EKG lecture 3 pt 1 Flashcards
List the 9 steps of EKG analysis
Heart Rate
Intervals – PR, QT, QRS duration
Axis
Rhythm – 4 questions
Conduction blocks
Preexcitation
Enlargement and hypertrophy
CAD
Other
List the 4 questions about rhythm
Are normal P waves present?
Are QRS complex narrow or wide?
What is the Relationship of P waves & QRS complexes?
Is the rhythm regular or irregular?
List 2 kinds of conduction blocks
AV blocks
BBB or hemiblocks
Define hypertrophy & what usually causes it
Increase in muscle mass
Usually due to pressure overload (afterload)
Define enlargement and what it’s usually due to
Dilation of chamber
Usually due to volume overload (preload)
1) What is defined as an increase in muscle mass?
2) What are 2 common causes of LVH?
1) Hypertrophy?
2) HTN + AS
(LVH = left ventricular hypertrophy)
1) What is defined as dilation of a chamber?
2) What are 2 causes of this?
1) Enlargement
2) AR =LVE
Mr = LAE
1) __________ regurgitation causes left ventricular enlargement
2) ___________ regurgitation causes left atrial enlargement
1) Aortic
2) Mitral
True or false: enlargement and hypertrophy freq. occur together, and can be pathologic or compensatory
True
What are 2 characteristics of hypertrophied muscle?
Required increased metabolic needs – oxygen to fuel the bigger muscle mass
Decreased capillary density - at risk for ischemia in pathologic hypertrophy
True or false: EKG poor @ distinguishing between hypertrophy and enlargement (TTE is much better)
True
What do enlargement and hypertrophy often refer to?
Often refer to “Atrial Enlargement” and “Ventricular Hypertrophy”
1) What can you use the P wave to evaluate?
2) What abt the QRS complex?
1) Atrial enlargement
2) Ventricular hypertrophy
True or false: EKG changes cannot occur with hypertrophy or enlargement
False; EKG changes may occur with hypertrophy or enlargement
What 3 EKG changes may occur with hypertrophy or enlargement?
- Increased duration of wave
- Increased amplitude of wave
- Shift in average electrical vector called mean electrical axis or just AXIS
-P wave, QRS, T wave
What does the mean electrical axis show?
Ventricular depolarization
Define average vector
Mean Vector
Each successive vector during depolarization: Septal depolarization starts and each ensuing vector swings ___________
leftward
1) Give a quick estimate of the axis +90 to 0 degrees
2) Give a quick estimate of the axis +90 to -30 degrees
1) Lead I and aVF QRS is positive = normal axis
2) If lead aVF QRS negative, & leads I & II positive = normal axis
How do you define the axis more precisely?
Look for the lead with biphasic QRS; axis must be perpendicular to this lead
What would aVF and lead 1 show in right axis deviation?
Negative in lead 1, positive in aVF
What does it tell you if lead 1 is positive?
Axis is toward the right (lower left on circle)
What direction is extreme right axis deviation?
Arrow pointing up and left
What does it tell you if lead I and lead aVF are both negative?
Extreme right axis deviation
Elderly patient with dyspnea and BP 190/115; what eventually happens to the heart?
??? didn’t hear him
slide 22
Increase afterload = Increased work of LV
Leads to Left Ventricular Hypertrophy (LVH)
Left axis deviation (LAD) on EKG – what would this look like on EKG? CXR?
Right axis deviation (RAD):
1) What does it result from?
2) How common is it?
3) What results from this?
1) Results from right ventricular hypertrophy (RVH) to extent that it dominates the LV (rare)
2) Less common than LVH
3) Massive change to overcome LV affect on axis
Normal P wave:
1) What is normal duration?
2) What is normal amplitude?
3) What does the first part of the P wave show?
4) What does the second part show?
1) Duration: < 0.12 sec duration (3 small boxes)
2) Amplitude: should not exceed 2.5 mm (.25 mV)
3) Right atrial depole
4) Left atrial depole
