Wal-Mart Stores Inc. is offering its U.S. employees and their families free heart and spine surgeries at six major health centers at no cost to the retailer's workers, as it tries to find better ways to cover costly, complicated procedures. Starting in January, workers and dependents enrolled in Wal-Mart's medical plans will receive free consultations and care for certain heart and spinal procedures along with travel, lodging and food for the patient and a caregiver. The six healthcare organizations include those that have won high marks in terms of patient care and keeping unnecessary costs at bay.