Last updated 11/9/26
Below is an ECG Exercise focused on the ST segment and T waves (part of the Self-Study Curriculum). ECGs are from Garcia, 12-Lead ECG: The Art of Interpretation, Chapter 14.
ST Segment and T Wave Basics
What are the upper limits of normal ST (J point) elevation? - Limb leads: < 1 mm
- V2-V3: 2 mm in men ≥ 40, 2.5 mm in men < 40, 1.5 mm in women
- Any elevation that is new or matches an ischemic story can be pathologic - judge it by the company it keeps
Where should T waves be upright, and where inverted? - Upright in I, II, V3-V6
- Inverted in aVR
- Variable in III, aVL, aVF, V1-V2
- These rules do not apply in bundle branch blocks
What makes a T wave pathologic? - Symmetry - normal T waves are asymmetric; symmetric T waves = ischemia, electrolytes, or CNS event until proven otherwise
- Height - > 6 mm in limb leads or > 12 mm in precordials; > 2/3 the height of the R wave is definitely abnormal
- Biphasic T wave that starts negative
- Tall, narrow = hyperkalemia; very broad = CNS event (especially intracranial hemorrhage)
- Check symmetry with a vertical line through the peak; if the ST segment distorts it, extend both legs of the T down to baseline
ECG 1
[Insert image - Garcia ECG 14-1]
Describe the ST segments and T waves. - Scooped ST segments
- Tall but asymmetrical T waves
Are these T waves pathologically tall? - No - they are not taller than 2/3 the height of the R wave
- If T waves this tall were symmetrical, they would be pathologic (think hyperkalemia, ischemia, CNS event)
ECG 2
[Insert image - Garcia ECG 14-2]
Are the T waves pathological? - No - close to symmetrical, but still asymmetrical and not tall
- Upright in I, II, V3-V6 and inverted in aVR = normal T wave vector
Which lead has an abnormal ST segment? Is it significant? - V1 - flat and concave downward, which is not normal
- No continuation into neighboring leads - one isolated abnormal lead is usually not clinically significant
What is the differential for the rest of the ST segments? - Scooped, concave-upward ST segments with slight elevation
- Subtle PR depression and QRS notching are also present
- Early repolarization - e.g., young patient here for a finger fracture
- Early pericarditis - e.g., patient here for chest pain
ECG 3
[Insert image - Garcia ECG 14-3]
Are there pathological T waves in the precordial leads? - Yes - flipped and symmetrical in V3-V6 = suggests ischemia
- Upright T waves in I and II are normal
Why are the T waves in V2-V4 harder to assess? - Slight ST elevation distorts the T wave
- Extend lines from the T wave itself down to baseline to reveal the symmetry
What about the limb lead T waves? - Flattened - also a sign of pathology
- Called a nonspecific ST-T wave change (NSSTTW)
ECG 4
[Insert image - Garcia ECG 14-4]
Identify the abnormal T waves. - Precordials: flipped, symmetrical, and deeper than 2/3 of the associated R or S wave
- Limb leads: flipped and symmetrical in I and aVL
- Use a clear straight edge to check symmetry
- Irregularly irregular with varying P wave morphology and PR intervals
- Wandering atrial pacemaker
What is the likely cause here? - No obvious COPD pattern
- The flipped, symmetrical T waves point toward ischemia
ECG 5
[Insert image - Garcia ECG 14-5]
Is atrial enlargement present? Identify the pathologic Q waves. What do they mean? - II, III, aVF - meet both criteria (≥ 0.03 s wide and > 1/3 the R wave height)
- Old inferior wall MI
Identify the abnormal T waves. - Similar to ECG 4, but more diffuse - flipped and symmetrical, including II and aVF
- Markedly flattened in aVF
What is the differential for diffuse, flipped, symmetrical T waves? - Ischemia
- CNS event
- Electrolyte abnormality
- Resolving pericarditis - especially post-infarct pericarditis given the old IWMI
- Needs clinical correlation
ECG 6
[Insert image - Garcia ECG 14-6]
Are these normal T waves? - No
- Flipped in I, II, and V3-V6
- Upright only in aVL and aVR (aVR should be inverted)
- Symmetrical
- More than 2/3 the height of the associated R wave in many leads
How would you describe the QT interval? - Prolonged - QT is more than 1/2 the R-R interval
There is an abnormal R:S ratio in V2 and an early transition. Is RVH causing the T wave changes? - RVH is probably present
- But the T waves are not from RVH - they are too diffuse and symmetrical (RVH strain gives asymmetric T waves)
- Intra-atrial conduction delay is present, but RAE criteria are not met
What is your differential diagnosis? - Electrolyte abnormality
- Diffuse ischemia
- CNS event
- Get an old ECG and correlate with the patient
ECG 7
[Insert image - Garcia ECG 14-7]
Identify the abnormal T waves. What is your suspected diagnosis? - Tall, symmetrical T waves in the mid-precordial leads
- Always think hyperkalemia first - arrhythmias can develop within minutes
- Ischemia is also on the differential
What other findings fit with a renal failure patient? - Small limb lead complexes (not quite < 5 mm) - possible small pericardial effusion, common in renal failure
- Prolonged QT - could indicate hypocalcemia, also common in renal failure
ECG 8
[Insert image - Garcia ECG 14-8]
- Sinus tachycardia with first-degree AV block
What quadrant is the electrical axis? The QRS is ≥ 0.12 s. What bundle branch block is present? - Neither - IVCD
- Not quite LBBB - rS in V1/V2 but no monophasic R in I/V6
- Not quite RBBB - slurred S in I and V6 but no increased R:S ratio in V1/V2
What is the diagnosis, and what is your next question? - T waves are very tall, narrow, and pointed - classic hyperkalemia
- Hyperkalemia is one of the most common causes of IVCD
- Next question: what is the potassium?
