Video 1. Transthoracic echocardiography, parasternal long axis – dilated left ventricle with hypokinesia of ventricular walls and atrial enlargement; Video 2. Transthoracic echocardiography – apical view revealing the moderate functional mitral regurgitation; Video 3. Intraprocedural standard anteroposterior fluoroscopic view with the atrial and ventricular lead in place; Video 4. Intraprocedural fluoroscopic view (right anterior oblique projection at 30 degrees): atrial lead in the anterior RAA, ventricular lead at the apex of the right ventricle; Video 5. Venography performed by standard fluoroscopy through a catheter placed at the level of the left median cubital vein: left SVC draining in the right atrium via the coronary sinus; obstruction of the innominate vein, with no contrast flow; residual stenosis/kinking at the border between left SVC and CS; Video 6. Venography performed by standard fluoroscopy through a catheter placed at the level of the right median cubital vein: right SVC draining in the right atrium; obstruction of the innominate vein with no contrast flow.