Wednesday, May 26, 2010

A Little Clarification

When people say they are experiencing heart palpitations it can mean many different things. Some people (my mom for example) think of palpitations as feeling as if your heart is pounding or racing (tachycardia). You may simply have an unpleasant awareness of your own heartbeat. When I refer to heart palpitations in my blog, I'm usually referring to a sensation of a skipped or stopped beats. Sometimes they feel like a flip-flop or a flutter. Of course, your heart does not stop. A premature ventricular contraction (PVC) or a premature atrial contraction (PAC) is simply the heart's ventricle or atrium prematurely contracting before the normal electrical discharges arrive from the SA node (or pacemaker of the heart). Immediately after a premature contraction, the electrical system of the heart resets. This resetting causes a brief pause in heartbeat (as the heart refills with blood). It's usually the normal after beat (and sometimes it can feel very strong) that one feels and not the actual pause. Also, it may be useful to note that it is very hard to distinguish a PVC or PAC unless a trained technician is watching your heart palpitations on an EKG. Some people claim they can tell a difference between the sensations of a PVC or PAC, but I generally cannot.

The intensity and frequency of my PVCs differ greatly. Sometimes I feel single mild misbeats. These I have learned to live with. Other times, I will have one really strong one that I can feel in my chest, throat, or neck. These sometimes make me feel a bit queasy or short of breath. A lot of times, these intense single palpitations cause me to panic causing my adrenaline to surge and my heart to race (but I attribute this to the anxiety and not the actual palpitation). Sometimes, I go into bigeminy where one PVC occurs after every normal beat, in an alternating pattern, or trigeminy where one PVC occurs after every two normal beats. These have usually only occurred when I was dealing with a major life stressor (like a loss of a job or continual lack of sleep). Going into bigeminy or trigeminy is no fun for me. But supposedly there are thousands of people (especially older people) that experience bigeminy and trigeminy on a daily basis and can't even feel them! There is no prognostic difference between the PVCs that are felt by the patient and those that are not. Obviously the symptomatic PVCs are of more concern to the patient because they can be annoying and distracting. Beyond that, the PVCs are all the same, prognostically. In most patients who are otherwise healthy, PVCs on a Holter are of little prognostic value regardless of whether they're experienced or not.

And the million dollar question? How many is too many heart palpitations? According to a Cleveland Clinic doctor, generally in a normal heart there is no "maximum limit" to PVCs; although in someone with underlying heart disease, doctors are somewhat more concerned if they are occurring more that 6 times a minute.