Please help me save Dexter before it is too late

Dexter is my lovely 16 month old rescue German Shepherd. He has recently been diagnosed with PDA (patent ductus arteriosus), a heart condition that, if left untreated, eventually leads to heart failure and potentially sudden death. If you are family or a friend, you already know how much Dex matters to me. When Dex was first seen at the veterinary clinic where my girlfriend works as a technician, he was diagnosed with a grade 4/6 heart murmur. Our veterinarian suggested consulting a cardiologist to get definitive answers. After months of saving money for the consult and waiting for our appointment date, we learned the news— Dex needs a surgical procedure to correct his PDA. Our cardiologist suggested immediate action; without intervention, the prognosis is poor, and heart failure is likely. An initial estimate for the cost of the procedure is $6,000, way beyond what I can afford as a PhD student. The necessary treatment is a surgical operation with a very high success rate. If he is able to get this procedure, he is expected to live a normal life. However, without receiving this life-saving operation, heart failure is the most likely outcome. Dexter deserves to see the many happy and healthy years that he has ahead of him—please consider helping us make that a reality.