ECG 9
[Insert image - Garcia ECG 14-9]
Is the rate fast or slow? Are the QRS complexes wide? - Fast (HR > 150) and wide (> 0.12 s) - wide-complex tachycardia
Are there P waves? Are they associated with the QRS complexes? - P waves are present but not associated - in lead II (and V1) they march into the QRS complexes and disappear
- AV dissociation
- Not third-degree block - the atrial rate is not much faster than the ventricular rate
- Wide-complex tachycardia + AV dissociation = ventricular tachycardia
How would you describe the T waves? - Peaked, symmetrical, and wide
- They start to descend and then flare out toward the next complex - a rare pattern, possibly from the rhythm
- Keep hyperkalemia on the differential
ECG 10
[Insert image - Garcia ECG 14-10]
Describe the T waves. What is at the top of your differential? - Tall, somewhat wide, clearly pathologic T waves
- Hyperkalemia first
What else is on the differential, and what is less likely? - CNS event and other electrolyte problems are the most probable culprits
- Ischemia is doubtful - the changes are global, not regional
- Slightly before V2 - early counterclockwise transition
- Normal axis, no atrial enlargement
ECG 11
[Insert image - Garcia ECG 14-11]
- Atrial rate is fast - atrial tachycardia
- Ventricular rate is very slow - about 40 bpm
- P waves are not associated with the QRS, and the atrial rate is much faster than the ventricular rate
- Third-degree AV block with atrial tachycardia and a ventricular escape rhythm
Describe the QRS complexes. Where are they coming from? - Wide and bizarre with an LBBB pattern - monophasic S in V1, monophasic R in I and V6
- Could be an underlying LBBB, but more likely a ventricular escape focus - from the right ventricle, given the LBBB pattern
- Extremely tall - always think potassium first
ECG 12
[Insert image - Garcia ECG 14-12]
Identify the pathologic T waves. - Impressively tall and wide T waves in the precordials
- Inferior leads: T waves tall relative to the QRS (> 2/3 amplitude)
- Together with the ST changes = hyperacute AMI (rarely captured - most patients present later)
Where is the ST elevation and depression? - Elevation: precordials and II, III, aVF (easy to miss if you only look at the precordials)
- Depression: I and aVL
Is this an anterior or inferior infarct? - Most people say anterior - but this is an IWMI with a hyperacute RV infarct
- Clues: inferior STE, STE in III > II, STE in V1 (can extend to V6)
- Echo: anterior wall functioning; inferior wall motion abnormality and RV infarct changes
ECG 13
[Insert image - Garcia ECG 14-13]
Describe the ST segments and T waves. - ST segments are diffuse and nebulous
- T waves are broad
- V1 is slightly asymmetrical; the rest are symmetrical or flattened - not normal
With no old ECG available, what do you assume? - Assume the worst: ischemia and CNS event
- Electrolyte abnormality is a distant possibility - small U waves in some leads, especially V2-V3
ECG 14
[Insert image - Garcia ECG 14-14]
- Looks fairly normal at first glance
- P waves are not associated with the QRS; some are buried in the QRS, ST, or T waves
- Map the P waves with calipers - they march out at a nearly constant interval
- Normal sinus rhythm with AV dissociation and junctional escape beats
Any abnormal ST segments? - Slight STE in V1-V3 with concave-upward scooping - appears benign
- Wide, but slightly asymmetrical (check with a clear ruler)
- The asymmetry is reassuring, but correlate with the patient given the AV dissociation
ECG 15
[Insert image - Garcia ECG 14-15]
Describe the ST segments and T waves. - Wide ST segments and very broad, grossly abnormal T waves
What is at the top of your differential? - Intracranial hemorrhage - this patient had very high ICP
- Classic but rare pattern; memorize it, because this patient will be comatose and unable to give a history
What are the small spikes in I, III, and aVL? A pacemaker? - No - artifact from electrical interference
- Rate is well over 300 bpm; pacemakers never fire that fast
ECG 16
[Insert image - Garcia ECG 14-16]
Describe the ST segments and T waves. - Wide ST segments and broad, grossly abnormal T waves - less dramatic than ECG 15, but still quite wide
- Another patient with intracranial hemorrhage
There is a second hump after the T wave in V1-V3. Is it a U wave? - No - compare with the QT interval in V5-V6: the hump falls inside the QT (intervals are the same in every lead)
- It is most likely the P wave, buried in the T wave by a first-degree AV block
- P waves are usually best seen in V1-V2
ECG 17
[Insert image - Garcia ECG 14-17]
Any abnormal ST segments and T waves? - Markedly elevated precordial ST segments - tombstones
- Flipped, symmetrical T waves in I, aVL, and V2-V6
What is the diagnosis? Do you need an old ECG? - Large AMI
- No - tombstoning is diagnostic on its own
Can a patient have this with little or no chest pain? - Yes - silent AMIs occur with neuropathy/altered pain sensation, and sometimes in otherwise normal patients
ECG 18
[Insert image - Garcia ECG 14-18]
Identify the abnormal T wave. - V2: biphasic, negative then positive = pathologic
- Normal biphasic T waves go up first, then down (roller coaster: climb first, then drop)
The ST elevation comes with QRS notching in the lateral precordials. Is it benign? - Notching usually means the STE is benign
