Episode 191: Rapid Atrial Fibrillation

We go over the treatment of rapid atrial fibrillation (afib with RVR).

Hosts:

Brian Gilberti, MD

Jonathan Kobles, MD

https://media.blubrry.com/coreem/content.blubrry.com/coreem/Rapid_Atrial_Fibrillation.mp3

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Tags: Cardiology

Show Notes

Understanding AF with RVR Categories

General AF with RVR: Definition and basic understanding.

Rapid AF with Pre-excitation: Characteristics and complications.

Chronic AF in Critical Illness: Identification and special considerations.

Stability Assessment in AF with RVR

ACLS Protocols: Distinction between unstable and stable patients.

Unstable Patients: Immediate need for synchronized cardioversion, standard dose at 200 J for adults.

Stable Patients: Rate vs. rhythm control strategies, consideration of underlying etiology.

Limitations in Chronic AF: Challenges in patients with AF secondary to critical illness.

ACLS Guidelines and ECG Findings

Tachycardia with a Pulse Approach: Initial assessment guidelines.

ECG Interpretation:

Irregularly Irregular Rhythm: Absence of discernible P waves.

Ventricular Rate: Typically over 100 bpm.

QRS Complexes: Usually narrow, alterations in the presence of bundle branch block or ventricular rate-related aberrancy.

Identifying Pre-Excitation Syndromes: Signs of shortened PR interval and slurred QRS, indication of Wolff-Parkinson-White Syndrome.

AF with Pre-Excitation (WPW Syndrome)

Risk Assessment: Dangers of using AV nodal blockers (BB/CCB, digoxin, adenosine).

Alternative Management: Utilization of procainamide for stable patients, synchronized electrical cardioversion for unstable patients.

Treatment Approaches for AF Types

General Rapid AF:

First Line Agents: Metoprolol vs. Diltiazem.

Metoprolol Considerations: Dosing (5 mg every 10-15 minutes, max 15 mg), benefits in CAD and HF, limitations in asthma/COPD patients.

Diltiazem Advantages: Faster action, suitability in asthma/COPD, typical dosing (0.25 mg/kg initial, followed by 0.35 mg/kg if needed).

Critically Ill Patients: Tailoring treatment to underlying pathology, avoiding typical AF pharmacologic treatments.

Systematic Evaluation of Tachycardia Causes (TACHIES Mnemonic)

Thyrotoxicosis, Alcohol withdrawal, Cardiac issues, Hemorrhage, Intervals (WPW), Embolus, Sepsis.

Application of the mnemonic for a comprehensive approach to differential diagnosis.

Ultrasound in Diagnostic Assessment

Application in Undiagnosed Tachycardia: Identifying EF, pericardial effusion, valvular pathology, and signs of pulmonary embolism.

Fluid Status Evaluation: Use of ultrasound for assessing b-lines in lung scans.

Management of Chronic AF with HD Instability

Assessment of Hemodynamic Impact: Effects of extreme tachycardia on cardiac output, preload and afterload considerations.

Chronic vs. Paroxysmal AF: Differentiation in clinical presentation and treatment response.

Approaches in Complex AF Cases

Addressing RVR of Unclear Etiology: Targeted therapies based on suspected underlying causes.

Medication Strategies:

Amiodarone: Bolus and drip approach, slow AV nodal without significant impact on contractility.

Esmolol: Titration for heart rate control, short-acting nature allowing for rapid cessation if adverse effects are observed.

Comprehensive Patient Disposition

Considerations: Hemodynamic stability, underlying cause, comorbidities, outpatient follow-up feasibility.

Decision-Making Process: Balancing acute management with long-term treatment strategies.

Take Home Points

Differentiation in AF with RVR Types: It’s essential to distinguish between primary AF with RVR, chronic AF with RVR related to other health issues, and new-onset AF (NOAF) with RVR in critically ill patients, as each type necessitates a unique approach to treatment.

ACLS Guidelines for AF with RVR: The ACLS guidelines provide a treatment framework, particularly recommending immediate synchronized cardioversion for unstable patients. However, these guidelines may have limited effect