If you are a cardiovascular patient, you really should be talking to your doctor about what you can and cannot safely do.
Most forms of exercise can be done moderately, or with more intensity. It is not the form of exercise that matters, but how hard and fast you work out.
A more realistic guide is how high your heart rate gets. The Reference Guide to Exercise Intensity www.sparkpeople.com/resource/fitness_artic
details how to calculate your Maximum Heart Rate, and guides as to what is moderate, medium and high intensity cardio.