Abnormalities of Cardiovascular Neural Control

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Research: Abnormalities of Cardiovascular Neural Control and Reduced

Orthostatic Tolerance in Patients with Primary Fibromyalgia

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09-21-2005 J Rheumatol. 2005 Sep;32(9):1787-1793.

Furlan R, Colombo S, Perego F, Atzeni F, A, Barbic F, Porta A,

Pace F, Malliani A, Sarzi-Puttini P.

From the Department of Internal Medicine II, Department of

Gastroenterology, and Department of Rheumatology, Ospedale L. Sacco,

Universita degli Studi di Milano, Milano; Department of Cardiology,

Ospedale Salvini, Rho; and Medicina del Lavoro, Ospedale Novara,

Novara, Italy.

OBJECTIVE: Fibromyalgia (FM) is a syndrome characterized by

widespread musculoskeletal pain. Symptoms of orthostatic intolerance

may also be present, suggesting underlying abnormalities of

cardiovascular neural regulation. We tested the hypothesis that FM

is characterized by sympathetic overactivity and alterations in

cardiovascular autonomic response to gravitational stimulus.

METHODS: Sixteen patients with primary FM and 16 healthy controls

underwent electrocardiography examination, finger blood pressure,

respiration, and muscle sympathetic nerve activity (MSNA) recordings

at rest and during stepwise tilt test, up to 75 degrees . The

autonomic profile was assessed by MSNA, plasma catecholamine, and

spectral indices of cardiac sympathetic (LFRR in normalized units,

NU) and vagal (HFRR both in absolute and NU) modulation and of

sympathetic vasomotor control (LFSAP) computed by spectrum analysis

of RR and systolic arterial pressure (SAP) variability. Arterial

baroreflex function was evaluated by the SAP/RR spontaneous-

sequences technique, the index a, and the gain of MSNA/diastolic

pressure relationship during stepwise tilt test.

RESULTS: At rest, patients showed higher values of heart rate, MSNA,

LFRR NU, LF/HF, LFSAP, and reduced HFRR than controls. During tilt

test, lack of increase of MSNA, less decrease of HFRR, and excessive

rate (44%) of syncope were found in patients, suggesting reduced

capability to enhance the sympathetic activity to vessels and

withdraw the vagal modulation to sino-atrial node. Baroreflex

function was similar in both groups.

CONCLUSION: Patients with FM have an overall enhancement of

cardiovascular sympathetic activity while recumbent. Lack of

increased sympathetic discharge to vessels and decreased cardiac

vagal activity characterize their autonomic profile during tilt

test, and might account for the excessive rate of syncope.