Can’t miss cases of Wellens Syndrome
Episode 103
August 19, 2013

If you love Wellens ECGs, here’s 4 cases and 16 minutes of love!

​Wellens Syndrome
  • T-wave abnormality in precordial leads (V2-V3, +/-V4)
  • Specific for obstructed LAD lesion
  • High risk for extensive anterior wall MI and death
    • 2 types
      • Type 1-Deeply symmetric TWI
      • Type 2- Biphasic T waves with terminal TWI. Goes up first, then down (often misdiagnosed as “normal” or “non-specific T-wave abnormality”).
  • ST changes are often absent and patient can be chest pain free!
  • Look carefully at the ECG when the machine tells you there are “non-specific ST abnormalities”
  • Cardiac biomarkers often initially normal
  • Medical management usually ineffective and patients are best treated with PCI, treadmill stress testing may be hazardous.
  • Do not diagnose in the presence of large amplitude QRS complexes
  • When in doubt get serial ECG’s!

Knowing how to diagnose Wellens saves lives. Make sure you know about it. These previous episodes will help, check them out…

 
Can’t miss cases of Wellens Syndrome
Episode 103
August 19, 2013

If you love Wellens ECGs, here’s 4 cases and 16 minutes of love!

​Wellens Syndrome
  • T-wave abnormality in precordial leads (V2-V3, +/-V4)
  • Specific for obstructed LAD lesion
  • High risk for extensive anterior wall MI and death
    • 2 types
      • Type 1-Deeply symmetric TWI
      • Type 2- Biphasic T waves with terminal TWI. Goes up first, then down (often misdiagnosed as “normal” or “non-specific T-wave abnormality”).
  • ST changes are often absent and patient can be chest pain free!
  • Look carefully at the ECG when the machine tells you there are “non-specific ST abnormalities”
  • Cardiac biomarkers often initially normal
  • Medical management usually ineffective and patients are best treated with PCI, treadmill stress testing may be hazardous.
  • Do not diagnose in the presence of large amplitude QRS complexes
  • When in doubt get serial ECG’s!

Knowing how to diagnose Wellens saves lives. Make sure you know about it. These previous episodes will help, check them out…

 

Syncope ECG Differentials

Episode 102

August 12, 2013


Look up. Look down. Look all around. Otherwise, you just might miss this diagnosis!


Always think of the following differentials when interpreting the ECG of patient’s with syncope:
  1. Acute Coronary Syndrome

  2. Tachy / Bradycardias & AV-blocks

  3. WPW / Pre-excitation

  4. Long / Short QT syndromes

  5. Hypertrophic cardiomyopathy

  6. Brugada syndrome

  7. Arrhythmogenic RV dysplasia

WPW Syndrome (pre-excitation)

“Classical triad”

  1. Short or no PR interval

  2. Widened QRS

  3. Delta wave (Not always present!)​

Pay close attention to intervals when interpreting ECG’s in patients with syncope. Look in all 12 leads for delta waves if you notice a short PR-interval and suspect WPW.


For more syncope cases, check out…

Interval interpretation in syncope


Syncope ECG Differentials

Episode 102

August 12, 2013


Look up. Look down. Look all around. Otherwise, you just might miss this diagnosis!


Always think of the following differentials when interpreting the ECG of patient’s with syncope:
  1. Acute Coronary Syndrome

  2. Tachy / Bradycardias & AV-blocks

  3. WPW / Pre-excitation

  4. Long / Short QT syndromes

  5. Hypertrophic cardiomyopathy

  6. Brugada syndrome

  7. Arrhythmogenic RV dysplasia

WPW Syndrome (pre-excitation)

“Classical triad”

  1. Short or no PR interval

  2. Widened QRS

  3. Delta wave (Not always present!)​

Pay close attention to intervals when interpreting ECG’s in patients with syncope. Look in all 12 leads for delta waves if you notice a short PR-interval and suspect WPW.


