ECG- INTERPRETATION WITH 100% CORRECT ANSWERS.

Normal PR segment length 0.12 - 0.2 sec 3 - 5 small boxes Normal QRS interval 0.06 - 0.1 sec 1 - 3 small boxes Brainpower Read More Previous Play Next Rewind 10 seconds Move forward 10 seconds Unmute 0:02 / 0:15 Full screen Normal QT interval 40% of cardiac cycle Normal P amplitude & duration < 0.12 sec (3 small boxes) < 0.25 mV (2.5 small boxes) Positive P waves in? left lateral (I, aVL, V5, V6) & inferior (II, III, aVF); usually most positive in II & most negative in aVR Often biphasic P in? III, V1 Tall R waves in? left lateral (I, aVL, V5, V6) & inferior (II, III, aVF) Q waves in? in one or several of left lateral leads (I, aVL, V5, V6), sometimes in inferior leads (II, III, aVF) T wave positive in? Usually in leads w/ tall R waves; left lateral (I, aVL, V5, V6) & inferior (II, III, aVF) R atrium enlargement? Leads II (parallel) & V1 (perpendicular; biphasic) 1) P wave > 0.25 mV in II, III, aVF aka "p pulmonale" p pulmonale? RA enlargement, almost always related to pulmonary system; usually causes backup into the ventricle & atria, causing enlargement of atria L atrium enlargement? 1) V1 terminal portion, P > 1mm below line 2) Terminal portion of P > 0.04 sec (1 small box) "p mitrale" p mitrale LA enlargement due to mitral valve issue RVH - criteria 1) R > S in V1 2) R progressively smaller from V1-V6 3) S > R in V6 - will cause right axis deviation (also tall R in III) LVH - precordial criteria 1. V5: R > 26 mm 2. V6: R > 18 mm **3. S (V1 or V2) + R (V5 or V6) > 35 mm (best) 4. V6 R > V5 R axis is not a great indicator (L axis shift) Sensitivity is low, specificity is high LVH - limb criteria 1. aVL: R > 13 mm 2. aVF: R > 21 mm 3. I: R > 14 mm 4. R (I) + S (III) > 25 mm 2º repolarization in ventricular hypertrophy - criteria? 1. Down-sloping ST segment depression 2. T wave inversion (R +, T -) Tends to be most evident in leads most affected by size change RVH = V1, V2 LVH = V5, V6 causes of arrhythmias HISDEBS: hypoxia, ischemia/irritability, SNS, drugs, electrolytes, bradycardia, stretch (hypertrophy/enlargement) symptoms of arrhythmias none, "palpitations," light-headedness, syncope, angina, HF, sudden death Types of arrhythmias 1. Sinus origin 2. Ectopic 3. Re-entrant (abnormally shaped path) 4. Conduction blocks (blocked signal) 5. Pre-excitation (shortcut in pathway) Arrhythmias - 4 quick questions 1. Normal P waves? 2. Wide QRS? (> 0.12 sec indicates pacemaker below Bundle of His) 3. One P for every QRS? 4. Normal rate & rhythym? Sinus arrhythmia Appearance is ALMOST NORMAL: Respiratory - Circulatory interaction Rate INCREASES with INSPIRATION (IN=IN) Sinus arrest - criteria Rate: Regular or Bradycardia P wave: Normal QRS: Normal Conduction: Normal Rhythm: Irregular: length of pause ≠ multiple of normal rate (random) Junctional Escape Beat/Rhythym - criteria Rate: Bradycardia P wave: Absent or Inverted P; if present, may occur during or after the QRS QRS: Normal Conduction: Escape beat: P-R interval < 0.12 seconds (if P present) Rhythm: Irregular when it occurs (late) If occurs 3 or more times in a row, is considered junctional escape rhythm Sinus exit block - criteria Rate: Regular or Bradycardia P wave: Normal QRS: Normal Conduction: Normal Rhythm: Irregular: length of pause = multiple of normal rate (Signal blocked leaving SA node; block is exactly equal to multiple of rate - one or more impulses "missed") PACs (premature atrial contractions/atrial premature beats) - criteria Rate: Regular underlying rate P wave: Abnormal - they originate from an ectopic pacemaker QRS: Normal Conduction: Normal (except for PACs) Rhythm: Irregular when PACs occur (early) PJCs (Premature Junctional Contractions) AKA: Junctional Premature Beats Rate: Regular underlying rate P wave: Absent or Inverted (like junctional escape) QRS: Normal Conduction: PJC: P-R interval < 0.12 seconds (if P waves are present) Rhythm: Irregular when PJCs occur (early) PSVT (Paroxysmal Supraventricular