- But the pathologic T wave in V2 means you cannot assume that - get an old ECG and correlate with the patient
Ischemia and Injury
What ST-T features suggest ischemia or injury rather than a benign process? - ST segment flat and/or downsloping (not concave)
- T wave symmetrical, or biphasic starting negative
- Changes in a regional distribution (septal, inferior, anterior, lateral, posterior)
- ST depression = ischemia or non-Q-wave infarction; ST elevation = injury/infarction
ECG 19
[Insert image - Garcia ECG 14-19]
Where is the ST depression, and is it ischemic? - Flat ST depression = ischemia
- II, III, aVF - inferior wall
- V5-V6 - lateral wall
- V2-V4 - extension of the ischemia into additional territory
- Severe inferolateral ischemia involving a large portion of the heart
Why does aVR show ST elevation? - aVR sits opposite the other limb leads on the hexaxial system
- When the rest show ST depression, aVR shows ST elevation
ECG 20
[Insert image - Garcia ECG 14-20]
Identify the injury pattern. - II, III, aVF: flat ST elevation with flipped T waves
- Q waves in III and aVF
- Inferior wall AMI with right ventricular involvement
Where is the ST depression, and what does it represent? - I, aVL, V2-V6 (minimal in V1)
- Ischemia - the lateral depression is a continuation of lateral wall ischemia from the infarct
LVH is present. Is the lateral ST depression just LVH with strain? - No - the morphology is not consistent with strain; treat it as ischemia
What other findings are present? - First-degree AV block - may be acute from vagal stimulation by the IWMI, or long-standing
ECG 21
[Insert image - Garcia ECG 14-21]
Identify the abnormal ST segment changes. - Marked STE in II, III, aVF and all precordials
- V1-V4 are tombstones
Identify the pathologic Q waves. - Significant Q waves in II, III, aVF
- QS in V1
- V2-V5 have a tiny initial r wave - not true QS waves
Where do the precordial leads transition from negative to positive? - Late clockwise transition (between V4/V5) - possibly from significant loss of anterior wall myocardium
What is the differential diagnosis? - Inferior leads: infarct of indeterminate age (significant Qs, minimal STE, no reciprocal change in I/aVL)
- Precordials: AMI vs ventricular aneurysm - aneurysm changes usually do not extend to V5-V6, so less likely
- Patient had active pain
- Simultaneous right and left coronary system AMI: aggressively rule out an aortic aneurysm
ECG 22
[Insert image - Garcia ECG 14-22]
Identify the abnormal ST segments and T waves. - Tombstone ST changes in V1-V4 with flipped T waves
- T waves symmetrical in the precordials, I, and aVL; asymmetrical in II, III, aVF
- QS waves cover at least V1-V3
What is your differential diagnosis? - Ventricular aneurysm after an old anteroseptal MI
- Acute MI
- These cannot be told apart on the ECG alone
- Aneurysm clues (experience, not a rule): minimal tombstoning, QS waves through at least V1-V3, normal to slightly short QT
How do you sort it out, and what should you avoid? - Old ECG with the same findings, history of current symptoms, physical exam
- Assume the worst until proven otherwise; if asymptomatic, get an old ECG and call cardiology
- Never give thrombolytics to an asymptomatic patient with this pattern without cardiology approval
Right Ventricular Strain Pattern
What does RV strain look like in V1-V2? - Increased R:S ratio (RVH itself)
- Plus depressed, concave-downward ST segment and a flipped, asymmetric T wave
- If biphasic, the T usually starts negative then positive (also seen in posterior AMI)
What are the criteria for RVH? How many do you need? - P-pulmonale (RAE)
- Right axis deviation
- Increased R:S ratio in V1-V2 (most important)
- RVH strain pattern
- S1Q3T3 pattern
- Need more than one
- Minor criteria: incomplete RBBB, R in V1 ≥ 7 mm, S in V1 ≥ 2 mm, qR in V1
What is S1Q3T3, and what does it mean? - S wave in I, Q (or q) wave in III, flipped T in III
- Acute RV strain (e.g., PE) rotating the heart and axis
- Supports PE when you already suspect it, but is not pathognomonic
ECG 23
[Insert image - Garcia ECG 14-23]
What is your differential diagnosis for an increased R:S ratio in V1 or V2? - Right ventricular hypertrophy
- Right bundle branch block
- Posterior wall AMI
- WPW type A
- Young children and adolescents
Of your differential above, what is the most likely diagnosis? - RVH - picture-perfect example (young woman with pulmonary hypertension)
- All five criteria present: P-pulmonale, RAD, increased R:S in V1-V2, RVH strain, S1Q3T3
ECG 24
[Insert image - Garcia ECG 14-24]
Does this ECG show RVH with strain? - No - tough one
- Right axis deviation is present, but the increased R:S ratio has another explanation
Run the tall R in V1/V2 differential. What is the most likely cause? - QRS in V4-V6 is at or slightly above 0.12 s = a block
- Slurred S in I and V6
- RBBB - with a tall R wave in V1 instead of a full RSR'
Is there evidence of ischemia? - T waves in the inferior leads and precordials are concordant - abnormal in RBBB and could indicate ischemia
- Needs an old ECG and clinical correlation
ECG 25
[Insert image - Garcia ECG 14-25]
There is no increased R:S ratio in V1/V2. What findings still suggest RVH? - Right axis deviation (down in I, up in aVF)
- P-pulmonale
- S1Q3T3 pattern
- Still an RVH-with-strain pattern
