Heart Palpitations

Hi. I'm a 24 year old female in good health. For the past 2 years I have been having heart palpitations. At first my heart would just beat about 120 a minute for several minutes. For the last several months it has changed to where I now have a single beat that feels like my heart is going to jump out of my chest and it is actually almost painful but only lasts for one beat. I get this up to about 200 times a day. However I don't always have them and a quick walk around the block will make them stop. I have had 3 EKG's in the last 2 years. I have also had blood work done to check for heart enzymes (sp?). All has come back fine and the last EKG the doctor caught the palpitations and said they were PAC's. Why does my heart beat like that and is this completely safe as he says? I have not seen a cardiologist as of yet. Any advice you can give me would be greatly appreciated. Thank you.

[Cleveland Clinic, MD]

Dear  Jenifer,

Thank you for your question. There are many causes of tachycardia  (fast heart beat) and they can be divided roughly into sinus (originating from the sinus node or heart's natural pacemaker) and non-sinus tachycardias.  Nonsinus tachycardias are either  supraventricular (coming from the upper chambers of the heart) or ventricular (coming from the lower chambers of the heart).  Supraventricular tachycardias include:  paroxysmal supraventricular tachycardia, atrial flutter, atrial fibrillation and AV nodal tachycardia. Ventricular tachycardias are more serious in nature and are due to a rapid depolarization of  the ventricles.  

Sinus tachycardia is defined as a heart rate of greater than 100 beats per minute originating from the sinus node.  Sinus tachycardia is classified as either appropriate or inappropriate.  There are many causes of appropriate sinus tachycardia such as exercise, anxiety, panic attacks, dehydration, deconditioning, volume loss due to bleeding or other loss of body fluids, hyperthyroidism, electrolyte abnormalities and many other conditions.

Inappropriate sinus tachycardia can only be diagnosed when all causes of appropriate sinus tachycardia have been ruled out.  It is not clear what causes inappropriate sinus tachycardia but possible etiologies are an increase in the rate at which the sinus node depolarizes and an increased sensitivity to adrenaline.  Once the diagnosis has been made by ruling out all of the potential causes of appropriate sinus tachycardia  there are several treatment options.  If the symptoms are not overly concerning no treatment needs to be done.  There is no increase in morbidity or mortality in persons with this condition and they can expect to have a normal life-span.  For persons in whom the symptoms are unbearable medications such as beta blockers or calcium channel blockers can be used, usually with good results.  In the rare person unable to tolerate medical treatment catheter ablation (burning) of the sinus node with insertion of a pacemaker or surgical removal of the sinus node have been used in the past.  Newer techniques are being developed using catheter ablation to modify and not destroy the sinus node thus avoiding the need for a pacemaker.   This procedure is still in it's infancy and should only be undertaken at a major medical center after consultation with an electrophysiologist.