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41 Cards in this Set

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action potential
change in electrical activity across the plasma membrane of a muscle or nerve cell

caused by changes in membrane permeability (stimulus)
atrioventricular bundle
specialized cardiac tissue that receives electrical impulses from the AV node and sends them to the bundle branches (Bundle of His)

AV Node -> AV Bundle -> Bundle of His
atrioventricular (AV) node
mass of cardiac tissue that receives electrical impulses from the SA node and conveys them to the ventricles

SA Node -> AV Node -> Ventricles
automaticity
ability to spontaneously generate an electrical impulse (a.k.a. action potential)
bradycardia
slow heartbeat (<60 bpm)
bundle branches
electrical conduction path in heart

leads from AV bundle down through the wall between the ventricles
calcium ion channel
pathway in a plasma membrane through which calcium ions enter and leave
cardioversion / defibrillation
conversion of fibrillation to a normal heart rhythm
catheter ablation
destruction of abnormal myocardial cells

restores normal cardiac rhythm
depolarization
plasma membrane charge is changed - inside is made less negative

loss of membrane potential
dysrhythmia
abnormal cardiac rhythm
ectopic foci / pacemakers
cardiac tissue (outside the normal cardiac conduction pathway) that generates action potentials
electrocardiogram (ECG)
device that records the electrical activity of the heart
fibrillation
dysrhythmia

complete disorganization of heart rhythm
flutter
dysrhythmia - contractions become extremely rapid & uncoordinated

ventricular flutter requires immediate treatment
implantable cardioverter defibrillator
device placed in the patient to detect and correct dysrhythmias as they occur

able to store information for future evaluation
polarized
inside of a cell is more negatively charged than the outside
potassium ion channel
pathway in a plasma membrane through which potassium ions enter and leave
Purkinje fibers
electrical conduction path going from the bundle branches to all portions of the ventricles
refractory period
period during which the myocardial cells rest and are not able to contract
sinoatrial (SA) node
pacemaker of the heart - located in the wall of the right atrium
sinus rhythm
number of beats per minute normally generated by the SA node

normal sinus rhythm = approx. 75 bpm
sodium ion channel
path in plasma membrane through which sodium ions enter and leave
supraventricular
located above the ventricles -or- in the atria

can refer to dysrhythmias
tachycardia
fast heartbeat (>100 bpm)
antidysrhythmic categories
* Class I - Sodium channel blockers

* Class II - beta-adrenergic blockers

* Class III - potassium channel blockers

* Class IV - calcium channel blockers

* miscellaneous antidysrhythmic drugs
A client with heart failure is prescribed digoxin (Lanoxin) 0.3 mg. It is available as digoxin 500 mcg/2 ml. How many ml's will the nurse administer?
a. 1 ml
b. 1.1 ml
c. 1.2 ml
d. 1.3 ml
c. 1.2 ml
The physician orders enalapril (Vasotec) 15 mg. It is available as 10 mg/ 5 ml. How many ml's will the nurse administer?
a. 6 ml
b. 6.5 ml
c. 7.5 ml
d. 8 ml
c. 7.5 ml
T.N., age 64, receives hydralazine (Apresoline) 50 mg. It is available as hydralazine 25 mg/ tablet. How many tablets are needed to administer this dose?
a. 2 tabs
b. 3 tabs
c. 4 tabs
d. 5 tabs
a. 2 tabs
Atrial dysrhythmias occur more commonly in men than women.

True or False
TRUE

p231
An action 1_____ begins when sodium ion channels located in the 2_____ membrane open and Na+ rushes into the cell producing a rapid 3_____, or loss of membrane potential. During this period, Ca++ also enters the cell through 4_____ ion channels, although the influx is 5_____ than that of sodium. It is this influx of Ca++ that is responsible for the 6_____ of cardiac muscle.
1 potential
2 plasma
3 depolarization
4 calcium
5 slower
6 contraction
Blocking potassium, sodium, or calcium ion channels is a pharmacological strategy used to terminate or prevent dysrhythmias.

True or False
TRUE

p235
During 1_____ and most of 2_____, the cell can't initiate another action 3_____. This 4_____ period allows the action potential to finish and the 5_____ cell to contract before a second action potential begins. Some antidysrhythmic agents work by causing 6_____ of the refractory period.
1 depolarization
2 repolarization
3 potential
4 refractory
5 muscle
6 prolongation
quinidine sulfate
AKA: Quinidex
CLASS: sodium channel blocker (class I)
ACTION: blocks sodium ion channels in myocardial cells - reduces automaticity - slows conduction of electrical impuls through myocardium - can correct variety of atrial & ventricular dysrhythmias
A/E: nausea - vomiting - diarrhea - serious interaction can occur w/digoxin
sodium channel blocker
propranolol
AKA: Inderal
CLASS: beta-adrenergic blocker (class II)
ACTION: reduces heart rate - slows conductive velocity - lowers blood pressure - non-specific beta-blocker
A/E: hypotension - bradycardia - diminished sex drive - impotence
beta-adrenergic blocker
amiodarone
AKA: Cardarone
CLASS: potassium channel blockers (class III)
ACTION: blocks inactivated Na+ channels, K+ channels, and interferes w/myocardial cell-to-cell coupling - half-life up to 100+ days
A/E: pneumonia-like syndrome - blurred vision - rashes - nausea - vomiting - fatigue - dizziness - hypotension - increases digoxin levels - enhances action of anticoagulants
potassium channel blocker
verapamil
AKA: Calan - Isoptin - Verelan
CLASS: calcium channel blocker (class IV)
ACTION: inhibits flow of Ca++ into myocardial cells & vascular smooth muscle - slows conduction velocity & stabilizes dysrhythmias in heart - lowers BP - dilates coronary arteries
A/E: headache - constipation - hypotension - bradycardia - increases digoxin levels
calcium channel blocker
After the action potential has passed and the myocardial cell is in a depolarized state, repolarization depends upon removal of _____ from the cell.
sodium
A blockade of sodium channels in myocardial cells will:
a. slow the spread of impulse conduction
b. increase the spread of impulse conduction
c. stop the spread of impulse conduction
d. worsen a dysrhythmia
a. slow the spread of impulse conduction
Lidocaine is given 1_____ to terminate 2____ dysrhythmias.
1 intravenously
2 ventricular
The way beta-adrenergic blockers prevent dysrhythmias is to:
a. speed up impulse conduction across the myocardium
b. slow impulse conduction across the myocardium
c. block calcium channels
d. block sodium channels
b. slow impulse conduction across the myocardium