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RELIAS DYSRHYTHMIA BASIC A TEST ANSWERS 2025-2026|
VERIFIED ECG STUDY GUIDE & CORRECT ANSWER KEY (A+
GRADED)
Normal Sinus Rhythm
ECG criteria: Rate 60–100 bpm; regular rhythm; P wave before
every QRS with identical morphology (usually upright in lead II);
PR interval 0.12–0.20 s; QRS <0.12 s. P:QRS = 1:1.
Mechanism: Impulse originates in the SA node and conducts
normally through atria → AV node → His–Purkinje system.
Common causes / context: Normal baseline rhythm in healthy
people. May be seen with normal physiological responses (exercise,
anxiety).
Clinical significance: Indicates intact sinus pacemaker and
conduction. NSR itself usually needs no treatment unless rate is
symptomatic (e.g., sinus bradycardia causing syncope).
Management: None required for asymptomatic NSR; treat
symptoms or underlying cause when present (e.g., treat bradycardia if
hemodynamically unstable).
Pitfalls: Don’t assume “normal” rules out ischemia — always assess
ST/T wave changes and clinical picture.
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Atrial Fibrillation
ECG criteria: Irregularly irregular rhythm; no discrete P waves
(chaotic fibrillatory baseline); variable R–R intervals; ventricular rate
variable (slow, controlled, or rapid).
Mechanism: Multiple reentrant wavelets or focal atrial firing →
chaotic atrial activation -> ineffective atrial contraction.
Common causes: HTN, CAD/ischemia, valvular disease (esp.
mitral), thyrotoxicosis, alcohol (“holiday heart”), post-op.
Clinical significance: Loss of atrial kick → reduced cardiac output;
risk of thromboembolism (stroke) due to stasis in left atrial
appendage.
Immediate management (unstable): Synchronized cardioversion.
Management if stable: Rate control (β-blocker, diltiazem, or
digoxin), anticoagulation guided by CHA₂DS₂-VASc, consider
rhythm control (cardioversion / antiarrhythmics) or ablation
depending on duration, symptoms, and comorbidities.
Pitfalls: If AF duration >48 hrs or unknown → anticoagulate or
perform TEE to rule out atrial thrombus before elective cardioversion.
RELIAS DYSRHYTHMIA BASIC A TEST ANSWERS 2025-2026|
VERIFIED ECG STUDY GUIDE & CORRECT ANSWER KEY (A+
GRADED)
Normal Sinus Rhythm
ECG criteria: Rate 60–100 bpm; regular rhythm; P wave before
every QRS with identical morphology (usually upright in lead II);
PR interval 0.12–0.20 s; QRS <0.12 s. P:QRS = 1:1.
Mechanism: Impulse originates in the SA node and conducts
normally through atria → AV node → His–Purkinje system.
Common causes / context: Normal baseline rhythm in healthy
people. May be seen with normal physiological responses (exercise,
anxiety).
Clinical significance: Indicates intact sinus pacemaker and
conduction. NSR itself usually needs no treatment unless rate is
symptomatic (e.g., sinus bradycardia causing syncope).
Management: None required for asymptomatic NSR; treat
symptoms or underlying cause when present (e.g., treat bradycardia if
hemodynamically unstable).
Pitfalls: Don’t assume “normal” rules out ischemia — always assess
ST/T wave changes and clinical picture.
, 2|Page
Atrial Fibrillation
ECG criteria: Irregularly irregular rhythm; no discrete P waves
(chaotic fibrillatory baseline); variable R–R intervals; ventricular rate
variable (slow, controlled, or rapid).
Mechanism: Multiple reentrant wavelets or focal atrial firing →
chaotic atrial activation -> ineffective atrial contraction.
Common causes: HTN, CAD/ischemia, valvular disease (esp.
mitral), thyrotoxicosis, alcohol (“holiday heart”), post-op.
Clinical significance: Loss of atrial kick → reduced cardiac output;
risk of thromboembolism (stroke) due to stasis in left atrial
appendage.
Immediate management (unstable): Synchronized cardioversion.
Management if stable: Rate control (β-blocker, diltiazem, or
digoxin), anticoagulation guided by CHA₂DS₂-VASc, consider
rhythm control (cardioversion / antiarrhythmics) or ablation
depending on duration, symptoms, and comorbidities.
Pitfalls: If AF duration >48 hrs or unknown → anticoagulate or
perform TEE to rule out atrial thrombus before elective cardioversion.
