Flashcards in Clinical EKGs Deck (49):
If you have a PR interval greater than 0.2 s (> 5 boxes), what do you have?
First degree AV heart block.
If you have a QRS interval greater than 0.12 s (> 3 boxes), what do you have?
A bundle branch block of some sort.
What again are the abnormal QTc intervals for men and women?
Men= > 0.45 s
Women= > 0.47 s
What is the definition of a sinus rhythm?
upright deflection of the P wave in Lead II
What is an easy way to think about what lead sees what?
The area of the heart that is closest to the + (ex. Lead I will look at the left lateral side of the heart because it's + is the left shoulder).
How can upward or downward deflection of lead I help you to determine axis?
If lead I is positive (upward deflection) then the axis will be pointing toward the left. If lead I is negative (downward deflection) then the axis will be pointing in the right direction.
How does ischemia affect polarization?
it leads to constant depolarization because the ions cannot be pumped back out for repolarization.
What do cardiologists call an ST elevation?
A current of injury, because it is not an infarction until you have Q waves. This is an injury current flowing between an injured (DEpolarized) tissue and a normally polarized tissue. So tissue that is ischemic can't repolarize itself :(
How are ST segment changes measured?
relative to the T-P segment, during which the heart is repolarized completely. So if the ST segment is above the T-P segment, you have ST elevation.
What is the J point?
the junction between the S point and T point. This is the point after depolarization has completed and the resting potential is 0.
What does ischemia cause?
low blood flow leads to an increase in CO2 and a lack of nutrients (fatty acids and glucose). Repolarization requires energy, therefore the process is impaired.
How is acute myocardial infarction (AMI) diagnosed?
only when Q waves are present.
What are the common areas for AMI?
LAD, LCX, or their Subepicardial, subendocardial, or collateral arteries.
What area infarcts first when a coronary artery becomes blocked by a thrombus?
the endocardium because it is farthest from the blood supply. After 24hrs the tissue becomes necrotic.
Will a subendocardial injury cause an ST elevation or ST depression?
ST depression of V5 because the positive electrode of V5 on the anterior chest wall detects the movement of positive charge away from the electrode (due to the current flowing from the more positive subepicardium to the less positive subendocardium) and record it as a downward deflection on the ECG paper.
Can you localize the coronary artery involved with ST depression?
Will a transmural (entire wall) injury cause an ST elevation or ST depression?
ST elevation. If you see this in V1-5, you know it is LAD coronary artery current of injury (ischemia), and not infarct yet because there is no Q wave.
What are the criteria for ST elevation in ischemia?
new ST elevation at the J point in 2 contiguous leads with >0.1 mV or mm in all leads excpet V2-3 (>0.2 mV or mm).
What are the criteria for ST depression in ischemia?
new horizontal downsloping ST depression >0.05 mV or mm in 2 contiguous leads or T wave inversion in two contiguous leads
What are some events that can cause inverted T waves in V2,3,4?
ischemia, cerebrovascular accident (CVA), or apical hypertrophic cardiomyopathy (apical HCM)
What are the 4 types of ST segment depression?
3. horizontal (worse)
4. downsloping (worse)
What leads view what areas?
I, aVL= lateral
II, III, aVF= inferior
Can you slight ST elevation everywhere and be normal?
YES. It is early repolarization. It is an upward deflection to the T wave however which is good (it is smiling; you could fill it with water).
What will you see if you're having ischemia in the posterior side of the heart?
ST depressions in V1-3.
What will hypocalcemia look like on an EKG?
A prolonged QT interval with a little T wave. AKA a flat line with a little bump for the T wave (like a tent in the desert). Lead I.
What will hypercalcemia look like on an EKG?
A shortened QT interval. Lead I.
What does hyperkalemia (5.5-6.5 mEq/L) look like on an EKG?
Tall, pointy, narrow T waves (they look sharp) first, and then as it gets worse the QRS gets wider. Seen more in precordial leads.
What does hypokalemia look like on an EKG?
prolonged QT interval with prominent U waves.
What is pericarditis?
inflammation of the pericardium, which will lead to EKG changes.
What will you see with acute pericarditis?
Stage 1= upward concave ST elevation all over the EKG.
Stage 2= J point returns to baseline and T wave amplitude decreases
Stage 3= T waves invert
Stage 4= EKG returns to normal.
*You may also see PR depression
What is electrical alternans?
amplitude of QRS alternates from big/small, big/small with every heart beat, due to heart rocking back in forth in its sac due to fluid build up (pericardial effusion).
What does hypothermia look like on the EKG?
Osborn waves (J point little spikes).
What can digoxin cause on EKG?
Sloping/scooping ST segment (could put water in it).
"Salvador Dali's Mustache"
Where are pacemakers placed?
The control box with computer and battery is placed under the left side of the chest and a wire is fed into the subclavian vein down through the superior vena cava, through the tricuspid valve, and they anchor it in the tip of the right ventricle.
What does a dual chamber pacemaker EKG look like?
It looks like a bundle branch block because you are pacing from the tip of the right ventricle (going from right to left) slowly.
Will pacemakers fire if there is a P wave present?
NO. They can sense this. If it doesn't sense a QRS in the amount of time you allow it, it will fire. When it fires you will see a tiny spike before the QRS.
Can you pace the heart from both sides?
YES (Bi-ventricular pacemaker), by placing a third lead through the coronary sinus and down the posterior vein of the left ventricle in the back of the heart.
For what patients is a bi-ventricular pacemaker required?
Those with congestive heart failure, a wide QRS, and left ventricular dysfunction.
What does the EKG look like with a bi-ventricular pacemaker?
very bizarre. No left bundle pattern or right bundle pattern, but a fusion of those.
What can premature ventricular complexes (PVCs) cause?
These are premature ventricular signals that cause an electrical impulse to travel retrograde through the AV node to the sinus node, causing inhibition (pause) of sinus impulse (that is equal to 2 P to P intervals).
Can PVCs be seen in normal patients?
If a patient has coronary heart disease with a wide complex tachycardia what is it?
ventricular tachycardia 90% of the time.
What is wide complex tachycardia?
QRS greater than 3 boxes (0.12 s) and HR > 100 bpm.
What are the features of ventricular tachycardia (VT)?
sustained= >30 s vs. non-sustained=
What is torsades-de-pointes?
polymorphic VT with prolonged QT interval. Looks like a party streamer (gets bigger then smaller...)
What's the first question you should ask with a wide complex tachycardia?
"What's the blood pressure and are they awake and conscious?"
If unstable= ACLS (shock them)
if stable= you can sedate them and then shock
What type of pattern will VT from the left ventricle show?
What type of pattern will VT from the right ventricle show?