ECG 3 Part 2 Flashcards
Sinus rhythm is present if each P wave is followed by a QRS complex. What leads should a p wave be upright for it to be considered normal? and what is a normal PR interval?
P wave should be upright in leads I and II. think about the direction the current sis moving away from the SA node. It is moving down and to the left. therefore leads I and II moving away from the body would be +.
it should be inverted in AvR. AvR moves towards the right upper border. The P wave should be moving in the opposite direction.
Normal PR interval is <0.12-0.20 (3-5 small boxes)
What is the PR interval? What should you consider if its shorter? longer?
PR is 120-200 ms (in this diagram, the PR interval is like 160ms, which is normal.
If it’s shorter: consider an arrythmia (a superventricular arrythmia because it includes the atria which is what makes the P wave)– WPW, ectopic atrial rhythm, junctional rhythm ( is where the heartbeat originates from the AV node or His bundle)
If longer: 1st degree AV block
normal range for qrs interval. what if its longer ?
normal range is under 120 ms.
- if its longer than 120 ms: RBBB, LBBB, Non-specific intraventricular conduction delay
- ventricular origin (PVC)
- drug effect
- hyperkalemia
QT interval duration. what if its longer?
normal should be under 440ms in males and under 460 in females.
if its longer it could be congneital, drug effect (long QT syndrome like antiarrythmics and anti-depressants can give), electrolyte abnormalities, or cardiac ischemia
What’s the Abnormal Interval?
the PR interval is pretty long. should be 120-200ms, but this one is 300.
- long Pr interval could indicate a 1st degree AV block (first degree because it is still sinus and thtere are no skipped/unpaired beats)
what is a. normal axis?
what is a right deviation? left deviation/
normal: positive QRS lead 1, positive QRS lead 2
right deviation: negative lead 1, positive AVF
+ lead I, - lead II = left deviation
- lead I, - avF = extreme RAD
causes of left axis deviation
LAD: - lead I, - lead II
could be due to inferior wall myocardial infarction, left block, left ventricular hypertrophy, or if the right ventricle is damaged– less concuction is happening on the right side and thus the cumulative vector is pointing more left.
causes of right axis deviation
right ventricular hypertrophy (the larger the myocardium, the more cells depolarizing tehrefore the larger the vector in that direction)
- acute right heart strain (massive pulmonary embolism)– it’s contracting hard.
- left posterior fascicular block
best leads to look at P wave
Leads II and V1
- v1 is most anterior and looks directly at the SA node. (in V1, the LA is negative)
- lead II goes from SA node then down, which is the best lead to visualize the direction of SA current.
how would P waves look in leads II and V1 for RA enlargement? LA enlargement?
-the Left atrium causes a dip in the leads because it’s opposing the direction that the current is indicating.
How does the RA look in Va? the LA?
RA is positive in leads V1. the La is negative in V1 becuase it oppos
Which ventricular hypertrophy is going on?
the is a positive V1, and a carachteristic shape in lead II that indicates right hypertrophy.
- R wave progression.
- the depolariziations on the V1-3 precordial leads are larger than 4-6– these are the front leads which are close to right ventricle
- in all this is a right heart hypertrophy– a ventricular hypertrophy
left of right ventricular hypertrophy?
- look at P waves in laed II and V1. In lead II, there is the cahracteristic shape that indicates right hypetrophy. the V1 is positive too.
- there is right axis deviation.
- negative V6
overall this is right axis deviation
left or right ventricular hypertrophy?
- axis is normal.
- P wave is difficult to characterize, but RA enlargement usually has larger P awave because of how the leads are placed in relation to RA. Here, it is not very large.
- negative P wave in V1. Left atria enlargement indicator
- HIGH voltages on leads 5 and 6.
- this could be normal, but voltage looks a little funny overall. this is left ventricular hypertrohpy.
- it doesn’t fulfill the sokoloq-lyon criteria for left ventricular hypertrophy where thee V1 + the R in V5 or V6 is over 35, but it is trending toawrds LVH.
2 characteristic patterns for RBBB
RSR’ in V1 and slurred wave in V6
- wide QRS over 120 ms.
- discordant T waves
LBBB
- • Wide QRS (>120 msec)
• Broad, slurred
monophasic R wave in I,
aVL, V5 and V6
• Absence of q in I, V5 and
V6
pathology happening?
Pathologic Q Waves
• Q waves greater than 40 msec (1 little box) and greater than 2 mm in depth are
consistent with infarction
A. Normal
C. STEMI
B. Pericarditis
D. Benign Early Repolarization
B. pericardiits.
- diffuse St elevation
- no reciproval ST depression– less likely to be STEMI
- characteristic curving of waves.
note: it’s normal for T waves to be inverted in AVR
65 year old female, smoker, hypertension, diabetes, presents with chest pain
- axis is normal
- looks sinus
- ST elevation in leads II and II (inferior leads), but ST depression in leads I (superior)
ST elevation in AvF and ST depresion in AVR and L.
- this looks like an inferior MI.
24 year old female, hockey player, no current medical issues, presents for routine physical
- rate is bradycardic
- positive in leads II and V1– more right preference atrially
- normal axis
- this is BENIGN early repolarization– common in atheles. ST changes in inferior lateral precordia leads.
- healthy.
• Benign early repolarization occurs in about 1 to 13 percent of the general population with a significant
increase in occurrence within athletes and adolescents
• early repolarization can be observed in 25 to 30% of elite athletes
24 year old male, baseball player, no current medical issues, presents for routine physical
this is a benign type of St elevation called benign early repolarization.
• Benign early repolarization occurs in about 1 to 13 percent of the general population with a significant
increase in occurrence within athletes and adolescents
• early repolarization can be observed in 25 to 30% of elite athletes
ST Elevation Site Reciprocal Changes Inferior & lateral Uncommon
precordial
58 year old male, smoker, recurrent chest pain, this ECG recorded during exercise stress testing. DDX?
NSTEMI. needs an expitied angiogram
DDx of T wave inversion
honestly it always indicates a myopathy.
- MI/infarction due to obstructive disease
2. left or right ventricular hypertophy because of strain (pulmonary embolsim)
2. left or right bundle branck block
3. WPW
A. Normal B. Pericarditis
C. Hyperkalemia D. Long QT
long QT
- characteristic QT shape too
normal QT= 500 ms.
this QTc = 632 msec
A. Normal
B. Atrial Fibrillation
C. Ventricular Fibrillation
D. Ventricular Tachycardia
E. Don’t Know
D. V tach. torsades de pointes.
- can be due to medication – antiarrythmics, type 1a, 1c and type III. Antibiotics, antipsychotics/depressents, anti-emetic.
reasons for low voltage ECGs
- increased BMI
- chronic obstructive pulmonary disaes
3. pericardial effusion
5. cardiac infiltation
6. myocardial infarction usually extensive
atrial fltuter with varaible block– saw tooth \
- also left ventricular hypertrophy
LBBB
Premature ventricular contractions can be associated with: Certain medications, including decongestants and antihistamines. Alcohol or illegal drugs. Increased levels of adrenaline in the body that may be caused by caffeine, tobacco, exercise or anxiety.
