Arrhythmias Overview

Arrhythmias

• Arrhythmia is an irregular heartbeat
• Prepared by Dr. Rebar Y. Abdullah, Assistant Professor, University of Duhok- College of Nursing, PhD Family and Community Health
• The SA node is the heart's primary pacemaker, generating impulses at 60-100 bpm.
• The AV node acts as a backup pacemaker, firing at 40-60 bpm if the SA node fails.
• Bundle branches divide into right and left, activating at 30-40 bpm.
• Purkinje fibers activate at 30-40 bpm.
• The electrical functions of the heart are influenced by sodium, calcium, potassium, and magnesium.
• Sinus tachycardia is a faster-than-normal heartbeat (>100 bpm) originating from the SA node.
• Causes of sinus tachycardia include exercise, anxiety, fever, hypoxemia, hypovolemia, or cardiac failure.
• Sinus bradycardia is slower than normal (<60 bpm) originating from the SA node.
• Causes of sinus bradycardia can include drugs, vagal stimulation, hypoendocrine states, hypothermia, or sinus node involvement in MI.
• Atrial fibrillation (A-Fib) is uncontrolled electrical activity in the atria, causing a rapid and irregular heartbeat.
• Atrial fibrillation often has a rate greater than 100 bpm, with an irregular rhythm
• Symptoms of atrial fibrillation often include fatigue, dizziness, or syncope
• Types of causes include after heart surgery, heart problems, COPD, or sleep apnea
• Treatment for atrial fibrillation depends on the patient's stability and symptoms.
• In stable patients, monitoring heart rate less than 100 bpm is important
• Unstable patients who have dropped blood pressure, reduced cardiac output, and an uncontrolled heart rate (over 100 bpm) require synchronized cardioversion.

Supraventricular Tachycardia (SVT)

• An arrhythmia with a rapid rate, making P waves hard to see.
• Rate is 150-250 bpm; rhythm regular; P waves usually buried in preceding T waves and hard to see; PR interval is usually not measurable; QRS is normal (0.06-0.10 sec) but may be wide if conducted abnormally.
• Causes include caffeine, nicotine, stress, or anxiety for healthy adults.
• Some patients may experience angina, hypotension, lightheadedness, palpitations, or intense anxiety.
• Management involves vagal maneuvers, intravenous beta-blockers, diltiazem, verapamil (class II), or synchronized cardioversion.

Vagal Maneuvers

• Physical actions to slow heart rate.
• Actions include coughing, bearing down, and raising one's legs to 45 degrees.
• Avoid in patients with low blood pressure, chest pain, shortness of breath, or oxygen shortages.

Cardioversion

• A procedure to reset the heart rhythm using electrical energy.

Catheter Ablation

• A procedure to destroy abnormal heart tissue causing arrhythmias.
• Uses thin, flexible tubes (catheters) inserted through a blood vessel

Atrioventricular (AV) Blocks

• Conduction defects within the AV junction, impairing AV node function.
• First-degree AV block: Slowing of electrical signal through the AV node; prolonged PR interval (usually >0.20 seconds); rate typically <60 bpm; QRS complex and rhythm is normal.
• Second-degree AV block Mobitz Type I (Wenckebach): Gradual lengthening of PR intervals until an atrial impulse is not conducted; rate is usually <60 bpm; pattern is regular until dropped QRS complexes; ventricular rhythm is irregular.
• Second-degree AV block Mobitz Type II: Constant PR interval, with occasional dropped QRS complexes; rate varies; ventricular rhythm is irregular.
• Third-degree/complete AV block: Electrical signal from atria doesn't reach ventricles; P waves and QRS complexes are independent; ventricular rate is often <40 bpm and irregular.

Ventricular Fibrillation (V-Fib)

• Rapid, chaotic ventricular rhythm, with no cardiac output or pulse.
• No P waves, QRS complexes, T waves, or PR intervals can be seen.
• Causes often include heart disease, low/high potassium levels, hypoxia, and drug overdose.
• Treatment is emergency CPR, oxygen, defibrillation, epinephrine, and antiarrhythmic medications.

Pacemakers

• Single chamber pacemakers stimulate only the lower right ventricle.
• Dual chamber pacemakers stimulate both the upper and lower right ventricles.
• Biventricular pacemakers (cardiac resynchronization therapy) stimulate both ventricles to help with heart failure.

This quiz provides an overview of arrhythmias, focusing on the electrical functions of the heart and various types of irregular heartbeats. It covers topics such as the role of the SA node, AV node, and other pacemakers, as well as conditions like sinus tachycardia and bradycardia. Test your knowledge on the causes and mechanisms behind these cardiac events.