What is an Arrhythmia?
The regular normal heartbeat is generated by electrical impulses arising from the sinus node located in the right upper chamber (atrium). The heart muscle must be activated electrically before it can initiate its mechanical function of pumping the blood out of the heart into the body. The sinus node creates these spontaneous electrical impulses at a rate of 60-100 per minute at rest. This is manifested as a regular pulse at the same rate when one puts the finger on the front of the wrist to feel the pulsation of the artery. The sinus node can increase or decrease its rate in relation to various needs such as reduction in the rate during sleep to as low as 40 per minute, and increase to as high as 150 per minute during physical activities. The sinus node thus regulates the pumping of the heart in a rhythmic fashion and this is the normal rhythm of the heart.An arrhythmia is an abnormal rhythm outside of the normal variations mentioned above. In essence, an arrhythmia is an abnormal rhythm or beating of the heart. It can be due to abnormal function of the sinus node or it can arise from other areas which normally do not initiate electrical impulses. The arrhythmia can be manifested as rapid and regular heart beats (tachycardia), rapid and irregular heartbeats (fibrillation), slow heart beats (bradycardia), and abnormal extra beats occurring before the anticipated normal beats in a periodic fashion (premature contractions). Arrhythmias originating from the upper chambers (above the ventricles) of the heart are called supraventricular arrhythmias. Those originating in the lower chambers (ventricles) are called ventricular arrhythmias. The symptoms caused by arrhythmias depend on the type, severity, duration and frequency of arrhythmia. The severity of symptoms is also related to the underlying function of the heart. A young person with a normal heart may tolerate the arrhythmia very well but an older person with some associated heart disease will tolerate the same arrhythmia poorly. The arrhythmia-related symptoms are variable and include palpitations (feeling of rapid beats), weakness, fatigue, chest discomfort, shortness of breath, dizzy spells, and in the most severe form as actual loss of consciousness and cardiac arrest.
How to Diagnose Arrhythmias:
EKG:
The normal as well as abnormal electrical activity of the heart can be recorded from the body surface by placing electrodes which are connected to a recording machine (EKG). However to detect an arrhythmia the recording must be done at the time when the patient is having the arrhythmia. Because of the sporadic nature of the arrhythmias, the better option is to attach the electrodes to the patient's chest which are then connected to a tape recorder. The heartbeats recorded in the tape are then transferred to a machine that can analyze, display, and record these beats. This is called Ambulatory ECG Recording or Holter Monitoring. This recording is usually done for 24 hours. If the patient does not have the arrhythmia in 24 hours, the recording may be repeated but at times the arrhythmia may not occur and thus not recordable after several attempts. For such type of a very sporadic arrhythmia, another type of recorder is available which is activated by thepatient. It is similar to the Holter Tape Recorder but is smaller (size of a pager). When the patient has symptoms presumed to be due to arrhythmia, he or she will push a button and the heartbeats will be recorded. This recording can be transmitted via telephone from this recorder to a receiver which is located in the hospital. The medical staff can then review the recording, relate with the symptoms, and make an accurate diagnosis. This is called Transtelephone ECG Recording.
Electrophysiology Study:
This is the study of the normal physiology of the electrical system of the heart and detection of arrhythmia by direct recording from inside the heart. This is an invasive study and involves introduction of catheters (long cables) through the blood vessels and guiding them to various locations in the heart. The patient is given mild sedation and local anesthesia with xylocaine administered locally at the site of catheter introduction in a similar way as local anesthesia given by a dentist. The specialist cardiologist (electrophysiologist) can provoke the arrhythmia, identify its mechanism, locate its focus, and thus make a decision about appropriate therapy.The abovementioned studies are done for direct recording of the arrhythmia. However, the patient may need other studies such as blood tests, chest x-ray, echocardiogram, and cardiac catheterization for overall assessment of the condition of the heart and diagnosing other related conditions. The King Faisal Specialist Hospital & Research Center is fully equipped with modern equipment for all these studies.
How to Treat Arrhythmias:
Arrhythmias may not require treatment if they are infrequent and associated with very little symptoms. Sometimes, the symptoms may be significantly improved by avoiding things which precipitate arrhythmias such as excessive use of caffeine. The treatment of underlying heart disease may also result in significant improvement in the occurrence of arrhythmia. When the arrhythmia is not correctable by these measures and requires specific treatment, various options are available.
Antiarrhythmic Drugs:
These drugs can reduce the occurrence of arrhythmia and/or decrease the severity. However, the patient has to take the medication on a lifelong basis. Further, the drugs may cause various side effects and rarely even aggravate the arrhythmia. Therefore, close monitoring and follow-up by the physician is necessary. The drugs only prevent the arrhythmia and do not result in permanent cure. If available, it is preferable to choose a mode of therapy which can achieve permanent cure without a significant risk (see below).
Radiofrequency Catheter Ablation:
Many types of abnormal, fast heart rhythm disturbances (tachycardia) can be permanently cured by this new non-surgical approach. Catheters (long cables) are introduced into the heart through the blood vessels and the focus of arrhythmia is identified by recording the electrical activity from inside the heart. A specialized computerized recording and analysis system is used for this purpose. Once the arrhythmia focus is identified, radiofrequency energy (modified high-frequency electrical current) is passed through the catheter to that area. This causes heating of tissue in that area and permanently destroys the tiny bundles of heart muscle responsible for the arrhythmia. The permanent cure rate is above 95% with a very low rate of recurrence (1-2%).
Surgery:
Surgery may be needed for the treatment of other associated conditions. The focus of arrhythmia can also be approached directly and excised. However, Radiofrequency Ablation has almost completely eliminated the need for this procedure.
Pacemakers:
Pacemakers are primarily needed for the treatment of slow heart rhythms (bradycardia). The artificial pacemaker is a small electrical device which monitors the heart beat and emits electrical impulses which stimulate the heart to maintain a regular rhythm. The pacemaker is embedded under the skin and is connected to the heart with electrical wires (leads) which are introduced through the blood vessels. The monitoring of heartbeats and transmission of electrical impulses is conducted through these leads. The modern pacemakers are very complex and advanced due to developments in computer applications. These pacemakers can regulate the heart rhythm for the varying needs of the patient i.e. rest, sleep, and exercise etc.
Implantable DefIbrillators:
These devices are similar to pacemakers but apply treatment for more serious and life-threatening arrhythmias. The device monitors the heartbeat and if a very fast and life-threatening arrhythmia (ventricular fibrillation) occurs, it will deliver an internal electrical shock and restore the heart rhythm back to normal. You may have observed various scenes of cardiac arrest when the paramedical personnel apply electrical shock to the chest of the patient for resuscitation. This device performs the same life-saving function automatically and is available to the high risk patients all the time. The current advanced forms of these devices also perform many other functions such as terminating the fast heart rhythm (tachycardia) by delivering rapid electrical impulses and regulating slow heartbeat like a pacemaker. There is a tremendous amount of memory in these devices and the patient's arrhythmias are stored in the device which can later be retrieved and analyzed by the physicians using special programmers. This is an excellent example of a beneficial use of modern technology for the diagnosis and treatment of life-threatening arrhythmias.
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