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Abstract
This study was designed to examine whether the occurrence of left ventricular hypertrophy
(LVH) in moderate to severe essential hypertension (EHT) was associated with alteration
in peripheral sympathetic drive.
In hypertension, LVH is an independent predictor of increased morbidity and mortality.
The reported mechanisms leading to LVH remain unclear but include hemodynamic and
humoral factors. The sympathetic nervous system may be important, particularly as
catecholamines have been shown to have trophic properties. We tested the hypothesis
that sympathetic activity measured using microneurography could be different in patients
with hypertension depending on the presence of LVH.
We examined 28 subjects with moderate to severe EHT (stages 2 to 3; Joint National
Committee [JNC]-VI classification). Fourteen had echocardiographic evidence of LVH
(EHT + LVH), while the other 14 subjects (EHT) did not. Subjects were matched in terms
of age, body mass index and levels of arterial blood pressure. Peripheral muscle sympathetic
nerve activity was measured from both multiunit bursts (MSNA) and single unit (s-MSNA)
vasoconstrictor impulses via the peroneal nerve.
The mean frequency of s-MSNA and MSNA was greater in the EHT + LVH group than it was
in the EHT group (mean +/- SEM; 75.9 +/- 6.9 impulses/100 beats vs. 52.1 +/- 2.9 impulses/100
beats, p < 0.001 and 64.2 +/- 5.7 bursts/100 beats vs. 48.9 +/- 2.8 bursts/100 beats,
p < 0.05).
These results indicate that, in subjects with moderate to severe hypertension, the
presence of LVH is associated with higher sympathetic discharge, evidenced by an increase
in unitary firing frequency and also by fiber recruitment.