This invention provides a catheter used for blocking abnormal conduction in the cardiac muscle using photodynamic therapy or treating arrhythmia and a method for evaluating the therapeutic effects of the catheter. The catheter has a structure that freely bends at its end, which is used for performing photodynamic ablation of cardiac muscle tissue via photochemical reactions in the blood vessel or cardiac lumen. The catheter comprises a light-emitting window for applying a light beam transmitted through an optical fiber to a target site of cardiac muscle tissue and at least two electrodes for potential measurement in the periphery of the light-emitting window.
