Flashcards in EKG Deck (40):
What is Coronary Artery Disease
-plaque builds up in the coronary arteries which causes narrowing/blockages which decrease blood flow to the heart
-the disease typically cycles in and out of clinically defined phases:
Acute Coronary Syndrome
What is Asymptomatic coronary artery disease?
-plaque is present but not significant
What is Stable Angina
-predictable symptom provocation
-collateral circulation usually present
-Example: Ask pt “are you able to go up 2 flights of stairs”- they know if they go up 1 flight of stairs they will have chest heaviness.
What is Accelerating Angina?
-unstable plaque with intermittent symptoms
-symptoms come and go
What is Acute Coronary Syndrome?
What does Acute Coronary Syndrome refer to?
What is the focal point in treatment decision strategies for a pt admitted with dx of unstable angina, chest pain or rule-out MI?
12 Lead ECG
-done in the field and transmitted right to the Cath Lab
What is Unstable Angina?
-occurs without cause ex. It wakes you up for sleep
-lasts longer than 15-20 minutes
-responds poorly to nitroglycerin
-may occur along with a drop in blood pressure or significant SOB
What is a NSTEMI?
Non-ST Segment Myocardial Infarction
-ST Segment elevation does NOT occur
-Coronary Artery is only partially blocked
-a smaller portion of cardiac tissue dies since there is not a complete artery blockage- that’s what causes the ST segment depression
-difficult to distinguish form unstable angina without measuring cardiac enzymes
What is a STEMI?
ST Elevation Myocardial Infarction
-ST elevation does occur indicating complete blockage of the coronary artery, occlusive clot
-a larger amount of cardiac tissue dies
-more sever than NSTEMI
-early intervention critical -door to ballon time <60 minutes!
What are the 3 Clues used to Diagnose Chest Pain?
1. The first assessment clue is focused around the characteristics of chest discomfort and the physical exam
2. The second assessment clue is rapid and accurate interpretation of the 12 lead ECG
3. The third assessment clue is the rise and fall of cardiac maker labs
What is the Primary Diagnostic Study that sits at the center of all decision making protocols?
The 12 lead ECG is the primary diagnostic study, although all 3 clues are important.
What is the format of the Printed 12 Lead ECG?
-there are 6 FRONTAL LEADS which are labeled Leads, I, II, III, aVR, aVL, and aVF
-Leads I, II, III represent a picture of the electrical conduction of the heart from view of the limb to the heart
-the sam “a” means AUGMENTED
-the augmented leads show the electrical conduction augmented from the heart to the right arm (aVR) from the heart to the left arm (aVL) and the heart to the right foot (aVF)
-There are 6 PRECORDIAL LEADS/Chest Leads/ V Leads named V1, V2, V3, V4, V5, and V6.**** placed at the 4th intercostal space****
I AVR V1 V4
II AVL V2 V5
III AVF V3 V6
What does ST segment inversion/ T wave inversion reflect?
What does ST segment elevation reflect?
-greater elevation- infarction- tissue death
-development of Q or QS waves
What is the Isoelectric Line?
-electrical activity is resting
-imaginary line on the ECG recording where your PR interval is recorded and where the S segment normally sits
-normal reference point for evaluating ST- T wave abnormalities
What is the atrial depolarization?
-the impulse travels from the sinoatrial (SA node) into the atrium-ventricular junction (AV node) and the Bundle of His. This conduction is reflected in the PR interval
What is the ST segment reflective of?
-followed by the T wave, which shows repolarization of the ventricles
What does the QRS tracing represent?
Where should the PR interval and ST segment sit?
-on the isoelectric line
What do normal Q waves look like?
Normal Q waves are skinny and not very deep
-narrow: < or + 0.04 seconds wide (1 small ECG box in width)
-short: < or = 25% of the total height of the R wave (< 1/4th the height of the R wave)
What do abnormal Q waves indicate and what do they look like?
-indicate heart damage and cannot conduct normally
-reflect that there has been a loss of electrical activity resulting from damaged myocardial tissue
-they are a permanent markers of damage and never go away
-the larger number of leads with abnormal Q’s the grater the amount of heart damage!!! “They got Q’ed out.”
-Abnormal Q Criteria
- >/= 0.04 wide
->/= 25% the height of the R wave
-permanent on ECG recording
What is a Left Bundle Branch Block (LBBB)?
-normally the septum is activated from left to right, producing small Q waves in the lateral leads.
-in LBBB the normal direction of septal depolarization is reversed (becomes right to left)
-impulse spreads first to the RV via the RBB and then to the LV via the septum
-this extends QRS duration > 120 ms and eliminates the normal septal Q waves in the lateral leads
-produces tall R waves in the lateral leads (I, V5-V6)
-deep S waves in right precordial leads (V1-V3)
-usually leads to left axis deviation
What causes LBBB?
