Chest X-ray is often used by cardiovascular specialists to assess the size of the heart chambers and the major blood vessels in the chest. If there is a question of heart failure a chest x-ray can help to assess the presence of edema or fluid in the lungs. X- ray is used to project a silhouette of the heart and lung structures on to a film or a digital recorder. The process will take about 5 to 10 minutes to complete. The doctors then interpret the recorded image and the report forwarded to your doctor. No special preparation is required prior to the test.