Lecture 2: ECG B6 Flashcards
Leads that go around the heart at mid-chest. Used to localize infarcts
Precordial leads
R-wave progresses from _________ to more ___________ through V1-V5.
negative to more positive
Vector that shows where most depolarization occurs. (where most muscle mass is)
Mean electrical axis
Why is the sum of al QRS vectors usually at 60 degrees?
that is pointing down and to the left towards the left ventricle (largest chamber with most muscle mass in heart)
If MEA changes, then heart has changed shape. What can this lead to?
Hypertrophy/ dilation in response to cardiac diseases. (Quick and dirty way of seeing how heart changes shape) Or which way depolarization is going to.
Calculating MEA. Which leads do you look at?
Lead I and aVF
Combining these 2 allows a good approximation of MEA
If someone is healthy, where will Lead I and aVF show up?
Lead I will be positive
aVF will be positive
There are two responses that the heart can do when it is under stress… what are they?
Hypertrophy- cells get bigger -response to hypertension -heart wall gets thicker Dilation-chamber gets bigger -fills with more load -response to volume overload
True/False: Atrial changes can overpower Ventricle changes. Right side changes can overpower right side changes.
False: Ventricle changes can overpower Atrial changes. (they are bigger)
Left side changes can overpower right side changes
You receive an ECG with a positive R wave in Lead I and a negative R wave in aVF. What is this persons MEA?
Left axis
You receive an ECG with a pos R wave in Lead I and a neg R wave in aVF. Which of the following could result in such an ECG change?
Left ventricular hypertrophy (most likely)
Left atrial hypertrophy
ANy alteration to normal rhythm, regularity, origin or conduction of the heart beat.
Arrhythmias
To determine Arrhythmias what 2 things do you look at to determine them?
Rate and Rhythm
How do you know that an Arrhythmia is a sinus?
One P wave for every R wave
How do you know if it is a Bradycardia?
HR less than 60 bpm is bradychardia
How do you know if it is a tachycardia?
HR over 100 BPM is tachycardia
What is a symptom of Bradycardia? What drug could lead to Bradycardia?
Long PR interval
M2 agonist
What state of the heart changes when you have really fast heart rates?
Diastole, when heart fills with blood.
If you start shortening the amount of blood that fills the heart. Shortening Diastole. what is this?
Tachycardia
What is worse, bradycardia or tachycardia?
Tachycardia, you could have another arrhythmia. Bradycardia you just pass out.
Rapid, regular atrial depolarizations
Sawtooth pattern
Normal QRS as AV node is refractory for most atrial depolarizations.
Atrial flutter
No coordination of atrial depolarization. Irregular QRS, AV node will fire as soon as it is no longer refractory.
Atrial fibrilation
Atrial fibrilation, what do you always make sure the patient is taking?
Anti-coagulant, blood thinner.
What are the conduction blocks we need to know? (SPOT THESE ON A TEST)
1st degree- prolonged PR interval (>.2s)
-due to increased AV node delay
2nd degree blocks- not all p-waves are conducted via AV Node
-Mobitz Type I- PR interval gets progressively longer until a beat is dropped
-Mobitz Type II- PR interval is set, but still drop beats
3rd degree- No conduction via AV node between atria and ventricles
-Both P-waves and QRS have regular rhythm but are not in sync
-QRS can be wide
Whats the diff between sinus tachycardia and ventricular tachycardia?
you are missing P waves in V tach (ischemic event, can lead to fibrillation)
-Vtach is very rapid contractions (probably not ejecting a whole lot of blood because it is going so fast)
Disruption of oxygen delivery
Ischemia
Whats going to start an ischemic event?
plaque in artery. Any interruption in delivery of oxygen.
What is Peaked T-waves, transitioning into inverted T-waves?
Early Ischemia… or local Hyperkalemia outside of ventricles
(T-wave= repolarization of ventricles)
What does ST-segment elevation do?
ST segment is rapidly approaching permanent dead tissue.
If you see Q-waves it is a sign of what?
Permanent damage or an old infarct
Early ischemia looks a lot like what else?
Hyperkalemia
Hyperkalemia has what characteristics on an ECG?
Peaked T-waves
Prolonged PR interval
Widened QRS, merges with T wave
Hypokalemia has what characteristics on an ECG?
- ST depression
- Flattened T-wave and long QT
- U wave
Know rate, Rhythm, Axis, what axis shift represents, if evidence of ischemia, predict how old ischemia is… Hypo and hyperkalemia levels and what they do…
RATE
RHYTHM
AXIS
INFARCT
What could result in widened QRS complex?
Hyperkalemia Sodium channel (Nav)blocker
