Podcast
Questions and Answers
Which type of myocardial infarction (MI) involves the full thickness of the heart muscle?
Which type of myocardial infarction (MI) involves the full thickness of the heart muscle?
- STEMI (correct)
- Subendocardial MI
- NSTEMI
- Incomplete MI
What is the primary characteristic of a NSTEMI on an EKG?
What is the primary characteristic of a NSTEMI on an EKG?
- ST segment elevation
- ST segment depression (correct)
- Inverted T wave
- Significant Q wave
What EKG change is associated with myocardial ischemia?
What EKG change is associated with myocardial ischemia?
- Depressed PR segment
- Elevated ST segment
- Significant Q wave
- Inverted T wave (correct)
Which EKG finding suggests that myocardial injury is occurring?
Which EKG finding suggests that myocardial injury is occurring?
The appearance of a significant Q wave on an EKG indicates what?
The appearance of a significant Q wave on an EKG indicates what?
What is the typical shape of the ST segment elevation associated with myocardial injury?
What is the typical shape of the ST segment elevation associated with myocardial injury?
What does ST segment depression typically imply?
What does ST segment depression typically imply?
What condition is suggested by a tall, pointy T wave?
What condition is suggested by a tall, pointy T wave?
A significant Q wave is defined as being at least what proportion of the R wave amplitude?
A significant Q wave is defined as being at least what proportion of the R wave amplitude?
In the context of myocardial infarction, what does 'akinesis' refer to?
In the context of myocardial infarction, what does 'akinesis' refer to?
What is the normal location of the transition zone in precordial leads on an EKG?
What is the normal location of the transition zone in precordial leads on an EKG?
Which wall of the left ventricle is supplied by the left anterior descending (LAD) artery?
Which wall of the left ventricle is supplied by the left anterior descending (LAD) artery?
Right ventricular infarction is suspected with an inferior MI, and which of the following?
Right ventricular infarction is suspected with an inferior MI, and which of the following?
In which EKG leads are reciprocal changes typically observed in an anterior MI?
In which EKG leads are reciprocal changes typically observed in an anterior MI?
In the context of an evolving MI, which EKG change typically occurs immediately before the actual MI starts?
In the context of an evolving MI, which EKG change typically occurs immediately before the actual MI starts?
Which coronary artery primarily supplies the inferior wall of the left ventricle?
Which coronary artery primarily supplies the inferior wall of the left ventricle?
Why would a right-sided EKG be performed when evaluating a suspected myocardial infarction?
Why would a right-sided EKG be performed when evaluating a suspected myocardial infarction?
What is a key characteristic observed in V1 and V2 leads that may indicate a posterior wall MI?
What is a key characteristic observed in V1 and V2 leads that may indicate a posterior wall MI?
What is the primary limitation of using a standard 12-lead EKG to diagnose a posterior MI?
What is the primary limitation of using a standard 12-lead EKG to diagnose a posterior MI?
Which set of leads would show ST elevation in an inferior MI?
Which set of leads would show ST elevation in an inferior MI?
In the context of R wave progression in precordial leads, what normally occurs from V1 to V6?
In the context of R wave progression in precordial leads, what normally occurs from V1 to V6?
Which of the following EKG changes is most indicative of cardiac tissue ischemia immediately before an MI?
Which of the following EKG changes is most indicative of cardiac tissue ischemia immediately before an MI?
After an ST elevation myocardial infarction, what EKG change is expected to persist, signifying permanent tissue death?
After an ST elevation myocardial infarction, what EKG change is expected to persist, signifying permanent tissue death?
Which of the following is a critical EKG criterion for identifying a significant Q wave suggestive of myocardial necrosis?
Which of the following is a critical EKG criterion for identifying a significant Q wave suggestive of myocardial necrosis?
A patient presents with symptoms suggestive of an acute myocardial infarction. The initial EKG shows ST depression in leads V1-V3 with tall, prominent R waves. What type of MI is most likely?
A patient presents with symptoms suggestive of an acute myocardial infarction. The initial EKG shows ST depression in leads V1-V3 with tall, prominent R waves. What type of MI is most likely?
A patient's EKG shows ST elevation in leads II, III, and aVF. Reciprocal changes are observed in leads I, aVL, and V1-V6. Which coronary artery is most likely occluded?
A patient's EKG shows ST elevation in leads II, III, and aVF. Reciprocal changes are observed in leads I, aVL, and V1-V6. Which coronary artery is most likely occluded?
In the context of diagnosing myocardial infarctions with bundle branch blocks (BBB), which statement is most accurate?
In the context of diagnosing myocardial infarctions with bundle branch blocks (BBB), which statement is most accurate?
After reviewing an EKG, you observe a normal Q wave. Which of the following characteristics would confirm its normal status rather than indicating myocardial necrosis?
After reviewing an EKG, you observe a normal Q wave. Which of the following characteristics would confirm its normal status rather than indicating myocardial necrosis?
A 60-year-old male presents to the emergency department with chest pain. His EKG shows ST elevation in leads V1-V6, I, and aVL, with reciprocal changes in the inferior leads (II, III, aVF). Given these findings, which coronary artery is most likely the culprit lesion?
A 60-year-old male presents to the emergency department with chest pain. His EKG shows ST elevation in leads V1-V6, I, and aVL, with reciprocal changes in the inferior leads (II, III, aVF). Given these findings, which coronary artery is most likely the culprit lesion?
Flashcards
STEMI
STEMI
Full thickness damage through the myocardium, indicated by ST elevation on an EKG.
NSTEMI
NSTEMI
Partial thickness damage to the myocardium, does not extend through the entire wall.
