Electrically Conductive Hydrogels Usable As Lead Extensions, Apparatus For Delivery Of A Hydrogel Into The Vasculature, and Methods Of Treating Ventricular Arrhythmia With Electrically Conductive Hydrogels Injected In The Venous System

A biostable, biocompatible conductive hydrogel for injection into a venous system or an organ, comprising:

• a crosslinked network formed by hydrophilic macromers;
• and
• at least one of ions solvated in an aqueous phase of the hydrogel and conductive elements that are tethered to the crosslinked network through biostable covalent bonds,
• wherein the hydrophilic macromers comprise a polyethylene glycol backbone of polyethylene glycol diacrylamide or polyethylene glycol dimethylacrylamide.

A biostable, biocompatible conductive hydrogel for injection into a venous system or an organ, comprising:

• a crosslinked network formed by hydrophilic macromers;
• and
• at least one of ions solvated in an aqueous phase of the hydrogel and conductive elements that are tethered to the crosslinked network through biostable covalent bonds,
• wherein the hydrophilic macromers include branched macromers having more than two functionalized arms.

A biostable, biocompatible conductive hydrogel for injection into a venous system or an organ, comprising:

• a crosslinked network formed by hydrophilic macromers;
• and
• at least one of ions solvated in an aqueous phase of the hydrogel and conductive elements that are tethered to the crosslinked network through biostable covalent bonds,
• wherein the hydrophilic macromers include polyolefin functionalized with amide groups.

A biostable, biocompatible conductive hydrogel for injection into a venous system or an organ, comprising:

• a crosslinked network formed by hydrophilic macromers;
• and
• at least one of ions solvated in an aqueous phase of the hydrogel and conductive elements that are tethered to the crosslinked network through biostable covalent bonds,
• made by the process of:
• mixing a first precursor with a second precursor to form a mixture;
• and
• curing the mixture,
• wherein the first precursor and the second precursor include hydrophilic macromers functionalized with acrylamide end groups,
• wherein the molecular weight of the macromers and the concentration of the macromers in the first precursor and the second precursor is such that the modulus of the hydrogel is 20 kPa to 500 kPa,
• wherein the first precursor or the second precursor includes the at least one of ions and conductive elements,
• wherein the concentration of the at least one of ions and conductive elements in the first precursor and the second precursor is such that the conductivity of the hydrogel is at least 104 S·cm−1,
• wherein the first precursor includes an oxidizing or initiator agent,
• wherein the second precursor includes a reducing agent,
• wherein the concentration of the oxidizing or initiator agent in the first precursor and the concentration of the reducing agent in the second precursor are such that the gelation time of the hydrogel is between one and ten minutes.

A method of making a biostable, biocompatible conductive hydrogel for injection into a venous system or an organ, comprising:

• combining a first precursor solution with a second precursor solution,
• wherein the first precursor solution comprises crosslinkable hydrophilic macromers, at least one of ions and crosslinkable conductive elements, and a reducing agent;
• wherein the second precursor solution comprises crosslinkable hydrophilic macromers, and a free radical initiator;
• and
• wherein after the first and second precursor solutions are combined, the crosslinkable hydrophilic macromers form a crosslinked network, and either the ions are solvated in an aqueous phase of the hydrogel or the crosslinkable conductive elements are tethered to the crosslinked network via biostable bonds.