Basic & Adv EKG Exam 1 Flashcards by Raymond Bas

In what leads should a p-wave be positive?

I, II, aVF, V4-V6

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What should the duration of a p-wave be?

< 0.12 seconds

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What should the duration of a PR interval be?

0.1 - 0.2 seconds

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What should the duration of a QRS complex be?

< 0.12 seconds

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Elevation/depression of an ST segment by __ mm is clinically relevant

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T-waves should be positive in which leads?

I, II, V3-V6

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What does Paroxysmal mean?

Intermittent

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Ventricular ectopy is usually indicative of what?

K⁺ imbalances

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What effects do halothane/enflurane have in regards to arrhythmias?

Halothane & enflurane sensitize the myocardium (increase sensitivity to arrhythmias)

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What arrhythmia in infants can result from sevoflurane?

Bradycardia (via oculo-cardiac reflex?)

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What can desflurane cause during induction?

Prolonged QT (>0.35 seconds)

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What two adverse events can occur from local anesthetic injection into the vasculature?

Severe bradycardia
Asystole

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How would excessive intravascular lidocaine be treated?

Lipid rescue

Administer IV lipid emulsion to sequester lidocaine from plasma, reducing its toxic effects.

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What is the exhaustive list of conditions that can result in perioperative dysrhythmias?

General anesthetics
Local anesthetics
Abnormal ABG or electrolytes
Endotracheal intubation (most common)
Autonomic reflexes
CVP cannulation
Surgical stimulation of heart/lungs
Location of surgery (eyes)
Hypoxemia
Cardiac Ischemia
Catecholamine excess

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What anatomic structure (discussed in class) causes dysrhythmias when stimulated during cardiac surgeries?

Pulmonary arteries

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What example was given of a surgical location where stimulation results in dysrhythmias?

Eyes (due to oculo-cardiac reflexes)
Heart/lungs

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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?

V3 - between V2 and V4

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Where do leads V4, V5, and V6 go?

5th ICS, left of sternum
(mid-clavicular, anterior axillary, and mid-axillary)

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

Q-wave
vector points toward right arm initially, signals beginning of ventricular contraction

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

R-wave
Peak of ventricular systole

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Describe an s-wave.

Negative deflection below baseline after an R wave
Represents movement of axis toward last remaining ventricular cell to depolarize (top of left ventricle)

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1 small box on an EKG strip equals _____?

0.04s

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1 large box on an EKG strip equals ______?

0.2s

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What mV is denoted by a small box on an EKG strip?

0.1mV

What mV is denoted by a large box on an EKG strip?

0.5mV

One full EKG strip is how many seconds? What is half a strip?

Full strip: 6 secs Half strip: 3 secs

If healthy, both the QRS complex and T-wave should be ______ deflections in leads I, II, & III.

positive.

What is the mean electrical axis of the heart?

59°

A clockwise shift (>59 degrees) of the mean electrical axis shift of the heart is indicative of what?

Right-axis deviation

A counterclockwise shift (<59 degrees) of the mean electrical axis shift of the heart is indicative of what?

Left-axis deviation

Regarding Lead I, where is the negative terminal connected? How about the positive terminal?

Negative terminal = Right arm Positive terminal = Left arm

Regarding Lead II, where is the negative terminal connected? How about the positive terminal?

Negative terminal = Right arm Positive terminal = Left leg

Regarding Lead III, where is the negative terminal connected? How about the positive terminal?

Negative terminal = Left arm Positive terminal = Left leg

What angle is viewed utilizing aVF?

90°

What angle is viewed utilizing aVL?

-30°

What angle is viewed utilizing aVR?

-150°

Which lead can be used as the determinant of posterior vs anterior injury?

V2 Positive deflection: posterior injury Negative deflection: anterior injury

In which precordial lead does the QRS complex have the most magnitude?

What are the positive & negative terminals for lead aVR?

Negative = left arm + left leg (+30°) Positive = right arm (-150°)

What are the positive & negative terminals for lead aVF?

Negative = left arm + right arm Positive = left leg

What are the positive & negative terminals for lead aVL?

Negative = left leg + right arm Positive = left arm

What cardiac EKG lead is the least useful in practice but most unique in its position?

aVR

What is the axis of Lead I?

0°

What is the axis of Lead III?

120°

What is the axis of Lead II?

60°

What degree change would characterize an extreme axis deviation?

-90° to 180°

What would the mV of this QRS complex be?

+1.5mV (1 big box = 0.5mV)

Determine the mV of leads I & III and subsequently the degree & axis of deviation noted by these strips.

Lead I ≈ -2.5mV Lead III ≈ +1.75mV Deviation ≈ inbetween +180° & +120° ≈ 170° due to greater Lead I magnitude. Significant right axis deviation

What is the diagnosis for this EKG?

Left axis deviation in Lead I & Lead III Possible LEFT ventricular hypertrophy (left ventricle depolarizes later than the right ventricle) more tissue = longer depolarization

What is the diagnosis of this EKG?

Right axis deviation in Lead I & Lead III Possible RIGHT ventricular hypertrophy

What is the diagnosis for this EKG?

Left axis deviation in Lead I & Lead III Left bundle branch block

A positive current of injury noted on V2 would be indicative of what?

Posterior MI abnormal depolarizing tissue posteriorly moving towards V2

A negative current of injury noted on V2 would be indicative of what?

Anterior MI abnormal depolarizing tissue anteriorly moving away from V2

What axis would be expected with a negative QS deflection in leads I and II and a positive R deflection in Lead III?

Right Axis Deviation

What axis would be expected with a negative QS deflection in leads II and III and a positive R deflection in Lead I?

Left Axis Deviation

A positive V1 QRS with negative QRS in leads I, II, and III would the resulting axis be?