For more syncope cases, check out…

Interval interpretation in syncope


Non-conducted PAC’s vs. Mobitz II
Episode 99
July 22, 2013
Non-conducted PAC’s vs. Mobitz II
Episode 99
July 22, 2013

How is the heart like a toilet??!!  Watch this week’s video and you will never flush before your toilet is finished repolarizing ever again!

 
  • Non-conducted PACs produce pauses that may mimic Mobitz II
  • Remember that the P-P interval must remain contant in Mobitz blocks
  • Management is very different for PAC’s vs. Mobitz II. True Mobitz II will require invasive procedures whereas non-conducted PAC’s are generally benign

Everything you want to know about 2nd degree AV Blocks

Episode 98​

July 15, 2013


​​When is 2nd degree AV block not the same as Mobitz? Here’s everything you want to know about 2nd degree AVB!

 
2nd Degree AV Block

Atrial impulses fail to conducts to the ventrcles. (ie P:QRS >1)

Type I (Mobitz I, Wenckebach)

  • Each atrial impulse has longer and longer conduction time until it fails to conduct to the ventricle.

  • Block usually at level of AV node, producing narrow QRS’s

  • May sometimes also have wide QRS’s in patient’s with pre-existing bundle branch block or intraventricular conduction delay

  • At least 2 consecutive P-QRS complexes demonstrate progressive PR-interval lengthening before a non-conducted P-wave

  • P-P interval remains constant​

Type II (Mobitz II)

  • Some but not all impulses are transmitted to the ventricles WITHOUT progressive PR lengthening.

  • Typically due infranodal block, producing wide QRS’s (can also sometime be narrow!)

  • At least 2 consecutive P-QRS complexes demonstrate constant PR-intervals before the non-conducted P wave

  • P-P interval remains constant

What if there are not any consecutive P-QRS complexes before the non-conducted P?

  • If there is a fixed 2:1 ratio throughout, you can’t tell if the PR-interval is lengthening, hence can’t differentiate between Type I & II

  • Just call it “2nd degree AV block with fixed 2:1 block”

Advanced (high-grade) AV Block

  • P:QRS conduction ratio of is 3:1 or higher

  • Produces extremely slow ventricular rates

  • Can be Mobitz I or II, may be able to differentiate based on width of QRS

Right Bundle Branch Block

3-Step approach to diagnosing AV blocks 

 

Everything you want to know about 2nd degree AV Blocks

Episode 98​

July 15, 2013


​​When is 2nd degree AV block not the same as Mobitz? Here’s everything you want to know about 2nd degree AVB!

 
2nd Degree AV Block

Atrial impulses fail to conducts to the ventrcles. (ie P:QRS >1)

Type I (Mobitz I, Wenckebach)

  • Each atrial impulse has longer and longer conduction time until it fails to conduct to the ventricle.

  • Block usually at level of AV node, producing narrow QRS’s

  • May sometimes also have wide QRS’s in patient’s with pre-existing bundle branch block or intraventricular conduction delay

  • At least 2 consecutive P-QRS complexes demonstrate progressive PR-interval lengthening before a non-conducted P-wave

  • P-P interval remains constant​

Type II (Mobitz II)

  • Some but not all impulses are transmitted to the ventricles WITHOUT progressive PR lengthening.

  • Typically due infranodal block, producing wide QRS’s (can also sometime be narrow!)

  • At least 2 consecutive P-QRS complexes demonstrate constant PR-intervals before the non-conducted P wave

  • P-P interval remains constant

What if there are not any consecutive P-QRS complexes before the non-conducted P?

