EKG 2 Flashcards
11 step method
-1. standardization- make sure settings are correct, check pt name and other input information
-2. heart rate
-3. intervals…PR and QT intervals, QRS width
-4. axis
-5. rhythm:
-normal P waves
-QRS wide or narrow
-relationship between P and QRS
-rhythm regular or irregular
-6. AV block?
-7. bundle branch or hemi block
-8. pre-excitation?
-9. enlargement or hypertrophy
-10. ischemia or infarction?
-11. utter confusion?…think of your non-cardiac or unusual conditions
AV block
-signal is blocked between the sinus node and the terminal purkinje fibers
-first degree
-second degree
-third degree
bundle branch block
-a block below the bundle of his
-conduction is blocked in one or both ventricular branches
-if only portion of branch is blocked it is called fascicular block or hemiblock
-tissue has electrical disturbance
first degree AV block
-prolonged delay at level of AV node
-normal sinus signal held longer at AV node
-PR interval greater than 200ms (one big box) -> prolonged PR interval
-every P waves gives a QRS -> all beats conducted but delayed
-every impulse arrive regularly
-the PR interval is increasingly prolonged until it drops
second degree AV block
-not every impulse arrives to the ventricles
-Two Types!
-1. Mobitz type I second degree AV block (Wenckebach Block):
-Block is within the AV node
-PR interval delay is increasing with each beat then drop
-Longer and longer PR interval then drop and reset of PR interval!
-No intervention needed
-1. Mobitz type II second degree AV block:
-Block below the AV node in the His bundle
-No lengthening PR interval, just drop QRS!
-Evidence of progressive severe conduction system disease requiring a Pacemaker implant
-2:1 when you don’t have PR intervals to compare -> usually make exercise to see a change and identify the issue
third degree AV block
-no communication between atrial and ventricular conduction
-Site can be AV node or below
-Atria are at the sinus rhythm 60-100 bpm.
-Ventricles will give escape rhythm around 30-40 bpm
-AV dissociation**
-Requires Pacemaker if not reversible
-p waves are regular with each other, QRS are regular -> BUT there is no P:QRS correlation
-atrial rhythm is normal
bundle branch blocks
-conduction block in either right or left bundle branch
-ventricular conduction should be less than 100 ms with a leftward axis (0-90)
-when width of QRS is greater than 120 ms and the configuration is changed you have a bundle branch block
right bundle branch block
-Right depolarization is delayed.
-QRS greater than 120 ms
-In V1 see the initial R wave then a second R wave as the delayed right ventricle depolarizes.
-“R-S-R prime”… Rabbit ears.
-In left precordial leads a late deep S wave
left bundle branch block
-Left depolarization is delayed
-QRS greater than 120ms
-Leads overlying left ventricle have a broad or notched R wave. Lead over the right ventricle have broad deep S wave.
-Left axis deviation may be present
is that ischemia I see? Nope!
-with RBBB the right precordial leads will show ST segment depressions and T wave inversions
-with LBBB the ST segment and T wave inversion will be seen in left lateral leads
-so cant use ST or T wave dx for ischemia with BBB
-cant use hypertrophy dx rules when BBB
who gets BBB
-RBBB- diseased conduction or normal phenomenon
-LBBB- rarely normal -> seen in underlying cardiac disease degenerative or ischemic
-critical rate: BBB:
-things only become abnormal when they are doing strenuous activity -> normal otherwise
-BBB can be intermittent or fixed
-sometimes only appears at faster rate “critical rate” -> so normal QRS at slow rate and wide (BBB) at faster rate
-rate related bundle
hemi-blocks (dont need to know)
-just 1 of 3 fascicles are blocked:
-septal
-left anterior fascicle
-left posterior fascicle
-QRS not wide, no ST segment or T wave changes
-left anterior:
-axis is redirected upward and to the left -> left axis
-tall R waves in left lateral leads and deep S waves in inferior leads
hemi-block: left posterior
-usually in a diseased heart
-reverse occurs
-current runs superior to inferior and left to right
-right axis deviation
hemiblock: are we concerned?
-when combined with a RBBB we are concerned!
-together called bifascicular block
-with a disease RBBB and a hemi block only one fascicile is supply both ventricles
-see EKG below for combined LAFB and RBBB
who needs a Pacemaker?
-sick sinus syndrome- sinus node broken
-mobitz 2- unreliable heart beat
-3rd degree AV block- ventricles and atria arnt talking to each other
-bifascicular block -> RBBB and 1 fascicle (dont need to know this for quiz 1)