Last updated 12/10/24
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ECG 1 (📷)
Estimate the heart rate and axis to the nearest quadrant. - Rate: slowish, HR 60s
- Axis (Normal, Left, Right, Extreme): normal
- Narrow complex, irregular rhythm with no p-waves → this is likely atrial fibrillation with slow ventricular response
Any concerning intervals, QRS morphology, ST segments or T waves? - Diffuse TWF in the limb leads
- TWI in V5-V6
- Abnormal T waves but not diagnostic of OMI
ECG 2 (📷)
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Estimate the heart rate and axis to the nearest quadrant. - Rate: fast to about 150s
- Axis: L axis (up in I and down in avF). There is a left anterior fascicular block (L axis + down in II).
- This is a regular wide complex tachycardia with p waves. This is the breakdown of the differential
- Sinus tach with bundle branch block? no, there are no p-waves
- Antidromic AVNRT? possible but here are no delta waves.
- SVT with bundle branch block? Likely, this appears to be classic RBBB morphology (see next section). The QRS is just above 120ms. It would be ideal to have a previous ECG
- Monomorphic VT? Less likely, but can’t be ruled out. If patient looks terrible, assume VT. Fascicular VTs can have to have a narrowish QRS.
Any concerning intervals, QRS morphology, ST segments or T waves? - Wide QRS + RSR’ in V1, slurred S wave in I and V6 are consistent with RBBB. Combined with LAFB, there is a bifascicular block.
- TWI in V1-V2 are consistent with classic RBBB morphology
- Non-diagnostic of OMI
- A new RBBB+LAFB + ischemic cp could represent an OMI, so you would need more information (go see the patient)
- This patient had prior history of SVT and prior RBBB+LAFB
- They were converted to sinus rhythm after av nodal blockade.
ECG 3 (📷)
Estimate the heart rate and axis to the nearest quadrant. - Rate: normal, 70s
- Axis: normal axis
Any concerning intervals, QRS morphology, ST segments or T waves? - STE III, avF, and STD in I and avL
- Tall R waves in V2-V4 with deep STD
- Yes. This is concerning for inferior + posterior MI
ECG 4 (📷)
Estimate the heart rate and axis to the nearest quadrant. - Rate: slow 20-30s
- Axis: normal axis
- Look at rhythm 1 or rhythm 2 lead
- There are multiple P waves for each qrs
- This could be high grade 2nd degree av block or third degree av block with ventricular escape. I think the latter as the qrs is wide, PR intervals change slightly, and hidden p wave in qrs complex (last beat) which suggest av dissociation.
Any concerning intervals, QRS morphology, ST segments or T waves? - Wide QRS that is neither LBBB or RBBB morphology (idioventricular conduction delay)
- There is STE in V2 but this may be from motion artifact
- This is a concerning ECG but not diagnostic of OMI
ECG 5 (📷)
Estimate the heart rate and axis to the nearest quadrant. - Rate: slow 30s
- Axis: normal
- This could be high grade 2nd degree av block (P>>> QRs complexes) vs. third degree av block.
- The PR intervals are constant which makes me think the p waves are conducting the qrs complexes.
Any concerning intervals, QRS morphology, ST segments or T waves? - Yes, STE in II, III, avF w/ STD in avL
- STD in V2
- Yes this is concerning for an inferior MI w/ possible posterior involvement advanced heart block
- RCA supplies the av node
ECG 6 (📷)
Estimate the heart rate and axis to the nearest quadrant. - Rate: fast, > 150s
- Axis: normal
- There are 2 atrial beats to every qrs complex and they atrial rate is close to 300
- This is likely atrial flutter vs. atrial tacycardia w/ 2:1 conduction
Any concerning intervals, QRS morphology, ST segments or T waves? - This is non-diagnostic for OMI
ECG 7 (📷)
Estimate the heart rate and axis to the nearest quadrant. - Rate: fast, 100ish
- Axis: left axis
Any concerning intervals, QRS morphology, ST segments or T waves? - Yes, tombstone hyperacute T / STE in I, avL, V2- V5
- STD in III, avF
- The patient should already be in the cath lab by the time you’ve reached this question
ECG 8 (📷)
Estimate the heart rate and axis to the nearest quadrant. - Rate: Fast 100
- Axis: Normal axis
Any concerning intervals, QRS morphology, ST segments or T waves? - AVR STE with diffuse STD in almost all leads except III
- STD are most pronounce in the precordial leads V2-V6
- The differential diagnosis includes primary OMI (BAD), subendocardial ischemia in triple vessel disease, anything causing global ischemia (eg, dissection, massive PE, hemorrhage, hypoxia) or repoloarization abnormalities (electrolytes, LVH, bundle branch blocks).
- This also could be a posterior MI as the STD in the anterior leads are the most impressive (out of proportion compared to other leads)
- This patient presented with syncope and AMS and was intubated for airway protection. He never was hypotensive.
- POCUS did not show R heart strain (eval for submassive PE), CTH ruled out ICH, and CTA ruled out aortic syndrome all of which could present with similar ECG findigs.
- Patient was extubated and did not complain of chest pain but was urgently taken to cath for rising troponins
- Cath showed severe 3vd. He had 80% pLAD, 90% OM w/ chronic total occlusions of mid LAD and RCA
ECG 9 (📷)
Estimate the heart rate and axis to the nearest quadrant. - Rate: normal 72
- Axis: normal
Any concerning intervals, QRS morphology, ST segments or T waves? - Wide QRS + rSR’ in V1-V2, slurred S wave in I and V6 is consistent with RBBB
- LVH as defined by I ≥ 12mm, LAE (biphasic P wave in V1 with inverted part ≥ 1 small box wide)
- AVR STE + diffuse TWI and STD
- Like the previous, this requires clinical presentation
- This patient had chest pain for months and normal vitals
- The differential diagnosis includes primary OMI (BAD), subendocardial ischemia in triple vessel disease, anything causing global ischemia (eg, dissection, massive PE, hemorrhage, hypoxia) or repoloarization abnormalities (electrolytes, LVH, bundle branch blocks).
