# Arrhythmia --- **Arrhythmia** or **dysrhythmia** is an abnormal [[cardiac cycle|heartbeat]] where it is either beating at an unhealthy rate or rhythm. Some are benign, but others are very dangerous. Sometimes a person can feel them happening, like a "fluttering" sensation. To understand the severity of a particular arrhythmia, it's useful to think of it in the context of [[cardiac conduction]] A healthy heartbeat starts in the SA node of the right atria, the signals propagate to the AV node between the atria and the ventricles, and then from the signals travel along the bundle of His and into the perjinke fibers in the ventricle walls. As the signal travels along the myocardium, a contraction happens. If the mess up in the signal occurs before the AV node, the AV node can "filter out" or try to make up some of the problem. If the mess up occurs in the ventricles, it's basically impossible to correct on it's own and needs immediate outside attention. There are **supraventricular arrhythmias** are arrhythmias that start in the atria (where they are supposed to). These are, as a general rule, less dangerous than ones that start lower, because the [[cardiac conduction|AV node]] can usually filter out noise and/or pick up the slack. **Ventricular arrhythmias** are the dangerous arrhythmias because the heartbeat originates in the ventricles and there is no other, lower node to "catch" any improper signals. >[!abstract]- Normal sinus rhythm for reference >![[normal sinus.png]] An [[electrocardiogram]] can be used to determine what type of arrhythmia someone is having. - **Tachycardia** is an inappropriately fast heartbeat. Typically over 100 beats per minute. There are two main types of tachycardia, **sinus** and **ventricular** tachycardia. - [[sinus tachycardia]] is a heart rhythm that is too fast, but otherwise regular. It is not great, but it's a lot better than ventricular tachycardia. - [[supraventricular tachycardia]] is a tachycardia that arises from some sort of feedback loop in the heart. - [[ventricular tachycardia]] is a heart rhythm that is too fast and since the origin of the arrhythmic signals are in the ventricles the heart is essentially no longer "listening" to the SA node to regulate it. - **Bradycardia** is when the heartbeat is inappropriately slow. - As far as I can tell [[sinus bradycardia]] is the only real type of bradycardia, which just means the rhythm is normal even if the rate is too slow. - **Fibrillation** is a type of heartbeat that is less of a solid beat and more of a wibbly-wobbly quiver. There are two types of fibrillation, **atrial** and **ventricular** - [[atrial fibrillation]] is not great, but it isn't an emergency. Since the origin of the arrhythmic signals is the atria, the SA node can take over and sort of "filter out" the noise. If that fails the heartrate can skyrocket in what we call **rapid ventricular response**. - [[ventricular fibrillation]] is a medical emergency, and results in death if not treated in 3-5 minutes. The whole heart is wobbling uncontrollably and hardly any blood is being moved around. - Other - **Premature ventricular contractions** or **PVCs** are extra heartbeats in the middle of a heartbeat, that feels like "fluttering". - **Asystole** is no beats at all, sometimes called a "flat line" - obviously unsustainable, CPR or ACLS must be begun immediately or they will definitely die. - this is not a shockable rhythm - sometimes epi and amiodarone are given alternately - [[Commotio cordis]] is a condition that occurs specifically when one's chest is struck very forcefully at a very specific part of the cardiac cycle, throwing it into arrest. ## Antiarrhythmics **Antiarrythmics** are a type of [[medicine]] that helps the heart beat in a steady, regular way. There are five groups of antiarrythmics: - **Group I** antiarrythmics are [[sodium channel blockers]], which slow the electrical impulses of the heart. - **Group II** antiarrythmics are [[beta blockers]], which block sympathetic nervous system stimulation to the heart. - **Group III** antiarrythmics are [[potassium channel blockers]], which prolong the repolarization of the heart cell membranes. - **Group IV** antiarrythmics are [[calcium channel blockers]], which reduce the movement of calcium during action potentials. - **Group V** antiarrythmics are all the other medicines that work to help control the heartbeat. ---