Converging methods in the assessment of sympathetic baroreflex sensitivity

Area of Science:

• Cardiovascular Physiology
• Autonomic Nervous System Regulation
• Medical Technology

Background:

• Sympathetic baroreflex regulation abnormalities are linked to various diseases.
• Direct sympathetic nerve activity recording for baroreflex gain calculation is invasive and impractical.
• Non-invasive methods are needed to assess sympathetic gain.

Purpose of the Study:

• To evaluate non-invasive methods for calculating sympathetic gain.
• To compare sympathetic gain derived from Valsalva manoeuvre (VM) and non-sustained ventricular tachycardia (NSVT).
• To assess the correlation of these gains with mean arterial pressure turbulence slope (MAP(TS)).

Main Methods:

• Assessed sympathetic gain in 25 subjects using VM and paced NSVT.
• Calculated sympathetic gain from mean arterial pressure (MAP) recovery after VM and NSVT.
• Determined MAP turbulence slope (MAP(TS)) following NSVT.

Main Results:

• VM-derived sympathetic gain (SBRS(vals)) and NSVT-derived gain (SBRS(NSVT)) showed a close correlation (R = 0.86, P < 0.001).
• Both SBRS(vals) and SBRS(NSVT) correlated strongly with MAP(TS) (R = 0.77 and R = 0.86, respectively, P < 0.001).
• Five patients were excluded due to unacceptable VM.

Conclusions:

• Arterial pressure recovery following VM and NSVT reflects similar sympathetic processes.
• NSVT-derived sympathetic gain (SBRS(NSVT)) or MAP(TS) show potential for assessing patients with antiarrhythmic devices.