L13. Complications of Heart Failure

Question 1

cardiac arrhythmia causes:

Answer 1

• abnormal pacemaker activity
• impaired cardiac conduction

Question 2

cardiac arrhythmia tx:

Answer 2

1. surgery to introduce an electrical device such as a pacemaker (which can act as a defibrillator)
2. electrical ablation of abnormal pathways
3. drugs (last resort bc they have a very low therapeutic index and can provoke arrhythmias and heart failure)

Question 3

3 ways of slowing down pacemaker activity:

Answer 3

1. make the rmp more hyperpolarized: administer drugs that open K+ channels causing hyperpolarization –> slow the onset of next depolarization
2. delay diastolic depolarization: administer drugs that block some voltage gated sodium channels which delays the occurence of the next action potential
3. make a more positive threshold: administer drug that change the voltage sensitivity of ion channels to prolong the time until the next action potential occurs

Question 4

class I anti-arrhythmic drug

Answer 4

Na+ channel blocker Quinidine that will slow down intra-ventricular conduction by increasing QRS and QT interval

Question 5

class II anti-arrhythmic drug

Answer 5

Beta-blocker Propranolol that will slow down AV conduction and prolonging PR interval

Question 6

class III anti-arrhythmic drug

Answer 6

K+ channel blocker Sotalol that will prolong the ventricular action potential by prolonging PR interval

Question 7

class IV anti-arrhythmic drug

Answer 7

L-type Ca2+ channel blocker Verapamil that will slow down intra-ventricular conduction by increasing QRS and QT interval

Question 8

class V anti-arrhythmic drug

Answer 8

adenosine, Mg2+ and K+ ions