Ex Vivo Thrombolysis to Salvage Free Flaps Using Machine Perfusion: A Pilot Study in a Porcine Model

Area of Science:

• Regenerative Medicine
• Vascular Surgery
• Biomedical Engineering

Background:

• Mechanical evacuation of capillary thrombi in free flaps is challenging, often necessitating thrombolytic therapy.
• Machine perfusion systems offer potential for ex vivo free flap salvage via high-dose thrombolytic agents.
• Developing effective methods for free flap preservation and salvage is critical in reconstructive surgery.

Purpose of the Study:

• To investigate the feasibility of ex vivo thrombolysis in free flaps using an extracorporeal perfusion machine.
• To establish a reliable porcine model for stasis-induced thrombosis in free flaps.
• To assess the efficacy of different dosages of tissue plasminogen activator (t-PA) in restoring microcirculation.

Main Methods:

• A stasis-induced thrombosis model was created in 12 free rectus abdominis flaps from six pigs.
• Flaps were ex vivo perfused with University of Wisconsin solution and treated with either 1 mg or 3 mg of t-PA, or no thrombolytic agent (control).
• Microcirculation was evaluated using near-infrared fluorescence angiography to assess blood flow restoration.

Main Results:

• Successful induction of thrombus formation in pedicled abdominal flaps.
• Near-infrared fluorescence angiography revealed delayed or absent perfusion in the control group.
• Flaps treated with 1 mg or 3 mg of t-PA showed significantly increased fluorescence intensity, indicating improved microcirculatory inflow.

Conclusions:

• The study established a reliable and reproducible porcine model for stasis-induced thrombosis in free flaps.
• Adding t-PA to an extracorporeal perfusion system successfully increased indocyanine green fluorescence intensity in treated flaps.
• This approach indicates restoration of capillary pressure and microcirculatory inflow, offering a promising method for free flap salvage.