Cardiovascular ppts Flashcards
Primarily Arterial Relaxation
Hydralazine
Greater effect on Venous Relaxation
Nitroglycerin
Venous & Arterial Relaxation
Sodium Nitroprusside
MOA of:
Sodium Nitroprusside
Nitroglycerin
Hydralazine
MOA of all 3 agents is believed to be primarily an induced increase in the concentration of vascular nitric oxide (not confirmed with hydralazine)
Sodium Nitroprusside:
Onset?
Duration?
Onset within seconds
Duration 1-3 minutes (3-5 minutes and 1-10 minutes)
How does Sodium Nitroprusside effect: Preload Afterload Cardiac filling pressures Stroke volume Cardiac output
Decreases preload afterload and filling pressures
Increases cardiac output and stroke volume
Using Nitroprusside contributes to a decreased in myocardial O2 consumption by?
Left ventricle volumes are decreased and diminished myocardial wall tension should contribute to a decrease in myocardial oxygen consumption
What is the starting dose of Sodium Nitroprusside
0.3 mcg/kg/min an titrated until a response occurs
Infusion rates of __________ is rarely exceeded when using Sodium Nitroprusside
3 mcg/kg/min
A top infusion rate of 3 mcg/kg/min is rarely exceeded when using Sodium Nitroprusside. However young, normotensive patients may require up to __________
5 mcg/kg/min
Maximum recommended infusion rate of Sodium Nitroprusside is
10 mcg/kg/min
How is Sodium Nitroprusside Reconstituted?
Reconstitute 50 mg by adding 2—3 ml of D5W injection. Further dilute in 250, 500, or 1000 ml of D5W injection to provide concentrations of 200, 100, or 50 mcg/ml, respectively.
The solution should be discarded after 24 hours.
The chemical structure of sodium nitroprusside contains how many cyanide ions? When are they released?
contains five cyanide ions, which are released upon metabolism by plasma hemoglobin
One cyanide ion binds with _________ to form cyanmethemoglobin
methemoglobin
One cyanide ion binds with methemoglobin to form cyanmethemoglobin, whereas the other 4 cyanide ions undergo rhodanese-catalyzed conversion to __________ in the __________
thiocyanate
Liver
One cyanide ion binds with methemoglobin to form cyanmethemoglobin, whereas the other 4 cyanide ions undergo rhodanese-catalyzed conversion to thiocyanate in the liver, with the thiocyanate undergoing ___________elimination
renal
One cyanide ion binds with methemoglobin to form cyanmethemoglobin, whereas the other 4 cyanide ions undergo rhodanese-catalyzed conversion to thiocyanate in the liver, with the thiocyanate undergoing renal elimination. This conversion to thiocyanate requires the cofactor ______.
thiosulfate B12.
Cyanide toxicity results when ______________________
metabolic pathway is quantitatively overwhelmed
In general, when more than ____ of sodium nitroprusside is administered faster than __, cyanide is generated faster than the patient can eliminate it.
500 mcg/kg
2 mcg/kg/min
What are the signs/symptoms of cyanide toxicity with sodium nitroprusside?
Clinically, the development of metabolic acidosis, increased mixed venous oxygen content, tachycardia, and tachyphylaxis during sodium nitroprusside use are signs of cyanide toxicity
What are the treatments of cyanide toxicity
Stop the sodium nitroprusside
Administer oxygen
Treat metabolic acidosis
Sodium nitrite 3% at 4-6 mg/kg over 3-5 minutes to promote production of methemoglobin to bind excess cyanide ions.
Sodium thiosulfate at 150-200 mg/kg over 14 min can be administered over 15 minutes and administered every 1 hours as needed.
Vitamin B12
Hydroxocobalamin can be effective (man made B12)
Methylene blue at 1-2 mg/kg may be useful
A new prodrug sulfanegen sodium is being tested.
Nitroglycerin has a rapid onset and short duration so it is easily titratable. Nitroglycerin causes a ______ dilation, with an _____ increase in venous capacitance and a resultant ___________ in preload
Nitroglycerin causes a venous dilation, with an increase in venous capacitance and a resultant decrease in preload.
