Arrhythmia Associates LLP

About Arrhythmias - Types

Types

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Originating in the Upper Chambers		Originating in the Lower Chambers
Bradycardia - Sick Sinus Syndrome - Heart Block Tachyarrhythmia - Atrial Fibrillation - Atrial Flutter - Atrial Premature Contractions (APC) - Atrial Tachycardia - Atrioventricular Reciprocating Tachycardia - AV Nodal Reentrant Tachycardia (AVNRT) - Inappropriate Sinus Tachycardia - Wolff-Parkinson-White Syndrome		- Ventricular Premature Complexes (VPC) - Ventricular Tachycardia - Ventricular Fibrillation - Sudden Cardiac Arrest - Congenital

Arrhythmias Originating in the Upper Chambers

Bradyarrhythmias

Bradycardia occurs when the heart rate is too slow, (usually less than 60 beats per minute), not enough oxygen is pumped to the body. The lack of oxygen causes symptoms such as dizziness, extreme tiredness, shortness of breath, or fainting. Bradycardia is when a heart rate is too slow and symptoms occur.

The heart can beat too slowly for several reasons.

Sick Sinus Syndrome (or Sinus Node Dysfunction) is when the heart's natural pacemaker (sinus node) sends electrical signals too slowly.

Sick Sinus Syndrome is a failure of the heart's primary natural pacemaker, the sinus node, which controls the rhythmic contractions of the heart. Fortunately, the body has additional (albeit slower) natural pacemaker cells but they are generally insufficient and people develop symptoms. As a result, the heart beats slow and irregular. Sometimes the rate changes back and forth between a slow rate (bradycardia) and a fast rate (tachycardia). Symptoms are palpitations, lightheadedness and shortness of breath. When patients develop symptoms in the setting of Sick Sinus Syndrome, the recommendation is often made to implant a pacemaker to better control the heart rate.

Heart Block occurs when there is a partial or complete block of the heart's electrical pathways between the atrium and the ventricles, resulting in a slow, unreliable heart rhythm. Many patients develop symptoms such as lightheadedness, syncope, shortness of breath. In the setting of profoundly slow heart rates or symptoms related to slow heart rates, a pacemaker is often recommended.

Tachyarrhythmias

Atrial Fibrillation is the most common arrhythmia in adults, especially in elderly patients. As atrial fibrillation is a very common arrhythmia, we have included it in a special section. Please refer to Management of Atrial Fibrillation for more specific details.

In general, atrial fibrillation is characterized as a rapid chaotic rhythm that originates from multiple sites within one or both atrial chambers. Small circuits simultaneously exist throughout the atrial chambers in a dynamic changing pattern. These circuits give rise to rapid impulses that bombard the connection between the top and bottom chambers of the heart, the AV node. The AV node serves as a natural "land bridge" to protect the bottom chambers (the ventricles) from being exposed to very rapid stimulation, which could be dangerous. Only some of these impulses can get through the AV node. Nonetheless, the ventricles will be stimulated in a more rapid fashion than normal and the pattern will be irregular and the irregularity of the rhythm is often symptomatic.

Symptoms of atrial fibrillation include palpitations, rapid heart-beat , chest discomfort, shortness of breath and dizziness. Contributing to the symptoms is the failure of the atria and the ventricles to have coordinated pumping action as they do in the normal situation, which can also lead to a less efficient cardiac pump. In some individuals, failure of the atrial chambers to contract properly can make them more prone to the formation of clot that can travel to distant organs where they may cause damage.

Treatment: Antiarrhythmic drugs are sometimes sufficient treatment for atrial fibrillation and are often used as a first line of therapy. In patients with normal structural heart function and recurrent intermittent atrial fibrillation, catheter ablation of atrial fibrillation may be used. In appropriate patients, atrial fibrillation ablation is curative in 70-80% of cases. In some patients, a surgical MAZE procedure may be recommended instead. A cardiothoracic surgeon performs this procedure. In certain cases, an implanted pacemaker (in conjunction with ablation of AV node) is used to control the heart rate.

