Palpitations are a common problem that is often referred to a Cardiologist for further investigation. Patients will often experience a sense that the heart is skipping or racing. This may be accompanied by shortness of breath, chest pain, and lightheadedness or rarely loss of consciousness. When this takes place, the physician is concerned about the possibility that the hearts rhythm is abnormal. The sensation of palpitations can be caused by a host of different things, including an irregular heartbeat, heart racing that is abnormal, or the normal acceleration of the heart that occurs with anxiety or exercise. The key goal of sorting this out is to record the heart rhythm when it is experienced. Typically, physicians will order an electrocardiogram (EKG or ECG). A monitoring test is often performed using a Holter monitor that continuously records the hearts rhythm for 24-48 hours.
The second form of monitor is a telephone or rhythm transmitter that is applied to the chest wall for 1 minute, recording a basic EKG during symptoms. The stored EKG can usually be sent to the recording center by phone line like a fax.
The final form of monitor is a loop recorder. This device is worn continuously with 2 skin electrodes attached by a thin wire to a pager style device. This stores a longer ECG signal (typically 4-10 minutes), including the previous 3-9 minutes after the activation button is pressed, allowing event capture to take place even though symptoms have passed. The stored EKG can also be sent to the recording center by phone line like a fax.
On the basis of these results, further testing may be warranted and referral to an Arrhythmia Specialist.
One of the most common causes of palpitation is the skipping of the heartbeat that occurs from extra beats or extra systoles. Most of the time these are simply beats from a secondary pacemaker in the heart that create irregularity in the pulse that feels unusual. The heart is otherwise normal, and the beats themselves are of no significant consequence. Usually a test is performed normal as an echocardiogram to verify that the heart is structurally normal.
The heart has a single dominant pacemaker called the sinus node. There are several sites within the heart that are additional pacemakers that at times can be overactive. These sites can produce skipped beats that may occur as infrequently as 50 times a day, or as often as thousands of times a day. These do not normally represent anything serious, but can produce new symptoms when a sense of irregularity occurs. Patients will often describe the feeling of "heart jumping, flipping or missing", with forceful beating after the skipped beat. This is illustrated in the adjacent figure, where the heart beat is regular followed by a skipped beat. After a short pause, there is a normal beat again. The pulse that this produces is illustrated below the trigger of the EKG and the figure. The normal pulse is followed by a very small pulse from the skipped beat. This is the sense of missing or skipping that occurs where the patient may feel the hearts stopping. This is followed by a very forceful beat when in effect two heart beats are pumped out at once or the volume of two heart beats is pumped out all at once with the resumption of normal rhythm. This often leads to the sense that the heart skips or misses count followed by a forceful pounding or impact in the chest with the normal beat.
This condition is benign, and is often an exaggerated version of the normal number of skipped beats that occurs in every person. Skipped beats are more common with any type of stimulant, including caffeine, decongestants, alcohol, bronchodilators (puffers for asthma) and occasionally with stress. Patients might find that modifying their lifestyle with respect to these agents reduces the frequency of skipped beats.
After recording these, reassurances is usually all that is necessary to confirm that there are no significant problems with the heart. Rarely, medication is used to suppress these skipped beats. Beta-blockers are used in the vast majority of patients. These agents reduce the adrenaline effect on the heart, making it less "irritable". These are only used in patients who are very symptomatic, since there is no need to treat these beats.
Rarely, these skipped beats result in brief or more sustained heart racing. When this occurs, it is again not life threatening, but can be more symptomatic. Patients in this situation may be candidates for medication, or consideration of catheter ablation. This procedure involves a heart catheterization where the source is identified by moving a catheter within the heart, and energy is applied to heat up the area of abnormal pacemaker activity to eliminate it. Further information regarding this procedure can be found under other educational sections on ablation.
Acknowledgements: Contributors to this information were: Dr. R. Yee M.D., Arrhythmia Service, LHSC (UC), Dr. A. Krahn MD, Arrhythmia Service, LHSC (UC), and various staff members.