Felson’s 10 Axioms for a Lifetime of Learning Medicine

Felson’s 10 Axioms for a Lifetime of Learning Medicine

1. You like it, you’ll learn it; so learn to like it.
2. Principles are as important as facts. If you master the principles, you can make up the facts.

Normal ECG characteristics

Normal ECG characteristics

Rhythm: Regular (<10% variation at RR intervals)
Rate: 60-100 per minute

Warfarin Toxicity Management

Warfarin Toxicity Management

Pharmacology and management of the Vitamin K antagonists: American College of Chest physicians Evidence-Based Clinical Practice Guidelines/ Chest 2008

Kerley Lines

We often read and hear about kerley lines on chest X-Ray. But what are they and what do they mean?

Here is a AP chest X-Ray film. Note the arrows and arrowheads:

Kerley's A lines (Arrows): Linear opacities extending from the periphery to the hila. They are caused by distension of anastomotic channels between peripheral and central lymphatics

Kerley's B lines (white arrowheads): Short horizontal lines situated perpendicularly to the pleural surface at the lung base. They represent edema of the interlobular septa.

Kerley's C lines (black arrowheads): Reticular opacities at the lung base. They represent Kerley's B lines en face.

All of these radiologic signs suggest cardiogenic pulmonary edema.

Narrow complex tachycardias

Narrow Complex Tachycardias

Definition: Tachycardia (QRS frequency >100/min) with QRS duration <100ms

Origin: Atria, sinus node, atrioventricular node, His bundle

Types:

1. Sinus tachycardia
2. Inappropriate sinus tachycardia
3. Sinoatrial reentrant tachycardia
4. Atrial tachycardia
5. Multifocal atrial tachycardia
6. Atrioventricular reentrant tachycardia
7. Atrioventricular nodal reentrant tachycardia
8. Junctional ectopic tachycardia
9. Atrial fibrillation
10. Atrial Flutter

Tachycardias with sinus node-like P wave

Based upon P wave morphology these tachycardias cannot be distinguished in 12 lead ECG:

1. Sinus Tachycardia (ST)

2. Inappropriate sinus tachycardia (IST)

3. Sinoatrial nodal reentrant tachycardia (SNRT)

4. Atrial tachycardia (AT), originating near the sinus node

But there are a couple of features that might assist in the differential.

• ST and IST usually range from 100-180 beats/min. AT, SNRT may be faster.
• In ST and IST there is almost always a 1:1 relationship between atrial and ventricular activity.
• If vagal manoeuvres or adenosine are administered, in ST and IST there is a gradual slowing of the atrial and ventricular rates. Whereas SNRT may terminate abruptly. AT may increase the atrial:ventricular rate ratio