ECG Abnormalities

Question 1

Paroxysmal supraventricular trachycardia (PSVT):

Answer 1

(Paroxysmal atrial tachycardia) - PSVT

-QRS normal, but frequent, P and T wave may be superimposed because of high heart rate

Question 2

What clinical symptoms are associated with PSVT?

Answer 2

Low bp, dizziness

Question 3

Sinus Node Dysfunction/Arrest:

Answer 3

SA node stops firing (can be for fraction of second (slight lengthening bw P and T wave) or full seconds of delay

Question 4

What is a conduction/heart block?

Answer 4

Delay or complete block of the electrical impulse as it travels from the sinus node to the ventricles.

• Level of block or delay may occur in AV node or HIS-Purkinje system
• Heart beat may be irregular

Question 5

First degree block:

Answer 5

Slow conduction

• Abnormally long PR interval (>.2 sec)
• ECG otherwise normal

Question 6

Second degree block:

Answer 6

Some atrial impulses transmit through AV node, not all do, due to slower than normal conduction
-Some but not all P waves are associated with a QRS & T wave

Question 7

Third degree block:

Answer 7

No impulses transmitted through AV node - Atrial and ventricular rates independent

• P waves and QRS are totally dissociated in ECG
• Ventricular rate likely slower than normal because of alternate pacemaker –> often slow enough to impair cardiac output

Question 8

Premature atrial contractions (PACs):

Answer 8

Early extra beats that originate in the atria.

• Normal complex w/o typical delay. It comes too early and butts up on the previous T wave
• Bc it came early, there is also a longer space before the next wave; all else is normal

Question 9

Accessory Pathway Tachycardias:

Answer 9

• Rapid heart rhythm due to an extra abnormal pathway or connection between the atria and the ventricles
• Impulses travel through the extra pathways (short cuts) as well as normal AV-HIS Purkinje system
• Shortcuts allow the impulses to travel around the heart very quickly, causing the heart to beat unusually fast
• -Characteristic DELTA WAVE - slurred upstroke of QRS complex

Question 10

AV Nodal Re-entrant Tachycardia (AVNRT):

Answer 10

Rapid HR due to more than one pathway through the AV node

Question 11

Atrial tachycardia

Answer 11

Rapid heart rate originating in the atria

Question 12

Atrial fibrillation

Answer 12

Very common irregular heart rhythm

• Many impulses begin and spread thru the atria, competing for a chance to enter the AV node
• Resulting rhythm is disorganized, rapid, irregular.
• No P waves appear on ECG
• Ventricular rate irregular (irregular time between R waves)

Question 13

Atrial flutter:

Answer 13

Atrial arrhythmia caused by one or more rapid circuits in the atrium.

• Usually more organized and regular than atrial fibrillation
• “Sawtooth” pattern- looks like blade

Question 14

What do atrial contractions play little role in?

Answer 14

Ventricular filling
-So atrial fibrillation may be well tolerated by most patients as long as ventricular rate is sufficient to maintain cardiac output

Question 15

Normal but frequent R waves:

Answer 15

Supraventricular tachycardia

Question 16

Normal but long PR interval:

Answer 16

First degree heart block

Question 17

Some independent P

Answer 17

Second degree heart block

Question 18

P, QRS not in sync

Answer 18

Third degree heart block

Question 19

No P, QRS irregular

Answer 19

Atrial fibrillation

Question 20

Bundle Branch Block

Answer 20

(aka hemiblocks)

• Often due to MI
• One part of purkinje system is blocks and doesn’t depolarize in sync with rest of ventricle
• Widening of QRS (>.12 sec)
• Splitting of R-wave (left and right ventricles depolarize separately)
• looks like “bunny ears” 0 forked R wave

Question 21

Premature ventricular contractions (PVCs):

Answer 21

• Extra beats, beginning in ventricles, feels like heart “skipped a beat”
• Common, tend to be asymptomatic and not need treatment
• Stress, caffeine, exercise
• Cells that normally have pacemaker functions spontaneously depolarize and bring their neighbors with them
• Ventricles depolarize early, followed by missing a beat
• Sometimes caused by heart disease or electrolyte imbalance
• Shapes are variable

Question 22

Ventricular Tachycardia (V-tach):

Answer 22

Rapid rhythm originating from lower chambers of heart.

• Rapid rate prevents heart from filling adequately – less blood pumped through body
• May have severe symptoms, especially in people with heart disease
• VERY SERIOUS CONDITION
• OFTEN prededes VENTRICULAR FIBRILLATION

Question 23

Long QT Syndrome

Answer 23

QT = time required for heart muscle to contract and then recover
-When QT is longer, it increases risk of Torsade de points, life threatening tachycardia
Normal: QT should be half or less of total time between R waves

Question 24

What can Torsades de pointes rapidly become?

Answer 24

Ventricular fibrillation

Question 25

Ventricular Fibrillation?

Answer 25

Erratic, disorganized firing of impulses from ventricles

• Ventricles quiver and can’t pump blood to body
• MEDICAL EMERGENCY - must be treated with cardiopulmonary resuscitation (CPR) & defibrillation ASAP
• ECG shows no discernible waves, rate, rhythm
• No pumping action occurring
• Fatal unless corrected quickly

Question 26

Widening of QRS:

Answer 26

Bundle branch block

Question 27

QRS wide, large amp, disrupting normal rhythm:

Answer 27

Premature ventricular contraction

Question 28

QRS wide, rapid rate - alternating waves:

Answer 28

Ventricular tachycardia

Question 29

Cyclic changes in QRS amplitude, wide QRS:

Answer 29

Long QT syndrome with torsades des pointes

Question 30

Nothing discernible:

Answer 30

Ventricular fibrillation