{"id":1383,"date":"2020-04-03T16:11:43","date_gmt":"2020-04-03T14:11:43","guid":{"rendered":"http:\/\/aritmije.kbcsm.hr\/?p=1383"},"modified":"2020-04-03T16:11:45","modified_gmt":"2020-04-03T14:11:45","slug":"permanent-cardiac-pacemaker","status":"publish","type":"post","link":"https:\/\/aritmije.kbcsm.hr\/en\/permanent-cardiac-pacemaker\/","title":{"rendered":"Permanent cardiac pacemaker"},"content":{"rendered":"
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Permanent cardiac pacemaker <\/h1>
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What is a pacemaker (PM)?<\/strong> A pacemaker is an electrical device that is installed under the patient’s skin to maintain or restore a normal heart rhythm.<\/p>\n

Cardiac conduction system and “natural heart pacemaker”.<\/strong> The heart is a hollow muscular organ located behind the sternum that pushes (“pumps”) blood through blood vessels, delivering oxygen and nutrients to the entire body. The heart is made of 4 cavities: the right and left atrium and the right and left ventricle. The left and right sides are separated by a cardiac septum. Blood flows through the heart only in one direction because the valves are located between the atria and the ventricles. At each beat, the blood is first squeezed from the atrium into the ventricle (both left and right), and then through the large blood vessels that go from the heart into the entire body. The heart normally beats 50-100 times per minute, thus maintaining circulation in the body.<\/p>\n

The heart has its own natural electrical conduction system<\/strong> called the cardiac conduction system. The conduction system sends electrical signals along the entire heart muscle, which coordinate the exact heart rate number and correct rhythm. The conduction system precisely stimulates the heart chambers, ensuring their contraction and relaxation and thus the circulation of blood. Electrical signals or impulses are generated in a special tissue called a sinus node<\/strong> (sinus atrial node, SA node). The sinus node is located in the right atrium and transmits regular electrical impulses which spread across the right and left atrium to the ventricle. The sinus node is also referred to as the “natural pacemaker” of the heart. The electrical impulse that comes from the atrium to another specific formation, which is located between the atrium and the ventricle, called the atrioventricular node (AV node)<\/strong>. The AV node slows down an electrical impulse to allow the atrium to contract enough. Through the AV node, the impulse is further transmitted by special fibres called the bundle of His and the right and left bundle branch. These fibres expand the impulse and coordinate the contraction of the right and left ventricle.<\/p>\n

Disorders in the conduction of cardiac impulses are called cardiac arrhythmias<\/strong>.<\/p>\n

Bradyarrhythmias (Bradycardias) <\/strong>are a heart rhythm disorders that describes abnormally slow heart rate (less than 50 beats per minute).<\/p>\n

Sinus bradycardia occurs when a “natural pacemaker” produces impulses very slow. This is a normal occurrence in healthy people during sleep or in athletes and heavy manual workers and is usually a harmless occurrence. However, there are heart diseases in which excessively slow pulses can significantly affect the person in whom they occur.<\/p>\n

A heart block<\/strong> is a term that describes the delay or interruption of impulse conduction through the conduction system, thus causing slow cardiac pulse or complete cardiac arrest. There are several types of heart blocks, and they are divided according to the region of the conduction system that is affected and difficulty by degrees (lower degree in which impulse conduction is slow and\/or difficult or higher degree in which the impulse conduction is completely disabled).<\/p>\n

Sick sinus syndrome.<\/strong> Typically, a reduced heart rate occurs, and the sinus node less frequently emits electrical impulses. Sometimes for a short period of time heart may skip a beat.<\/p>\n

The interruption of impulse transmission often occurs between the atrium and the ventricle, called the atrioventricular or AV block<\/strong>, and is divided according to different degrees of difficulty.<\/p>\n

1st<\/sup> degree <\/strong>AV block: t<\/strong>he cardiac impulse to the ventricle comes from the atrium but abnormally slows down as it passes through the AV node.<\/p>\n

2nd<\/sup> degree AV block:<\/strong> some impulses from the atrium fail to pass into the ventricle, resulting in slow and ir\/regular heartbeats.<\/p>\n

In the most difficult 3rd<\/sup> degree AV block<\/strong>, impulses from the atrium are not transmitted at all to the ventricule. This condition is most commonly referred as the total AV block<\/strong>. In order for the heart to function normally in this case, a separate rhythm from the lower centre in the ventricle occurs. In the absence of this separate rhythm there is a great danger of cardiac arrest with underlying asystole.<\/p>\n

Tachyarrhythmia (Tachycardias) <\/strong>are a heart rhythm disorder that describes abnormally accelerated heart rate (more than 100 beats per minute). The tachycardia form which is most commonly treated with a cardiac device implantation is ventricular tachycardia (VT)<\/strong>. Very fast impulses coming from diseased area in the ventricle\/s and causes rapid contractions whereby the heart cannot efficiently squeeze blood out of the ventricles and can cause cardiac arrest. For this reason, VT is a potentially dangerous tachyarrhythmia.<\/p>\n

Symptoms of arrhythmias vary depending on the arrhythmia involved and on certain factors, such as a heart disease in the background. While some people have no symptoms, others may have different symptoms and signs that may include:<\/p>\n