Your father's heart does not stop, what happens is that he has either premature ventricular contractions (PVC) o premature atrial contractions (PAC). When they occur there is long pause in the heart beat (missing pulse) and it appears that the heart has stopped. Premature contractions are usually harmless, but occasionally may be associated with heart disease. The best way to tell what type of premature contractions your father is having, is by an electrocardiogram (EKG) or by a Holter monitor that is a 24-hour EKG. If he has symptoms like dizzy spells, shortness of breath, palpitations, fatigue or chest pains, he has to see a doctor. You can't make a diagnosis of arrythmia by only feeling the pulse.