Atrial Flutter also involves rapid firing of the electrical impulse as in atrial fibrillation, but the rhythm or heart-beat is more regular or organized. The rhythm is due to a circuit (reentry) within the atria and it is likely curable with catheter ablation. The electrical impulse travels in circles arriving back at the same point, usually around 300 times per minute. Signs and symptoms often experienced with atrial flutter are similar to those of atrial fibrillation, such as a pounding heart rate or pulse, shortness of breath, or dizziness.

The treatment for atrial flutter in most patients is catheter ablation, which is curative in over 90 percent of cases. Antiarrhythmic drugs are only sometimes successful in treating atrial flutter but are sometimes used for unusual forms of atrial flutter.

Atrial Premature Contractions (APC) are a common heart rhythm disorder that involves a premature firing of cells within the atrium. These premature beats often cause the sensation of an irregular heartbeat. Symptoms often include palpitations and fluttering. APC is generally a benign condition; however, some patients may experience symptoms that require medical therapy. In very rare circumstances, symptomatic APC's may require catheter ablation in highly symptomatic patients.

Atrial Tachycardia is an electrical circuit originating in the upper or atrial chambers. This electrical circuit or focus takes over and generates rapid impulses across the atrial chambers. These impulses are transmitted to the ventricular chambers resulting in a rapid rate. This arrhythmia may originate from a variety of places across the atria and are often associated with patients who had previous cardiac surgery. They may exist as an isolated problem or be related to an ongoing structural problem within the heart.

Antiarrhythmic drugs are sometimes sufficient treatment for atrial tachycardia. In some cases, cardiac ablation is needed to cure this condition.

Atrioventricular Reciprocating Tachycardia Patients who have this arrhythmia are often young and otherwise healthy at the time this diagnosis is made. This type of arrhythmia involves "accessory pathway," which is an extra electrical pathway from the atria to the ventricles. This accessory pathway allows electrical impulses to be transmitted rapidly, thus creating a circuit leading to a rapid arrhythmia. Atrioventricular reciprocating tachycardia is similar to Wolff-Parkinson-White (WPW) Syndrome in that the abnormal electrical pathway bypasses the AV node. The difference, however, between WPW and this condition is that the abnormalities do not show up on a patient's resting EKG. The most common symptoms people experience is palpitations, dizziness, and chest discomfort. Some patients are misdiagnosed as having "panic attacks."

The standard treatment for this arrhythmia is catheter ablation, which is curative in more than 95 percent of patients. Rarely, certain forms of drug therapy will be used in lieu of ablation.

AV Nodal Reentrant Tachycardia (AVNRT) AV nodal reentrant tachycardia is the most common form of paroxysmal supraventricular tachycardia or PSVT in young, healthy patients. Patients afflicted with this arrhythmia do not usually have other structural problems with their heart. The arrhythmia originates in the tissues near the AV node, the electrical structure that transmits impulses between the upper and lower chambers of the heart. Susceptible individuals will have two pathways that can channel impulses to and from the AV node. Under the right conditions, usually following a premature beat, these pathways can form an electrical circuit. An impulse will revolve around this circuit and each revolution will lead to impulse propagation to the atria and the ventricles, and thus a rapid heart-beat results.

The standard treatment for this arrhythmia is catheter ablation, which is curative in more than 95 percent of patients. Rarely, certain forms of drug therapy will be used in lieu of ablation.

Inappropriate Sinus Tachycardia originates in the sinus node and is characterized by an abnormally fast heart rate greater than 100 beats per minute for prolonged periods of time. Symptoms are palpitations, fatigue, and lightheadedness.

The standard treatment for this arrhythmia begins with common antiarrhythmic medications that may be used alone or in combination. Occasionally, catheter ablation will be recommended for highly symptomatic patients who do not respond to medications.

