EKG Intro Flashcards
What are some limitations of the EKG?
- Is only a “snapshot.”
(May not capture the cardiac problem at that exact moment) - Done at rest (Cannot reproduce CV issues that only occur during times of stress)
- Represent electrical activity; not mechanical
What happens to the myocytes during depolarization?
Myocyte membrane potential is made more NEGATIVELY CHARGED to physically CONTRACT the myocyte.
What is the primary function of the myocyte?
To contract.
Contraction creates knock-on/chain reaction effect between myocytes
What is the pacemaker of the heart?
What is it innervated by?
SA Node (Initiates electrical impulses and action potentials)
Can depol without stimulation (Automaticity), but also innervated by symp. and parasymp. (vagal) fibers
Where do action potentials travel from the SA Node?
SA Node to Bachmann’s bundle to contract atria
SA Node to AV node, signal passed along to bundle of His –> Purkinje fibers –> Endocardium –> Vent. myocardium
What does the P wave represent in an EKG?
Depolarization of atria.
What is the quick estimation method for Rate of EKG’s?
300-150-100-75-60-50-(
or a NORMAL 6 sec strip x 10
What is the Q wave
Intraseptal depolarization
What does the QRS complex represent?
RAPID depolarization of both ventricles. (If prolonged start thinking LBBB/RBBB, LVH, Ventricular defects, HOCM, etc.)
How can you determine if a PT is displaying LVH on an EKG?
The sum of the deep S wave in V1 and R wave in V5 = >35 mm
R wave in aVL > 11mm
If Extreme/Marked RAD what should you consider?
- Leads are reversed
2. Dextracardia
What would indicate an infarct on an EKG?
Q wave >.04 sec (one small block
OR
Q wave (1/3rd amplitude or more of the QRS complex)
Leads II, III, and aVF would indicate what kind of infarct?
Inferior wall: Leads II, III, and aVF
Leads V1 and V2 would suggest what kind of infarct?
Anteroseptal wall defect: leads V1 and V2. (same as posterior wall MI)
What leads would indicate a lateral wall defect? What about anterolateral?
Lateral wall MI: I and aVL
Anterolateral are V5 and V6
What leads would indicate an anterior wall MI?
Anterior wall MI: V3 and V4
What leads would indicate a posterior wall MI?
Posterior wall MI: V1 and V2. (same as anteroseptal wall) MI)
What is a normal PR interval on an EKG?
0.12 to 0.20sec
What is a normal QRS duration?
<0.12sec
Chest pain with a new Left BBB on a PT what should you be concerned with?
MI. Order cardiac enzymes. You cannot interpret the EKG the same as you usually would though due to the LBBB (depolarization dysfunction)
Where will a RBBB be visualized?
V1 and V2 with “Bunny ears” (b/c bunny ears are always right). If visualized look back at leads I and III for (Q1S3) for left anterior vasicular block/ a biphasic block
What defining characteristic would clue you into a Mobitz 1 block (Wenckebach)?
Progressive elongation of PR intervals. Then a dropped beat (due to AV node inability to conduct stimulus)
What is the rate of Atrial flutter and what is its general appearance on an EKG?
Sawtooth pattern
250-350bpm (THE FLUTTERS ARE 250 to 350 / FIBRILLATION is 350-450)
Smooth, fine, sine waves appear on the EKG with very rapid intervals. The rate on the EKG is appx. 300bpm. What condition do you suspect?
V-flutter. Can also present as Torsades des Pointes with the “ribbon-like” appearance
