Weak heart & swellin. If you know that you have a "weak heart", I presume you mean that you have been diagnosed with congestive heart failure. Swelling is one of the most common symptoms of this condition. It can usually be adequately treated by finding the proper dose of a potent diuretic like Furosemide (lasix). Consult your doctor. It would not be a good or safe idea to manage diuretics on your own.