Ischemia
Ischemia
Heart starving for blood/oxygen, causing pale tissue. Evidenced by inverted T wave on EKG.
Injury
Injury
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Infarction
Infarction
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Normal ST Segment
Normal ST Segment
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ST Elevation
ST Elevation
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ST Depression
ST Depression
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Normal T Wave
Normal T Wave
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Tall Pointy T Wave
Tall Pointy T Wave
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Flattened T Wave
Flattened T Wave
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Normal Q Waves
Normal Q Waves
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Significant Q Wave
Significant Q Wave
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Transition Zone
Transition Zone
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Anterior Wall
Anterior Wall
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Inferior Wall
Inferior Wall
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Lateral Wall
Lateral Wall
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Posterior Wall
Posterior Wall
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Right Coronary Artery (RCA)
Right Coronary Artery (RCA)
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Left Coronary Artery
Left Coronary Artery
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Posterior MI
Posterior MI
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Inferior MI
Inferior MI
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Lateral MI
Lateral MI
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Anterior MI
Anterior MI
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Study Notes
- Chapter focuses on ST segments & Myocardial Infarction (MI)
Two Types of MIs
- ST elevation MIs, also known as STEMI or transmural involves full thickness through the myocardium
- Non-STEMI or NSTEMI, also called subendocardial or incomplete, involves partial thickness and does not go through the entire wall
- That portion of the wall will never move the same again if that area is infarcted
- Akinesis is the absence of movement
The Three I's of Infarction
- Ischemia occurs when the heart is starving for blood and oxygen, resulting in pale whitish tissue, and is noted by an inverted T wave on the EKG
- Injury occurs when tissue is being injured by a lack of perfusion, with the tissue appearing bluish, and is noted by ST segment elevation on EKG
- Infarction occurs when tissues necroses and turns black, and is noted by a significant Q wave on EKG
ST Segment
- A normal ST segment is at the same baseline as the PR segment
- ST elevation is when the ST is above the baseline
- Convex ST elevation (coved) is associated with myocardial injury
- Concave ST elevation (rounded) is associated with pericarditis, but also seen with MI
- ST depression is when the ST is below the baseline and implies ischemia
T Wave
- Normal T wave is rounded with amplitude <= 5 mm in frontal leads
- All abnormal T's can imply ischemia
- Tall pointy T wave indicates hyperkalemia or hyperacute change of MI
QRS Complex
- Normal Q waves (Right Ventricle Deflection) imply septal and right ventricular depolarization
- Significant Q wave must be either 0.04 secs wide OR at least one-fourth the size of the R wave, implying myocardial necrosis
R Wave Progression and Transition
- Look in precordial leads, R wave starts out small in V1, becomes progressively larger each lead until V6 is tallest
- Transition zone is the lead in which the QRS becomes equally negative and positive in deflection and should be V3 or V4
Evolution of an MI (Timeline of EKG Changes and Implications)
- Immediately before MI: T wave inversion indicates cardiac tissue ischemia
- Within hours: Marked ST elevation and upright T waves indicate acute MI and myocardial injury onset
- Hours Later: Significant Q with ST elevation and upright T waves point to some myocardial tissue death, others injured
- Hours to a day or two later: Significant Q, less ST elevation, marked T inversion indicates almost complete infarction
- Days to weeks later: Infarction Complete: Significant Q, T wave inversion means no more ischemic tissue, T-wave inversion persists
- Weeks, months, years later: Significant Q only signifies permanent tissue death
Walls of the Left Ventricle
- Anterior: Front wall
- Inferior: Bottom and right side wall
- Lateral: Left side wall
- Posterior: Back wall
- RCA (Right Coronary Artery) feeds bottom wall of LV and a large portion of RV (Right Ventricle)
- LAD (Left Anterior Descending Artery) feeds LV & RV
- Widowmaker happens in the Left Coronary Artery
Leads Looking at the Ventricular Walls
- Inferior wall: II, III, AVF
- Lateral Wall: I, aVL, V5-V6
- Anterior wall: V2-V4
Posterior Wall MI: Reciprocal ST Segment Changes
- No indicative changes are seen due to no leads looking directly at the posterior wall
- Diagnosis is made by reciprocal changes in V1 and V2 (large R wave, upright T wave, and possibly ST depression); seen as a mirror image of an anterior MI
MI Locations and EKG Changes
- Anterior MI: Indicative changes in V2 to V4, Reciprocal changes in II, III, aVF; coronary artery = Left anterior descending (LAD)
- Inferior MI: Indicative changes in II, III, aVF; Reciprocal changes in I, aVL, and V leads; coronary artery = Right coronary artery (RCA)
- Lateral MI: Indicative changes in I, aVL, V5 to V6; May see reciprocal changes in II, III, aVF; coronary artery = Circumflex
- Posterior MI: No indicative changes, since no leads look directly at posterior wall; Diagnosed by reciprocal changes in V₁ and V2 (large R wave, upright T wave, and possibly ST depression) Seen as a mirror image of an anterior MI; coronary artery = RCA or circumflex
- Extensive anterior MI: Indicative changes in I, aVL, V₁ to V6; Reciprocal changes in II, III, aVF; coronary artery = LAD or left main
- Anteroseptal MI: Indicative changes in V₁ plus any of leads V2-V4; Usually no reciprocal changes; coronary artery = LAD
Right Ventricular Infarction
- Should be suspected when symptoms are more severe than an inferior MI alone should cause, usually see ST changes in II, III, aVF
- Does not show up on precordial leads of standard 12-lead EKG; right-sided EKG must be done
- Diagnosis by ST segment elevation in right-sided EKG leads V3-4R
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