Cardiac Arrhythmias: Atrial

• Normal Sinus rhythm is characterized by a heart rate between 60 and 100 beats per minute

Normal Sinus Rhythm Characteristics

• The SA node initiates the impulse
• The impulse travels to the AV node in 0.12 to 0.2 seconds
• Ventricles depolarize in 0.12 seconds or less
• The impulse occurs regularly

Types of Atrial Arrhythmias

• Sinus bradycardia and sinus tachycardia originate in the sinus node
• Premature atrial contractions, supraventricular tachycardia, atrial flutter, and atrial fibrillation develop in sites outside the sinus node

Cardiac Arrhythmias: Atrial #1 - Sinus Bradycardia

• This arrhythmia proceeds normally through the conduction pathway, but at a slower rate of ≤60 beats/minute
• Healthy athletes, heart disorders, increased intracranial pressure, hypothyroidism, and digitalis toxicity can cause sinus bradycardia
• The danger is that the slow rate may be insufficient to maintain cardiac output
• Atropine sulfate, a cholinergic blocking agent, is given IV to increase a dangerously slow heart rate

Cardiac Arrhythmias: Atrial #2 - Sinus Tachycardia

• This arrhythmia proceeds normally through the conduction pathway but at a faster rate than usual, specifically 100 to 150 beats/minute
• Physiologic responses to strenuous exercise, anxiety, fear, pain, fever, hyperthyroidism, hemorrhage, shock, and hypoxemia can cause sinus tachycardia
• In premature atrial contraction (PAC), neural tissue in the atrial conduction system initiates an early electrical impulse, identified by an irregularity in the underlying rhythm
• The causes are caffeine, nicotine, other sympathetic nervous system stimulants, heart disease, metabolic disorders, and hyperthyroidism

Cardiac Arrhythmias: Atrial #5 - Atrial Flutter

• A single atrial impulse outside the SA node causes the atria to contract at an exceedingly rapid rate (200 to 400 contractions/minute)
• Atrial waves in atrial flutter have a characteristic sawtooth pattern

Cardiac Arrhythmias: Atrial #6 - Atrial Fibrillation

• Atria quiver rather than contract
• Ventricles respond to the atrial stimulus randomly, causing an irregular ventricular heart rate, which may be too infrequent to maintain adequate cardiac output
• A complication of atrial fibrillation is the formation of blood clots within the atria, leading to stroke-causing emboli if they enter the circulation

Cardiac Arrhythmias: Atrial #7 - Medical Management

• Chemical cardioversion is a medical management technique
• Heparin is prescribed initially if the arrhythmia persists longer than 48 hours, while Coumadin is used for persistent atrial fibrillation
• Dabigatran (Pradaxa), rivaroxaban (Xarelto), and apixaban (Eliquis) are newer anticoagulants
• Elective cardioversion-digitalis is used for atrial fibrillation if the ventricular rate is not too slow
• The maze procedure is a surgical management approach to restore the normal conduction pathway in the atria by eliminating the rapid firing of ectopic pacemaker sites using scar-forming techniques

Cardiac Arrhythmias: Atrioventricular - Heart Block

• Heart block, disorders in the conduction pathway, interferes with the transmission of impulses from the SA node through the AV node to the ventricles
• Heart block can be classified as first degree, second degree, or third degree (complete heart block)
• First and second-degree heart block is characterized by a delayed impulse
• In complete heart block, the atrial impulse never gets through, and the ventricles develop their own rhythm independent of the atrial rhythm, resulting in a slow ventricular rate of 30 to 40 beats/minute
• Treatment involves pacemaker insertion

Cardiac Arrhythmias: Ventricular #1

• Types include premature ventricular contractions, ventricular tachycardia, and ventricular fibrillation
• A premature ventricular contraction (PVC) is a ventricular contraction that occurs early and independently in the cardiac cycle before the SA node initiates an electrical impulse; no P wave precedes the wide, bizarre-looking QRS complex
• Assessment findings include pallor, nervousness, sweating, faintness, and a "fluttering" sensation in the chest
• Occasional PVCs may be harmless and related to anxiety, stress, fatigue, alcohol withdrawal, or tobacco use

Cardiac Arrhythmias: Ventricular #2

• Precursors of lethal arrhythmias: six or more PVCs per minute, runs of bigeminy (every other beat is a PVC), two PVCs in a row (couplets), runs of PVCs (three or more in a row), multifocal PVCs (originating from more than one location), a PVC whose R wave falls on the T wave of the preceding complex (R-on-T phenomenon)
• When dangerous PVCs occur, the client is given an IV bolus of lidocaine (Xylocaine) followed by a continuous IV infusion

Cardiac Arrhythmias: Ventricular #3 - Ventricular Tachycardia

• Single, irritable focus in the ventricle that initiates and then continues the same repetitive pattern; ventricles beat very fast (150 to 250 beats/minute), and cardiac output is decreased
• The client may lose consciousness and become pulseless depending on how long the arrhythmia is present
• Ventricular tachycardia sometimes ends abruptly without intervention but often requires defibrillation and may progress to ventricular fibrillation

Cardiac Arrhythmias: Ventricular #4 - Ventricular Fibrillation

• Rhythm of a dying heart
• PVCs or ventricular tachycardia can precipitate it; ventricles do not contract effectively, resulting in no cardiac output
• Treatment involves cardiopulmonary resuscitation (CPR) and defibrillation

Cardiac Arrhythmias #1 - Diagnostic Findings

• Monitor rhythm strip or 12-lead ECG to identify arrhythmias
• Electrophysiology study produces actual arrhythmias by stimulating structures in the conduction pathway
• Determines the best method for preventing further arrhythmic episodes; eradicates tissue in the area of the heart that is producing the arrhythmia

Cardiac Arrhythmias #3 - Medical and Surgical Management

• Defibrillation is the only treatment for a life-threatening ventricular arrhythmia
• Defibrillation Uses: pulseless ventricular tachycardia, ventricular fibrillation, and asystole (cardiac arrest) when no identifiable R wave is present
• Types: automatic external defibrillator (AED) - Most Common
• Automatic implantable cardioverter defibrillator (AICD): internal electrical device used for select clients with recurrent life-threatening tachyarrhythmias; (cardiomyopathy)
• Implantable cardioverter defibrillator (ICD)

Cardiac Arrhythmias #4 - Medical and Surgical Management

• Pacemaker: provides an electrical stimulus to the heart muscle to treat an ineffective bradyarrhythmia
• Types: demand (synchronous) mode pacemakers self-activate when the client's pulse falls below a certain level (set at 72 beats/minute)
• Fixed-rate (asynchronous) mode pacemakers produce an electrical stimulus at a preset rate (usually 72-80 beats/minute) despite the client's natural rhythm; can be permanent or temporary

Cardiac Arrhythmias #5

• Radiofrequency catheter ablation is performed
• Heated catheter tip destroys arrhythmia-producing tissue
• Potential complications include: bleeding, perforation, thrombus, pericardial tamponade

Nursing Care Plan: Client With Arrhythmia

• Nursing Diagnosis: Decreased Cardiac Output
• Maintain physical and emotional rest
• Provide supplemental oxygen