  • If there is a fixed 2:1 ratio throughout, you can’t tell if the PR-interval is lengthening, hence can’t differentiate between Type I & II

  • Just call it “2nd degree AV block with fixed 2:1 block”

Advanced (high-grade) AV Block

  • P:QRS conduction ratio of is 3:1 or higher

  • Produces extremely slow ventricular rates

  • Can be Mobitz I or II, may be able to differentiate based on width of QRS

 

Have you mastered AV blocks to make sure your patients get the best care possible? If not, check out these previous episodes…

AV blocks & Rabbit ears for RBBB vs. PVC

Right Bundle Branch Block

3-Step approach to diagnosing AV blocks 

 
AV blocks & Rabbit ears for RBBB vs. PVC
Episode 97
July 8, 2013

Virtually a full review of AV blocks from a single patient…in 14 minutes!​

When interpreting rhythms, always do these three things:
1. Find out what the atrium is doing
2. Find out what the ventricle is doing
3. Figure out the relationship between the atrium and ventricle (PR-interval)

The answer usually lies in the PR-interval!

1st Degree AV Block = “delay” > 200ms at AV node or His bundle.

When the P:QRS>1, consider 2nd and 3rd degree AV Blocks

2nd Degree AV Block = Not every atrial impulse goes through to the ventrcles. (ie P:QRS >1)

  • Mobitz Type I (Wenckebach) -Each atrial impulse has longer and longer delay until it fails to conduct to the ventricle. Progressive PR-interval lengthening before a dropped beat.

  • Mobitz Type II - typically due to block below AV node in His bundle. Some but not all impulses are transmitted to the ventricles WITHOUT progressive PR lengthening.

3nd Degree AV Block = P waves march out normally at 60-100 bpm with no relation to the ventricular rate which is typically slower than sinus or the atrial rate.
 

RBBB vs PVC’s

Wide QRS complexes, with large R waves in V1 can be caused by both RBBB and PVC’s. An RSR’ pattern or the “rabbit ear appearance” is typically seen in V1 with RBBB. PVC’s from a left ventricular source will also have dominant R waves in V1. One way to differentiate between RBBB and a PVC is to pay attention to the morphology of the QRS complex.

 
  • RBBB - typically has a small R wave (left rabbit ear) and a tall R’ (right rabbit ear).
  • PVC’s - will have a larger R wave (left rabbit ear) and a smaller R’ (right rabbit ear) or a “hitched” downslope to the wave.
 

Extra Pearl

R wave > 15mm in setting of RBBB + Rightward Axis = Right ventricular hypertropy (RVH)


Bunny ears not enough? Want more? Check out these related episodes…
 
 
 
AV blocks & Rabbit ears for RBBB vs. PVC
Episode 97
July 8, 2013

Virtually a full review of AV blocks from a single patient…in 14 minutes!​

When interpreting rhythms, always do these three things:
1. Find out what the atrium is doing
2. Find out what the ventricle is doing
3. Figure out the relationship between the atrium and ventricle (PR-interval)

The answer usually lies in the PR-interval!

1st Degree AV Block = “delay” > 200ms at AV node or His bundle.

When the P:QRS>1, consider 2nd and 3rd degree AV Blocks

2nd Degree AV Block = Not every atrial impulse goes through to the ventrcles. (ie P:QRS >1)

  • Mobitz Type I (Wenckebach) -Each atrial impulse has longer and longer delay until it fails to conduct to the ventricle. Progressive PR-interval lengthening before a dropped beat.

  • Mobitz Type II - typically due to block below AV node in His bundle. Some but not all impulses are transmitted to the ventricles WITHOUT progressive PR lengthening.

3nd Degree AV Block = P waves march out normally at 60-100 bpm with no relation to the ventricular rate which is typically slower than sinus or the atrial rate.
 

RBBB vs PVC’s

Wide QRS complexes, with large R waves in V1 can be caused by both RBBB and PVC’s. An RSR’ pattern or the “rabbit ear appearance” is typically seen in V1 with RBBB. PVC’s from a left ventricular source will also have dominant R waves in V1. One way to differentiate between RBBB and a PVC is to pay attention to the morphology of the QRS complex.

 
  • RBBB - typically has a small R wave (left rabbit ear) and a tall R’ (right rabbit ear).
  • PVC’s - will have a larger R wave (left rabbit ear) and a smaller R’ (right rabbit ear) or a “hitched” downslope to the wave.
 