What findings suggest LVH? Why might the R:S ratio in V1/V2 be normal? - (S in V1 or V2) + (R in V5 or V6) ≥ 35 mm
- Significant LVH can offset the RV forces and mask the tall R in V1-V2
How would you describe this heart anatomically? - Four-chamber enlargement - RAE, LAE (V1), RVH, LVH
- Could signify a cardiomyopathy
- The second beat is a PVC
- Borderline first-degree AV block
Left Ventricular Strain Pattern
What does LVH with strain look like? - V4-V6 (and often I, aVL): ST depression with downward concavity and a flipped, asymmetric T wave
- V1-V3: ST elevation with upward concavity and an upright, asymmetric T wave (often 1-3 mm, sometimes more)
- Strain is greatest in the lead with the tallest R or deepest S
- J point usually diffuse in V1-V3
How do you tell LVH with strain from ischemia? - Ischemia: flat ST segments, symmetric T waves, sharp J point
- V5-V6 can flatten in strain, but somewhere around V4-V5 the classic concave-down, asymmetric morphology should appear
- Strain can only be called in obvious LVH
- ST depression is always pathologic - correlate with the patient; if they look sick, treat the AMI
ECG 26
[Insert image - Garcia ECG 14-26]
Identify findings that suggest LVH. - S in V1-V2 + R in V5-V6 > 35 mm
- R in aVL ≥ 11 mm
- R in I ≥ 12 mm
Is atrial enlargement present? - LAE - wide inverted P wave in V1; commonly seen with LVH
Are the ST-T changes ischemic or consistent with strain? - Typical LVH with strain
- V5-V6: concave-downward ST depression with flipped, asymmetric T waves; deepest depression in the lead with the tallest R
- V1-V2: concave-upward ST elevation; highest elevation in the lead with the deepest S
- Pattern carries over to I and aVL (high lateral)
ST depression is always pathologic. What is the differential? - Ischemia
- Strain pattern
- Bundle branch block
- WPW
- Resolving pericarditis
- CNS event
- Look for clues on this ECG, an old ECG, and the patient
ECG 27
[Insert image - Garcia ECG 14-27]
What findings meet LVH criteria? - R in aVL ≥ 11 mm
- R in I ≥ 12 mm
- S in V1 or V2 + R in V5 or V6 ≥ 35 mm
Identify the ST segment and T wave abnormalities. What is your diagnosis? - Concave-upward STE in V1-V3; concave-downward ST depression in I, aVL, V4-V6
- Asymmetrical T waves
- Greatest ST deviation in the leads with the tallest/deepest complexes
- LVH with strain
The ST segments in V6, I, and aVL are flat. Is that ischemia? - No - judge them by the company they keep
- The neighboring leads show concave-downward depression, and the flat segments are just a continuation of that process; the T waves remain asymmetric
- Ischemia in LVH would fail to show this concave transition
ECG 28
[Insert image - Garcia ECG 14-28]
What findings meet LVH criteria? - S in V1 or V2 + R in V5 or V6 ≥ 35 mm
Trace the ST segments from V1 to V6. Should you be concerned? - V1-V2: concave upward
- V3: flat
- V4-V5: concave downward
- V6: depressed, downsloping, and flat
- A benign strain transition - in a patient with obvious LVH
What if LVH were not obvious? - Then all bets are off - the same changes could be ischemia
- No LVH = no LVH with strain
ECG 29
[Insert image - Garcia ECG 14-29]
What findings suggest LVH? - S in V2 + R in V5 > 35 mm
What findings suggest strain pattern? - Precordial ST segments progress to a flatter presentation in V6 (like ECG 28)
- Inferior leads: flipped, asymmetric T waves with slightly concave-downward ST segments - also from LVH
What else must you consider, and what else is present? - Ischemia secondary to tachycardia or CAD
- LAE and a prolonged QT
ECG 30
[Insert image - Garcia ECG 14-30]
- Irregularly irregular with no obvious P waves = atrial fibrillation
- Undulating baseline in V1 = coarse AF
How do you tell coarse AF from artifact on this ECG? - Coarse AF: obvious, rolling undulation of the baseline
- Artifact (beginning and end of the tracing): very fine, narrow spikes
What is the 8th beat (the one that looks different)? What findings suggest LVH? - S in V2 + R in V5/V6 > 35 mm
- R in aVF > 20 mm
What findings suggest strain? - Inferior concave, downsloping ST depression with asymmetric T wave inversion
- Precordial ST depression progressing V2-V6 with asymmetric T wave inversion
- Deepest ST depression in the lead with the tallest R
- LVH with strain
ECG 31
[Insert image - Garcia ECG 14-31]
- Yes - LVH is obvious on this ECG
Are there findings of the typical LVH strain pattern here? - No - the classic downsloping ST depression with flipped asymmetric T waves is absent
- Instead: small q waves in V6 with concave, upward scooping of the ST segments
What causes this alternate LVH pattern, and how does it differ from typical strain? - Typical strain = systolic pressure overload (systolic hypertension, aortic outflow obstruction)
- This pattern = diastolic / volume overload in a large, dilated LV (severe aortic or mitral regurgitation)
- Advanced concept (described by Hurst) - know it exists so it does not surprise you
Benign ST Changes vs Infarct
How do benign (strain) ST changes differ from ischemic ST changes? - Strain / benign: ST segments are concave, T waves asymmetric, smooth transition from ST to T
- Ischemia / infarct: ST segments flat (horizontal or straight-sloped), T waves symmetric, often a sharp J point
- In strain, the biggest ST deviation is in the lead with the tallest R or deepest S
- "If it's flat, you've got to treat that!"
