There are a number of possible causes. Sometimes palpitations (feeling the heartbeat) are the result of anxiety and have nothing to do with a heart abnormality. Palpitations can also be
caused by irregular heartbeats, which may feel like extra beats or skipped beats. Even though this is common and usually isn't serious, it can still be worrisome.
On the other hand, palpitations can also indicate a more serious condition, such as atrial fibrillation, in which the heart beats rapidly and irregularly. Palpitations can also represent bursts of abnormal heartbeats that can degenerate into rhythms that don't produce adequate blood flow, which may result in passing out or cardiac arrest.
How can you tell the difference between a benign cause and a more serious underlying condition? If palpitations occur along with symptoms such as dizziness, passing out, or nearly passing out, this is a cause for concern. A previous heart attack or heart failure increases the likelihood that the palpitations may reflect a more serious abnormality.
Because your father's palpitations are occurring more frequently, he should see his physician. The doctor will probably order an electrocardiogram (EKG) and perhaps other tests, like a 24-hour ambulatory electrocardiogram recording or a stress test.