ECG Analysis Flashcards

(46 cards)

1
Q

What physiological activity happens during phase 0 of the cardiac action potential?

A

Rapid Na+ influx through open fast Na+ channels

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2
Q

What physiological activity happens during phase 1 of the cardiac action potential?

A

Transient K+ channels open and K+ efflux returns TMP to 0Mv

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3
Q

What physiological activity happens during phase 2 of the cardiac action potential?

A

Influx of Ca2+ through L-type Ca2+ channels is electrically balanced by K+ efflux through delayed rectifier K+ channels

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4
Q

What physiological activity happens during phase 3 of the cardiac action potential?

A

Ca2+ channels close but delated rectifier K+ channels remain open and return TMP to -90Mv

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5
Q

What physiological activity happens during phase 4 of the cardiac action potential?

A

Na+, Ca2+ channels closed, open K+ rectifier channels keep TMP stable at -90Mv

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6
Q

What is actually measured with ECG?

A

The electrical events that cause mechanical events in the heart

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7
Q

What determines the size and the magnitude of an ECG lead’s signal?

A

it’s position relative to the mean vector, the more in line it is with the mean vector and the large tissue, the greater the magnitude

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8
Q

What is the general direction of the mean vector of the heart?

A

Toward Left-Inferior (towards left ventricle)

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9
Q

If a vector is in the opposite direction of the mean vector how will it show up on the ECG?

A

Negative direction

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10
Q

What is the positive terminal referred to as?

A

The “Eye”-it captures and receives the signal

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11
Q

What do bipolar leads utilize?

A

A negative and a positive electrode and record the electrical activity between the two of them

Uses limbs 1, 2, and 3

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12
Q

What do Unipolar Leads utilize?

A

a single positive recording electrode and a combo of the other electrodes to serve as a composite negative electrode

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13
Q

Where are the V1 thourgh V6 leads located?

What type of leads are they?

A

V1-4th intercostal (IC) space to the right of sternum
(septal)
V2-4th IC soace to the left of the sternum (septal)
V3-between V2 and V4 (ant. wall)
V4-midclavicular line, 5th IC space (ant. wall)
V5-anterior axillary line @level of V4 (lateral wall)
V6- midaxillary line @ level of V4 (lateral wall)

Unipolar Precordial (Chest) Leads

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14
Q

Which augmented lead type will give you the biggest magnitude of the ECG?

Which augmented lead type will give you an inverted reading?

A

Lead aVF (inferior wall) ((electrical signal goes from left to right arm, eye is on belly button))

Lead aV R (Orphan lead) ((electrical signal goes from belly button to left arm and eye is on right arm))

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15
Q

What is the main purpose of using a 3 lead ECG? Where are the 3 leads?

A

basic monitoring and research purposes

RA/LA/LL

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16
Q

What is the main purpose of a 5 lead ECG? Where are the leads?

A

Used for Acute Care

RA/LA/V1/RL/LL

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17
Q

What is the benefit of a 12 lead ECG and what is it used for?

What 12 the 12 leads that is monitors?

A

Allows interpretation of specific areas of the heart and is used for diagnostics and stress testing

(V1-V6), (1, 2,and 3) and (aVR, aVF, aVL)

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18
Q

Which ECG leads can tell you information about the LAD artery?

A

V1-V4 (V1 and V2 are spetal and V3-V4 are anterior wall)

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19
Q

What does each thin line on an ECG represent?

What does each thick line on an ECG represent?

What does each thick lined box represent?

What do 5 boxes represent?

A

1 mm intervals or .04 sec

5mm intervals or .2sec

.2 sec or 5mm

1 sec of time

20
Q

What do the tick marks on a rhythm strip represent?

21
Q

how many milimeters equals 1 mV on an ECG?

A

10mm or 2 thick boxes

22
Q

What does the P wave represent?

What is a normal duration and amplitude?

A

Atrial depolarization

normal duration is less than .12s or 3 small boxes
normal amplitude is less than 2.5mm or 2.5 small boxes

23
Q

What does the P-R interval represent?

What is a normal duration?

A

represents the propagation of the cardiac action potential from the atria through the AV node into ventricles

Normal distribution is .12-.2 sec OR 3-5 small boxes
normally will shorten during exercise as heart rate increases

24
Q

What does the QRS complex represent?

