Lumen stenosis and size is not as important as plaque vulnerability 
Episode 95
June 24, 2013

Size isn’t everything! Here’s the most important video of the year! (no joke)

Plaque vulnerability based on 3 major factors

  1. Fibrous cap
  2. Lipid core
  3. Inflammatory cells

Recent stress testing and catheterizations are NOT predictive of new plaque rupture!

  • Small plaques may be more unstable and more prone to rupture
  • Infarct related arteries often have non-obstructing plaque, before rupture and MI
  • Angiography can not distinguish stable vs. unstable plaque composition, and give no information about the fibrous cap or lipid core

Key point: Nothing will risk stratify you to zero! You can’t always rely in the recently negative stress test or “unremarkable” cath.  History of presenting illness is the most important information and should guide your management.


Must read references:

Libby, P. (2013). Mechanisms of Acute Coronary Syndromes and Their Implications for Therapy. New England Journal of Medicine, 368(21), 2004–2013.

 
References:

Virmani, R., Burke, A. P., Farb, A., & Kolodgie, F. D. (2006). Pathology of the Vulnerable Plaque. Journal of the American College of Cardiology, 47(8), C13–C18.


 
Lumen stenosis and size is not as important as plaque vulnerability 
Episode 95
June 24, 2013

Size isn’t everything! Here’s the most important video of the year! (no joke)

Plaque vulnerability based on 3 major factors

  1. Fibrous cap
  2. Lipid core
  3. Inflammatory cells

Recent stress testing and catheterizations are NOT predictive of new plaque rupture!

  • Small plaques may be more unstable and more prone to rupture
  • Infarct related arteries often have non-obstructing plaque, before rupture and MI
  • Angiography can not distinguish stable vs. unstable plaque composition, and give no information about the fibrous cap or lipid core

Key point: Nothing will risk stratify you to zero! You can’t always rely in the recently negative stress test or “unremarkable” cath.  History of presenting illness is the most important information and should guide your management.


Must read references:

Libby, P. (2013). Mechanisms of Acute Coronary Syndromes and Their Implications for Therapy. New England Journal of Medicine, 368(21), 2004–2013.

 
References:

Virmani, R., Burke, A. P., Farb, A., & Kolodgie, F. D. (2006). Pathology of the Vulnerable Plaque. Journal of the American College of Cardiology, 47(8), C13–C18.


 
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:

 ST-segment depression in LAD and LMCA occlusion
Episode 82
March 25, 2013
 ST-segment depression in LAD and LMCA occlusion
Episode 82
March 25, 2013

Can you diagnose a STEMI without STE in contiguous leads? You’ll know how in 15 minutes.

de Winter T- waves
  • 1-3 mm of ST-depression upsloping at the J-point in the precordial leads, leading into tall symmetric T-waves
  • Suggestive of an acute LAD lesion
  • Suggestive of an acute LAD lesion and may precede STE
 

Don’t forget that STE in aVR that is > STE in V1 with ST-depression in other leads is highly suggestive of a left main coronary artery lesion!


Want to learn more about T-waves in ischemia? Check these out…

What are “de Winter T-waves”?

Killer T-wave inversions in aVL

Hyperacute Ischemic T-waves

 

Low Voltage Tachycardia
Episode 80
March 12, 2013
Low Voltage Tachycardia
Episode 80
March 12, 2013

A patient with cancer presents with dyspnea. Easy clinical diagnosis, right? But check out the ECG first!
 
“Classic triad” of Pericardial Effusions on ECG
  • Low Voltage (I+II+III < 15mm or V1+V2+V3 < 30mm)
  • Tachycardia
  • Electrical alternans (Not always present!)
Low Voltage Differential
  • “Low Power”
  • Myxedema
  • End stage cardiomyopathy
  • Infiltrative diseases
  • Conduction blockage
  • Fluid (pericardial or pleural)
  • Fat (obesity)
  • Air (COPD)
Low voltage + Tachycardia = Pericardial effusion until proven otherwise!
Dyspnea in the setting of cancer is not always PE, consider pericardial effusion!

