Functional magnetic stimulation: a new modality for enhancing systemic fibrinolysis.

OBJECTIVE: To investigate whether functional magnetic stimulation (FMS) of the leg muscles could enhance systemic fibrinolysis. DESIGN: A within-subject analysis of systemic fibrinolysis before and after 60 minutes of FMS. SETTING: The Functional Magnetic Stimulation and Special Coagulation Laboratories in the Spinal Cord Injury Service at a Veterans Administration health care facility. PARTICIPANTS: Twenty healthy volunteers were recruited. The exclusion criteria were: (1) personal or family history of venous or arterial thrombosis, (2) personal or family history of cardiac arrythmias, (3) current use of medication, and (4) the presence of a cardiac pacemaker or other metallic implants. MAIN OUTCOME MEASURES: Whole blood clot lysis time (WBCLT) and tissue plasminogen activator (t-PA) antigen determined at baseline and 10 and 60 minutes after FMS. RESULTS: A significant decrease was observed in the mean WBCLT after FMS. The WBCLT decreased from 17+/-1.3 h before FMS to 12+/-1.0 h and 11+/-0.8 h at 10 and 60 minutes post-FMS, respectively. The mean t-PA antigen levels did not show a significant change (p = .6701) from pre-FMS (6.7+/-0.91 ng/mL) to 10 min post-FMS (6.8+/-0.91 ng/mL) and 60 min post-FMS (7.0+/-1.02 ng/mL). Several patterns of fibrinolytic response to FMS were observed. They differed in relation to the degree of enhancement, the period at which maximum enhancement occurred, and the corresponding t-PA antigen levels observed. CONCLUSIONS: The FMS-induced contractions of the leg muscles enhanced systemic fibrinolysis ex vivo. The improvement in fibrinolysis occurred immediately after FMS and was also observed at 60 minutes post-FMS. FMS appears to produce a sustained enhancement of systemic fibrinolysis that may prove useful in deep-vein thrombosis prophylaxis.