Electrocardiography Flashcards
What is the point of electrocardiopathy?
- Measures electrical activity of the heart
- Heart rate
-
Conduction disturbances
- Chamber enlargement
- Electrolyte disturbances
- Myocardial ischemia
Normal conduction through the heart?
- Sino-atrial node
- AV node
- Bundle of His
- L and R bundle branches
- Purkinje fibers
- Rate depends on tone–SNS and PNS
Normal EKG–what are the dif. waves?
Which lead is the best regarding arrhythmias on an EKG?
Lead II
What is the basic unit on EKG paper?
What does 1 cm equal? 1mm?
What dimensions are the tiny boxes? The big ones?
- Basic unit = 1mm
- 1 cm = 1 mV
- 1 mm = 0.1 mv
- Tiny box = 1x1mm
- Big box = 5x5 mm
What artifact is this?
60 Hz interference
What artifact is this?
Shivering
What artifact is this?
Purring
How do you determine HR from an EKG?
- Determine speed (provided)
- # of PQRST’s in ENTIRE strip
- ^ convert to PQRST’s in 1 minute
How do you find the mean electrical axis? Is it useful?
- Average direction of activation of ventricular myocardium during systole
- No–often inacurrate and can just use ultrasound instead
How do you assess atrial size?
- P pulmonade (peak)
- Too tall = right atrial enlargement
- P mitrale (mound)
- Too wide = left atrial enlargement
How do you assess ventricular size?
- QRS complex–septal and ventricular depolarization
- First neg. inflection = Q wave–don’t always get it, not unusual
- R wave too high = left ventricular enlargement
- Very deep S wave = right ventricular hypertrophy
What is the most common EKG abnormality in cats?
Hypertrophic cardiomyopathy
What is the most common cause of right atrial and right ventricular enlargement in dogs?
HEARTWORMS
Right bundle branch block
- Deep S
- QRS prolonged
- R decreased
- Impulses come down –> jump from one cell to another via tight junctions–very slow –> QRS complex gets wider b/c process takes longer
Left bundle branch block
- Wide QRS
- Normal height
- Infections, trauma
- Normal CO
- Blocks/VPDs
- Left atrium activated more slowly–look at septum via US
Low voltage complexes
- <1 to 1.5 mV
- Obesity, pleural or pericardial effusion (picture), pneumothorax
- Hypothyroidism, or diffuse myocardial disease
What does it mean if there’s depression of the whole S-T segment?
Entire heart is deprived of oxygen = PROBLEM
How is the Q-T segment related to heart rate? What can it change with?
- Inversely proportional to heart rate
- Changes w/ K, Ca, drugs
How tall is the T wave supposed to be?
- < 1/4 of the R wave (cats can be 1/3)
- No rules as to whether it should be +/-, but should be consistent
- If increased in amplitude (height) = hyperkalemia
- Often due to hypertrophic cardiomyopathy
