The half-life of ramipril is variable (3–16 hours), and is prolonged by heart and liver failure, as well as kidney failure.
You should probably listen to your cardiologist in this case, although the nephrologist should have known better. Take your own blood pressure if you can and monitor it every fifteen minutes to half hour when and if you get back on the lower dosage ramipril again. If you see that your blood pressure drops below 100/70, call someone to watch over you.
http://en.wikipedia.org/wiki/Ramipril