What else helps when the call is not obvious? - Reciprocal changes (e.g., inferior STE with I/aVL depression) point to AMI
- Look at "the company it keeps": the lateral leads, an old ECG, and the patient's symptoms
- You cannot diagnose LVH with strain unless LVH is obvious
ECG 32A
[Insert image - Garcia ECG 14-32A]
In the setting of LVH, are the ST segments / T waves benign or ischemic? - Benign - typical LVH with strain
- T waves are asymmetrical throughout
ECG 32B
[Insert image - Garcia ECG 14-32B]
In the setting of LVH, are the ST segments / T waves benign or ischemic? - Ischemic - ST segments are flat, either elevated or depressed
- Elevated in II, III, aVF; depressed in I and aVL
Why does the ST depression in I and aVL matter? - It is reciprocal to the inferior STE - in AMI, I and aVL should show changes opposite to II, III, aVF
What else supports infarct? - A pathologic Q wave starting in lead III
ECG 33A
[Insert image - Garcia ECG 14-33A]
In the setting of LVH, are the ST segments / T waves benign or ischemic? - Benign - another LVH with strain
- Flipped T waves in I, aVL, II, and aVF are asymmetrical
ECG 33B
[Insert image - Garcia ECG 14-33B]
In the setting of LVH, are the ST segments / T waves benign or ischemic? - Ischemic - inferior wall MI (IWMI)
- ST segments in the reciprocal leads are flat from the start - little or no concavity, no gradual transition
- T waves are symmetrical and almost blend into the ST segments
ECG 34A
[Insert image - Garcia ECG 14-34A]
What hypertrophy pattern is present? Are the ST segments / T waves benign or ischemic? - Benign (strain) - ST segments clearly concave
- T waves asymmetrical with a smooth transition from the ST segment
ECG 34B
[Insert image - Garcia ECG 14-34B]
Are the ST segments / T waves benign or ischemic? - Ischemic - posterior wall AMI
- Obvious ST depression with a negative slope
- ST segments go straight to horizontal and flat without any concave phase
Look at the rhythm strip (lead II). What else is suggested? - ST elevation in II - suggests an inferior wall MI as well
ECG 35A
[Insert image - Garcia ECG 14-35A]
What conduction abnormality is present? (You have seen this ECG before - ECG 24.) - RBBB without a classic RSR' in V1 - the R wave in V1-V2 is very wide because of the block
Are the ST segments / T waves benign or ischemic? - Benign - diffuse ST changes, all concave
ECG 35B
[Insert image - Garcia ECG 14-35B]
The R wave in V2 is wide (> 0.03 s) with an increased R:S ratio. Is this RBBB? - No - no increased R:S in V1 and no slurred S in V6
Are the ST segments / T waves benign or ischemic? What is the diagnosis? - Ischemic - ST depression in V2-V6 is pathologic
- Run the tall R in V1/V2 differential: posterior wall AMI
ECG 36A
[Insert image - Garcia ECG 14-36A]
Are the ST segments / T waves benign or ischemic? - Benign - minimal pericarditis or early repolarization
What features support a benign cause? - QRS notching in the lateral leads
- All ST segments concave upward except V1
- The lead with the tallest R wave has the most STE
- Minimal PR depression, within normal limits
ECG 36B
[Insert image - Garcia ECG 14-36B]
Are the ST segments / T waves benign or ischemic? - Ischemic - ST goes from depression to elevation but stays flat throughout
- T waves are symmetrical and broad
There is an increased R:S ratio in V2. What is the most likely cause here? - Posterior wall AMI
- Lateral STE = lateral wall MI - lateral and posterior MIs often occur together
ECG 37A
[Insert image - Garcia ECG 14-37A]
Are the ST segments / T waves benign or ischemic? Why? - Benign - same two causes as ECG 36A (early repolarization vs pericarditis)
- Notching is more obvious and STE slightly more prominent
Notching is usually benign. What else can cause it, and how do you sort it out? - Early repolarization - young, asymptomatic
- Pericarditis - chest pain worse lying back, better sitting up
- Hypothermia - cold patient, altered mental status, cold exposure
- Use "the company it keeps"
ECG 37B
[Insert image - Garcia ECG 14-37B]
Are the ST segments / T waves benign or ischemic? Why? - Ischemic - lateral infarct
- STE starts flat, then slopes upward in V4 - an injury/infarct pattern
- Compare the lateral leads with ECG 37A - the difference is dramatic
Look at the rhythm strip. What else is involved? - STE in lead II suggests the inferior wall is involved too
ECG 38A
[Insert image - Garcia ECG 14-38A]
The patient is asymptomatic. In the setting of LVH, are the ST segments / T waves benign or ischemic? Why? - Benign - LVH with strain
- Lateral leads show classic strain; anterior leads fit strain but are a bit flat - concerning on their own
