Last updated 12/2/24
10 random cases taken from:
Nathanson LA, McClennen S, Safran C, Goldberger AL. ECG Wave-Maven: Self-Assessment Program for Students and Clinicians. http://ecg.bidmc.harvard.edu.
ECG #1
CC: 78 yo F presenting with chest pain
Estimate the heart rate (slow, fast, or normal), rhythm, and axis to the nearest quadrant. - Heart Rate: Normal
- Rhythm: Sinus rhythm with premature atrial complexes (PACs)
- Axis: Normal
What conduction abnormality is present on the ECG? - Wide QRS (≥ 120ms), R dominant QRS in V1-v2, + slurred S wave in I and V6 suggest RBBBB
Are there pathologic Q waves present? What makes them pathological - Yes in V1-V3 , q waves ≥ 0.04 ms or ≥1/4 the depth of the QRS complex
Overall, is this ECG concerning for ischemia? - Findings support ischemia
- TWI in V1-V2 could be due to repolarization seen in RBBB but does not explain TWI in V3-V4, and avL which could be from ischemia
- Typically there are STD in V1-V2 in a regular RBBB but here the ST segment is isoelectric which could suggest relative STE and therefore ischemia
- Q waves in V1-V3 are pathologic
- Not necessarily STEMI but overall this is ischemic. The patient ended up having a proximal LAD occlusion
ECG #2
CC: 65 year old F complains of severe dyspnea.
The ECG could be found in which following diagnosis?
- Inferior MI
- Mitral stenosis
- Acute COPD exacerbation
- Left pneumothorax
- Severe aortic stenosis
- c. Acute COPD Exacerbation
- ECG is concerning for acute cor pulmonale (R heart strain)
- Sinus tachycardia
- R axis (down in I and up in avF)
- S1Q3T3
- Why not the other answers>
- Inferior MI - TWI in lead III but not STEMI equivalent
- Mitral stenosis - no clear left atrial enlargement or RVH
- Left pneumothorax - ECG findings are non-specific but you may see low voltage in the lateral most leads (V4-V6, I and avL) which are not seen here
- Severe aortic stenosis - no LVH here
- Source (Case #213): 🔗 Link
ECG #3
What is the pathology / diagnosis? - Tented / symmetrical T waves are classic for hyperkalemia
- The serum K+ was 7.7 mEq/L
ECG #4
CC: 85 yo M with history of CAD, Afib and CHF presents with syncope.
- The ECG shows sinus rhythm with prolonged QU prolongation with bursts of wide complex tachycardia (WCT)
Is the WCT regular or irregular? What is the differential diagnosis? - Irregular - the qrs complexes are not identical
- Ddx: Afib with WPW, Polymorphic ventricular tachycardia, Torsades de pointes(a form of polymorphic VT)
- This is likely Torsades given the prolonged QU/QT in the sinus beat
- Patient was on dofetilide therapy (a class III drug) for treatment of atrial fibrillation which likely induced Torsades in the setting of underlying CAD, CHF and AKI on CKD
- Source (Case #402) - 🔗 Link
Case #5
CC: Chest pain x 3 days
Estimate the heart rate (slow, fast, or normal), rhythm, and axis to the nearest quadrant. - Heart Rate: borderling tachycardic
- Rhythm: Sinus rhythm
- Axis: left
What conduction abnormality is present on the ECG? - Wide QRS (≥ 120ms), rS in V1-V2, and monophasic R wave in I and AVL suggest LBBB
There are a lot of STE and STD but are they ischemic? Remember that discordant ST findings in LBBB can be normal. A review of concordance and discordance can be found below - Discordance: the ST segment is depressed or elevated in the opposite direction of the QRS complex. This can be normal in a typical LBBB.