Extra Pearl

R wave > 15mm in setting of RBBB + Rightward Axis = Right ventricular hypertropy (RVH)


Bunny ears not enough? Want more? Check out these related episodes…
 
 
 
Scarbossa’s criteria identifies MI in patients with LBBB 
Episode 94
June 17, 2013

Tombstones, checkmarks, and bundles, oh my!

Criteria for left bundle branch block (LBBB)

  • Widened QRS > 0.12 sec in adults
  • Broad notched or slurred R waves in I and V6 WITHOUT Q-waves
  • Broad S waves in V1, V2, V3, may have a small r wave

LBBB causes ST-segment and T wave changes that make the diagnosis of acute MI difficult. Patients with LBBB can be expected to have ST-segment and T waves that are discordant to the direction of the QRS complex. This is expected and referred to as the “rule of appropriate discordance”. In fact, it is very concerning when the QRS complex and the ST-segment are concordant (point in same direction).

You CAN diagnose MI in LBBB, once you understand Sgarbossa’s criteria.

Sgarbossa’s criteria is used to diagnose MI in the setting of a known chronic LBBB. The following 3 ECG criteria can help diagnose AMI in patients with LBBB.

1. STE ≥ 1mm concordant with QRS deflection in any single lead (odds ratios for AMI of 25.2!)

2. STD ≥ 1mm in V1, V2, OR V3 that is concordant. Does NOT need to be in contiguous leads (odds ratios for AMI of 6.0)

3. Discordant STE ≥ 5mm (lower specificity) or STE >20% of size of QRS.


Everything you nees to know about Scarbossa…
Scarbossa’s criteria identifies MI in patients with LBBB 
Episode 94
June 17, 2013

Tombstones, checkmarks, and bundles, oh my!

Criteria for left bundle branch block (LBBB)

  • Widened QRS > 0.12 sec in adults
  • Broad notched or slurred R waves in I and V6 WITHOUT Q-waves
  • Broad S waves in V1, V2, V3, may have a small r wave

LBBB causes ST-segment and T wave changes that make the diagnosis of acute MI difficult. Patients with LBBB can be expected to have ST-segment and T waves that are discordant to the direction of the QRS complex. This is expected and referred to as the “rule of appropriate discordance”. In fact, it is very concerning when the QRS complex and the ST-segment are concordant (point in same direction).

You CAN diagnose MI in LBBB, once you understand Sgarbossa’s criteria.

Sgarbossa’s criteria is used to diagnose MI in the setting of a known chronic LBBB. The following 3 ECG criteria can help diagnose AMI in patients with LBBB.

1. STE ≥ 1mm concordant with QRS deflection in any single lead (odds ratios for AMI of 25.2!)

2. STD ≥ 1mm in V1, V2, OR V3 that is concordant. Does NOT need to be in contiguous leads (odds ratios for AMI of 6.0)

3. Discordant STE ≥ 5mm (lower specificity) or STE >20% of size of QRS.


Everything you nees to know about Scarbossa…
Digoxin Toxicity & AV block: Will IV calcium cause “stone heart”?
Episode 91
May 28, 2013
Digoxin Toxicity & AV block: Will IV calcium cause “stone heart”?
Episode 91
May 28, 2013

Potassium, digoxin, calcium, AVBs, stone heart…so much to discuss this week!

  • When considering AV blocks, always pay attention to the PR segments to help distinguish between Mobitz I, Mobitz II, & AVD/CHB.
  • Hyperkalemia can cause just about anything, including AV blocks!
  • Calcium in probably safe in digoxin toxicity.
  • Levine et al. in their retrospective review of 129 patients who had digoxin toxicity, found that IV calcium did not seem to cause malignant dysrhythmias or increase mortality. They found no support for the historical belief that calcium is contraindicated for these hyperkalemic patients.
  Impressive Syndrome
  Impressive Syndrome
Episode 90
May 21, 2013

Impressive horses, syphilis, and strokes…all in 14 minutes!
 
