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
