Exam II: CV Drugs Inotropes Flashcards
Plant family from which many ___ ___are derived.
[Digitalis]
cardiac glycosides
Inotrope used for patients with ___ and to slow ventricular response of patients with ___(PAT, afib, aflutter).
[Digitalis]
congestive heart failure, supraventricular tachydysrhythmias
Digoxin decreases the risk of ___ due to heart failure, but increases the incidence of ___ ___(arrhythmias).
[Digitalis]
death, sudden death
Digoxin probably still plays a role in patients with ____ with evidence of congestion who are unable to tolerate ___ ___ of disease-modifying agents due to borderline blood pressure/renal function.
[Digitalis]
severe HF, high doses
Digoxin should be used with the aim of ___ ___ ___, while SDC and ___ and ___levels should be closely monitored to minimize the risk of toxicity.
[Digitalis]
reducing hospital readmissions, creatinine and potassium
In the treatment of SVT, ___ can be given in combination with a ___-___ at smaller doses of each and yet obtain more rapid control.
[Combination therapy]
digoxin, beta-antagonist
Contraindications:
Wolff-Parkinson-White – ___% develop ___ from increased ___ down the alternate path
[Combination therapy]
30, Vfib, conduction
Contraindications:
Hypertrophic cardiomyopathy (subaortic stenosis) –___
[Combination therapy]
increased obstruction with increased contractility
Contraindications:
Acute myocardial infarction – increase ___ ___ with increased ____
[Combination therapy]
oxygen demand, contractility
[Digoxin (Lanoxin) Therapy in Congestive Heart Failure]
Digoxin has been shown to improve ____ without any benefit on _____.
morbidity
mortality
[Digoxin (Lanoxin) Therapy in Congestive Heart Failure]
Digoxin may act by ____ sympathetic activity.
decreasing
[Digoxin (Lanoxin) Therapy in Congestive Heart Failure]
Digoxin may not be effective in patients who have normal ___ ___ ____ function.
left ventricular systolic
[Digoxin (Lanoxin) Therapy in Congestive Heart Failure]
The benefits of digoxin therapy are greatest in patients with ___ ___ ____, an enlarged heart and a ___ ___ ____ ____.
severe heart failure
3rd heart sound gallop
[Digoxin (Lanoxin) Therapy in Congestive Heart Failure]
Digoxin may be used in patients with mild to moderate heart failure if they do not respond to an ___-___ ___ ___ or a ___ ____.
angiotensin-converting enzyme inhibitor
beta blocker
[Digoxin (Lanoxin) Therapy in Congestive Heart Failure]
___ dosages of digoxin can be effective.
Low
[Digoxin (Lanoxin) Therapy in Congestive Heart Failure]
___ function and possible ___ ____ must be considered in deciding on an appropriate dosage of digoxin.
Renal
drug interactions
[Digoxin (Lanoxin) Therapy in Congestive Heart Failure]
In general, digoxin therapy should be _____ in the acute phase after myocardial infarction.
avoided
Digoxin MOA:
___ Effects
Inhibition of ______ ion transport system – causing increased Na inside the cell
Increased intracellular Na then affects the Na/Ca exchanger and ___ ____ is taken out of the cardiac cell.
More ___ inside the cell accounts for increased contraction force.
Direct
Na/K ATPase
less Ca++
Ca++
Decrease (less negative) resting membrane potential (automaticity)
Increases in the slope of phase 4 (automaticity)
Decrease in duration of action potential due to shortening of phase 2 (corresponds to vent contraction)
Decreased resting membrane potential (less negative) and increased automaticity are due to changes in the potassium gradient.
Phase 2 reflects closure of sodium ion channels and inward flux of calcium ions through specific slow calcium ion channels. Phase 2 corresponds to ventricular contraction.
Digoxin ANS activity -
Enhanced _____ activity
___ node activity decreased
Slowed conduction through the ___ node
PNS
SA
AV
(Enhanced PNS - activation of vagal nuclei and the nodose ganglion in the CNS. Results in slowed HR – especially with a fib)
Digoxin CV effects: Increased ____ ____, ____, decreased heart ____, ____, ______
myocardial contractility, SV
size, preload, LVED pressure
Digoxin CV: increased CO, ____ perfusion, and diuresis of newly ___ ____
renal
metabolized edema
Digoxin CV effects: Improved ____ perfusion, decreased _____ outflow, decreased ____ (____) leading to even better SV
tissue
sympathetic
SVR (afterload)
Digoxin CV: increased PNS activity, slowed HR - negative ____ and negative ____
chronotropic
dromotropic
Digoxin CV: In the normal heart, increased contractility is offset by decreases in ___ and direct _____ in the arterial smooth muscle. Cardiac output may remain unchanged or even ____.
HR
vasoconstriction
decrease
Digoxin CV: In the failing heart, no change in HR with positive inotropic effects - decreased p____, a____, wall tension, and oxygen c_____.
preload, afterload
consumption
Cardiac glycosides cause changes shown on the EKG:
Prolonged ___ – delay through the AV node
PR
Cardiac glycosides cause changes shown on the EKG:
Shortened QT – more rapid ____ ____
ventricular repolarization
Cardiac glycosides cause changes shown on the EKG:
___ segment depression – decreased slope of ___ ___
ST
phase 3
Cardiac glycosides cause changes shown on the EKG:
Smaller or inverted __ wave – decreased slope and duration of phases __ and __
T
2 and 3
Digoxin -
Dose:
Onset:
Route:
Clearance:
Elimination 1/2 life:
Dose: up to 10 mcg/kg over 30 minutes
Onset: 5 to 30 minutes
Route: IV
Clearance: 35% excreted daily via kidneys
Elimination ½ life: 31-33 hours
Dig - Prolonged with ___ failure to up to ___ days
renal
4.4 days
Dig - ___% bound to protein (skeletal muscle) – decreased muscle mass in ___
25%
elderly
Digitalis Toxicity: ____ therapeutic range 0.5 – 2.5 ng/ml
narrow
TC says we dont need to know this range
Digitalis Toxicity: Incidence: __% of patients on digoxin will have some form of toxicity
20%
Digitalis Toxicity: MOA - inhibition of ____ ion transport system; Ca accumulates in the cell causing ____.
Na/K ATPase
dysrhythmias
Digitalis Toxicity: Causes: most commonly ____ dysfunction; hypo____ (due to diuretic) increases myocardial ____ of drug (may also be due to hyperventilation); increased sympathetic activity related to hypo___; hyper____, hypo____, decreased muscle mass (elderly).
renal
hypokalemia
binding
hypoxemia; hypercalcemia, hypomagnesia
Digitalis Toxicity: Hyperventilation related to hypokalemia – for every __ mm Hg decrease in PaCO2, serum potassium decreases an average of __ mEq/L
On the other hand, increased serum potassium ___ ___ of cardiac glycosides to the ____ enzyme complex
10
0.5
inhibits binding
Na-K ATPase
Digitalis Toxicity: Symptoms
Arrhythmias – first symptom of arrhythmia is worsening of pre-existing CHF (8)
PVCs
junctional tachycardia
Wenckebach’s AV block
sinus bradycardia or arrest
atrial tachycardia – most common w dig toxicity
bidirectional Vtach – two different foci
Atrial flutter
Vfib – most frequent cause of death with dig toxicity