Accurate guidance of an ablation catheter is critical in the RF ablation (RFA) of ventricular tachycardia (VT). With current technologies, it is challenging to rapidly and accurately localize the site of origin of an arrhythmia, often restricting treatment to patients with hemodynamically stable arrhythmias. We investigated the effectiveness of a new guidance method, the inverse solution guidance algorithm (ISGA), which is based on a single-equivalent dipole representation of cardiac electrical activity and is suitable for patients with hemodynamically unstable VT. Imaging was performed in homogeneous and inhomogeneous saline-filled torso phantoms in which a catheter tip was guided toward a stationary electrical dipole source over distances of more than 5 cm. Using ISGA, the moving catheter tip was guided to within 0.61 +/-0.43 and 0.55 +/-0.39 mm of the stationary source in the homogeneous and inhomogeneous phantoms, respectively. This accuracy was achieved with less than ten movements of the catheter. These results suggest that ISGA has potential to provide accurate and efficient guidance for RFA procedures in the patient population with hemodynamically unstable arrhythmias.