- Reassuring: some ST concavity remains, the highest STE is in V1 (deepest S wave), the pattern was on an old ECG, and the patient is asymptomatic
ECG 38B
[Insert image - Garcia ECG 14-38B]
In the setting of LVH, are the ST segments / T waves benign or ischemic? Why? - Ischemic - lateral ischemia
- Lateral ST depression is deep and flat - not a strain pattern, even though LVH is present
How concerned should you be about V1? - Troublesome, but isolated to one lead - not highly significant for infarct
ECG 39A
[Insert image - Garcia ECG 14-39A]
Which LVH criterion is met? - S in V2 + R in V6 ≥ 35 mm
In the setting of LVH, are the ST segments / T waves benign or ischemic? Why? - Benign - strain or early repolarization pattern
- ST segments concave; the lead with the deepest S wave has the highest ST
- Diffuse J point in V2, and even V1
ECG 39B
[Insert image - Garcia ECG 14-39B]
Are the ST segments / T waves benign or ischemic? Why? - Ischemic - STE through all precordial leads
Why do the complexes look so bizarre? Are the lateral Q waves significant? - Short QT interval gives the bizarre appearance
- Lateral Q waves are not significant
ECG 40A
[Insert image - Garcia ECG 14-40A]
In the setting of LVH, are the ST segments / T waves benign or ischemic? Why? - Benign - LVH with strain (meets multiple LVH criteria)
What atrial abnormality is present? ECG 40B
[Insert image - Garcia ECG 14-40B]
Are the ST segments / T waves benign or ischemic? Why? - Ischemic - suggests a posterior wall AMI
- Increased R:S ratio, flat ST segments, and a terminal positive deflection of the T wave
- Unlike ECG 34B, no associated inferior infarct
Lead II also shows ST depression. What can diffuse ST depression represent? - Global subendocardial ischemia (ischemia of the inner lining of the ventricles)
ECG 41A
[Insert image - Garcia ECG 14-41A]
In the setting of LVH, are the ST segments / T waves benign or ischemic? Why? - Benign - a clear example of LVH with strain
- Check the strain features: concave ST segments, asymmetric T waves, biggest ST deviation in the leads with the tallest/deepest QRS
ECG 41B
[Insert image - Garcia ECG 14-41B]
This patient had markedly elevated blood pressure. Are the ST segments / T waves benign or ischemic? - Ischemic - diffuse subendocardial ischemia (like ECG 40B, but much more pronounced)
- STE in V1 also suggests injury or infarction
What is the differential for ST depression in V1-V2 in an adult? - Always pathologic in adults:
- RVH
- RBBB
- Posterior wall MI
- WPW
ECG 42A
[Insert image - Garcia ECG 14-42A]
- No - measure with calipers: the QRS does not quite reach 0.12 s
- This is a very wide LVH with strain
Which LVH voltage criterion stands out? - QRS amplitude more than meets the "any precordial lead ≥ 45 mm" criterion
ECG 42B
[Insert image - Garcia ECG 14-42B]
Are the ST segments / T waves benign or ischemic? Why? - Ischemic - obvious ischemic ST deformities
- ST segments are flat and downsloping
ECG 43A
[Insert image - Garcia ECG 14-43A]
In the setting of LVH, are the ST segments / T waves benign or ischemic? Why? - Benign - LVH with strain
- V1-V3 show upwardly concave STE - but this alone can be deceptive (compare with ECG 43B)
What helps separate this from ECG 43B? - The lateral leads show typical strain changes here and not in 43B
- The lateral leads often sort out the right precordial leads
ECG 43B
[Insert image - Garcia ECG 14-43B]
Are the ST segments / T waves benign or ischemic? Why? - Ischemic - anteroseptal AMI
- J point is diffuse, but the ST segments are flat, especially in V1-V2
- The apparent concavity is really a broad, symmetrical T wave rising off the ST segment - extend both legs of the T wave in V2 to the baseline to see it
- STE in V4 is also very flat
ECG 44A
[Insert image - Garcia ECG 14-44A]
Are the ST segments / T waves benign or ischemic? Why? - Benign ST elevation - clinical correlation still mandatory
- Strain pattern is not obvious; could be LVH with strain or early repolarization in a young man
- Diffuse J point, notching in V4-V6, definite T wave asymmetry
ECG 44B
[Insert image - Garcia ECG 14-44B]
Look only at V1-V2. Could this be strain? - Possibly - some LVH with strain looks just like these leads
Now look at V3 onward. Benign or ischemic? - Ischemic - anteroseptal AMI with lateral extension
Compare V6 here with V6 in ECG 44A. What is the lesson? - They look strikingly similar - always look at the rest of the ECG and at the patient
ECG 45A
[Insert image - Garcia ECG 14-45A]
- Wide LVH with strain, not LBBB
What other findings are present? - Late intrinsicoid deflection
- U wave after the T wave in most leads - a benign finding
ECG 45B
[Insert image - Garcia ECG 14-45B]
