An ablation catheter for treating cardiac arrhythmias by ablating near pulmonary venous tissue is described. The ablation catheter includes a system of optical fibers containing respective fiber Bragg gratings (FBG) that are susceptible to changes in strain to thereby indicate to the physician the amount of force that the ablation head is exerting on the myocardial tissue during the ablation procedure. Optionally, the FBGs are used to indicate the exact orientation of the catheter and its ablation head inside the vasculature.
