Sympathetic toggled paroxysmal atrial fibrillation and recurrent premature atrial contractions in ambulatory patients.

Background: Autonomic nerve activity is important in the mechanisms of paroxysmal atrial fibrillation (PAF).

Objective: The purpose of this study was to test the hypothesis that a single burst of skin sympathetic nerve activity (SKNA) can toggle on and off PAF or premature atrial contraction (PAC) clusters.

Methods: Simultaneous recording of SKNA and electrocardiogram (neuECG) recording was performed over 7 days in patients with PAF.

Sympathetic toggled sinus rate acceleration as a mechanism of sustained sinus tachycardia in chronic orthostatic intolerance syndrome.

Background: The role of sympathetic nerve activity to maintain sinus rate acceleration remains unclear.

Objective: The purpose of this study was to test the hypothesis that sustained (>30 seconds) sinus rate acceleration can be associated with either a sympathetic driven or a sympathetic toggled mechanism.

Methods: We used a patch monitor to record skin sympathetic nerve activity (SKNA) and electrocardiogram over 24 hours.

Skin sympathetic nerve activity in patients with chronic orthostatic intolerance.

Background: Chronic orthostatic intolerance (OI) is characterized by the development of tachycardia and other symptoms when assuming an upright body position.

Objective: The purpose of this study was to test the hypothesis that skin sympathetic nerve activity (SKNA) bursts are specific symptomatic biomarkers in patients with chronic OI.

Methods: We used an electrocardiogram monitor with a built-in triaxial accelerometer to simultaneously record SKNA and posture in ambulatory participants.