ECG midterm up to chap 10 Flashcards
where are the semilunar valves
btwn pulm artery and right vent
btwn aorta and left vent
AV valves names and locations
tricuspid: btwn right atrium and right vent
mitral/bicuspid: btwn left artia and vent
what is the RCA and what does it feed?
Right coronary artery.
Feeds SA node 55%, AV node and right ventricle
LCA?
left coronary artery
Feeds septum, bundle branches, anterior heart wall
Circumflex
left side off of LCA
feeds: SA node (45%), lateral wall of heart
what else is LCA called?
left main
widow maker
LAD
Left anterior decending branch off of the LCA. block here called widow maker
S1 =
LUB
closure of AV valves
Tricuspid/Mitral
S2 =
DUB
closure semilunar valves
Pulmonic and Aortic
What if you ECG is too slow? 2
interventions:
- Slow vent rate
- decreased CO
Inter: atropine/ pacemaker
what if your ECG too fast? 3
Interventions:
- decreased vent fill time
- increased O2 demands
- decreased coronary perfusion time
inter: vagal maneuver, electrical, BB, amiodarone, adenosine
If ECG shows no P waves? 1
Interventions:
loss atrial kick = decreased preload and CO
(if preload decreased, HR increases compensatory)
inter: chemical or electrical conversion depending on rhythm
If ST changes? 4
Interventions: 3
potential ischemia (ST depression), injury (ST elevation), decreased contractility, and decreased CO
inter: MONA (morphine, O2, nitro, ASA), thromobytic, cath lab
what do you always do if you have ECG changes? 4
Assess PT, IV, O2, call MD
What is Electromechanical coupling?
2 types of cardiac cells pacemaker (electrical) and mechanical (working cell, muscle contraction)
Electrical Cells
- pacemaker cells
2. Generates Electrical Impulses
Mechanical Cells
muscle for SV
- working cell of the heart
- produces CArdiac Muscle Contractions
5 properties of electrical cells : AERCR
- Automaticity
- Excitability
- Rhythmicity
- Conductivity
- Refractoriness
Automaticity
ability to generate electrical impulse spontaneously without external stimulus
Excitability
ability of cell to depolarize in response to an electrical stimulus
rhythmicity
ability of pacemaker cells to fire at regular intervals
SA node
conductivity
spread of electrical activity from one cardiac cell to another
refractoriness
period of time where the cell cannot respond to any stimulus
when cell is busy
what is an action potential
change in electrical energy across the cellular membrane
AP occurs in phases
depolarization, repolarization, restoration
resting membrane potential:
-90mV
created by distribution of K, Na and Ca
threshold potential:
-70mV
triggers AP
Antiarrythmic drugs :
work on diff phases of the AP
refractory
unresponsiveness to stimulus
absolute refractory period
cardiac cell cannot respond to another stimulus regardless of strength
relative refractory period
cells can respond to a stronger than normal stimulus
vulnerable period
part of relative refractory period where a strong stimulus can cause lethal arrhythmias
step-by-step conduction system
SA node, intraatrial and internoal pathways to AV node, bundle of His, left bundle branch to right bundle branch, then purkinje fibers
SA node fires?
60-100 BPM
AV junction fires?
40-60 BPM
Purkinje fibers fire?
20-40 BPM
what records the electrical activity between two electrodes?
leads
ECG tracing represents?
conduction of electric impulses from atria to vents
in one cardiac cycle
consists of 5 waveforms PQRST
waveform
deflection or movement away from the baseline (+ or -)
segment:
line between 2 waveforms
interval
consists of a waveform and a segment
complex
collection of waveforms, QRS complex
P wave
represents atrial depolarization
PR interval
atrial depolar and AV node delay
QRS complex
vent depolarization
ST segment
early vent repolarization
T wave
vent repolarization
QT interval
total vent activity (depolar and repolar)
U wave
purkinji repolar
what is 6 sec method?
count how many R in 6 sections. 7 = 70 BPM
Sequence
find R on the line and at each 5 small boxes count 300, 150, 100, 75, 60
what is a normal range for PR interval
where does it start and end?
0.12 - 0.20 sec
start of P wave and ends at start of QRS
Characteristics of QRS complex
begins/ends/normal range
begins where the first wave deviates from baseline
ends when the S wave begins to flatten out
normal range: 0.04-0.10 (narrow complex)
J point
junction where the QRS meets the St segment
- where we start to look to see if the ST segment is elevated. depressed or isoelectric (normal)
- look at the amplitude when considering ST segment changes
ST segment, beginning and end
Begins at end of the QRS and ends when the T wave begins
can be elevated, depressed or isoelectric
what does it mean if there is ST elevation?
- myocardial injury (MI)
1-2mm or 1-2 small boxes above the isoelectric line (most diagnostic is 1mm)
other causes: Coronary artery vasospasm, pericarditis, ventricular aneurysm
ST depression?
- myocardial ischemia
1-2mm or boxes below the isoelectric line
other causes: R or L vent hypertrophy, PE
How do you find/read the ST segment?
Find the J point and go over 1 1/2 boxes and see how far away from isoelectric line
T wave start, end
starts after ST segment and ends when it returns to isoelectric line
what is the QT interval
time between the onset of ventricle depolarization and end of vent repolarization
- refractory period of ventricles (immediate following stimulus when further stimulus has no effect
- QTc intervals is affected by HR
Lengthening of the QT interval can lead to?
Life threatening arrhythmias
What are 2 differences between SA node block and Sinus Arrest?
SA node block: SA node generates the impulse but is blocked when exits the SA node. And P-P interval maps out (exact multiples)
Sinus Arrest: SA node does not generate impulse. And P-P does not map out (not exact multiples
Common causes of sinus arrhythmia: 3
MI
Drugs
Hypoxia
what is common in children
sinus arrhythmia
