ECG Flashcards

Stress Induced Myocardial Ischemia
- inc. O2 consumption with inability to inc. coronary flow appropriately
- depression of ST segment

Ischemia- Acute Coronary Syndrome
- ischemia due to acute coronary artery obstruction during low oxygen demand causes T wave inversion

Transmural Infarct
- ST elevation
- Q wave

Evolving Transmural Myocardial Infarct
- peaked T wave
- T wave inversion
- ST elevation
- Q wave, ST elevation, T inversion

Subendocardial Infarct
- ST depression
- no Q wave
- shortened QT interval
Hypercalcemia
- prolonged QT interval
Hypocalcemia
- S and T waves broaden in sine wave pattern
Hyperkalemia
- P & R waves gone
- S & T waves broaden in sine wave pattern

- T wave merging with U wave
Hypokalemia

- big R waves in L sided leads (I, aVL, v5, v6)
- normal QRS duration with extremely high voltage

Left Ventricular Hypertrophy
- big R waves in R sided leads (v1, v2)

Right Ventricular Hypertrophy
Limb Leads
Lateral Leads
- aVL/aVR
- I
Inferior Leads
- II, III, aVF
Bipolar
- I, II, III
- (standard limb leads)
Unipolar
- aVR, aVL, aVG
- augmented limb leads

Polarity
- depolarization moving toward a positive electrode produces a positive electrode
- QRS will be upright (+) in L and lateral leads
- QRS will be downward (-) in R sided leads
- regular, fast HR (>100)
- P waves precede QRS

Sinus Tachycardia
Sympathetic Activation
- exercise, emotion, hypotension, resonse to actue lung or abdominal patholgy, thyrotoxicosis
Treatment
- usually none, bea blockers in thyrotoxicosis
- regular, slow HR (<60)
- P waves precede each QRS

Sinus Bradycardia
- athletes
- vagotonic states: faint
- treatment: none, atropine, pacemaker if sx
- PR interval prolonged

First Degree AV Block
- causes: drug induced, conduction system disease
- usually benign
- PR interval prolonged (inc. junctional delay)
- some P waves conduct but some do not

Second Degree Heart Block
- Mobitz 1/Wenchebach
- progressive lengthening of PR interval followed by non conducted P wave
- Mobitz 2
- intermittently dropped ventricular beats preceded by constant PR intervals
- no relationship between P waves and QRS

Third Degree Heart Block
- P waves at faster rate the QRS
- serious condition
- causes
- severe conduction system disease
- rarely drugs
- tx
- pacing if ventricular rate or BP are too low
- early beat often preceded by an abnormal P wave
- narrow QRS resembling normally conducted beats usually

Premature Atrial Contraction
- wide QRS, no P wave
- common in normal subjects, acute MI, and heart failure

Premature Ventricular Contractions
- tx: usually not required, beta blockers
- P waves at rate of 240-320 beats/min
- pulse may be regular or irregular
- ventricular rates vary widely

Atrial Flutter
- tx:
- anticoagulation
- rate control with drugs
- cardioversion
- ablation- curative
- rapid HR
- narrow QRS
- P waves present but abnormal

Atrial Tachycardia
- tx:
- adenosine
- vagal maneuver
- beta blocker
- verapamil or diltiazem
- no P waves
- undulating baseline
- irregularly irregular ventricular rhythm

Atrial Fibrillation
- causes
- hyperthyroidism
- heart disease
- post-op
- aging
- hypertension (most common)
- tx
- anticoagulation
- rate control with drugs
- beta blockers
- digoxin
- verapril
- diltiazem
- amiodarone
- cardioversion (rhythm control)
- class 3 agents (ibutilide, amiodarone, dofetilide, sotalol)
- class 1C agents (flecainide, propafenone)
- ablation
- shick
- regular, narrow QRS
- no antecedent P waves

Junctional Rhythm
- tx usually unnecessary
- regular, wide complexes (100-200/min)
- in most cases no P wave visible
- termed sustained if longer than 30 sec
- often life threatening

Ventricular Tachycardia
- tx:
- amidarone
- lidocaine
- cardioversion
- wavy, irregular baseline
- life threatening

Ventricular Fibrillation

Asystole
P Wave Abnormalitites in Sinus Rhythm


- widened QRS with terminal WRS
- upright (+) in R sided leads
- downward (-) in L sided leads

RIght Bundle Branch Block
- widened QRS away from v1 and towards v6
Left Bundle Branch Block
- axis shift without widening the QRS
Hemiblock
- ST elevations and Q waves in inferior leads (II, III, aVF)
- reciprocal ST depressions in anterior leads

Acute Inferior MI
- ST elevations and Q waves in anterior leads (v1-v4)

Acute Anterior MI
- diffuse ST elevations in multiple leads: no localization

Acute Pericarditis
- QRS positive in lead I
- QRS negative in lead II
Left Axis Deviation