Cardio9

Question 1

What does the P wave represent?

Answer 1

Atrial Depolarization

Question 2

What does the PR interval represent?

Answer 2

Conduction delay through AV node

*normally <200 msec

Question 3

What does the QRS complex represent?

Answer 3

Ventricular depolarization

*normally <120 msec

Question 4

What does the QT interval represent?

Answer 4

Mechanical contraction of the ventricles

Question 5

What does the ST segment represent?

Answer 5

Ventricles depolarized; Isoelectric

Question 6

What does a U wave represent?

Answer 6

Hypokalemia, Bradycardia

Question 7

Atrial repolarization is masked by what?

Answer 7

QRS complex

Question 8

Describe the speed of conduction through the electrical tissue of the heart.

Answer 8

Purkinje > Atria > Ventricles > AV node

Question 9

Describe the conduction pathway.

Answer 9

SA node
  Atria
    AV node
      Common bundle
        Bundle branches
          Purkinje fibers
            Ventricles

Question 10

What is the hearts inherent “pacemaker”?

Answer 10

SA node

*due to its slow phase of upstroke

Question 11

The AV node has a 100 msec delay (atrioventricular delay) that allows for what?

Answer 11

Ventricular filling

Question 12

What is the relative conduction of the intrinsic “pacemakers”?

Answer 12

SA > AV > bundle of His/Purkinje/Ventricles

Question 13

What is torsades de pointes?

Answer 13

Ventricular tachycardia
Shifting sinusoidal waveforms on ECG
Can progress to Ventricular Fibrillation

Question 14

What conditions predispose to torsades de pointes?

Answer 14

Anything that prolongs the QT interval

Question 15

What is the treatment for torsades de pointes?

Answer 15

Magnesium sulfate

Question 16

Congenital long QT syndromes are most often due to what?

Answer 16

Defects in cardiac sodium or potassium channels

Question 17

Jervell and Lange-Nielsen syndrome.

Answer 17

Congenital long QT syndrome

Presents w/ severe congenital sensorineural deafness