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COMMON DYSRHYTHMIAS

Lynne Modlin, MSN, RN
This section discusses various types of dysrhythmias, their characteristics, causes, assessments, and treatments. Each type is categorized and explained in detail.

ATRIAL (NARROW) DYSRHYTHMIAS

  • Also referred to as supraventricular tachycardia (SVT).

  • The impulse causing the dysrhythmia originates outside of the sinus node, typically from atrial tissue or the AV node.

  • Characterized by narrow complex QRS that is less than 0.12 seconds.

TERMINOLOGY

  • Valsalva Maneuver: A technique used to assess and manage certain types of tachycardia.

  • Adenosine: A medication used to convert supraventricular tachycardia to normal sinus rhythm.

  • Carotid Sinus Massage: A manual technique that can help in diagnosing and treating supraventricular tachycardia.

  • Tachycardia: A faster than normal heart rate, generally considered to be over 100 beats per minute.

  • Narrow-Complex Tachycardia: Refers to tachycardias with QRS complexes measuring less than 0.12 seconds.

  • Accessory Pathway: A pathway in the heart that can contribute to certain dysrhythmias by allowing an impulse to bypass the normal conduction system.

COMPARISONS

  • Sinus Tachycardia:

    • Rate: 25 mm/sec, 10 mm/mV

  • Supraventricular Tachycardia (SVT):

    • Lead II: 25 mm/sec, 10 mm/mV

  • Reference: Jason Winter 2016, ECG Educator.

PREMATURE ATRIAL CONTRACTIONS (PAC)

  • Definition: PACs are characterized by a premature “P” wave, which appears differently than the typical P wave generated by the SA node.

  • Two main components of PACs:

    • Abnormal P waves: Shaped differently than normal P waves.

    • Early timing: The PAC occurs before the expected sinus beat.

PAC: CAUSES & TREATMENT

  • Potential causes of PACs:

    • Stress, Fatigue, Anxiety, Excitement: Emotional and physical states can trigger PACs.

    • Stimulants: The intake of caffeine and tobacco.

    • Medications: Use of sympathomimetic drugs (e.g., catecholamines), amphetamines.

    • Electrolyte Imbalances: Conditions such as hypokalemia (low potassium) and hypomagnesemia (low magnesium).

  • Typically, no specific treatment is required unless a cause is identified. - Treatment focuses on managing underlying issues such as reducing stress, avoiding stimulants, and replenishing potassium and magnesium levels.

ATRIAL FLUTTER

  • Description: Atrial flutter involves a rapid and recurring atrial focus, often associated with a reentrant circuit within the right atrium.

  • Visual characteristics: The hallmark appearance is a sawtooth pattern (described as “picket fence”) of flutter waves observed on an ECG.

ATRIAL FLUTTER: ASSESSMENT

  • Consequences: Loss of the atrial kick, which can reduce cardiac output (CO) by 15-25%.

  • Symptoms:

    • Variability in manifestations depending on the rate of ventricular response.

    • Controlled ventricular response: Less than 100 beats per minute.

    • Rapid (uncontrolled) ventricular response: Greater than 100 beats per minute.

    • Possible presentations include palpitations, weakness, fatigue, shortness of breath (SOB), nervousness, anxiety, syncope (fainting), chest pain, heart failure, and shock.

ATRIAL FIBRILLATION

  • Definition: Atrial fibrillation (AFib) is recognized as the most common dysrhythmia.

  • ECG Characteristics:

    • Absence of identifiable P waves, replaced instead by a wavy baseline.

    • The rhythm is irregularly irregular, considered narrow.

    • Results from continuous, rapid, disorganized, chaotic discharges originating from multiple atrial foci, leading to quivering of the atria and loss of atrial kick, which may reduce cardiac output.

  • Associated Risks: Increases the risk of stroke and embolism.

ATRIAL FIBRILLATION: CAUSES

  • Common underlying conditions:

    • Hypertension (HTN)

    • Coronary Artery Disease (CAD)

    • Valvular Disease

    • Chronic Obstructive Pulmonary Disease (COPD)

    • Congestive Heart Failure (CHF)

    • Heart Surgery

    • Congenital Heart Disease

    • Hyperthyroidism

  • Noteworthy anatomical involvement: The left atrium is often the site of clot formation, particularly in the appendage, which plays a role in the pathophysiology of AFib.