Extreme Axis Deviation

What block would you expect to present with a right axis deviation 90 to 180 degrees?

Posterior Hemiblock Right axis deviation is always pathological small R in lead I, small Q in lead III

What block would you expect to present with a left axis deviation that is -40 to -90 degrees?

Anterior Hemiblock this is a pathological left axis small Q in lead I, small R in lead III

What is physiologic left axis deviation?

Left axis deviation that is 0 to -40 degrees normal variant especially in obese or athletic people

What is an MCL1 lead? How is it placed?

Modified V1 lead ## Footnote Negative on left arm, positive in 4th ICS right of sternum.

What would leads I, II, and III look like with normal axis?

All + QRS

What is the most common cause of right ventricular hypertrophy?

Lung disease, pulmonary embolus, and pulmonary valve disease.

Bundle Branch Block diagnosis is dependent on ______. Hemiblock diagnosis is based on _______________.

time axis deviation

What pertinent anatomical features of the heart are fed via the RCA?

Inferior & posterior LV wall Right ventricle SA & AV node Posterior fascicle of LBB

What pertinent anatomical features of the heart are fed via the LAD?

Anterior wall of LV Septal wall Bundle of His & BB

What severe outcome should you worry about with septal infarct?

Septal rupture

What pertinent anatomical features of the heart are fed via the circumflex artery?

Lateral wall of LV *SA & AV nodes (?) Posterior wall of LV

Why is morphine now avoided in MI’s?

Morphine causes histamine release.

What percentage occlusion would be assumed with chest pain on exertion?

70 - 85% occlusion

What percentage occlusion would be assumed with chest pain at rest?

90% occlusion

What percentage occlusion would be assumed with chest pain unrelieved by nitroglycerin?

100% occlusion

What should be administered before nitroglycerin with an acute right-sided MI?

fluid bolus

Are EKGs better in regards to sensitivity or specificity?

Specificity (If MI is shown on EKG then its likely an MI) but sensitivity is 50% for EKGs so a negative EKG result doesn’t rule out MI)

What sign would indicate **ischemia**?

Symmetrical inverted T-waves in **two or more** related leads.

What sign would indicate an **injury pattern**?

ST segment elevation of **more than 1mm** in two or more related leads.

What sign would indicate **infarction**?

**Pathologic Q waves** ( >40ms wide or ⅓ the depth of r-wave height) coupled with ST elevation.

Which leads indicate a true lateral MI? Which would indicate a high lateral?

True lateral = V5 & V6 High lateral = I, aVL

What is the most commonly seen MI? What is commonly seen with this type of MI? Do you use nitrates?

Inferior Bradycardia, hypotension, 1st degree or Mobitz 1 blocks, and nausea. Caution with nitrates due to RV’s being preload dependent w/ inferior MI’s

What is the most lethal MI? What dysrhythmias are commonly seen with this type of MI? Do you use nitrates?

Anterior Wall (LAD) CHB and VF/Vtach Yes to nitrates.

What would cause one to prepare defibrillation pads for a patient undergoing an anterior MI? (other than vfib/vtach)

Presence of BBB or hemiblock whilst undergoing an anterior MI

What condition presents with ST elevation on all leads? How is it diagnosed?

Pericarditis Patient feels better when they lean forward and there won’t be reciprocal ST depression. Diagnosed via fever, WBCs, hx of IVDU, etc.

What condition looks like myocardial infarction on an EKG but can be fatal if thrombolytics are administered?

Dissecting thoracic aorta aneurysm.

What four conditions mimic myocardial infarction in their EKG presentation?

LBBB LV hypertrophy Pericarditis Thoracic aortic dissection

What is the intrinsic rate of the SA node?

110 bpm w/out SANS or PANS stimulation

What is the intrinsic rate of the AV node?

40-60 bpm

What is the intrinsic rate of the bundle branches?

20-40 bpm

What is the intrinsic rate of the Purkinje system?

20-40 bpm

What is the name of the nerve that branches off the SA node to innervate the left atrium?

Bachmann's bundle (interatrial bundle)

When does atrial repolarization occur?

During QRS interval Cannot be seen because it occurs during ventricular depolarization

What is Einthoven's formula?

Lead I + Lead III = Lead II

What is SALI? What leads are associated?

S: V1, V2 (SEPTAL) A: V3, V4 (ANTERIOR) L: V5, V6, aVL, I (LATERAL) I: II, II, and aVR (INFERIOR)

Hyperkalemia EKG changes are (3)

1. Wide and low P wave 2. Wide QRS 3. Tall T waves

Hypokalemia EKG changes? (3)

1. ST depression 2. Flat or negative T wave 3. **U-waves**

Hypercalcemia EKG changes (2)

**broad**, tall peaking T waves Severe: extremely **wide QRS**, disappearance of P wave, tall peaking T waves

Hypocalcemia EKG changes?

1. Narrow QRS 2. **Flattened T waves Severe** 3. **Prolonged QT interval** 4. **U-wave** 5. Prolonged ST and ST depression

What are the 3 I's of infarction?

1. Ischemia (inverted T waves >2 leads) 2. Injury pattern (ST elevation > 1mm in >2 leads) 3. Infarction (pathologic Q waves)

What is reciprocal change on an EKG? What do we see?

ST changes that appear in leads that are opposite (reciprocal) to the leads where the primary changes are observed. We see ST depression or inversion/flattening

Where do we see reciprocal changes for ST elevations in: Leads V3, V4, V5, V6, aVL, and I? (anterior and lateral MI)

Leads II, III, and aVF (inferior leads)

Where do we see reciprocal changes for ST elevations in II, III, and aVF? (Inferior MI)

I and aVL (Lateral leads)