Wolff-Parkinson-White Syndrome (WPW) Many patients with WPW syndrome are otherwise healthy and often quite young when this arrhythmia is diagnosed. This type of arrhythmia involves an extra electrical pathway from the atria to the ventricles. Known as the "accessory pathway," electrical impulses may be transmitted rapidly via this pathway and the rapid rhythm sometimes can be dangerous. Other times, the pathway allows a circuit to form leading to a rapid arrhythmia. The most common symptoms people experience with WPW syndrome are palpitations, dizziness, and chest discomfort. Some people with WPW do not have arrhythmias and the abnormality is identified during a routine ECG recording. The standard treatment for this arrhythmia is catheter ablation, which is curative in more than 95 percent of patients. Rarely, certain forms of drug therapy will be used in lieu of ablation.

Arrhythmias Originating in the Lower Chambers

Ventricular Fibrillation is a potentially fatal arrhythmia characterized by rapid, disorderly contraction of the ventricles. This arrhythmia can occur in the setting of a heart attack or can sometimes occur from drug toxicity. Rarely, patients with intrinsic genetic electrical heart problems are prone to this dangerous arrhythmia. If immediate defibrillation is not administered when this occurs, blood pressure cannot be maintained and death will occur. Symptom is usually syncope.

The treatment for patients with this dangerous arrhythmia included immediate cardiac defibrillation. Unless a clear reversible cause of this arrhythmia is identified, most patients who survive this arrhythmia will require implantation of a permanent cardiac defibrillator.

Ventricular Premature Complexes (VPC) An extra beat originating from the ventricles is called a VPC and is an extremely common arrhythmia. In patients with normal hearts, this is a benign condition. However, in patients with an underlying heart disorder, this can indicate a life-threatening problem. Patients are often symptomatic with palpitations or skipped beats.

The treatment of VPC's is determined by the presence of any structural heart disease. In patients with normal hearts, asymptomatic VPC's generally do not require treatment; however, some patients may experience symptoms that require medical therapy. Cardiac ablation is successful in curing this condition when these extra beats arise in the right side of the heart. If significant heart dysfunction is suspected, then an electrophysiology study is recommended to determine whether a life threatening abnormal heart rhythm is present, which may require treatment with an ICD.

Ventricular Tachycardia is an arrhythmia that originates in the pumping chambers, or the ventricles. It is usually seen in patients who have damaged ventricular chambers, frequently in the aftermath of a heart attack or myocardial infarction. Scar tissue in the ventricles will alter many local electrical properties and set up conditions favorable to formation of a local electrical circuit. Under specific circumstances, the circuit can be activated leading to a rapid arrhythmia arising from within the pumping chambers. As this is always more rapid than the heart's natural electrical activity, it takes over the heart-beat for the duration of the arrhythmia. Due to the fact that this rhythm is usually very fast and occurring in damaged chambers, the heart may not function properly or efficiently and low blood pressure of fainting may result. In its most extreme form, ventricular tachycardia can lead to fatal consequences. This is a potentially dangerous arrhythmia that almost always requires therapy.

In some patients, ventricular tachycardia may occur when there is no structural heart disease. This "idiopathic" form often arises from the right ventricle and less often from the left ventricle. These arrhythmias are less dangerous, but also often require therapy.

Treatment: In symptomatic patients with normal hearts, VT can be cured with cardiac ablation. In those with a history of heart disease, an ICD, possibly combined with medical therapy, is required to control the condition. Patients with recurrent episodes who are not controlled with medications need cardiac ablation.

Sudden Cardiac Arrest (SCA) Sudden cardiac arrest is when the heart's lower chambers (ventricles) suddenly develop a rapid, irregular rhythm (ventricular fibrillation) and the quivering ventricles cannot pump blood to the body. Within seconds, the person will not have a pulse and will be unconscious. Without immediate treatment, the condition is usually fatal.

Sudden cardiac arrest is not a heart attack, which is a problem with the plumbing of the heart; when blockage of one or more coronary arteries results in heart muscle damage. .

There are no prior symptoms of sudden cardiac arrest. However, these risk factors have been identified as increasing the risk of sudden cardiac arrest.