ATRIAL FIBRILLATION: TREATMENT

  • Objective: Control the heart rate first, then convert the rhythm, with treatment options including:

    • Medications:

    • Digoxin

    • Amiodarone

    • Beta blockers

    • Ibutilide

    • Anticoagulant Therapy:

    • Heparin

    • Enoxaparin

    • Warfarin (target INR 2-3)

    • Procedures:

    • Synchronized cardioversion

    • Radiofrequency ablation

CHECKPOINT QUESTIONS

  • Identify the hallmark sign of atrial fibrillation from the given options:

    • A. Sawtooth pattern

    • B. Irregularly irregular rhythm

    • C. Pauses

    • D. Absence of P waves

    • E. Widened QRS

  • What is the distinguishing factor of atrial flutter?:

    • A. Sawtooth pattern on the baseline

    • B. Wide QRS complexes

    • C. The patient is pulseless.

    • D. Possible hypotension

    • E. Ventricular ectopic foci

  • Rate comparison for controlled atrial fibrillation and atrial flutter:

    • A. 40-60 bpm

    • B. Between 60-100 bpm

    • C. Greater than 100 bpm

    • D. They do not have the same controlled rate

PREMATURE VENTRICULAR CONTRACTION (PVC)

  • Description: PVCs occur from an irritable focus in the ventricles.

  • ECG Characteristics:

    • No P wave observed.

    • QRS complex is wide (> 0.12 seconds) and appears bizarre.

    • Can be classified as unifocal or multifocal, with variations:

    • Singles or couplets.

    • Bigeminy: PVCs occurring every other heartbeat.

    • Trigeminy: PVCs occurring every third heartbeat.

PVCs: CAUSES

  • Generally common in healthy hearts, but the incidence increases with age.

  • Identified causes include:

    • Ischemia and Acidosis: Related to myocardial infarction (MI) and coronary artery disease (CAD).

    • Stimulants: Smoking, alcohol, caffeine, and stress can provoke PVCs.

    • Medications: Unwanted effects of digoxin toxicity.

    • Electrolyte Imbalances: Such as hypokalemia and hypomagnesemia.

    • Notably, PVCs are a common reperfusion dysrhythmia following MI.

“SIGNIFICANT” PVCs

  • Defined by certain criteria:

    • PVCs that develop within the first four hours of an MI are deemed significant.

    • Frequent PVCs (e.g., six or more per minute) are also concerning.

    • Multifocal PVCs and R-on-T phenomenon (where PVCs occur on the T wave) are additional indicators of significance.

    • Other forms such as bigeminy or couplets may also be noted.

PVCs - TREATMENT

  • Typically, if PVCs are not deemed significant, management focuses on identifying and removing contributing factors (like caffeine and stress).

  • For hypomagnesemia, magnesium sulfate is administered, while potassium is given for hypokalemia.

  • Other treatments include:

    • Oxygen therapy

    • Amiodarone (preferred)

    • Lidocaine (less preferred due to potential side effects)

VENTRICULAR TACHYCARDIA (VTACH)

  • Types of VTach: Runs of VTach, Monomorphic VT, Polymorphic VT.

  • Visual: Example from Lead II was noted with certain parameters (25 mm/sec, 10 mm/mV).

VTACH - TREATMENT

  • Treatment protocols vary whether the patient has a pulse or not:

    • For Positive Pulse:

    • Obtain a 12 Lead EKG, evaluate heart monitor.

    • Administer defibrillator or pacemaker in demand mode.

    • Utilize Amiodarone, Atenolol.

    • For Negative Pulse:

    • Activate Rapid Response Team: Code.

    • Shockable rhythm management required.

    • Identify causes: H’s and T’s which include hypoxia, hypovolemia, hydrogen ion imbalance, hypothermia, electrolyte imbalances (hypokalemia or hyperkalemia), toxins (drugs), tamponade, tension pneumothorax, thrombosis.

VENTRICULAR FIBRILLATION (VFIB)

  • Management protocols similar to that for VTach.

  • For Negative Pulse:

    • Rapid Response measures: Code.

    • CPR is essential.

    • Medications such as Epinephrine, Amiodarone, and Lidocaine may be administered.

ASYSTOLE

  • Characteristics: Heart rhythm with no electrical activity and no pulse.

ASYSTOLE - TREATMENT

  • Protocol: Check for pulse, expected response is negative.

  • Response includes:

    • Rapid Response: Code.

    • Administer Epinephrine while simultaneously identifying causes similar to those in VTach and VFib (H’s and T’s).

NURSING CONSIDERATIONS

  • Potential nursing diagnoses and desired outcomes should be identified in conjunction with high-priority interventions.