SBP<160mmHg, N=30; group 2, SBP>160 mmHg, N=20). AVI in group 1 showed significantly correlation with MSNA (r=0.49, p<0.05), but no correlation was seen in group 2. Conclusions: AVI was significantly increased in patients with HT compared to control, and AVI is significantly associated with MSNA in HT patients with SBP<160mmHg. These results indicate that AVI is helpful to estimate augmented SNA in patients with mild or moderate hypertension. Further study is warranted to exam the relationship AVI and SNA in reality.