Are the ST segments / T waves benign or ischemic? Why? - Ischemic - anteroseptal infarct with lateral extension (V1 through V6)
- Marked STE with symmetrical T waves
ECG 46A
[Insert image - Garcia ECG 14-46A]
This ECG looks benign at first glance. What is troubling about it? - STE in V1-V2 is flat
- T waves are symmetrical across the whole precordium
- LVH is present, but there is no classic strain pattern
- Get an old ECG and correlate closely with symptoms - do not dismiss it as benign
ECG 46B
[Insert image - Garcia ECG 14-46B]
Are the ST segments / T waves benign or ischemic? What is the diagnosis? - Ischemic - anteroseptal infarct that has been evolving for some time
- QS waves through V4 with tombstoning ST segments - Q waves have already formed
What interval abnormality is present? ECG 47A
[Insert image - Garcia ECG 14-47A]
Are the ST segments / T waves benign or ischemic? - Benign - early repolarization or LVH with some strain in the right precordial leads
ECG 47B
[Insert image - Garcia ECG 14-47B]
Are the ST segments / T waves benign or ischemic? Why? - Ischemic - anteroseptal AMI with lateral extension
- ST segments flat with a positive slope
- Lateral T waves are flipped and symmetrical
ECG 48A
[Insert image - Garcia ECG 14-48A]
Are the ST segments / T waves benign or ischemic? - Benign elevation - LVH or early repolarization
Why do V1-V2 look unusual? - Incomplete RBBB - rSr' pattern
ECG 48B
[Insert image - Garcia ECG 14-48B]
Are the ST segments / T waves benign or ischemic? Why? - Ischemic - anteroseptal AMI
- Flat STE (V1-V3) with QS waves and a late transition
- Age indeterminate, but probably not brand new - at least a few hours old, long enough for QS waves to form
ECG 49A
[Insert image - Garcia ECG 14-49A]
In the setting of LVH, are the ST segments / T waves benign or ischemic? - Benign - wide LVH with strain with typical features
ECG 49B
[Insert image - Garcia ECG 14-49B]
Are the ST segments / T waves benign or ischemic? - Ischemic - significant STE in V1-V2 = injury/ischemia of the septal wall
ECG 50A
[Insert image - Garcia ECG 14-50A]
In the setting of LVH, are the ST segments / T waves benign or ischemic? - Benign - obvious LVH with strain
- T waves are not completely flipped by V6
What QRS finding is best seen in V5? - Late intrinsicoid deflection (not delta waves)
ECG 50B
[Insert image - Garcia ECG 14-50B]
What do you see in V1-V4? - STE associated with QS waves
What is the differential? - AMI of indeterminate age
- Ventricular aneurysm
- Clinical correlation (and an old ECG) required
ECG 51A
[Insert image - Garcia ECG 14-51A]
In the setting of LVH, are the ST segments / T waves benign or ischemic? - Trick question - this is not LVH, it is a textbook LBBB
- Wide QRS, monomorphic S in V1, monomorphic R in V6
- You cannot diagnose LVH in the presence of LBBB
Why study this one closely? - Memorize these expected LBBB ST segments and T waves - it makes ischemia in a block (or AMI) much easier to spot
ECG 51B
[Insert image - Garcia ECG 14-51B]
Describe the ST segments, T waves, and QRS in V1-V5. - Diffuse STE with flipped (asymmetric) T waves
- QS waves in these leads - very late, clockwise transition
What is the differential? - Age-indeterminate anteroseptal AMI with lateral extension
- Ventricular aneurysm
- Both
- An aneurysm is always preceded by an AMI - weak, non-contractile scar bulges outward
- An old ECG and clinical correlation are needed to tell them apart
How do you separate LBBB from LVH with a QS wave in V1-V2? - LBBB usually (not always) has a small initial r in V1, and the rest of the LBBB criteria are present
- In LVH, a QS (no r wave) in V1-V2 suggests an age-indeterminate anterior MI
ECG 52A
[Insert image - Garcia ECG 14-52A]
The patient has intermittent substernal chest pain, including pain that wakes him from sleep, but is pain free now. What do you see? - Late clockwise transition with QS waves in V1-V2
- Slight ST depression with flattened T waves in V5-V6
- Admit for unstable angina
ECG 52B
[Insert image - Garcia ECG 14-52B]
Twenty minutes later the same patient develops chest pain. What changed? - Lateral (and inferior - see the rhythm strip) ST segments now downsloping with much deeper depression
- T waves now pronounced and flipped
- Classic unstable angina changes - subendocardial ischemia
What is the lesson from this pair? - An ECG is a 12-second snapshot - repeat it when symptoms or the story change, or when the monitor rhythm changes
Pericarditis vs Early Repolarization
What are the ECG criteria for pericarditis? - PR depression
- Diffuse ST elevation (can reach 4-5 mm)
- Scooped, upwardly concave ST segments
- Notching at the end of the QRS
- Tachycardia is common; criteria need not be in every lead
