The key compound is quinidine, now a standard anti-arrhythmic medication. Since you get a few of these compounds when you drink tonic water, I'd drink plenty of tonic if I had arrhythmia. Hawthorn is a centuries-old heart tonic, and modern research has confirmed its traditional use. Many studies show that it helps prevent heart problems, gently strengthening the heart muscle, improving blood circulation through the heart and reducing the heart's need for oxygen. It also helps the heart circulate blood with less effort.
Naturopathic physicians recommend taking standardized extracts.
The kind of extracts is important, and I'm going to include these details so that you can discuss them with your physician and make sure you are getting the right herbal medication if your doctor gives you the go-ahead to try this. Also note that many states do not require naturopaths to be licensed. If you have any hint of a heart condition, you must look into your naturopath's credentials and training. If the extracts are standardized to 18 percent OPCs, the recommended dosage is 240 to 480 milligrams once a day. To obtain these extracts, you must consult a naturopath.