Pre-Excitation Syndrome And Axis Flashcards
What is Wolff-Parkinson-White Syndrome? (WPW)
- An abnormal, accessory AV conduction pathway
*bundle of Kent will prematurely depolarize a portion of the ventricles
What does WPW syndrome cause?
- A delta wave on EKG
- Upsloping at the beginning of the QRS complex
What does the delta wave create on the EKG?
- Shortened PR interval
- Lengthened QRS complex
What are the identifying EKG characteristics of WPW Syndrome?
- Shortened PR interval (<0.12)
- P wave is sinus
- Wide QRS complex (>0.11)
- Presence of a delta wave
People with WPW syndrome are predispose to what?
- Paroxysmal Tachycardia
What are the mechanisms that WPW can cause paroxysmal tachycardia?
- Rapid conduction
*Supraventricular tachycardia - Kent bundles that contain automaticity foci can initiate an paroxysmal tachycardia
- Re-entry
What is Lown-Ganong-Levine (LGL) syndrome?
- James bundle (which is an extension of the anterior internodal tract)
*There will be conduction of the atrial depolarizations directly to the Bundle of His without delay
What are some characteristics of LGL syndrome?
- No significant PR interval delay
- P waves are adjacent to the QRS complex
What does axis refer to?
- The direction of depolarization as it passes through the heart
What is vector?
- The direction in which depolarization is moving
*the average direction of all of the positive charges as they travel through the myocardium
What is the direction of the mean vector called?
The mean electrical axis
Where is the average vector?
- Towards the left
*since the left ventricles is thicker, its vectors are bigger
What is the normal mean electrical axis?
- Between 0 to 90 degrees
How does axis and hypertrophy relate to each other?
- The larger ventricle would alter the axis
What is the normal deflection in lead aVR?
Downward
What is the normal deflection in lead aVL?
Upward
What is the normal deflection in lead aVF?
Upward
What is the angle of orientation of lead I
- 0 degrees
*Lead or is right arm (-) to left arm (+)
What is the angle of orientation of lead II?
- +60 degrees
*Right arm (-) to left leg (+)
What is the angle of orientation of lead III?
- +120 degrees
*Left arm (-) to left leg (+)
What is the angle of orientation of aVR?
- -150 degrees
*Right arm (+) and other limbs (-)
What is the angle of orientation of aVL?
- -30 degrees
*Left arm (+) and other limbs (-)
What is the angle of orientation of aVF?
- +90 degrees
*Left leg (+) and other limbs (-)
What are the anterior leads?
- V1 and V2
*Over right ventricle - V3 and V4
*over interventricular septum