EKG stuff Flashcards
Pathway of electrical conduction in the heart
SA node → Internodal pathways → AV Node → Bundle of His → R & L bundle branch → Purkinje Fibers
The way to determine the HR based on EKG?
300 → 150 → 100 → 75 → 60 →50 (count every dark line/big box).
Order to exam an EKG strip?
Rate → Rhythm → Axis → Hypertrophy → Infarction
What are the different inherent rates of the different areas of the heart?
Sinus Rhythms – 60-100 bpm
Atrial foci inherent rate – 60-80 bpm
AV Juntion inherent rate – 40-60 bpm
Ventricular foci inherent rate – 20-40 bpm
Orhtostatic Hypotension (from EKG lecture)
Typically when you stand there is a compensatory sympathetic response that constricts the peripheral arteries to prevent distal blood pooling, and stimulates sinus pacing.
However if there is a failure of these compensatory mechanisms you get OH or a syncope.
Neuro-cardiogenic syncope
Paradoxical parasympathetic response to prolonged standing, causes vasodilation and slowing of the pulse resulting in LOC.
Atrial Flutter
- Sawtooth appearance
- 220-430 bpm
- QRS <1.2 sec
Ther implications:
Fatigue
Palpitation
SOB
Hypotension
Atrial Fibrillation
- Irregular rhythm; continuous chaotic atrial spike; irregular ventricular rhythm. >350bpm
- Continuous rapid-firing of multiple atrial automaticity foci.
- No impulse depolarized the atria completely, and only an occasional, random atrial depolarization reaches the AV Node to be conducted to the ventricles.
- Produces irregular QRS complex
Ventricular Fibrillation
Rate = 300-600 bpm
Very irregular rhythm
Bunch of big squiggles
Emergency need defibrillator
Escape Rhythms
- When the automaticity focus escapes the overdrive suppresses to pace at its own inherent pace (atrial, junctional, or ventricular)
- Atrial – p’ waves (p prime)
- Junctional – Options: no p wave, inverted p’ after QRS, inverted p’ before QRS.
- Ventricular – very wide QRS complexes. This is so slow that blood flow to the brain is significantly reduced to the point of unconsciousness (syncope)
Causes of ventricular foci irritability?
Low O2 – this is the most common
- Airway obstruction
- Absence of air (near drowning)
- Air with poor O2 content
- Minimal blood oxygenation in lungs (pulmonary embolus or pneumothorax)
- Reduced cardiac output (hypovolemic or cardiogenic shock)
- Poor to absent coronary blood supply (coronary insufficiency or infarction)
Low K+ - Reduced serum potassium (hypkalemia)
Pathology – mitral valve prolapse, stretch, myocarditis, etc.
PVC (preventricular contractions)
- Ectopic foci in the ventricle
- Following the PVC there is a long compensatory pause
- There is a wide QRS and absent p wave
- 6 or more PVC’s in a min = pathological! They need help!
- A run of 3 or more PVCs is a run of v-tach! stop exercise!
- Usually opposite polarity as a normal QRS complex
- Bigeminal PVC (every other beat is PVC): cardiac output is decreased by ~50%. Won’t tolerate exercise much
Difference between tachycardia, flutter, and fibrillation
Tachycardia = 150-250 bpm
Flutter = 250-350 bpm
Fibrillation = 350-450 bpm
1st deg AV block
lengthen the delay between atrial and ventricular depolarization
Prolonged QR interval (typically should be less than .2 sec [1 big box]…in this case it would be longer)
2nd deg AV block types
Wenckeback (Type 1)
Mobitz (Type 2)
