18.2: Dysrhythmias II: Classification of Tachyarrhythmias

Tachyarrhythmias are a type of dysrhythmia where the heart rate exceeds 100 beats per minute. Here are some common types of tachyarrhythmias:

Sinus Tachycardia

Sinus tachycardia originates from increased impulses from the sinus node, leading to an elevated heart rate. It is often triggered by stress, fever, or exercise.

Patients may experience palpitations, a sensation of a racing heart, dizziness, and chest discomfort.

Causes and Risk Factors: Common causes include physical exertion, emotional stress, fever, dehydration, anemia, and hyperthyroidism. It is generally a normal physiological response but can also indicate underlying health issues.

Premature Atrial Contractions (PACs)

PACs are early heartbeats initiated by an ectopic focus within the atria, resulting in sensations of skipped beats or palpitations.

Causes and Risk Factors: PACs can be caused by stress, stimulants such as caffeine or nicotine, alcohol consumption, or underlying lung disease. They are generally benign and can occur in otherwise healthy individuals.

Atrial Flutter

Atrial flutter is caused by a conduction defect in the atrium. This defect leads to a rapid and regular atrial impulse that often exceeds the A-V node's conduction capacity.

Patients typically present with palpitations, fatigue, and shortness of breath. There is an increased risk of thromboembolism, particularly stroke.

Causes and Risk Factors: It is often associated with valvular disorders, structural heart disease, such as coronary artery disease, and post-operative conditions.

Atrial Fibrillation (AF)

Atrial fibrillation is characterized by chaotic atrial signals leading to irregular and often fast heartbeats. It poses a risk for stroke due to potential thrombus formation in the atria.

Symptoms range from none to severe, including palpitations, fatigue, dizziness, and shortness of breath. Some patients may experience chest discomfort.

Causes and Risk Factors: It is Commonly linked to heart disease, hypertension, diabetes, hyperthyroidism, and alcohol use. AF significantly increases the risk of thromboembolism, especially stroke.

Paroxysmal Supraventricular Tachycardia (PSVT)

Sudden rapid heartbeats characterize PSVT due to abnormal electrical pathways above the ventricles.

Symptoms include a sudden onset of rapid heartbeat, dizziness, shortness of breath, and chest discomfort.

Causes and Risk Factors: It can be triggered by stress, stimulants, or pre-existing accessory pathways like AV nodal reentrant tachycardia (AVNRT) or AV reentrant tachycardia (AVRT).

Ventricular Tachycardia (VT)

Ventricular tachycardia occurs when the ventricles beat uncontrollably fast, often due to previous heart damage, such as a myocardial infarction.

Patients may experience palpitations, chest pain, dizziness, or syncope. VT can lead to hemodynamic instability and, in severe cases, cardiac arrest.

Causes and Risk Factors: VT is commonly associated with ischemic heart disease, cardiomyopathies, and electrolyte imbalances.

Ventricular Fibrillation (VF)

Ventricular fibrillation involves disorganized electrical activity in the ventricles, severely disrupting blood circulation. VF typically leads to sudden collapse, loss of consciousness, and pulselessness, requiring immediate medical intervention.

Causes and Risk Factors: Often a result of acute myocardial infarction, severe heart disease, or significant electrolyte imbalances.