- ECG alone gets you ~80% of the way - the history and exam must match
How do you separate pericarditis from early repolarization? - PR depression > 0.8 mm is pathologic - favors pericarditis
- Early repol: benign, usually minimal, upwardly concave STE in young people; in middle age, document it on an old ECG first
- Never make either call in a vacuum - take a history
ECG 53
[Insert image - Garcia ECG 14-53]
What findings suggest pericarditis? - STE in I, II, aVF, and V1-V6
- QRS notching (a marker of benign STE)
- Rate near 90 bpm - not technically tachycardic
- PR depression is not very impressive here; the history clinched the diagnosis
What defines pathologic PR depression? - PR depression > 0.8 mm (just under one small box)
If the same ECG came from a patient with a knee injury, what else could it be? - Early repolarization - acceptable as long as the PR depression is not > 0.8 mm
ECG 54
[Insert image - Garcia ECG 14-54]
What findings suggest pericarditis? - Diffuse, upwardly concave, scooping STE in I, II, III, aVF, and V1-V6
- Some notching in the lateral leads
- Not tachycardic
How can this be differentiated from early repolarization? - PR depression in lead II is 1 mm - pathologic (> 0.8 mm)
- History was consistent with pericarditis
ECG 55
[Insert image - Garcia ECG 14-55]
A 24-year-old man is being admitted for a noncardiac problem and has no cardiac symptoms. Early repolarization or pericarditis? - Early repolarization - ECG fits the pattern and there are no cardiac symptoms
- All STE in young patients is early repol and not pathologic - False
- Pericarditis patients can have underlying early repol on an old ECG - True
- STE from early repol is flat - False (it is upwardly concave)
ECG 56
[Insert image - Garcia ECG 14-56]
A young patient has chest pain after using cocaine. No old ECGs are available. What pattern do the ST segments show? - Consistent with early repolarization - diffuse STE with QRS notching, no reciprocal depression
- Some PR depression - consider pericarditis as well
Can you send him home with outpatient follow-up? - No - rule out MI before discharge
- Drug-associated MIs are often from coronary spasm, not plaque, and can look benign
- Chronic drug users also develop accelerated atherosclerosis
ST Segments and T Waves in Bundle Branch Blocks
Why is the T wave normally upright, and why does it flip in a BBB? - Normal: depolarization goes endocardium to epicardium, but repolarization starts at the epicardium and travels inward - so the T wave points the same way as the QRS
- BBB / PVC: slow cell-to-cell conduction, so repolarization follows the same path as depolarization - the T wave points opposite to the QRS
What are discordance and concordance? - Discordant (expected in BBB): T wave opposite to the terminal part of the QRS
- Concordant (bad): T wave in the same direction as the terminal QRS - suggests ischemia unless present on old ECGs
- Memory aid: con- = with, dis- = against
ECG 57
[Insert image - Garcia ECG 14-57]
Is this a bundle branch block? Which pattern? - QRS ≥ 0.12 s - yes
- Matches LBBB in every lead except V6
Leads I and V6 should look nearly identical. Why does V6 look different here? Is this actually an IVCD? - Lead misplacement - the V6 electrode was too high or too anterior, giving a different viewing angle
- Picture V6 looking like lead I: the ECG fits LBBB, not IVCD
The T waves in V3-V6 point the same way as the S waves. What is the significance? - They are concordant with the terminal QRS - suspicious for ischemia unless present on an old ECG
- The other leads are discordant, as expected in BBB
ECG 58
[Insert image - Garcia ECG 14-58]
What type of bundle branch block is present? - RBBB - wide QRS, increased R:S ratio with RSR' / RR' morphology in V1-V2, slurred S wave in I and V6
Identify the concurrent fascicular block. What do you call the combination? - Left anterior fascicular block (LAFB / LAH) - evident in the limb leads: left axis, negative lead II, qR in I, rS in III
- RBBB + LAFB = bifascicular block
Identify the concordant and discordant T waves. - Concordant: II, aVF, V2-V3
- All other leads are discordant
ECG 59
[Insert image - Garcia ECG 14-59]
Identify ECG findings that suggest LBBB. - Wide QRS, rS in V1-V2, monophasic R wave in I and V6
Which leads have concordant T waves? - Definitely concordant: II and V3-V5
- III and aVF: T waves start negative and end positive - the negative start makes them discordant
Is the ST depression in II, III, and aVF expected in LBBB? - ST depression can be normal in LBBB, but here it appears only inferiorly - suspicious for ischemia
- Concordance plus inferior ST depression = strong possibility of inferolateral ischemia
