why does viagra last longer than viagra Health heart health center search heart health center reduce risk heart disease related conditions share free heart health center newsletter! Sign up discuss in my forum sinus bradycardia by richard n. Fogoros, m. D. , about. Com guide updated november 02, 2011 about. Com health's disease and condition content is reviewed by our medical review board see more about: bradycardia sinus bradycardia pacemaker sinus bradycardia is one of the two major causes of bradycardia, or slow heart rate. In sinus bradycardia, the slowing occurs because the heart's sinus node has reduced the rate at which it generates the electrical impulses that control the heart rhythm. In many circumstances, sinus bradycardia is entirely normal. In other circumstances, sinus bradycardia causes the heart rate to become inappropriately low, which can lead to symptoms and may require a pacemaker. Read about the heart's electrical system. Read about heart block, the other major cause of bradycardia. At rest, the rate at which the sinus node produces electrical impulses (referred to as the "sinus rate") is between 60 and large integer times per minute. A sinus rate within this range is referred to as "normal sinus rhythm. " when the sinus rate is faster than one c times per minute, it is referred to as "sinus tachycardia. " and a sinus rate slower than 60 times per minute is called "sinus bradycardia. viagra from cananda without prescription cheap viagra online buy cheap viagra cheap viagra http://classicmotocrossimages.com/mbs-uk-viagra-sales-yg/ buy viagra online viagra without a doctor prescription order viagra online usa cheap generic viagra cheap generic viagra " when the sinus node produces a heart rate that is too slow for the body's needs, symptoms can develop. Most typically, these symptoms are lightheadedness, fatigue, poor exercise tolerance, or syncope (transient loss of consciousness). Usually, sinus bradycardia is not considered to be a serious problem unless it is producing one or more of these symptoms. When is sinus bradycardia considered normal? Quite often, sinus bradycardia is completely normal. Healthy young people, and even older people when they are in good physical condition, will frequently have resting heart rates in the 40s or 50s. It is also common (and normal) to have heart rates in this range while sleeping. Transient sinus br.