Hyperpolarization-Activated Cyclic Nucleotide Gated Channel Blockers (HCN blockers)

Question 1

HCN blockers action/indications

Answer 1

Blocking the HCNs slows the heart’s pacemaker, the sinus node, in the repolarizing phase of the action potential

Question 2

HCN blockers drug names

Answer 2

Ivabradine

Question 3

HCN blockers contraindications

Answer 3

Known allergy
Active, decompensated, HF; hypotension; sick sinus syndrome of AV block; resting heart rate under 60 beats/min; patients completely dependent on a pacemaker and severe hepatic impairment

Question 4

HCN blockers caution

Answer 4

Atrial fibrillation

moderate heart block

Question 5

HCN blockers drug-drug interactions

Answer 5

CYP3A4 inhibitors or inducers

Negative chronotropic drugs

Question 6

HCN blockers adverse effects

Answer 6

Bradycardia, hypertension, atrial fibrillation, and luminous phenomena (sudden changes in brightness in parts of the visual field, colored bright lights, image decompensation, multiple images)

Question 7

HCN blockers nursing implications

Answer 7

Hx & physical
contraindications/cautions
family allergies
condition that slow down the heart rate
if their HR is 60bpm DON'T GIVE MEDS
Cardiac status; ECG
Monitor input/output
Record daily weight
Fall risk, socks on
Signs & symptoms of heart failure
Vision disturbances - provide safety measurements
Teach to take own pulse
Adverse effects

Question 8

HCN blockers prototype

Answer 8

Ivabradine

Question 9

Ivabradine action

Answer 9

blocks HCNs to slwo the heart’s pacemaker and reduce heart rate with no effect on muscle contraction

Question 10

Ivabradine indications

Answer 10

Tx of chronic heart failure in stable patients at maximum beta-blocker doses, to prevent rehospitalizations

Question 11

Ivabradine adverse effects

Answer 11

Bradycardia, atrial fibrillation, hypertension, luminous phenomena (visual changes)