Thank you for presenting this complex case. There is no simple answer. A very clear and thoughtful process is required.
There are two limb threatening priorities 1) Presence of infection and 2)Critical Limb Ischemia (CLI). I will address CLI first: With your case presentation with a 50% occlusion, I would want this patient to have an urgent evaluation by a Vascular Surgeon/ Interventionalist if not already done Indication for revascularization needs immediate attention. You have not mentioned whether patient is a diabetic: evaluating for micro vascular disease as well as Understanding of diabetic control.
2) Infection: establishing clinically whether this is wet vs dry gangrene, infected vs colonized vs deep space infection, and or the presence of osteomyelitis. Have you performed any imaging, plain X-ray? MRI? Wound cultures.both aerobic and anaerobic You described wet draining ? That is concerning for infection.
My typical management for heel Eschar/ necrosis
1) Determine if there is infection:if wound is dry not infected: I typically paint the eschar with betadine daily to keep it dry, off load and address other comorbidities
If infected most likely should be hospitalized and have a multidisciplinary team management
2)Address vascular status with formal vascular evaluation and definitive treatment
This is a multidisciplinary problem that requires a team approach with a clear prioritization of management of critical limb ischemia.
Once the above has been addressed then the best management going forward can be determined. Other might have other suggestions.