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Hypertensive left ventricular hypertrophy: relation to peripheral sympathetic drive
J P Greenwood1, E M Scott, J B Stoker
1Department of Cardiology, St. James's University Hospital, Leeds, United Kingdom. john_greenwood@hotmail.com
Insights
In essential hypertension (EHT), left ventricular hypertrophy (LVH) is linked to increased peripheral sympathetic nerve activity. This suggests higher sympathetic drive contributes to LVH development in hypertensive patients.
Area of Science:
- Cardiology
- Hypertension Research
- Autonomic Nervous System Studies
Background:
- Left ventricular hypertrophy (LVH) is a significant predictor of morbidity and mortality in hypertension.
- Mechanisms driving LVH are not fully understood but may involve hemodynamic, humoral, and sympathetic nervous system factors.
- The sympathetic nervous system's role in LVH is investigated due to catecholamines' trophic properties.
Purpose of the Study:
- To investigate the association between left ventricular hypertrophy (LVH) and peripheral sympathetic drive in moderate to severe essential hypertension (EHT).
- To test the hypothesis that sympathetic activity, measured by microneurography, differs in hypertensive patients with and without LVH.
Main Methods:
- Studied 28 patients with moderate to severe EHT (JNC-VI stages 2-3), divided into EHT with LVH (n=14) and EHT without LVH (n=14).
- Matched subjects for age, body mass index, and arterial blood pressure.
- Measured peripheral muscle sympathetic nerve activity (MSNA) using microneurography, assessing both multiunit bursts (MSNA) and single-unit vasoconstrictor impulses (s-MSNA) via the peroneal nerve.
Main Results:
- The EHT + LVH group exhibited significantly higher mean s-MSNA frequency (75.9 +/- 6.9 impulses/100 beats) compared to the EHT group (52.1 +/- 2.9 impulses/100 beats; p < 0.001).
- MSNA burst frequency was also greater in the EHT + LVH group (64.2 +/- 5.7 bursts/100 beats) than in the EHT group (48.9 +/- 2.8 bursts/100 beats; p < 0.05).
Conclusions:
- The presence of LVH in moderate to severe hypertension is associated with elevated sympathetic discharge.
- Increased unitary firing frequency and fiber recruitment of sympathetic nerves are evidenced in hypertensive patients with LVH.
Objectives:
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.
Background:
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.
Methods:
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.
Results:
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).
Conclusions:
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.