I have had two major surgeries in the past 4 years and after each I experienced slow heart rate and abnormal heart rhythm... cardio consults for each only indicated it was related to the anesthetic. Is this a common occurence? 

Bradycardia is the medical term for slow heart rate. A normal heart rate is usually somewhere between 60 and 90 beats per minute. A slower heart rate is sometimes a sign of good health. Many highly trained athletes have slow heart rates, as low as 35 beats per minute. So, bradycardia is not a bad thing provided your blood pressure is okay, your cardiac (heart) output is normal, and the heart rhythm is normal. A normal heart rhythm is called "sinus" rhythm. Under normal circumstances the part of the heart that controls the rate at which the heart beats is the "sino-atrial node" (the sinus), hence "sinus" rhythm. After an anesthetic and surgery, a higher than normal heart rate is common, for a variety of reasons, including pain or discomfort. Bradycardia can also occur. The reasons for bradycardiaﾠinclude the lingering effect of certain drugs used in the anesthetic, including pain medicines like morphine or fentanyl, drugs used to reverse the muscle relaxants, and drugs used intentionally to slow the heart, like beta-blockers. If the rhythm is sinus, the blood pressure is normal, and there aren't any signs of low cardiac output, then bradycardia is not usually a cause for concern.