What is a normal duration and amplitude?

A

Ventricular Depolarization

normal duration is .06-/1 sec or 1.5-2.5 small boxes (some healthy pts may have wider QRS but the cut off is .12s)

normal apmplitude is above .5mV in at least one standard lead (5 small boxes) and above 1.0mV in at least one precordial lead (10 small boxes)
-upper limit 2.5-3.0 mV (25 small boxes)

25
What does the ST Segment represent? What is normal?
the interval between ventricular depolarization and repolarization a discrete ST segment distinct from the T wave is usually absent (often at higher rates the ST-T segment is a smooth, continuous line beginning at the j-point (end of QRS) slwoly rising to the peak of the T-wave
26
What does the T wave represent? What is normal?
ventricular repolarization it's deflection should be the same direction as the largest component of the QRS wave complex (usually the R wave) (i.e if R wave is positive the T wave should be too)
27
What does the RR interval represent? What is normal?
the duration between subsequent 'heart beats', this is the duration used to calculate heart rate it should be regular and consistent especially at rest and will shorten during exercise as HR inceases
28
What does the Q-T interval represent? What is normal?
represent the time for ventricular depolarization and repolarization (shortens during fast HR and lengthens during slow HR) Normal duration for men is .4-.44s or 10-11 small boxes Normal for women is .44-.45s or 11-11.5 small boxes
29
What is the more often used form of the QT interval? How is it calculated?
the corrected QT (QTc) interval QT interval divided by square root of R-R interval normal value is less than .44 sec
30
What does the J-point represent? What is a normal duration and amplitude?
the initiation of ventricular repolarization and junction between the termination of the QRS complex and the beginning of the ST segment normally should be in line with the isoelectric line
31
What should be a normal atrial to ventricular rate?
a 1:1 ratio
32
What would be a sign of an irregular rhythm for an ECG?
RR interval and ectopy variable with no pattern, totally irregular
33
What are ectopic pacemakers?
abnormal pacemaker sites located outside of the SA node that display automaticity normally their activity is suppressed via overdrive supression by the higher rate of the SA node
34
What is atrial flutter? (Aflutter)
regular atrial activity with a saw-tooth appearance ventricular rate usually 60-100 bpm conduction ratio usually between 2:1 and 4:1
35
What is atrial fibrillation? (Afib) whats causes afib?
atrial activity is poorly defined; may see course or fine undulations or no atrial activity at all multiple ectopic pacemakers in the atria ventricular response is usually irregularly irregular and can be rapid moderate or slow
36
If the P-R intervals are over .2 sec what does that indicate?
an AV block is present (primary AV block is PR over .2 sec)
37
What are the two types of 2nd degree AV block?
Type 1-(mobitz 1 or wenckeback)- increasing PR interval until a QRS complex is dropped, it usually is benign Type 2 (mobitz 2): QRS dropped without any progressive increase in PR interval (PR interval is constant but still over .2 sec)
38
What is a 3rd degree AV node block?
"complete heart block" 3rd degree AV block: atria and ventricles are electrically dissociated P waves and QRS complexes will occur independent of each other
39
What is the most common cause of ST segment elevation?
Myocardial ischemia and infarction
40
What are the threshold values for ST-segment elevation consistent with STEMI?
J-point elevation of over 2 mm in leads | V2 and V3 or over 1 mm in all other leads
41
What leads correspond with the septal location? What artery do they correspond with?
V1 and V2 LAD
42
What leads correspond with the anterior location? What artery do they correspond with?
V3 and V4 LAD
43
What leads correspond with the interior location? What artery do they correspond with?
2, 3, and avF PDA (80% RCA 20% LCx)
44
What leads correspond with the lateral location? What artery do they correspond with?
1, V5, V6, and avL LCx
45
What are some nonischemic causes of ST depression?
- RVH (right precordial leads) or LVH (left precordial leads, 1 and aVL) - digoxin effect on ECG - hypokalemia - mitral valve prolaspe - CNS disease
46
What are some nonischemic causes of ST elevation?
- LVH (left precordial leads, 1 and aVL) - conduction abnormalities - early repolarization pattern - anuerysms/old myocardial infarctions - pericarditis/myocarditis - brugada pattern - apical ballooning (takotsubo syndrome) - hyperkalemia/hypercalcemia