Atrial Dysrhythmias

Junctional or Premature Atrial Complex (PAC)

  • Interchangeable terms.

Paroxysmal Atrial Tachycardia (PAT)

  • Also known as Supraventricular Tachycardia (SVT).
  • PAT and SVT are often used interchangeably because their heart rates are similar.
  • In PAT, the P wave to P wave is measured, while in SVT, the R to R is measured.
  • Clinically, SVT is more commonly discussed.

Case Study

  • A patient had SVT for six minutes.
  • Adenosine IV push was administered, converting the SVT to rapid atrial fibrillation (A-fib).
  • Amiodarone drip was then given.
  • Eventually, the patient converted to sinus rhythm with a heart rate in the high 90s.
  • Pattern: SVT -> Rapid A-fib -> Sinus Rhythm.

Atrial Dysrhythmias

  • Includes atrial fibrillation and atrial flutter.
  • Characterized by increased automaticity in the atrium, resulting in increased electrical activity.
  • This primarily affects the P waves.
  • In A-fib, P waves are absent.
  • In atrial flutter, flutter waves (F waves) or sawtooth patterns are observed instead of P waves.
  • Possible causes of atrial dysrhythmias include:
    • Digoxin toxicity
    • Electrolyte imbalance
    • Pericarditis
    • Atrial injury

Premature Atrial Complex (PAC)

  • Premature beats do not occur with every single beat.
  • In a six-second strip (30 big boxes), the underlying rhythm may be sinus rhythm.
  • R to R interval is usually regular in the underlying rhythm.
  • P waves are present, and the PR interval is normal.
  • QRS complex is generally normal.
  • The rhythm is irregular only where the PAC occurs.
  • PAC involves a single contraction occurring earlier than expected.
  • Normally, the heart rests after the T wave, and the SA node initiates the next impulse.
  • In PAC, an irritated focus in the atrium fires prematurely.
  • This premature contraction occurs beside the T wave.
  • The distance following the premature P wave (QRST) is wider because of the early impulse.
  • The rhythm resumes its normal pattern unless another PAC occurs.
  • Interpretation: "Sinus rhythm with X number of PACs."
  • Etiology: Electrolyte imbalance.
  • Treatment: Replace electrolytes.
  • PACs can occur sporadically within a normal sinus rhythm.
  • The interval after the PAC will be wider.
  • Treatment is only necessary if the patient is symptomatic.
  • Frequent PACs should be reported as they can affect cardiac output.
  • If the presence of a p wave is unclear next to a T wave, compare the height of the T waves to others in the strip. A taller T wave suggests a P wave is present within it.

Non-Conducted PAC

  • PQRST complexes are present, indicating sinus rhythm.
  • A taller T wave indicates a P wave is hidden within it, signifying a premature atrial contraction.
  • However, the QRS complex is missing after the P wave.
  • This occurs because the premature P wave contracts so quickly that the impulse to the ventricle is dropped, resulting in a dropped beat.
  • The impulse does not reach the ventricles.
  • Important not to confuse with sinus block or sinus arrest, where the entire PQRST complex is absent.

Wandering Atrial Pacemaker (WAP)

  • The pacemaker site shifts from the SA node to other atrial or AV junction sites, then back.
  • Irritated foci cause different P wave shapes.
  • Latent pacemaker sites can fire, causing variations in P wave morphology.
  • A normal P wave originates from the SA node, whereas an inverted P wave may originate from the AV junction.
  • More than two different P wave shapes indicate a wandering atrial pacemaker.
  • Cannot be called sinus rhythm because impulses do not originate exclusively from the SA node.
  • Rhythm can be irregular, depending on the presentation.
  • May occur in healthy individuals due to fluctuations in vagal tone or in patients with cardiac illnesses or COPD.

Paroxysmal SVT

  • Paroxysmal refers to sudden, abrupt onset and cessation.
  • Paroxysmal SVT involves an abrupt start and stop of rapid heart rate.
  • The impulse is rerouted repeatedly at a fast rate in the AV node area.
  • Causes include alcohol, anxiety, hypoxemia, and caffeine.
  • Can lead to decreased cardiac output, indicated by lightheadedness, palpitations, and hypotension.
  • Underlying pathophysiology may involve CAD or cardiomyopathy.
  • Heart rate ranges from 150 to 250 beats per minute.
  • If the paroxysmal SVT becomes sustained, continuous treatment is necessary.
  • P and T waves appear together due to the rapid heart rate, making it difficult to distinguish the PR interval.

