EKG Flashcards
(36 cards)
Normal P wave
atrial depolarization
no taller than 3 mm (3 small boxes)
not wider than 0.11seconds
Normal PR interval
delayed at AV node to optimize ventricular filling
no longer than one big box (0.2sec)
can be longer if atrial infarction or pericarditis
Normal QRS Complex
ventricular depolarization
less than half of a big box wide (0.07 to 0.11 sec)
Leads I-III: no smaller than 6mm tall
Leads V1-V6: no taller than 25-30mm
**if taller in V1//2 then RVH; V5/6 then LVH
Normal Q wave
septal depolarization
usually cannot see the Q wave unless pathological b/c a thin tissue
- may only see in leads I, aVL, V5-6
less than 0.04seconds (one small box)
no deeper than 1/3 of QRS complex
R progression in precordial leads
V1 –> V6
the r wave starts small and the S wave is big…
then the R wave gets bigger and the s wave gets smaller
tallest R wave in V5 or V6
Axis Deviation
- what is it
- normal
average direction of depolarization as the impulse travels through the ventricles
- referring to the QRS complex
Normal = -30 to +90
Left axis deviation
- causes
more negative than -30 (-30 to -90)
limb lead I is positive, aVF is negative
Causes: left anterior hemiblock Q waves of inferior MI artificial cardiac pacing emphysema hyperkalemia
Right axis deviation
- causes
more positive than 90 (90 to 180)
limb lead I is negative, aVF is positive
Causes: RVH chronic lung disease anterolateral MI left posterior hemiblock pulmonary embolus atrial and/or ventricular septal defect
**may be normal in tall thin adults and children
Interval VS Segment
Interval - always includes a wave
Segment - isoelectric line from wave to wave
ST Segment
starts at the J point (junction at end of QRS complex) & ends with the t wave
represents time when ventricular cells are in a plateau phase
- absolute refractory period, will not respond to a stimulus
T wave
earliest time ventricles can respond to another stimulus usually coincides w/ apex of T wave
- time of relative repolarization
Same polarity of the QRS complex
Sinus arrhythmia
normal sinus rhythm but w/ unequal distances between R-R
- beat to beat variability
Sinus bradycardia
- causes
- symptoms
- associated w/
less than 60 bpm
Causes: beta blockers, decreased function of SA node, athlete in good shape
Generally asymptomatic unless pathologic condition persists
- may c/o dizziness, syncope, angina (decreased Q)
Associated w/ development of dementia
Sinus tachycardia
- causes
- symptoms
> 100bpm
Generally benign
Causes:
fear, anxiety, stress, obesity, caffeine, nicotine, amphetamines or demands of O2 are increased (exercise, infection, MI, hemorrhage)
Sinus Exit Block
- cause
- symptoms
block in conduction of impulse from SA node causing a skipped beat
May c/o SOB if block gets longer and multiple beats are missed
Premature Atrial Contraction
- what is it
- causes
- symptoms
P wave is premature (always present) w/ an abnormal configuration due to ectopic focus in either atria that initiates the impulse
Causes: stress, nicotine, caffeine, alcohol, infection, hypoxemia, MI, atrial damage
Usually asymptomatic
Atrial Tachycardia
- what is it
- causes
- symptoms
aka supraventricular contraction
R-R interval very close together (HR 100-200) and hard to make out a p wave
Same causes as PAC + pulmonary HTN, altered pH and COPD
IF prolonged, Q is compromised –> SOB, dizziness, fatigue
Atrial flutter
- what is it
- causes
- symptoms
Normal R-R intervals w/ excess “saw tooth” pattern of p waves due to rapid firing of ectopic source in atria
Causes: pathological (mitral valve disease, CAD, MI, stress, renal failure, pericarditis, RHD)
usually asymptomatic d/t normal R-R intervals
Atrial Fibrillations
- what is it
- causes
- symptoms
- at risk for…
uncontrolled R-R rhythm with undiscernable p waves due to erratic quivering of the atria (multiple ectopic foci) causing no true depolarization of the atria
Causes: age, CHF, HTN, ischemia/infarction, drug, cardiomyopathy, stress, pain, renal failure
Symptoms: palipitations, fatigue, dyspnea, lightheadedness, syncope, chest pain
–> decreased Q b/c decreased blood from no atrial kick
A fib is at risk for stroke b/c blood will pool in the atria (may be prescribed baby aspirin to thin blood)
Premature junctional contraction
- what is it
missing p wave for QRS complex (just one beat) and a NORMAL QRS width w/ a shortened R-R interval
impulse comes from the AV node/bundle and the SA node does not fire
Junction Escape Rhythm
- what is it
- causes
- symptoms
missing p wave throughout entire rhythm due to SA node not functioning properly;
typical rate = 40-60 bpm
Causes: inc vagal tone, digoxin, infarction/severe ischemia to right coronary artery
Symptoms: dizziness, fatigue, SOB, chest pain, extreme fatigue w/ ADL’s
(decreased HR –> decreased Q)
Premature Ventricular contractions
- what are they
- symptoms
- types (6)
p wave absent and QRS has a wide and aberrant shape due to ectopic foci in ventricle causing premature depolarization
Symptoms: SOB, dizziness, decreased tolerance to activity
–> if increased frequency of PVCs leading to decreased SV and decreased Q
Types:
- unifocal, multifocal, couplet, run, bigeminy, trigeminy
Can be life threatening and should be considered serious!
Ventricular tachycardia
- what is it
- causes
- symptoms
3 or more consecutive PVCs at a ventricuar rate >150
Causes: ischemia, acute infarction, HTN, digoxin
Symptoms: lightheadedness, disorientation, weak/thready pulse –> leading to syncope (w/n 10 seconds)
–> severly diminshed Q and BP
NOT shockable rhythm; leads to V-fib
Ventricular fibrillations
- what is it
- causes
no R-R interval, ventricles are not beating, they are quivering/fibrillating asynchronously & ineffectively
Causes: heart disease, MI, cocaine
Sequel to v-tach
NO Q, patient is unconscious and needs defibrillation immediately!
