- Negative deflection below baseline after an R or Q wave.

Exam 1 - ECG Flashcards by Brandon Simpson

How does an action potential spread from the SA node to the right and left atria?

Right atria - Internodal pathway
Left atria - Bachmann’s Bundle

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What is the inherent rate of the SA node, AV node, Bundle of His, and bundle branches/purkinjie fibers?

SA node: 60-100 bpm
AV node and Bundle of His: 40-60 bpm
Bundle branches and purkinjie fibers: 20-40 bpm

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How many seconds is 1 large box?
1 small box?

0.2 seconds
0.04 seconds

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What is the voltage of 1 large box?
1 small box?

0.5 mV
0.1 mV

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What is a normal p wave duration?
PR interval?

P wave: < 0.12 secs
PR: .10-.20 secs

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Normal QRS duration?

< 0.12 secs

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What is a significant ST segment elevation/depression?

> 1 mm, usually in contiguous leads

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What identifies a junctional rhythm?

Rate 40 - 60 ( AP originating from AV node/Bundle of His)
Loss of p waves or inverted p waves from retrograde depolarization of the atria

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What identifies a junctional tachycardia?

Loss of p wave, or inverted
Rate > 60

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What defines supraventricular tachycardia?

Narrow complex QRS
P wave may be buried due to fast rate

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How do you identify a PAC?

A complete complex that occurs immediately following another but at lower voltage

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What is a first degree AVB?

Prolongation of the PR interval > .20 secs

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What is a 2nd degree type I AVB?

Progressive elongation of the PR interval followd by a p wave without a QRS

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What is a 2nd degree type II AVB?

Random P waves with unconducted QRS complexes, usually in a defined ratio

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What anesthetics can induce arrythimias?

Halothane/enflurane - sensitize myocardium
Keatmine - tachyarrythmias
Sevoflurane - bradycardia in infants
Desflurane - prolonged QT during induction
Local anesthetics - severe bradycardia from sympathetic block

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Where does lead V1 go? V2?

V1 - 4th ICS, right of sternum
V2 - 4th ICS, left of sternum

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Where does lead V3 go?
V4?

V3 - between V2 and V4
V4 - 5th ICS, left of sternum

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Where does lead V5 go?
V6?

V5 - 5th ICS, left of sternum
V6 - 5th ICS, mid axillary line

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What wave is the first negative deflection after the p-wave on any lead?

Q-wave

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What wave is the first positive deflection after a p-wave?

R-wave

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Describe an s-wave.

Negative deflection below baseline after an R or Q wave.

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What QRS is denoted by 1 in the figure below?

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What QRS is denoted by 2 in the figure below?

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What QRS is denoted by 3 in the figure below?

qRs

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What QRS is denoted by 4 in the figure below?

What QRS is denoted by 5 in the figure below?

What QRS is denoted by 6 in the figure below?

rSR'

What happens to the QRS in hyperkalemia?

QRS widening, fusion of QRS-T, loss of ST segment

What is a characteristic ECG change caused by hyperkalemia?

Tall tented T waves

What is a u-wave? When might it be present?

Spike after T wave and before p wave Hypokalemia, hypocalcemia

What ECG changes are seen in hypercalcemia?

VERY wide QRS, low R wave, loss of p waves, tall peaked T waves

What ECG changes are see in hypocalcemia?

Narrowed QRS, T wave flattened/inverted, prlonged QT, prominent U wave, ST depression

What is a "J" wave? When is it seen?

A positive deflection seen at the J point (precordial and limb leads) or negative reciprocial (aVR and V1) Hypothermia and hypercalcemia

What is a delta wave? When is it seen?

Slurred upstroke of the QRS WPW

What drug should you avoid in patients with WPW?

Cardizem

How many electrodes are there in a 12 lead ECG?

What is the J point?

Where the QRS ends and the ST segment begins

What creates a positive and negative deflection in any lead?

Positive: electricity flowing towards a positive lead Negative: electricity flowing away from a positive lead

What QRS deflections are seen in normal axis in leads I, II, and III?

Positive in all leads

What degrees constitute a physiologic left axis deviation?

0 to -40

What QRS deflections are seen with a physiologic left axis deviation?

Lead I: Positive Lead II: Positive Lead III: Negative

What degrees consititue a pathological left axis deviation? What are the causes?

- -40 to -90 - Anterior hemiblock - Hypertrophy of LV - Extreme exercise

What QRS deflections are seen in pathological left axis deviations?

Lead I: positive Lead II: negative Lead III: negative

What degrees constitute a right axis deviation?

90 - 180

What QRS deflections are seen in right axis deviation?

Lead I: negative Lead II: positive or negative Lead III: positive

What are causes of a right axis deviation?

All right axis are pathological: posterior hemiblock, severe lung disease, valve disease, pulmonary embolus

What axis deviation causes negative QRS in all limb leads? What is the cause?

Extreme right axis Ventricular injury of origins

How do you determine a right or left BBB?

- Must use lead V1 - QRS must be wider than .12 secs - Find the J point - Draw a line back to the complex, then up or down to the QRS - fill in the triangle Arrow up → turn signal up → RBBB Arrow down → turn signal down → LBBB

What is a bifasicular block?

RBBB + Anterior hemiblock RBBB + Posterior hemiblock LBBB (takes out both anterior and posterior fasicles)

What 5 things does the RCA supply?

- Inferior wall LV - Posterior wall LV - Right ventricle - SA and AV nodes - Posterior fasicle of LBB

The LAD feeds what 3 things?

- Anterior wall LV - Septal wall - Bundle of His and BB

The circumflex artery feeds what 3 things?

- Lateral wall of LV - SA and AV nodes - Posterior wall of LV

What 2 drugs can interupt MI plaque formation?

Heparin and aspirin

Chest pain on exertion equals what percent vessel occlusion?

70-85%

Chest pain at rest means what percent of vessel occulusion?

90 % occlusion

Chest pain at rest unrelieved by nitro means what percent of vessel occlusion?

100 %

Why is morphine not indicated for MI anymore?

Causes hypotension from histamine release

What ECG changes accompany ischemia?

Symmetrical inverted T waves or ST depression in 2 or more leads

What ECG changes accompany myocardial injury?

ST segment elevation of more than 1 mm in 2 or more related leads

WHat ECG changes accompany infarction?

Pathologic Q waves (1/3 depth of R height)

What is the system for assessing a 12 lead?

I See ALL Leads Inferior = II, III, aVF Septal = V1 and V2 Anterior = V3 and V4 Lateral = V5, V6, I, and aVL

What ECG changes can be signs of posterior MIs?

Reciprocal changes of ST depression in V1-V4

What other involvement do 1/2 of inferior MIs have? What would you caution in these patients?

Posterior and RV involvement Nitrates - preload already effected with RV dysfunction and can cause drop in BP, **may need fluids**

What is the most lethal MI?

What is the treatment for anterior wall MI?

Nitrates, spare fluids

What 4 things can mimic an MI? What makes an MI an MI per 12 lead ECG?

1. LBBB 2. LVH 3. Pericarditis 4. Dissecting thoracic aortic aneurysm MI on 12 lead will usually have reciprocal ST changes

What are the symptoms of pericarditis?

- ST elevation in all leads - No reciprocal ST depression - Feels better when leaning forward