A new heat source for thermochemical ablation based on redox chemistry: Initial studies using permanganate

Purpose: To evaluate exothermic permanganate redox chemistry for utility in tumour ablation. Materials and methods: Sodium permanganate (13 mL, 1 or 2 M) and glycerol (1 mL, 1 M) were injected in triplicate into a beaker using three injection orders: (1) simultaneous, (2) glycerol injection then permanganate injection, (3) permanganate injection then glycerol injection. Selected experiments were repeated with glucose, sucrose, dextrin, maltodextrin, different polysaccharides, and polyvinyl alcohol as substrates. Simultaneous injections of permanganate (0.5 and 1 mL, 2 M) and glucose (1 mL, 1 M) into explanted porcine muscle were also performed. Temperatures were recorded with a thermocouple probe or an infrared camera. Results: With optimal conditions of 2 M permanganate and 1 M glycerol at 1 mL each, an average maximum temperature of 97.4°C was obtained for all three injection orders. When glucose and sucrose were used as the substrates, similar temperatures were achieved but at different rates. Dextrin and maltodextrin (180 g/L) led to maximum temperatures of 42.5° and 51.1°C respectively when simultaneously injected with permanganate (1 mL, 2 M). Polysaccharides and polyvinyl alcohols under the same conditions resulted in a minimal temperature increase. Intramuscular injections of glucose (0.5 mL, 1 M) and permanganate (0.5 mL, 2 M) reached an average temperature of 76.5°C at the lesion site. Conclusions: The permanganate redox reaction is a powerful system with potential to reach tumouricidal temperatures. The reagent volumes, concentrations, injection order, and substrate choice allow a measure of control over the reaction.