SVT Management

  • Assess vitals, administer oxygen, and lower the head of the bed if hypotensive.
  • Assess for chest pain, which may occur due to altered oxygen flow at heart rates above 150 or below 50.
  • Perform a 12-lead EKG.
  • Assess level of consciousness.
  • Vagal maneuvers may be performed for heart rates above 160 bpm.
  • Medications, such as adenosine, may be administered to stop the heart momentarily.
  • Adenosine is given as a rapid IV push (2-3 seconds) followed by a 20 mL normal saline flush.
  • If no conversion within 2 minutes, a second dose of adenosine (12 mg) may be given.
  • If medications are ineffective, synchronized cardioversion may be necessary.
  • Post cardioversion medications: amiodarone drip, beta-blockers (metoprolol), calcium channel blockers (diltiazem).
  • Synchronized cardioversion involves delivering a shock synchronized with the R wave of the QRS complex to avoid causing more dangerous dysrhythmias.
  • TEE (Transesophageal Echocardiogram) is performed to assess for clots in in the valves of the heart, before cardioversion.
  • If the patient becomes pulseless during synchronized cardioversion, switch to defibrillation.
  • Important to turn the knob on the defibrillator to "sync" mode before cardioversion.

Supraventricular Tachycardia (SVT)

  • A SVT will start and stop abruptly.

Atrial Fibrillation (A-Fib)

  • Characterized by quivering of the atrial muscle, resulting in the absence of P waves.

  • Rapid, erratic electrical discharge from multiple areas in the atrium.

  • Fibrillatory waves are present instead of P waves.

  • Hallmarks: absence of P waves and irregularly irregular rhythm.

  • Paroxysmal A-fib: occurs suddenly and reverts to normal rhythm.

  • Persistent A-fib: continuous.

  • Controlled A-fib: heart rate less than or equal to 100 bpm.

  • Uncontrolled A-fib (A-fib with RVR): heart rate greater than 101 bpm.

  • Ventricular rate is the primary concern.

  • Patients at risk for clot development are often prescribed blood thinners.

  • A-fib can be a complication of heart failure.

  • Carries a risk for decreased cardiac output and embolic stroke (90% cardiac-related).

  • Treatment and management:

    • Establish IV access.
    • Administer medications to strengthen contractility and lower heart rate (beta-blockers, calcium channel blockers, amiodarone).
    • Ablation (radiofrequency or cryoablation) may be performed to eliminate irritated foci.
    • Synchronized cardioversion.

  • After meds if the patient doesn't convert back into normal: ablation of the area, cardioversion.
    Example Case:

    • Patient with a history of A-fib presenting with palpitations after heavy drinking.
    • Treated with diltiazem drip but did not convert.
    • Underwent TEE to rule out blood clots, then proceeded with synchronized cardioversion.

  • Clear the patient and state ''CLEAR'' prior to shocking the patient as accidental shock can affect other individuals or cause death.

  • Controlled A-fib: less than 100 bpm. Uncontrolled A-fib with RVR: More than 100 bpm.

Atrial Flutter

  • Flutter waves (sawtooth pattern) instead of P waves.

  • A flutter can have rounded atrial flutter waves.

  • Atrial rate is typically fast, ranging from 250 to 350 bpm, but the ventricular rate is the primary concern.

  • No P waves and, therefore, no PR interval.

  • QRS complex is typically normal.

  • Regular vs. Irregular Rhythm:

    • Regular rhythm occurs when there is a consistent AV conduction ratio (e.g., 4:1).
    • Irregular rhythm occurs with a variable AV conduction ratio.

  • An irritated focus creates a circular pattern, causing flutter waves.

  • Asymptomatic patients with controlled rates may not require treatment beyond monitoring and maintenance medications.

  • Medical interventions include medications, ablation, and cardioversion.

Wolff-Parkinson-White (WPW) Syndrome

  • Accessory conduction pathway between atria and ventricles can cause rapid conduction.

  • Characterized by:

    • Short PR interval

    • Wide QRS complex

    • Delta wave (slurred upstroke of the QRS complex)

  • Can cause rapid heartbeat.

  • Treatment involves medications or ablation.

Key Points

  • Most important information to remember: Assess the patient, do the things you are suppose to do (Vitals, IV Access) and if things are not improving: Call the doctor.