Rhythm Analysis: Atrial/Junctional Flashcards

Which medication class is commonly used to achieve rate control in atrial fibrillation with rapid ventricular response?

Answer: Beta-blockers and non-dihydropyridine calcium channel blockers (diltiazem, verapamil)

Beta-blockers and non-dihydropyridine calcium channel blockers slow AV nodal conduction, reducing the ventricular response rate in AFib without necessarily converting it to sinus rhythm.

What ECG feature distinguishes atrial flutter with variable block from atrial fibrillation?

Answer: Flutter waves are organized, regular sawtooth waves at a consistent rate (250-350 bpm); AFib shows disorganized chaotic baseline (f waves) with no consistent cycle length

In atrial flutter, the atrial activity appears as organized, regular sawtooth flutter waves with a consistent atrial cycle length. AFib shows completely chaotic, disorganized atrial activity (f waves) with no consistent atrial cycle length.

A patient presents with a regular narrow-complex tachycardia at 180 bpm. P waves are inverted in leads II, III, aVF and appear just before each QRS with a very short RP interval. What is the most likely diagnosis?

Answer: AV nodal reentrant tachycardia (AVNRT) or junctional tachycardia with short VA conduction

A regular narrow-complex tachycardia at ~180 bpm with retrograde P waves (inverted in inferior leads) immediately before the QRS (very short RP interval, typically < 70 ms) is classic for the slow-fast form of AVNRT.

Which of the following best describes the term 'paroxysmal supraventricular tachycardia' (PSVT)?

Answer: An umbrella term for sudden-onset, regular narrow-complex tachycardias originating above the ventricles, including AVNRT, AVRT, and atrial tachycardia

PSVT is a general term for various tachyarrhythmias that originate above the bundle of His, begin and end abruptly (paroxysmal), and usually present as a regular narrow-complex tachycardia — most commonly AVNRT, AVRT (with accessory pathway), and atrial tachycardia.

In a patient with pre-excited atrial fibrillation (AFib in WPW), what is the characteristic ECG appearance and why is this a medical emergency?

Answer: Very rapid (>200-300 bpm), irregularly irregular, wide and bizarre QRS complexes; dangerous because the accessory pathway can conduct extremely rapidly, potentially triggering VF

Pre-excited AFib produces a wide-complex, irregularly irregular tachycardia at extremely rapid rates (>200-300 bpm) because the accessory pathway, unlike the AV node, lacks rate-limiting properties and can conduct each AFib impulse to the ventricles, risking degeneration to VF.

What ECG pattern is characteristic of type I (Wenckebach) second-degree AV block?

Answer: Progressively lengthening PR intervals culminating in a non-conducted P wave (dropped QRS), then the cycle resets

Mobitz type I (Wenckebach) second-degree AV block shows progressive PR interval lengthening with each beat until one P wave fails to conduct (dropped QRS), then the cycle repeats — the classic 'footprints in the sand' pattern.