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 all 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 all 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
 

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 

 
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…
  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. 


 
  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:
 
 
 
 
 
 
 
 
  Dangers of  “Non-specific ST-segment abnormalities” ​
  Dangers of  “Non-specific ST-segment abnormalities” ​
Episode 87
April 29, 2013

 
 
When in doubt, order serial ECG!
Get good at ECG’s and you will save lives!
 
  • ST-segment depression or elevation <1mm are typically interpreted as “Non-specific ST-segment abnormalities” by the ECG machine. Ischemia causes dynamic ECG changes, and this can be an early sign of MI.
  • Beware of STE in aVR! STE in aVR with other ischemic findings is BAD! (LMCA occlusion, proximal LAD occlusion, or triple vessel disease)
 

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

 
Anteroseptal ischemia or Posterior STEMI? ​
Episode 86
April 22, 2013

Syncope leads to cardiac arrest within 15 minutes. What’s the diagnosis? Find out in 15 minutes!​

Always think of the following differentials every time you are looking at an ECG in a patient who presents with syncope:
  1. Acute Coronary Syndrome
  2. Tachy/Brady-dysrhythmias (AV-blocks)
  3. WPW
  4. Brugada syndrome
  5. Hypertrophic cardiomyopathy
  6. Long/Short QT syndrome
  7. Arrhythmogenic RV dysplasia
 
Differential for ST-Depression in Anteroseptal Leads
  • Posterior STEMI
  • Anteroseptal ischemia
  • Miscellaneous
  • RBBB, Hypokalemia, etc.
Posterior Myocardial Infarction
  • ST-segment depression (STD)  instead of ST-elevation (STE)
  • Usually associated with Inferior MI due to RCA or circumflex occlusion
  • Mirror image of septal MI in leads V1-V2
  • Large R-waves instead of Q’s
  • Upright T-waves instead of T-wave inversions

ECG changes in leads V1-V3

Septal MI

STE

Inverted

T-waves

Q-waves develop over hours

Posterior MI

STD

Upright

T-waves

Tall R’s develop over hours

 

 



 
Anteroseptal ischemia or Posterior STEMI? ​
Episode 86
April 22, 2013

Syncope leads to cardiac arrest within 15 minutes. What’s the diagnosis? Find out in 15 minutes!​

Always think of the following differentials every time you are looking at an ECG in a patient who presents with syncope:
  1. Acute Coronary Syndrome
  2. Tachy/Brady-dysrhythmias (AV-blocks)
  3. WPW
  4. Brugada syndrome
  5. Hypertrophic cardiomyopathy
  6. Long/Short QT syndrome
  7. Arrhythmogenic RV dysplasia
 
Differential for ST-Depression in Anteroseptal Leads
  • Posterior STEMI
  • Anteroseptal ischemia
  • Miscellaneous
  • RBBB, Hypokalemia, etc.
Posterior Myocardial Infarction
  • ST-segment depression (STD)  instead of ST-elevation (STE)
  • Usually associated with Inferior MI due to RCA or circumflex occlusion
  • Mirror image of septal MI in leads V1-V2
  • Large R-waves instead of Q’s
  • Upright T-waves instead of T-wave inversions

ECG changes in leads V1-V3

Septal MI

STE

Inverted

T-waves

Q-waves develop over hours

Posterior MI

STD

Upright

T-waves

Tall R’s develop over hours

 

 


Everything you need to freshen up your skills on this topic…

 
  T-waves in Acute Pulmonary Hypertension ​
Episode 85
April 15, 2013
  T-waves in Acute Pulmonary Hypertension ​
Episode 85
April 15, 2013

T-wave inversions are not just cardiac ischemia! Find out what else they can be….you’ll save a life!

Leftward Axis Differential

  • LBBB
  • Pacer
  • WPW
  • Inferior MI (from Q-waves)
  • LAFB
  • LVH
  • Hyperkalemia
  • Normal Variant

Poor R-wave progression Differential

  • Prior anteroseptal MI
  • LVH
  • High precordial electrode placement
  • Normal variant

New TWI’s, especially in anteroseptal +/- inferior leads = Acute Pulmonary Hypertension = PE until proven otherwise!  



 
When pericarditis isn’t pericarditis
Episode 84
April 8, 2013

Young patients can and will have MIs. Don’t miss the diagnosis!

