ECG in Bradycardia and Conductance Disturbances Flashcards
What is Sinus Bradycardia?
What are the symptoms?
rate: <60bpm
p-waves separated by >5 big boxes whic is 1 second
symptoms: fatigue, listlessness, dyspnea, worsening CHF
pauses <____ sec are common and rarely symptomatic
pasues >____ sec, not occuring during sleep may result in symptoms
pauses <3 sec are common and rarely symtomatic
pauses >3 sec that don’t occur during sleep may result in symptoms
What is Brady Tachy Syndrome? What causes it? How do we usually treat it?
- concomitant intermittent atrial arrhythmias (such as AF) and sinus pauses or bradycardia when in SR
- caused by
- high prevalence of both AF and SN dysfunction in the elderly
- both SN dysfunction and atrial arrhythmias are commonly caused by atrial fibrosis associated wth advancing age
- use of drugs to treat AF may promote SN dysfunction and asscociated bradycardia
- treatment: usually drugs to treat the tachycardia (Ca or beta blockers) and pacemaker to prevent worsening bradycardia from the required drugs
what is a stable junctional escape?
complete block in the upper AV node leaved junctional foci to escape and pace the ventricles (40-60/min)
What is an unstable ventricular escape?
complete block ot the entire AV, His block, or below the His block knowkcing out all paths completely so a ventricular focus escapes
20 or less-40/min
What is seen in a 1st degree AV block?
- AV conduction delay only
- PR prolongation >0.2 seconds (1 big box)
- 1:1 AV Relationship (everytime you have a p you have a QRS)
******prolonged PR-slow AV******
What is a 2nd degree AV Block?
- Intermittent failure of AV conduction
- some p-waves conduct, others are blocked
What is a 3rd degree (complete) AV block?
- No AV Conduction
- Ventricular rate is usually regular and unrelated to atrial activity (regular rhythm)
- the atrium and ventricle beat independently (AV Dissociation)
How does a proximal AV node block progress? Is QRS usually narrow or wide? what kind of escape is it oftn accompanied by?
- progresses from a simple PR prolongation to occasional dropped beats to more frequent dropped beats to eventual late complete block
- Conducted QRS usually narrow (disease in AV node, not his-purkinje system)
- tends to be accompanied by stable well tolerated underlying “Junctional Escape Rhythms” (rates 40-60). typically benign.
What does a Distal level block of His-Purkinje involve? How does it progress? Describe the QRS? WHat are the escape rhythms?
- His bundle or bilateral bundle branches
- rapidly and abruptly progresses from occassional dropped beats to long periods of dropped beats to complete block
- QRS wide?120ms
- accompanied by unstable and slow underlying “ventricular escape rhythms”. sometimes there is no escape rhythm (asystole)
- clinically malignant
What is Mobitz type I block? What usually causes it?
Mobitz type I AV Block commonly called Wenckebach block
- progressive PR interval prolongation followed by blocked beat
- the most common for of 2nd degree AVB
- usually caused by block within the AV node
WHat is Mobitz type II AV Block?
sometime just called “MObitz” block!
- sudden intermittent loss of AV conduction without preceeding PR prolongation
- usually due to infranodal block (block within His bundles or BOTH bundle branches)
- once block starts, multiple P-waves may fail to conduct
- may progress abruptly and unexpectedly to complete heart block
What is high grade AV block?
2 or more consecutive p-waves are not conducted (ie the majority of p-waves are not conducted with occasional conducted p-waves)
WHat is 3rd degree AV block?
**complete** AV block
regular escape rhythm
junctional escape 40-60bpm, usually narrow (associated w AV level block)
ventricular escape 20-40 bpm, always wide (associated with infranodal level of block)
What is seen in a left bundle branch block?
QRS > 0.12 sec
Broad deep S in V1
Broad R in V6
(whoop, whoop)
WHat is seen with a right bundle branch block?
QRS> 0.12 sec
RSR’ in V1 (rabbit ears)
Deep S in V6
WHat is seen with a Left Anterior Fasicular Block (LAFB)?
Left Axis Deviation (beyond ~45 deg)
qR in Lat Leads (I and aVL)
rS in Inf leads (II, III and aVF)
What is seen with a left posterior fasicular block?
right axis deviation (90 to 180 degrees)
rS in Lat leads (I and avL)
qR in Inf leads (II, III, aVF)
(no evidence of RVH)
Think about LAFB when you see __________
Think about LPFB when you see ____________
LAFB: Unexplained left axis deviation (>45)
LPFB: unexplained right axis deviation (>90+)
Is a 3rd degree junctional escape usually wide or narrow
Is a 3rd degree ventricular escape usually wide or narrow
junctional : narrow
Ventricular: wide
