ECG Flashcards
(26 cards)
How long and high are little and big boxes?
Little box: 0.04s, 0.1mV
Big box: 0.2s, 0.5mV
Three ways to determine heart rhythm
- 300, 150, 100, 75, 60, 50
- 1500/#lil boxes
- 10*(#boxes/6s)
Standard PR Interval (where to where, how long)
Start of P to Start of QRS
0.12-0.20s
Standard QRS Interval (how long)
less than or = 0.10s
QT Interval (where to where, how long, equation)
Beginning of QRS to end of T QTc corrects for HR (because high HR = shorter QT) QTc = QT/sqrt(RR) must be in seconds Female < 0.46s Male < 0.45s
Identify angle measurements for all leads (aVR, aVL, aVF, I, II, III)
I: 0 II: +30 III: +60 aVR: -150 aVF: +90 aVL: -30
Physiologic Difference b/w STEMI/NSTEMI
STEMI: transmural ischemia (whole wall)
NSTEMI: partial wall, subendocardial ischemia
How does NSTEMI result in ST depression? How much ST depression do we need to see?
Diastole (TQ): Ischemic area naturally depolarized, current flows ischemic to normal (outward) - precordial leads elevated
Systole (QT): Ischemic has slow AP response - plateaus lower + more negative, current flows normal to ischemia (away from leads) - precordial leads depressed
Need >1mm depression (1+ small boxes)
How does STEMI result in ST elevation?
How much ST elevation do we need to see?
Diastole (TQ): Ischemic area naturally depolarized, current flow ischemic to normal (away from precordial leads) - precordial leads depressed
Systole (QT): Ischemic slow AP response, lower plateau, current flows normal to ischemic - towards precordial leads - precordial leads elevated
Need >1mm elevation (1+ small boxes)
What are the criteria for abnormal Q waves? How do they occur?
Q wave = sustained ischemia, infarcted tissue with no electrical conductivity
Criteria: >0.03s duration (~1 small box) with amplitude >1mm (1 small box) AND present in two contiguous leads
Small q waves normally found in III, V5, V6 (due to septum depolarizing left to right)
How to localize disease to artery?
LAD vs LCirc vs PDB of RCA
Anterior LV (LAD): V1-V4 Lateral LV (LCirc): I, aVL, V4-V6 Inferior LV (PDB of RCA): aVF, II, III
Signs of RA Abnormality (enlargement/hypertrophy)
Exaggerated 1st part of P-wave
Lead II: voltage change > 2.5mm (2.5 lil boxes)
OR
Lead V1: voltage change > 2.5 little boxes
Signs of LA Abnormality
enlargement/hypertrophy
Exaggerated 2nd part of P-wave
Lead II: width > 3mm (3 little boxes, may be two peaked)
OR
Lead V1: negative deflection of P wave >1mm2 (1 square small box area) P wave goes up and down
Signs of RVH
V1: R wave larger than S wave
+/- V6: S wave larger than R wave (or equal)
Right Axis Deviation (+90-+180)
Usually RA abnormality also seen
Signs of LVH
Harder b/c LV usually larger than RV
Strain pattern: Volt changes and ST depression +/- T wave inversion in inferior & lateral leads due to different repolarization
V1 S wave AND V5 or V6 R wave > 35mm (3.5 BIG boxes)
Also:
Lead I R-wave Plus III S-wave > 25mm
or
aVL R-wave > 12mm
PPL <35yo have big volts, can’t use the criteria!
Characteristics of First Degree AV Block
No dropped beats, PR interval longer than 1 big block
Characteristics of 2nd Degree AV Block Mobitz type 1
Dropped beats, progressively increasing PR
Irregularly irregular rhythm
Characteristics of 2nd Degree AV Block Mobitz type 2
Dropped beats, fixed PR interval, regularly irregular, more dangerous (problem in His-Purkinje system)
Characteristics of 3rd Degree AV Block
Complete AV Block
SA Node & Ventricles depolarize independently of each other
Junctional Escape Rhythm: Narrow QRS, 40-60bpm (uses His/Purkinje)
Ventricular Escape Rhythm: Wide QRS, 20-40bpm (cell-to-cell)
AVNRT (type of arrhythmia, features)
Paroxysmal Supraventricular Tachyarrhythmia
reentry within AVN (fast/slow limbs), requires Premature Beat
Fast rhythm, narrow QRS, no P-wave present, may be retrograde P wave, regularly irregular
AVRT (type of arrhythmia, features)
Paroxysmal Supraventricular Tachyarrhythmia
reentry with AVN and accessory pathway, requires premature beat
WPW Pattern: signal goes down both AVN and accessory pathway - shortened PR with pre-excitation/gradual sloping of QRS (SINUS RHYTHM)
Orthodromic AVRT: signal goes down AVN and up Accessory Path, narrow QRS, p-wave may be abnormal, regularly irregular
Antidromic AVRT: signal goes down accessory and up AVN, wide QRS, RARE
Atrial Fibrillation
Most common arrhythmia
Disorganized atrial activity, irregularly irregular, no discernible p-waves
Reentry: usually micro-reentrant circuits
Atrial Flutter
Organized atrial activity, regularly irregular (Nauseatingly predictable)
Giant reentry circuit around right atrium
Monomorphic Ventricular Tachycardia
Idiopathic or Assoc. with structural heart disease
single, consistent WIDE QRS (reentrant within ventricle)
