Cardiac resynchronization therapy with biventricular stimulation is an accepted treatment procedure for patients with severe heart failure (NYHA class III/IV), low left ventricle ejection fraction, and left bundle branch block, in spite of optimal medical treatment (Smith, S. C. Jr, Feldman, T. E., Hirshfeld, J. W. Jr, Jacobs, A. K., Kern, M. J., King, S. B. et al. Circulation, 113(7), e166-e286, (2006)). In the ventricular resynchronization procedure, an electrode must be implanted, via the coronary sinus (CS), in a coronary vein of the left ventricle (LV). Insertion of guide catheters and guide wires through the CS towards the target vein may produce more or less extensive dissections and staining which makes visualizing the target vein opening difficult and gives rise to deferment of the procedure. We describe a case of CS dissection, produced by the catheter guide, resulting in a venous wall flap which impeded further advancement of the lead. This was treated with prolonged inflation of a coronary angioplasty balloon, which allowed completion of the procedure in the same surgical intervention. To our knowledge, this is the first report of the successful use of a coronary angioplasty balloon to resolve this complication of electrode implantation.