More cases on the same topic…

When diagnosing pericardial effusions saves lives


 
 
Obtunded patient? ECG can clinch the diagnosis!
Episode 79
March 4, 2013

A patient presents obtunded, GCS 3, RR 8. The ECG makes the dx!
 
Go through the following steps EVERY TIME you interpret a tough ECG
 
5 Step Approach to ECG Interpretation
  1. Rate and Rhythm
  2. Axis
  3. Intervals
  4. Enlargement
  5. Ischemia & Infarction (Q-waves, ST-segment changes, T-wave inversions)​

​​Recognize abnormalities and stop to think about the differential diagnoses that explain them.

Right Axis Deviation Differential

  • LPFB
  • Lateral MI (from Q-waves)
  • RVH
  • Acute (PE) and chronic (COPD) lung disease
  • Ventricular ectopy
  • Hyperkalemia
  • Na-channel blocking drugs (TCA)
  • Normal thin adults with horizontally positioned hearts
  • Lead misplacement

Causes of QRS prolongation

  • BBB (LBBB or RBBB) or paced rhythm
  • Pre-excitation (WPW)
  • Ventricular ectopy
  • Metabolic/Electrolytes (i.e. acidosis, hyperkalemia)
  • Medications - Na2+channel blocking drug toxicity (TCA’s, Quinidine & Anti-arrhythmics)
  • Nonspecific intraventricular conduction delay (ex. from LVH, hypothermia) or congenital

Causes of QT-interval prolongation

  • Hypothermia
  • Hypokalemia (due to U-wave), Hypomagnesemia , Hypocalcemia
  • AMI
  • Increased ICP
  • Na2+channel blocking drugs (TCA’s, Quinidine & Anti-arrhythmics)
  • Congenital

Na2+ channel blocker toxicity (ex. TCA’s)

  • Tall R wave in aVR
  • Tachycardia
  • Right Axis Deviation
  • Prolonged QRS

Approach each ECG systematically so that you don’t miss things. These previous episodes are loaded with pearls and differentials that will help you save lives…

The 5 step approach to ECG interpretation

Deadly, can’t miss ECG!

 

 
 
Obtunded patient? ECG can clinch the diagnosis!
Episode 79
March 4, 2013

A patient presents obtunded, GCS 3, RR 8. The ECG makes the dx!
 
Go through the following steps EVERY TIME you interpret a tough ECG
 
5 Step Approach to ECG Interpretation
  1. Rate and Rhythm
  2. Axis
  3. Intervals
  4. Enlargement
  5. Ischemia & Infarction (Q-waves, ST-segment changes, T-wave inversions)​

​​Recognize abnormalities and stop to think about the differential diagnoses that explain them.

Right Axis Deviation Differential

  • LPFB
  • Lateral MI (from Q-waves)
  • RVH
  • Acute (PE) and chronic (COPD) lung disease
  • Ventricular ectopy
  • Hyperkalemia
  • Na-channel blocking drugs (TCA)
  • Normal thin adults with horizontally positioned hearts
  • Lead misplacement

Causes of QRS prolongation

  • BBB (LBBB or RBBB) or paced rhythm
  • Pre-excitation (WPW)
  • Ventricular ectopy
  • Metabolic/Electrolytes (i.e. acidosis, hyperkalemia)
  • Medications - Na2+channel blocking drug toxicity (TCA’s, Quinidine & Anti-arrhythmics)
  • Nonspecific intraventricular conduction delay (ex. from LVH, hypothermia) or congenital

Causes of QT-interval prolongation

  • Hypothermia
  • Hypokalemia (due to U-wave), Hypomagnesemia , Hypocalcemia
  • AMI
  • Increased ICP
  • Na2+channel blocking drugs (TCA’s, Quinidine & Anti-arrhythmics)
  • Congenital

Na2+ channel blocker toxicity (ex. TCA’s)

  • Tall R wave in aVR
  • Tachycardia
  • Right Axis Deviation
  • Prolonged QRS

Approach each ECG systematically so that you don’t miss things. These previous episodes are loaded with pearls and differentials that will help you save lives…

The 5 step approach to ECG interpretation

Deadly, can’t miss ECG!

