Review Questions

Question 1

How would the stroke volume be altered in a patient with aortic regurgitation?

Answer 1

In AR, blood leaks from the aorta back into the left ventricle during diastole
The volume at the end of diastole (EDV)
increases
This results in 1 stroke volume

Question 2

How would acute hemorrhagic shock alter stroke volume and cardiac output?

Answer 2

Hemorrhagic shock -> blood loss - decreased blood returning to heart -› decreased EDV
• decreased EDV - decreased SV
Although SV is decreased, HR is increased resulting in a constant CO

Question 3

What drugs prolong phase 3 of the cardiac myocyte action potential?

Answer 3

• Potassium channel blockers (Ibutilide, sotalol, amiodarone, and dofetilide)

Question 4

Which phase or phases of the pacemaker action potential is altered by adenosine?

Answer 4

• Adenosine decreases influx of calcium and increases the efflux of potassium
• This results in a decreased resting membrane potential -> increased phase 4 and phase 0

Question 5

What drugs block the L-type calcium channel?

Answer 5

Non-dihydropyridine calcium channel blockers (Diltiazem & Verapamil)

Question 6

How does SVT alter stroke volume

Answer 6

Increased EDV will cause increased SV

Question 7

Delta wave on EKG indicates?

Answer 7

• The QRS complex represents ventricular depolarization
• A delta wave indicates early depolarization of the ventricles

Question 8

Delta wave in which disease

Answer 8

Wolff parkinson white

Question 9

What ion channel is defective in a patient with QT prolongation?

Answer 9

• The QT interval represents depolarization and repolarization of the ventricles
• In QT prolongation, the T wave is particularly long — delayed ventricular repolarization
• Phase 3 of the action potential is responsible for repolarization (potassium channels)