Pericarditis vs. STEMI
  • First, make sure you are not missing an acute MI by looking for factors strongly associated with AMI. Ask yourself:
  1. Is there reciprocal ST-segment depression in any leads (except for aVR and V1)? If yes, it’s a STEMI. If not,…
  2. Is the ST-segment morphology convex or horizontal? If yes, it’s a STEMI. If not,…
  3. Is the STE in lead III> the STE in lead II? If yes, it’s a STEMI.
  4. Are there new Q waves? If yes, it’s likely a STEMI
 
  • If the answer to all three questions is no, then you should consider the possibility of it being pericarditis. Factors associated with pericarditis:
  1. Is there pronounced PR-segment depression in all leads? If so, it’s possibly pericarditis. (But could also be due to cardiac ischemia, so make sure you are not missing an MI first by answering the first 3 questions!)
  2. Is there a pericardial friction rub? If so, it’s possibly pericarditis
When in doubt, do serial EKG’s!


 
When pericarditis isn’t pericarditis
Episode 84
April 8, 2013

Young patients can and will have MIs. Don’t miss the diagnosis!

Pericarditis vs. STEMI
  • First, make sure you are not missing an acute MI by looking for factors strongly associated with AMI. Ask yourself:
  1. Is there reciprocal ST-segment depression in any leads (except for aVR and V1)? If yes, it’s a STEMI. If not,…
  2. Is the ST-segment morphology convex or horizontal? If yes, it’s a STEMI. If not,…
  3. Is the STE in lead III> the STE in lead II? If yes, it’s a STEMI.
  4. Are there new Q waves? If yes, it’s likely a STEMI
 
  • If the answer to all three questions is no, then you should consider the possibility of it being pericarditis. Factors associated with pericarditis:
  1. Is there pronounced PR-segment depression in all leads? If so, it’s possibly pericarditis. (But could also be due to cardiac ischemia, so make sure you are not missing an MI first by answering the first 3 questions!)
  2. Is there a pericardial friction rub? If so, it’s possibly pericarditis
When in doubt, do serial EKG’s!

Everything you every wanted to know about diffuse ST-segment elevation, covered in these related episodes
 

 
How to diagnose acute MI in patients with known LBBB
Episode 83
April 1, 2013

Myth: “You can not diagnose acute MI in patients with LBBB”

Don’t believe it! You CAN diagnose MI in LBBB,

once you understand Sgarbossa’s criteria.

Complete LBBB causes delayed left ventricular depolarization causing a wide QRS (>120 ms in adults). Findings include broad notched (RSR’ or “rabbit ear pattern”) in leads I, aVL, V5, & V6. Also, absence of Q waves in leads I, V5, & V6.

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 appropriate discordance”. In fact, it is very concerning when the QRS complex and the ST-segment are concordant (point in same direction).

Positive concordance = STE or positive T waves in leads with positive QRS complexes

Negative concordance = STD or negative T waves in leads with negative QRS complexes

Sgarbossa’s criteria is used to diagnose MI in the setting of a known chronic LBBB. When combined, the following 3 ECG criteria yielded a sensitivity and specificity of approximately 78% and 90%, respectively.

  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.

Still don’t believe it? Keep watching…

References:

How to diagnose acute MI in patients with known LBBB
Episode 83
April 1, 2013

Myth: “You can not diagnose acute MI in patients with LBBB”

Don’t believe it! You CAN diagnose MI in LBBB,

once you understand Sgarbossa’s criteria.

Complete LBBB causes delayed left ventricular depolarization causing a wide QRS (>120 ms in adults). Findings include broad notched (RSR’ or “rabbit ear pattern”) in leads I, aVL, V5, & V6. Also, absence of Q waves in leads I, V5, & V6.

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 appropriate discordance”. In fact, it is very concerning when the QRS complex and the ST-segment are concordant (point in same direction).

Positive concordance = STE or positive T waves in leads with positive QRS complexes

Negative concordance = STD or negative T waves in leads with negative QRS complexes

Sgarbossa’s criteria is used to diagnose MI in the setting of a known chronic LBBB. When combined, the following 3 ECG criteria yielded a sensitivity and specificity of approximately 78% and 90%, respectively.

  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.

Still don’t believe it? Keep watching…

References: