Cardiac arrhythmias are the result of disorganised electrical signalling in the heart, affecting up to 33.5 million people worldwide and about 1-3% of the Belgian population. Moreover, as the prevalence of atrial fibrillation is expected to double the next 20 years, the clinical and economic impact of the disease is huge. The goal of the project is two-fold: (1) Establish a new and innovative tool for the synchronous stimulation of cardiomyocytes using light and circumventing the need for genetic manipulation and (2) Provide a proof of concept and initial protocol for a safer alternative for RF/cryo balloon cathether ablation. Both aims will be achieved by using a gold nanoparticle label, which specifically targets a cardiomyocyte surface marker. The gold nanoparticle will absorb LASER/LED light and produce heat. Depending on the rate of change in temperature, either photothermal stimulation or photothermal ablation is accomplished.