What is Cardiac Arrhythmia?
A heart is made up of four chambers — two upper chambers (atria) and two lower chambers (ventricles).
The heart rhythm is normally controlled by a natural pacemaker (sinus node) located in the right atrium. The sinus node produces electrical impulses that normally start each heartbeat. These impulses cause the atria muscles to contract and pump blood into the ventricles.
The electrical impulses then arrive at the atrioventricular (AV) node. The AV node slows down the electrical signal before sending it to the ventricles. This slight delay allows the ventricles to fill with blood. When electrical impulses reach the muscles of the ventricles, they contract, causing them to pump blood either to the lungs or to the rest of the body.
Heart rhythm problems (cardiac arrhythmias) occur when the electrical impulses that coordinate your heartbeats don’t work properly, causing your heart to beat too fast, too slow or irregularly.
If the heart rate is too fast – above 100 beats per minute in adults – it is called tachycardia, and a heart rate that is too slow – below 60 beats per minute – is called bradycardia.
While most types of arrhythmia are not serious, some predispose a person to complications such as stroke or heart failure. Others may result in sudden death.
Detection of Cardiac Arrhythmia
Arrhythmias may not cause any signs or symptoms. The cardiologist might find an arrhythmia during a routine examination.
The cardiologist will then perform further heart-monitoring tests.
Electrocardiogram (ECG): During an ECG, sensors (electrodes) that can detect the electrical activity of the heart are attached to the chest and sometimes to the limbs.
Holter monitor: This portable ECG device can be worn for a day or more to record the heart’s activity as the patient goes about his routine.
Event recorder: For sporadic arrhythmias, the patient keeps this portable ECG device available, attaching it to the body and pressing a button when the patient has symptoms.
Echocardiogram. In this noninvasive test, a hand-held device (transducer) placed on the chest uses sound waves to produce images of the heart’s size, structure and motion.
Implantable loop recorder. If the symptoms are very infrequent, an event recorder may be implanted under the skin in the chest area to continually record the heart’s electrical activity and detect abnormal heart rhythms.
Stress test. Some arrhythmias are triggered or worsened by exercise. During a stress test, the patient will be asked to exercise on a treadmill or stationary bicycle while the heart activity is monitored.
Electrophysiology study: A more advanced study of the heart’s electrical activity can be performed to assess the source of the aberrant heart beats.
Noticeable arrhythmia symptoms may include:
– a fluttering in the chest
– a racing heartbeat (tachycardia)
– a slow heartbeat (bradycardia)
– chest pain
– shortness of breath
Other symptoms may include
– lightheadedness or dizziness
– fainting (syncope) or near fainting
Risk factors for Cardiac Arrhythmia
Certain conditions may increase the risk of developing an arrhythmia.
Coronary artery disease, other heart problems and previous heart surgery: Narrowed heart arteries, a heart attack, abnormal heart valves, prior heart surgery, heart failure, cardiomyopathy and other heart damage are risk factors for almost any kind of arrhythmia.
High blood pressure: This increases the risk of developing coronary artery disease. It may also cause the walls of the left ventricle to become stiff and thick, which can change how electrical impulses travel throughthe heart.
Diabetes. The risk of developing coronary artery disease and high blood pressure greatly increases with uncontrolled diabetes.
Obstructive sleep apnea. This disorder, in which the breathing is interrupted during sleep, can increase the risk of bradycardia, atrial fibrillation and other arrhythmias.
Drinking too much alcohol: Drinking too much alcohol can affect the electrical impulses in the heart and can increase the chance of developing atrial fibrillation.
Caffeine, nicotine or illegal drug use: Caffeine, nicotine and other stimulants can cause the heart to beat faster and may contribute to the development of more serious arrhythmias. Illegal drugs, such as amphetamines and cocaine, may profoundly affect the heart and lead to many types of arrhythmias or to sudden death due to ventricular fibrillation.
Treatment of Cardiac Arrhythmia
If an arrhythmia is diagnosed, treatment may or may not be necessary. Usually, it’s required only if the arrhythmia is causing significant symptoms or if it’s putting a patient at risk of a more serious arrhythmia or arrhythmia complication.
There are many different kinds of arrythmia, and the treatment naturally depends on the specific arrythmia.
Treating slow heartbeats:
If slow heartbeats (bradycardias) don’t have a cause that can be corrected, doctors often treat them with a pacemaker because there aren’t any medications that can reliably speed up the heart.
A pacemaker is a small device that’s usually implanted near the collarbone. One or more electrode-tipped wires run from the pacemaker through the blood vessels to the inner heart. If the heart rate is too slow or if it stops, the pacemaker sends out electrical impulses that stimulate the heart to beat at a steady rate.
For fast heartbeats (tachycardias), treatments may include one or more of the following:
Medications. For many types of tachycardia, the patient may be prescribed medication to control the heart rate or restore a normal heart rhythm. It’s very important to take any anti-arrhythmic medication exactly as directed by the doctor in order to minimize complications.
If one has atrial fibrillation, the doctor may prescribe blood-thinning medications to help keep dangerous blood clots from forming.
Cardioversion. If the patient has a certain type of arrhythmia, such as atrial fibrillation, the cardiologist may use cardioversion, which can be conducted as a procedure or by using medications. In the procedure, a shock is delivered to the heart through paddles or patches on the chest. The current affects the electrical impulses in the heart and can restore a normal rhythm.
Catheter ablation. In this procedure, the cardiologist threads one or more catheters through the blood vessels to the heart. Electrodes at the catheter tips can use heat, extreme cold or radiofrequency energy to damage (ablate) a small spot of heart tissue and create an electrical block along the pathway that’s causing the arrhythmia.
Treatment for heart arrhythmias also may involve use of an implantable device:
– Pacemaker. If a pacemaker detects a heart rate that’s abnormal, it emits electrical impulses that stimulate your heart to beat at a normal rate.
– Implantable cardioverter-defibrillator (ICD). The cardiologist doctor may recommend this device if the patient is at high risk of developing a dangerously fast or irregular heartbeat in the lower half of your heart (ventricular tachycardia or ventricular fibrillation). If one has had sudden cardiac arrest or has certain heart conditions that increase the risk of sudden cardiac arrest, the doctor may also recommend an ICD.
Prevention of Cardiac Arrhythmia
One should live a healthy lifestyle and have regular controls with the cardiologist.
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