Previous sudden cardiac arrest episode
Previous Heart Attack
Heart Failure
Family history of sudden cardiac arrest
History of heart disease or heart rhythm disorders

Treatment begins with cardiopulmonary resuscitation (CPR) {emergency measures to keep the blood flowing to the vital organs of the body}. An external defibrillator is needed to reset the heart rhythm. After the heart is in a normal rhythm, medications and an implantable defibrillator are usually prescribed.

Congenital / Inherited Arrhythmias

There are several forms of arrhythmia that are inherited in families. This is an active area of research and this may have an effect on treatment in the future. It is possible that in the future we will identify genetic components to many clinical arrhythmias. There are several types of congenital arrhythmias that we see in our clinical practice today. Let's discuss some of them briefly.

Long QT Syndrome
For many years, patients with normal heart function were identified that were much more prone to dangerous ventricular arrhythmias. Recently, scientific advances have given us further insight about this mystery. While questions about this syndrome remain, we have identified genetic mutations that affect the conduction system. In particular, these genetic mutations affect the way that the heart cells electrically "reset themselves" and this process is called repolarization. It seems that people with this syndrome have abnormal repolarization and this makes them particularly prone to sudden, dangerous arrhythmias from the bottom of the heart called ventricular tachycardia (see ventricular tachycardia). A variety of genetic mutations have been identified so far and some of these genetic mutations appear to be inherited in families. However, some of these genetic mutations do not seem to be inherited and seem to occur spontaneously.

The diagnosis of long QT syndrome is sometimes very difficult to make. It is often initially suggested when a young, healthy patient passes out (see syncope) and a review of an electrocardiogram or ECG, which has very specific findings to suggest the diagnosis. There are other methods to confirm this diagnosis and your physicians at Arrhythmia Associates can discuss this with you at length. In general, patients who have passing-out spells (syncope) and are diagnosed with long QT syndrome benefit from placement of a internal cardiac defibrillator (see ICD implantation).

Hypertrophic Cardiomyopathy
This is an inherited process where the heart muscle thickens in an unusual way. The lower chamber of the heart (ventricle) seems to become very thick or hypertrophied for no clear reason. Additionally, this hypertrophy is seen more on one side of the heart called the interventrcicular septum. This abnormality can sometimes affect young, healthy people and can cause dizziness or syncope. Dizziness can occur because the blood cannot move efficiently through the heart but may also be due to dangerous heart arrhythmias such as ventricular tachycardia.

The diagnosis of hypertrophic cardiomyopathy is generally made when a young, healthy patient describes dizziness and an electrocardiogram (ECG) is obtained that suggests that the heart muscle is inappropriately thickened. A cardiologist can then obtain an echocardiogram of the heart muscle that uses ultrasound to visually image the heart muscle to confirm this diagnosis. Sometimes patients with hypertrophic cardiomyopathy have about_symptoms.htm#palpitationspalpitation. A holter monitor test might be used to evaluate for arrhythmia problems. These patients sometimes are found to have atrial fibrillation and this is frequently treated with medications. Some patients with hypertrophic cardiomyopathy are found to have ventricular arrhythmias. In general, patients with hypertrophic cardiomyopathy who have ventricular arrhythmias benefit from placement of a internal cardiac defibrillator (see ICD implantation).

Brugada Syndrome
In the 1970's refugees from Laos in Southeast Asia immigrated to the United States. In regions of the United States with large Laotian immigrant population, it was noted that a surprising number of young children were dying in their sleep. Throughout Southeast Asia, there are numerous words to describe this "sleeping death." Subsequent research by a cardiologist named Ramon Brugada in the 1990's identified unusual patterns of the electrocardiogram or ECG that appears to correlate with this syndrome. This syndrome is now called Brugada Syndrome. While very little is known about this condition, the diagnosis of Brugada Syndrome is generally made in a patient who describes dizziness/syncope and who demonstrates very specific ECG findings. If this diagnosis is made, the physicians at Arrhythmia Associates generally recommend protecting the patient with an internal cardiac defibrillator or ICD.