What medicine do you take?
Do you take diuretics? Your frequent urination may be related to taking diuretics.
What's your blood pressure? Dizziness may be related to hypotension.
You may need a brain CT scan to see exactly what is going on in your brain. It could be a brain tumor, a stroke, etc.. Or it could be caused by too high or too low blood pressure. Your frequent urination may be caused by the medication you take for your heart problems. Drugs like furosemide may increase your urine.
What heart problems? Congestive heart failure? How is your blood pressure? You should rule out a low or high blood pressure for your lightheadedness and brain pressure. If your blood pressure is normal, it might be reassuring to get a head CT or MRI scan. Your increased peeing may be probably related to the medications you use, such as water pills.