- This patient ended up receiving dissection study that revealed calcified aortic valve and and echo confirming severe aortic stenosis which could have caused diffuse subendoardial ischemia and LVH.
ECG 10 (📷)
Estimate the heart rate and axis to the nearest quadrant. - Rate: slow, 50s
- Axis: normal
- Focus on the rhythm lead (II)
- There P, QRS then P hidden at the back of T wave then no QRS which is 2:1 av block
- Then there is P-QRS, P-QRS, then P (hidden in T wave) and then no QRS which is a 3:2 av block (3 ps to 2 qrs)
- Based on the 3:2 block, the PR interval seems to be getting longer so this type 1 second degree block with alternating 2:1 and 3:2 block
Any concerning intervals, QRS morphology, ST segments or T waves? - RBBB morphology but QRS ≤ 120ms. (rsR’ and RSr in V1-V2) with possible slurred s wave in lead I. This is likely an incomplete RBBB
- TWI in V1-V2. Could be from RBBB or could be from something else.
Nathanson LA, McClennen S, Safran C, Goldberger AL. ECG Wave-Maven: Self-Assessment Program for Students and Clinicians. http://ecg.bidmc.harvard.edu.
ECG 11 (📷)
Estimate the heart rate and axis to the nearest quadrant. - Rate: fast 110-120
- Axis: normal axis
Any concerning intervals, QRS morphology, ST segments or T waves? - Low voltage in the precordial leads (≤ 10 mm qrs complexes)
- STD in V5-V6
- Q waves III, V1, V2
- Poor R wave progression
- Not diagnostic
- Low voltage and tachycardia should have you ruling out pericardial effusion/cardiac tamponade or large pleural effusion
- The POCUS did not reveal a pericardial effusion, but it did show dilated RV and a clot in the RA
ECG 12 (📷)
Estimate the heart rate and axis to the nearest quadrant. - Rate: very irregular, normal rate with a brief episode of tachycardia
- Axis: normal
- Lets look at rhythm 1. This starts off as sinus rhythm followed by 3 narrow complex beats without P waves so this could non-sustained SVT from PACs or PJCs (junctional beats)
- Then it reverts back to 3 sinus beats then a string of 5 wide complex beats without p waves. Is this non-sustained VT? Lets hope not.
- This could be something called Ashman Phenomenon. This occurs when a supraventricular beat (PAC or PJC) occurs shortly after a long R-R interval and if it occurs while the right bundle is still in refractory, it will be wide complex (RBBB morphology). This can be see more commonly in atrial fibrillation where there are more variable in R-R intervals. LITFL has a good explanation.
Any concerning intervals, QRS morphology, ST segments or T waves? Not anything outside of what was described above - Not diagnostic
- More reading on ashman phenomenon: LITFL
ECG 13 (📷)
Estimate the heart rate and axis to the nearest quadrant. Any concerning intervals, QRS morphology, ST segments or T waves? - Wide QRS + rS in V1-V2 + monomorphic R in I and V6 consistent with LBBB
- Discordant STE/STD and TWI
Nah. Let’s review concordance and discordance once again. - 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 Sgarbossa Criteria or modified Smith Sgarbossa 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 STD here. There are discordant STE in V1-V2, but are they excessive discordant? No they are not
Lead | S wave | STE |
V1 | 20 mm | 1.5 mm |
V2 | 21 mm | 1.5 mm |
ECG 14 (📷)
Estimate the heart rate and axis to the nearest quadrant. - Rate: fast, somewhere between 200-250
- Axis: extreme (down in I and avF)
- This a regular wide complex tachycardia likely monomorphic VT
- Is this SVT with aberrancy? Don’t waste your time
- Extreme axis, dominant R in avR, very wide QRS (180 ms, see V2), high rate → just assume the worst
- This is actually a fasicular VT coming from the posterior left fascicle. How do I know? I’m that good. Just kidding, I read the EP report.
- A fascicular VT typically has RBBB + L axis morphology. Why is that? This is because the left heart is depolarized first before the right side. What’s interesting here is that the axis i not left.
- More on fasicular VTs: 🔗 LIFTL, 🔗 Dr. Smith’s ECG blog
Any concerning intervals, QRS morphology, ST segments or T waves? - Non-diagnostic
- Cardiovert, stabilize and repeat the ECG
ECG 15 (📷)
Estimate the heart rate and axis to the nearest quadrant. - Rate: slow 60s
- Axis: L axis
- Sinus brady with 1st degree av block
Any concerning intervals, QRS morphology, ST segments or T waves? - Peaked T waves in V1-V3
- STD depressions in V1-V4 but not tall R waves
- STE in V5
- This could very well be a posterior + lateral MI however it does look weird
- STD are upsloping, the T waves are peaked.
- The STE in V5 is undeniable
- Bizarre, bradycardia…think hyperkalemia
- This patient presented with non-specific symptoms in the setting of missed dialysis. His K was found to be 9 meQ/L.
ECG 16 (📷)
Estimate the heart rate and axis to the nearest quadrant. - Rate: 40-50s
- Axis: normal axis
Any concerning intervals, QRS morphology, ST segments or T waves? - Not diagnostic of OMI
- Patient ended up being diagnosed with a kidney stone.
This post is for education and not medical advice.