Effects of nitroglycerin on preload, venous capacitance, cardiac filling pressures, myocardial wall tension and myocardial oxygen requirements
Nitroglycerin causes a venous dilation, with an increase in venous capacitance and a resultant decrease in preload. This results in lowering cardiac filling pressures, a lessening of myocardial wall tension and ultimately a decrease in myocardial oxygen requirements
Nitroglycerin’s primary mechanism of action in the relief of angina is a ______ in preload and cardiac work.
decrease
Using nitroglycerin can cause some of the larger coronary vessels to become dilated with a resultant ________ and _______ in blood flow to ischemic myocardium.
redirection
increase
At higher concentrations of nitroglycerin, ________ dilation also can occur
Arterial vasodilation
IV Nitroglycerin has an onset and duration of action of:
Onset 1-2 minutes
Duration 10 minutes
Nitroglycerin is extensively metabolized in the _______ and has a half life of _______
liver
3 minutes
IV nitroglycerin is used for “unloading” of the heart in CHF and MI. Guidelines suggest that IV infusions should be instituted following 3 sublingual doses of 0.4 mg every 5 minutes in patients having an ________
ST-segment elevation MI (STEMI).
Nitroglycerin infusions are usually started at _____ and titrated to effectiveness
10-20 mcg/min
Nitrates should be avoided in patient with:
BP of
HR of
Type of infarction
BP of < 90 mmHg
HR of < 50 or >100
Type of infarction of: Right ventricle
Nitroglycerin has the ability to relax the smooth muscle of the biliary tract and provide relief from _______ induced biliary spasm
narcotic
Generally nitroglycerin is mixed how?
Generally , 50 mg of nitroglycerin is mixed with 250 ml of D5W.
Epi is used to treat
Anaphylaxis
Cardiopulmonary resuscitation
Treatment of shock with poor tissue O2 delivery and hypotension are combined (this is b/c of its alpha and beta effects)
May be useful as a sympathomimetic agent in patients unresponsive to indirect-acting agents and in those in whom simultaneous Beta 1 (cardiac stimulation) and Beta 2 receptor stimulation (vasodilation).
Dominance of alpha or beta effects is dose related
Beta-1 produces:
+ inotropic (force of contraction)
+ chronotropic (heart rate)
+ dromotropic (conduction velocity)
EPi Beta 2 stimulation results in?
Bronchodilation
Vasodilation
Stabilization of mast cells (resulting in decreasing histamine release)
Concurrent alpha stimulation promotes a decrease in bronchial secretion. Net effects are a decrease in airway resistance with an improvement in oxygenation
Dose dependent effects of Epinephrine
Low Doses 10 mcg/min: The peripheral vasculature promotes the redistribution of blood flow to skeletal muscle, thus producing a decrease in SVR
As doses increase, alpha effects predominates resulting in vasoconstriction and increase in SVR: SBP increases, DBP remains relatively unchanged, Pulse Pressure increases
Beta stimulation leads to activation of the renin-angiotensin system and also: to an increase in:
lipolysis Glycogenolysis Gluconeogenesis Ketone production Lactate release by skeletal muscle Insulin secretion is inhibited by an overriding Beta 2 stimulation
Epinephrine induced Beta 2 stimulation also can cause a transient hyperkalemia as potassium follows glucose out of the hepatic cells
This is followed by a longer hypokalemia as Beta 2 stimulation then forces potassium (that is extracellular) into red blood cells
Hydralazine elimination half-life
~ 1 hour
Hydralazine metabolism
Hepatic metabolism with renal excretion
Acetylation is partly responsible for the metabolism of hydralazine as well.
Slow acetylators may be more prone to a drug induced lupus syndrome that can result from high serum concentrations during chronic treatment.
Calcium Channel Blockers Proven to be useful in treatment of?
Angina HPTN arrhythmias Peripheral vascular disease Esophageal spasm Cerebral vasospasm Controlled hypotension
All CCB have negative ________and _____ actions
inotropic and chronotopic
CCB are class _______ that block calcium channels, therefore depressing electrical impulses in the SA and AV nodes
4 antiarrhythmics
Depolarization of the SA and AV nodes is dependent on?
the inward flux of calcium during the depolarization phases of the cardiac action potential
Diltiazem is effective with
Atrial Tachycardia (Verapamil is effective too)
WPW
Controlling Ventricle responses to A-Fib/Flutter
