Increased sympathetic nerve activity in renovascular hypertension

Area of Science:

• Cardiovascular Physiology
• Hypertension Research
• Autonomic Nervous System

Background:

• Renovascular hypertension is a complex condition.
• The role of sympathetic nerve activity in its progression is not fully understood.
• Previous studies yielded inconclusive results regarding sympathetic overactivity.

Purpose of the Study:

• To investigate whether patients with renovascular hypertension display increased total and regional sympathetic nerve activity.
• To quantify sympathetic nerve activity in renovascular hypertensives compared to healthy controls.

Main Methods:

• Sixty-five patients with renovascular hypertension underwent renal angiography, plasma renin activity, and angiotensin II measurements.
• Sympathetic nerve activity was assessed using radiotracer dilution (norepinephrine spillover) and muscle sympathetic nerve activity (MSNA) recordings.
• Fifteen age-matched healthy subjects served as controls.

Main Results:

• Total body norepinephrine (NE) spillover, an index of sympathetic activity, was 100% higher in hypertensive patients versus controls (P<0.01).
• Muscle sympathetic nerve activity (MSNA) was 60% higher in hypertensive patients (P<0.01).
• Elevated NE spillover correlated with higher plasma renin activity and angiotensin II levels.

Conclusions:

• This study provides unequivocal evidence of elevated sympathetic nerve activity in renovascular hypertension.
• Adrenergic overactivity likely contributes to elevated blood pressure in these patients.
• This overactivity may also be a factor in the high cardiovascular mortality associated with renovascular hypertension.