- A discordant ST segment would be depressed with a tall R wave
- A discordant ST segment would be elevated with a deep S wave
- Concordance: The ST segment is depressed or elevated in the same direction of the QRS complex. This is abnormal for LBBB
- A concordant ST segment would be depressed with a deep S wave
LITFL
- A concordant ST segment would be depressed with a tall R wave
LITFL
To diagnose MI in LBBB, use modified Smith Sgarbossa critieria MI if one of the findings is present |
Concordant ST elevation ≥ 1 mm in ≥ 1 lead |
Concordant ST depression ≥ 1 mm in ≥ 1 lead of V1-V3 |
Proportionally excessive discordant STE in ≥ 1 lead anywhere with ≥ 1 mm STE, as defined by ≥ 25% of the depth of the preceding S-wave |
- There are no concordant STE or concordant STD but are there proportionally excessive discordant STE? These are my estimates based on my interpretation of the J point.
Lead | S wave | STE | STE/S ≥ 25%? |
V1 | 23 mm | 3 mm | No |
V2 | 16 mm | 1 mm | No |
V3 | 10 mm | 2.5 mm | No |
Case #6
CC: 17 year old F with history of palpitations, syncope and ventricular arrhythmias (s/p ICD) here for a med refill.
Based on this ECG, what is the etiology of the patient’s history of ventricular arrhythmias?
- Dilated cardiomyopathy
- Long QT syndrome
- Brugada syndrome
- Hypertrophy cardiomyopathy
- Arrhythmogenic right ventricular cardiomyopathy (ARVC)
- e. Arrhythmogenic right ventricular cardiomyopathy (ARVC)
- Classic findings of ARVC
- T wave inversions in right precordial leads (V1-V3/V4) – present in this case. Most sensitive finding
- Right ventricular conduction delays (e.g., rSr’ in V1/V2) – present here.
- Wide right precordial S waves >55ms in V1-V3 (not present here).
- Epsilon waves: Small amplitude, high-frequency deflections in the ST segment of V1/V2 (not seen here). Most specific finding.
ECG #7
CC: 30 year old M presents with lower chest pain that occurred after eating a greasy cheeseburger that’s worse with twisting his upper body
What is the most likely diagnosis?
- Acute pericarditis
- Early repolarization with musulo-skeletal pain
- Acute pulmonary embolism
- Anterolateral STEMI
- Hyperkalemia
- d. Anterolateral STEMI
- Do not be fooled by the age and chief complaint. There are massive STE in the precordial and high lateral leads and reciprocal STD in the inferior leads
- This is an occlusive MI until proven otherwise. Don’t think too hard on it.
- Cath: 100% proximal LAD occlusion
- Source (Case #276) - 🔗 Link
ECG #8
CC: 44 yo F with no medical history presents with routine checkup.
Which of the following abnormalities is likely present?
- Hypoaldoesteronism
- Hypokalemia
- Hypocalcemia
- Hyponatremia
- Hypophasphatemia
- b. hypokalemia
- There are prominent U waves best seen in V2
- The QTC/QU is prolonged (calculate it if you don’t believe me)
- Serum K was 2.4 mEq/L
ECG #9
CC: 77 yo F with intermittent chest pain for 1 week.
Is this ECG concerning for ischemia? - Yes
- Pathologic Q waves + STE In II, III and avF with reciprocal STD in avL suggest inferior MI. Q waves may suggest subacute nature especially given chest pain started a week ago.
- There is subtle V2 STD which may suggest posterior involvement
Your medical student notices a loud, harsh holosystolic murmur. What can be the cause? - Acute ventricular septal defect OR
- Posterior papillary muscle dysfunction (with possible rupture) causing acute mitral valve regurgitation
- Both can be seen in inferior MI
- Source (Case #209) - 🔗 Link
ECG #10
CC: 88 yo F presents diffuse abdominal pain and hypotension
Estimate the heart rate (slow, fast, or normal), rhythm, and axis to the nearest quadrant. - Heart rate: 54, slow
- Rhythm
- P:QRS > 1, PR intervals varying and P-P intervals are fixed….which suggests av dissociation / complete av block (see lead II rhythm lead)
- Axis: left (up in I and down in avF)
What else is going on here? - Tombstone STE in V1-V5 concerning for anterior STE
- There are pathologic q waves in the inferior leads II, III, avF with subtle STE and reciprocol STD in avL that may suggest acute on prior MI
- Cath: patient had LAD occlusion in the setting of diffuse LAD disease, was placed on mechanical support and received pacemaker placed
- Source (Case #298) - 🔗 Link
This post is for education and not medical advice.
