chapter 24- pharm of cardiac contractility Flashcards
what is the mechanism of action of digoxin and digitoxin in the myocardium
inhibit plasma membrane Na+/K+ ATPase, leading to increased cytoplasmic Ca++ concentration, which results in positive inotropy
what is the mechanism of action of digoxin and digitoxin in ANS
inhibit sympathetic outflow and increase parasympathetic (vagal) tone
what is the mechanism of action of digoxin and digitoxin at AV node
prolong effective refractory period and slow conductive velocity
what drug is used to as symptomatic treatment of chronic systolic heart failure
digoxin
what are the serious heart side effects with digoxin/digitoxin
arrhythmias (PVCs), heart blocks
what are the major vision change side effects with digoxin
blurred vision, yellow-green halo around visual images
what are the contraindications of digoxin/digitoxin
ventricular fibrillation; ventricular tachycardia
what is the major thing that alters digoxin levels
chronic kidney disease
when is digitoxin used over digoxin
when there is renal failure
who should digoxin immune fab be used with caution in
patients allergic to ovine proteins
what is given to treat digoxin toxicity
digoxin immune Fab
what is digoxin derived from
fox glove plant
what are some side effects with dopamine use
widening of QRS complex, cardiac arrhythmias, hypo/hypertension
what are the contraindications for dopamine use
pheochromocytoma, uncorrected tachyarrhythmias, ventricular fibrillation
what receptors do lose doses of dopamine stimulate
dopaminergic D1 receptors in renal and mesenteric vascular beds
what do intermediate doses of dopamine stimulate
Beta2 receptors and increased contractility and heart rate via activation of beta1 receptors
what do high doses of dopamine stimulate
cause generalized vasoconstriction via stimulation of alpha1- receptors
what drug is used for short-term treatment of cardiac decompensation secondary to depressed contractility (cardiogenic shock)
dobutamine
what is the contraindication of dobutamine
idiopathic hypertrophic sub aortic stenosis
what can high doses of epinephrine cause
tachycardia and life-threatening ventricular arrhythmias
what beta adrenergic agonist can be used for cardiac resuscitation
epinephrine
what IV drug can be used for emergency treatment of arrhythmias
isoproterenol
what are the contraindications of isoproterenol use
tachycardia caused by digitalis intoxication; angina pectoris; active coronary artery disease
what does milrinon inhibit
phosphodiesterase
what drug used in co-administration with milrinone cause hypotension
disopyramide
what is long-term use of PDE inhibitors linked to
increased mortality
what is the mechanism of action of levosimendan
enhances sensitivity of troponin C to calcium, which increases the extent of actin-myosin interactions without a substantial increase in myocardial oxygen consumption
what does the EKG look like with side effect of digoxin
scooped concave ST segments
what are side effects of digoxin immune fab
heart failure, anaphylaxis
what is heart failure most commonly caused by
systolic dysfunction of the LV
what are cardiac glycosides
positive ionotropes= agents that increase contractile force of cardiac myocytes
what is the definition of preload
intraventricular blood volume