 

 
 
ECGs that differentiate syncope from “seizure”
Episode 77
February 18, 2013
ECGs that differentiate syncope from “seizure”
Episode 77
February 18, 2013

What do you do with a 12 year old having a second seizure? Or if your nanny has her first seizure? Practical answers in just 13 minutes.

Always get a screening ECG in patients with new onset “seizures”!

  • Remember that juvenile T-wave abnormalities (TWI in V1-V3 through age 8) are normal and can persist in young females (persistent juvenile T-wave pattern).
  • Evaluate ECG for dysrhythmias and syncope (especially prolonged QT)
New T-wave inversions in anteroseptal & inferior leads 
Episode 76
February 12, 2013
New T-wave inversions in anteroseptal & inferior leads 
Episode 76
February 12, 2013

What should you consider when a patient with pneumonia gets worse and flips their T-waves?

Pulmonary embolism (PE) can be associated with normal ECG’s and normal heart rates.

  • Large PE’s commonly cause T-wave inversions (TWI’s).
  • Simultaneous TWI’s in the inferior and anteroseptal leads = PE until proven otherwise 
 
 
One ECG begets another 
Episode 75
February 4, 2013

”One EKG begets another”

- Dr. Corey Slovis

Electrocardiography is the BEST diagnostic test in Emergency Medicine

  • Don’t forget that we are in the business of discovering the most deadly diagnosis…not the most common
  • Repeat the ECG when the patient’s symptoms change (improve or worsen)
  • Young people can have MI’s.
  • Chest pain associated with the following four things should make you consider acute coronary syndromes:
  1. ​Exertion
  2. Radiation (to right>both>left)
  3. Diaphoresis
  4. Vomiting

 
 
 
 
One ECG begets another 
Episode 75
February 4, 2013

”One EKG begets another”

- Dr. Corey Slovis

Electrocardiography is the BEST diagnostic test in Emergency Medicine

  • Don’t forget that we are in the business of discovering the most deadly diagnosis…not the most common
  • Repeat the ECG when the patient’s symptoms change (improve or worsen)
  • Young people can have MI’s.
  • Chest pain associated with the following four things should make you consider acute coronary syndromes:
  1. ​Exertion
  2. Radiation (to right>both>left)
  3. Diaphoresis
  4. Vomiting

 
 
 
 
AV Block in a tachycardic rhythm? 
Episode 74
January 28, 2013
AV Block in a tachycardic rhythm? 
Episode 74
January 28, 2013

Can you have a Mobitz I in a tachycardic patient?? You’ll have an answer in 11min.

Don’t trust the computer’s EKG interpretation…that’s your job!

  • Computer may commonly miss p-waves that are buried in the T-waves.
  • AV Dissociation can be seen in BOTH fast and slow rhythms.
  • When in doubt, map out atrial beats with calipers and search for buried p-waves.
Right Bundle Branch Block
Right Bundle Branch Block
Episode 73
January 22, 2013

Got questions about RBBB? Get some answers in 11 minutes.

ANY ST-ELEVATION IN RBBB IS ALWAYS ABNORMAL!
No special criteria need to be met to have STEMI in RBBB
Uncomplicated RBBB
  • QRS duration > 120ms
  • Tall R wave or R’ in V1 & V2 (conversely, LBBB has an S waves in V1 & V2)
  • ”Wide-ish” S waves in the lateral leads
  • Expected ST-depression and TWI in V1-V3

Concordant STE is BAD! Don’t forget that you can dignose STEMI even in the setting of LBBB or paced rhythms. Watch these for a refersher…