Anterior MI—-this is our biggest concern
Aortic Stenosis-calcification can grown into the tissue the ECG pattern can not get through it
Ischemic Heart Disease
Primary degenerative disease (fibrosis) of the conducting system (Lenegre Disease)
What is LBBB diagnosis criteria?
-QRX duration of 120 ms
-Dominant S wave in V1
-Broad monophonic R wave in lateral leads (I, aVL, V5-V6)
-Absence of Q waves in lateral leads (1, V5-V6; small Q waves are still allowed in aVL)
-Prolonged R wave peak time > 60ms in left precordial leads (V5-V6)
*** you will have a W in V1 and a M in V6 this is reversed in RBBB M in V1 and W in V6****
What do normal R waves and wave progression look like?
-there should be an R wave in each of the 12 leads except in aVR
-Some R waves are very short- ie. V1
-commonly attributed to anterior MI, LBBB, Wolff-Parkinson-White Syndrome, right and left LVH as was a by faulty ECG placement
-normal increase and decrease in the isoelectric line in the V3 and V4
-early R wave progression in V2
-late R wave progression in V5
What is important to observe about ST segment?
-observe the ST segment and the junction point (J point) morphology
-the J-point is located at the end of the QRS where the T wave begins
- to be clinically significant the ST deviation from the isoelectric line should be greater than 1-2mm in 2 leads for MI diagnosis
-—exception V1 and aVR have abnormal looking ST segments——
What is Myocardial Ischemia?
-temporary or transient deprivation of the Myocardial oxygenation resulting in ST segment and/or T wave inversion on the ECG
-the ST-T wave abnormalities typically return to the normal ST on the isoelectric line and upright T wave position when the myocardial oxygen supply meets the demand
What are the 5 steps to looking at EKG’s?
1. Examine all 12 leads closely with the exception of aVR.
2. Go on a Q wave search- normal Q waves are seen best in leads I, aVL, V5, and V6. Circle abnormal Q waves. (> 0.04 sec wide and > than 25% of the height of the R wave)
3. Go on an R wave search- 11/12 leads should have an R wave. Missing in the aVR circle all leads without an R wave because that is abnormal
4. Examine the ST segment..... does it live on the isoelectric line?
With the exception of V1, all eleven leads should have ST segments that begin and end on the isoelectric baseline. Mark abnormal leads
5. Examine the T wave... the should be upright in all 11 lead except it might be biphasic in V1 which is normal Circle any T waves that are not upright
What are cardiac markers?
CK - normal 0-170 IU/L
CK-MB normal 0-6 mg/ml
CK Index or Ration normal 0-1.5%
Troponin 1- normal < 0.4ng/ml
Borderline: 0.4-2 ng/ml
Elevated: > 2 ng/ml
-these lab test will be elevated in the setting of acute myocardial tissue damage
- we mostly use Trop and order series labs Q8 x3
-In transient or temporary myocardial oxygen deprivation resulting in abnormal ST-T waves on ECG, called myocardial ischemia the markers will not be elevated since the pt is not having a STEMI
What is our role in relation to ACS?
-Acute STEMI is very dangerous, it is when pt are most likely to develop sudden death- VT and V fib
1. Assess and stabilize
Assess for chest pain, and hemodynamic response (BP, P, Cardiac Rhythm)
Decrease myocardial oxygen demand while increasing supply-MONA
2. Obtain 12 lead- assess for new ST-T wave elevations
3. Evaluate cardiac marker labs for elevation(Troponin 1, CK, CKMB, Myoglobin)
4. Stay in close communication with the provider
What is Infarction?
-we see deep and wide Q waves because damaged myocardial tissue cannot conduct normally
-the pt may lose some of the height/voltage on the R wave
-abnormal Q waves usually develop within 1-4 days of an acute STEMI
What are the Coronary Arteries and their Major Branches
Right Coronary Artery RCA
Left Main Coronary Artery LM
Left Anterior Descending LAD
Circumflex Artery CX
What does the RCA supply?
SA node in 55% of pop watch for bradycardia
AV node in 90% of pop watch for AV blocks
Posterior wall in 90% of pop
RCA feeds the posterior descending artery in 85% of the pop
-PDA feeds inferior wall
-leads II, III, and aVF
What does the LAD supply?
Antierior wall LV- watch for pump disturbances (decreased EF)
Interventricular septum- watch for arrhythmia
RBB- watch for RBBB
Anterior division of LBB- watch for LBBB
Papillary muscles to mitral valve- rupture of pap muscle
- anterior leads
What does the L CX supply?
Lateral wall LV
Posterior wall LV (10% of population is left dominant)
SA node in 45% of the pop
AVL, V5, V6
Which leads do you look at for Inferior Wall?
II, III, aVF
Which leads do you look at for Anterior Wall?
V1,V2, V3, V4
Which leads do you look at for Lateral Wall?
I, aVL, V5, V6