A method of forming pre-fabricated units used in production of transcatheter aortic valve implantation (TAVI) prosthesis devices comprising a nanofiber material integrally joined to a stent, wherein the unit has a non-thrombogenic smooth surface layer or has a porous fibrous layer constituting a scaffold for epithelium cell culture, comprises the following steps: (a) preparing between 1- 133 stents made of a cobalt-nickel alloy and having wall thickness of 150-500μm: (b) preparing a solution of polymer in DMAC solvent, wherein the polymer has an average molecular weight of 50 000 -200 000 g/mol and is chosen from one or more of polymers selected from polycarbonate silicone and alternatively polycarbonate urethane or polyurethanes; (c) forming a first smooth layer by electrospraying a 2-11 wt. % solution of polycarbonate silicone in DMAC solvent onto a roller and/or by electrospinning an 8-20 wt.% solution of polycarbonate urethane or polyurethane in DMAC onto a roller, over a period of 0.5-40 hours, whereby the solution delivery rate to the electrospinning heads is 0.1-5 ml/h, whilst controlling the number of electrospinning heads, the capillary dimensions, the roller rotation speed, the voltage between the capillary and roller, and the distance between the capillary and roller, resulting in a first smooth layer with a thickness of about 1-100 μm and length of 50-6000 mm: (d) forming a first intermediate layer by electrospraying a 2-8 wt.% solution of polycarbonate silicone in DMAC and/or by electrospinning an 8-20 wt.% solution of polycarbonate silicone in DMAC, over a period of 0.5-40 hours, whilst controlling the number of electrospinning heads, the capillary dimensions, the roller rotation speed, the voltage between the capillary and roller, and the distance between the capillary and roller, to the form a first intermediate layer with a thickness of about 5-100 μm and length of 50-6000 mm: (e) placing the one or more stents over the first intermediate layer and positioning them so that distance between two adjacent stents is always 30mm: (f) repeating step (d) over a period 0.5-40 hours in order to apply a second intermediate layer having a thickness of about 5-100 μm over the entire length of the roller; and (g) repeating step (c) until a pre-fabricated unit with a polymer material thickness of 50-250 μm is obtained. (a) preparing between 1- 133 stents made of a cobalt-nickel alloy and having wall thickness of 150-500μm: (b) preparing a solution of polymer in DMAC solvent, wherein the polymer has an average molecular weight of 50 000 -200 000 g/mol and is chosen from one or more of polymers selected from polycarbonate silicone and alternatively polycarbonate urethane or polyurethanes; (c) forming a first smooth layer by electrospraying a 2-11 wt. % solution of polycarbonate silicone in DMAC solvent onto a roller and/or by electrospinning an 8-20 wt.% solution of polycarbonate urethane or polyurethane in DMAC onto a roller, over a period of 0.5-40 hours, whereby the solution delivery rate to the electrospinning heads is 0.1-5 ml/h, whilst controlling the number of electrospinning heads, the capillary dimensions, the roller rotation speed, the voltage between the capillary and roller, and the distance between the capillary and roller, resulting in a first smooth layer with a thickness of about 1-100 μm and length of 50-6000 mm: (d) forming a first intermediate layer by electrospraying a 2-8 wt.% solution of polycarbonate silicone in DMAC and/or by electrospinning an 8-20 wt.% solution of polycarbonate silicone in DMAC, over a period of 0.5-40 hours, whilst controlling the number of electrospinning heads, the capillary dimensions, the roller rotation speed, the voltage between the capillary and roller, and the distance between the capillary and roller, to the form a first intermediate layer with a thickness of about 5-100 μm and length of 50-6000 mm: (e) placing the one or more stents over the first intermediate layer and positioning them so that distance between two adjacent stents is always 30mm: (f) repeating step (d) over a period 0.5-40 hours in order to apply a second intermediate layer having a thickness of about 5-100 μm over the entire length of the roller; and (g) repeating step (c) until a pre-fabricated unit with a polymer material thickness of 50-250 μm is obtained. (f) repeating step (d) over a period 0.5-40 hours in order to apply a second intermediate layer having a thickness of about 5-100 μm over the entire length of the roller; and (g) repeating step (c) until a pre-fabricated unit with a polymer material thickness of 50-250 μm is obtained.