Hyperkalemia is the syphilis of electrocardiography. It is the great imitator!
 
  • Hyperkalemia can cause STE and mimic STEMI’s & is the most rapid killer in DKA
  • Renal patients with systemic complaints should get an ECG and hyperkalemia should be considered
  • Bizarre Rhythm? Wide QRS? Think Tox/metabolic…get Calcium & Bicarb ready!
  • Hyperkalemic periodic paralysis, aka. Impressive Syndrome - Inherited autosomal dominant condition that affects Na+ channels in muscle and the ability to regulate K+ in the blood. 


 
  T-wave changes of severe hypokalemia
  T-wave changes of severe hypokalemia
Episode 89
May 13, 2013

 
Ever heard of “Reverse-Wellens syndrome” ? Watch this to learn about this dangerous Wellens syndrome mimic.
“Reverse-Wellens” waves deflect downward before going up & are seen in cases of severe hypokalemia that produce U-waves. See below…

Compare this to Wellens waves that may also be biphasic, but deflect upward before going down!
What anatomical distribution of ischemia is associated with the ECG changes of Wellens Syndrome? Review Wellens by watching the videos below!  

Review these previous episodes and master Wellens syndrome…

 
  When STE in aVR = Left main coronary artery stenosis
Episode 88
May 6, 2013

aVR - the forgotten 12th lead

  • BEWARE OF STE in aVR for patients with acute coronary syndromes
  • STE in aVR with other ischemic findings on ECG is BAD! (LMCA occlusion, proximal LAD occlusion, or triple vessel disease)
  • In the setting of ACS, STE in aVR…
    • + STE in avL = LMCA occlusion
    • + STE in V1 = LMCA or proximal LAD occlusion
    • STE in avR > STE V1 = LMCA occlusion
    • ST-elevation in aVR not applicable in setting of SVT or in asymptomatic patients without ischemic symptoms
  • aVR STE > 1.0mm should make you worry
  • LMCA occlusion may require CABG, so avoid drugs like clopidogrel
  • 70% mortality without immediate PCI
  • Medical therapy including lytics does not improve mortality
  • Emergent PCI may decrease mortality to 40%
  • Time delay to PCI is the only predictor of survival
  • STE of aVR in very tachycardic rhythms (i.e. SVT), and in the setting of severe hypertension and LVH may be a normal variant or have no clinical significance.

Learn more about the forgotten lead, aVR! This episode is loaded with important references you can share with your cardiologist as needed…

References:
 
 
 
 
 
 
 
 
  When STE in aVR = Left main coronary artery stenosis
Episode 88
May 6, 2013

aVR - the forgotten 12th lead

  • BEWARE OF STE in aVR for patients with acute coronary syndromes
  • STE in aVR with other ischemic findings on ECG is BAD! (LMCA occlusion, proximal LAD occlusion, or triple vessel disease)
  • In the setting of ACS, STE in aVR…
    • + STE in avL = LMCA occlusion
    • + STE in V1 = LMCA or proximal LAD occlusion
    • STE in avR > STE V1 = LMCA occlusion
    • ST-elevation in aVR not applicable in setting of SVT or in asymptomatic patients without ischemic symptoms
  • aVR STE > 1.0mm should make you worry
  • LMCA occlusion may require CABG, so avoid drugs like clopidogrel
  • 70% mortality without immediate PCI
  • Medical therapy including lytics does not improve mortality
  • Emergent PCI may decrease mortality to 40%
  • Time delay to PCI is the only predictor of survival
  • STE of aVR in very tachycardic rhythms (i.e. SVT), and in the setting of severe hypertension and LVH may be a normal variant or have no clinical significance.

Learn more about the forgotten lead, aVR! This episode is loaded with important references you can share with your cardiologist as needed…

References: