Cardiac and Renal Flashcards
1
Q
Fast response fibers
cardiac muscle and purkinje
A
phase 0: depolarization (fast Na) phase 1: overshoot phase 2: plateau (slow Ca) phase 3: repolarization (delayed K) phase 4: resting potential (-90mV)
2
Q
Slow response fibers
SA and AV node, specialized cells
A
resting potential -70mV
slow Ca for depolarization
delayed K for repolarization
pacemaker current (Na, K, Ca)
3
Q
Na channels
A
- resting (-90mV): M gate closed, H gate open
- open, active (phase 0): M gate open, H gate slowly closing
- inactive, refractory: H gate closed, M gate open still
- M gate closes at -50mV and H gate reopens at -85mV
4
Q
Class IA
- MOA
- drugs
A
- decreases slope of phase 0–>increase ADP and ERP (antiarrhythmic)
- quinidine, procainamide
5
Q
Quinidine
A
- class IA Na ch blocker
- also has anti-muscarinic effects
- needs initial digitalization (give digoxin)
- AE: cinchonism (GI, tinnitus, occular dysfunction, CNS excite), hypoTN, prolonged QRS, increased QT, torsades
- drug interaction: hyperkalemia–>more effect, displace digoxin–>enhanced toxicity
- use: a fib
6
Q
Procainamide
A
- class IA Na ch blocker
- less muscarinic than quinidine
- genotypic variation
- AE: SLE-like syndrome, hematotoxic, CV effects (torsades)
7
Q
Class IB
- MOA
- drugs
A
- block fast Na ch (antiarrhythmic)
- block inactivated ch (prefer hypoxic tissue)
- decrease ADP–>increased diastole
- lidocaine, mexiletine, tocainamide
8
Q
Lidocaine
Mexiletine
A
- class IB Na ch block
- use: post-MI, digoxin toxicity, open heart surgery
- SE: seizures, least cardiotoxic
- must give IV (first pass)
- mexiletine is the oral version
9
Q
Class IC
- MOA
- drugs
A
- blocks fast Na ch
- no effect on ADP, no ANS effect
- flecainide: limited use due to proarrhythmic effect
10
Q
Class II
A
- beta blockers
- decrease SA and AV nodal activity
- propranolol, acebutolol, esmolol
- use: prophylaxis post-MI, SVT
11
Q
Class III
A
K ch blockers
- slow repolarization
- increase ADP and ERP (purkinje and ventricular)
- Amiodarone, sotalol
12
Q
Amiodarone
A
K ch blocker
- use: any arrhythmia
- t1/2 = >80 days
- extensive tissue binding
- SE: pulmonary fibrosis, blue smurf skin, phototoxic, corneal deposits, hepatic necrosis, thyroid dysfuction
13
Q
Sotalol
A
beta 1 selective and K ch blocker
- decreased HR and decreased AV conduction
- use: life threatening ventricular arrhythmia
14
Q
Class IV
A
Ca ch blockers
- block L type
- decrease SA and AV nodal activity
- verepamil and diltiazem
15
Q
verapamil and diltiazem
A
Ca ch blockers (cardioselective)
- use: SVT
- SE: constipation, dizzy, flush, hypoTN, AV block
- drug interaction: additive AV block with beta blockers and digoxin
- verapamil displaces digoxin
