The first visible sign that the health care system in Puerto Rico was seriously in trouble was when a steady stream of doctors — more than 3,000 in five years — began to leave the island for more lucrative, less stressful jobs on the mainland, the New York Times reported today. Now, as Puerto Rico faces another hefty cut to a popular Medicare program and grapples with an alarming shortage of Medicaid funds, its health care system is headed for an all-out crisis, which could further undermine the island’s gutted economy. And while the crisis is playing out most vividly today, its cause dates back decades and stems, in large part, from a vast disparity in federal funding for health care on the island compared with the 50 states. This disparity is partly responsible for $25 billion of Puerto Rico’s $73 billion debt, as its government was forced to borrow over time to keep the Medicaid program afloat, according to economists.