Interval - QT

Question 1

What, electrically, does the QT interval represent?

Answer 1

Ventricular depolarization (QRS complex) to ventricular depolarization (end of T-wave).

Question 2

What, mechanically, does the QT interval represent?

Answer 2

Isovolumetric contraction of the ventricle to isovolumetric relaxation.

Question 3

The QT interval is (proportional/inversely proportional) to heart rate.

Answer 3

inversely proportional

Question 4

An abnormally prolonged QT is associated with an increased risk of ventricular arrhythmias, especially _______.

Answer 4

Torsades.

Question 5

Congenital short QT syndrome has been found to be associated with an increased risk _____, _____, and _____.

Answer 5

paroxysmal atrial tachycardia, v-fib, sudden cardiac death.

Question 6

In what leads should the QT interval be measured?

Answer 6

Lead II or V5-V6 (this closely approximate the actual axis of the heart).

Question 7

The corrected QT interval (QTc) estimates what the QT would be at what heart rate?

Answer 7

60 BPM

Question 8

The QTc allows comparison of the QT interval over different____, allow comparison of QT over time.

Answer 8

heart rates

Question 9

QTc is prolonged if > _____ ms in men or > ____ ms in women

Answer 9

440; 460

Question 10

QTc > ______ is associated with increased risk of torsades de pointes

Answer 10

500