Tachycardia) AKA: AV nodal Re-entrant Tachycardia Rate: Tachycardia (usually 150 - 200) P wave: Absent or Inverted (like junctional escape) QRS: Normal (may be wide, pseudo R') Conduction: P-R interval < 0.12 seconds (if P) Rhythm: Regular (abrupt onset and termination) Carotid massage: slows or terminates Atrial flutter Rate:Atrial 250-350 Ventricular: 100 -175 P: Irregular or absent, often "saw tooth" QRS: Normal Conduction: AV Block (2:1 > 3:1, 4:1) Rhythm: Regular (usually) - Often underlying cardiac disease Carotid massage: increases block Atrial fibrillation Rate: Atrial 400-650; Ventricular usually 120 - 180 P wave: Not present; often wavy baseline QRS: Normal Conduction: Variable AV conduction Rhythm: Irregularly Irregular - chaotic, unpredictable depolarizations w/i atrium, no atrial kick - CAD, HTN, COPD, etc. Carotid massage: may slow ventricular rate MAT (Multifocal Atrial Tachycardia): Rate: Atrial varies, Ventricular 100-200 P wave: ≥ 3 different 'P' waves QRS: Normal Conduction: AV conduction, P-R intervals vary Rhythm: Irregularly irregular Carotid massage: no effect Etiology: longstanding COPD, etc. Wandering Atrial Pacemaker Rate: Atrial & Ventricular 45 - 100 (slow MAT) P wave: ≥ 3 different 'P' waves QRS: Normal Conduction: P-R intervals vary Rhythm: Irregularly irregular Carotid massage: no effect PAT (Paroxysmal (episodic) Atrial Tachycardia) Rate: 100 - 200; Ventricular 1:1 (or 2:1, 3:1, 4:1) P wave: Usually present, abnormal QRS: Normal Conduction: P-R interval varies (dt ectopic sites) Rhythm: Regular (warm up &/or cool down) Carotid massage: no effect, or only mild slowing bigeminy? 1:1 ratio of normal:PVC trigeminy? 2:1 ratio of normal:PVC PVCs (Premature Ventricular Contractions) Rate: Regular underlying rate (usually) P wave: Absent (or abnormal) in PVC QRS: PVC: wide > 0.12 seconds; shape is bizarre; T wave inversion Conduction: Normal before & after PVC Rhythm: Irregular; may occur in singles, couplets or triplets Reasons to worry about PVCs? - Frequency increasing - Runs of 3 or more consecutively - Multiple PVC foci - R-on-T Phenomenon - PVC in acute MI Multiple PVC foci Beats 1 and 4 are sinus in origin. The other three beats are PVCs. The PVCs differ from each other in shape (multiform), and two occur in a row. PVC - R on T A PVC falls on the T wave of the second sinus beat, initiating a run of ventricular tachycardia. Ventricular tachycardia Rate: 120 - 200 usually P wave: Usually absent (unrelated to the QRS) QRS: Wide & bizarre shape (PVCs) Conduction: No correlation between 'P' if present and QRS Rhythm: Regular or Irregular * Cannon A waves may be present Carotid massage: no effect Ventricular Fibrillation Rate: Not attainable P wave: Obscured by ventricular waves QRS: No true QRS Conduction: Chaotic electrical activity Rhythm: Irregularly Irregular Accelerated Idioventricular Rhythm Rate: 50 - 100 (usually slow) P: Obscured by V waves - SA node is slower than faster ventricular pacing QRS: Wide QRS Conduction: Ventricular only Rhythm: Regular - benign rhythm sometimes seen in acute MI/early after reperfusion. Rarely sustained, does not progress to vfib, rarely requires treatment Torsades de Pointes Rate: 120 - 200 usually P wave: Obscured by ventricular waves QRS: Wide QRS - "Twisting of the Points" Conduction: Ventricular only Rhythm: Slightly irregular 1º AV block Rate: Normal (usually) P wave: Normal QRS: Normal Conduction: P-R interval is > 0.2 seconds (delay) Rhythm: Regular 2º AV Block - Wenckebach/Mobitz Type I Rate: Normal or Bradycardia P wave: Normal & constant P-P interval QRS: Normal Conduction: P-R interval is progressively longer until P wave is blocked; the cycle begins again Rhythm: Irregular 2º AV Block - Mobitz Type II Rate: Bradycardia P wave: Normal & constant P-P interval QRS: Normal or widened (usually associated with a bundle branch block) Conduction: P-R interval normal or prolonged (constant); some P waves are not conducted to ventricles (varies)