cardiovascular 1 Flashcards by Linda Chao

Sympatholytics are mainly used as _________

medication which inhibits the postganglionic functioning of the sympathetic nervous system
mainly used as AntiHTN

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sympatholytics work on which receptors ?

alpha antagonist
beta antagonist
mixed alpha and beta antagonist
clonidine ( a2 agonist)

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What do nitrates do to vascular smooth muscle?

vasodilate

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This process is a part of normal endothelial function

NO (nitric oxide) release

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How does Sildenafil (Viagra) work?

increases local availability of endogenous NO, which in turn vasodilates surrounding tissues and increases blood flow to genitals.

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When is the best time to treat for cyanide toxicity?

EARLY if suspicious. Do not wait for lab results!

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What is an early sign of cyanide toxicity?

Acidosis due to inactivation of cytochrome oxidase

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What are the symptoms of cyanide toxicity?

Tachycardia, changed mental status, seizures, hypertension due to tachyphylaxis

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What happens when cytochrome oxidase is inactivated during cyanide toxicity?

Uncoupling of mitochondrial oxidative phosphorylation, inhibited cellular respiration
Anaerobic metabolism and lactate formation
Decreased affinity of oxygen to Hb.

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What can be used to treat acidosis associated with cyanide toxicity?

NaHCO3

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How is cyanide toxicity treated?

STOP nitroprusside
Cyanide buffers (sodium nitrate IV or amyl nitrate inhaled) followed with sodium thiosulfate IV
Vitamin B12a

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What are examples of cyanide buffers?

Sodium nitrate IV or Amyl nitrate inhaled

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How do cyanide buffers work?

They convert ~10% of Hb to met-Hb, which sequesters the cyanide.

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What is an indicator that there is no further need for nitrate therapy for cyanide toxicity?

> 10% met-Hb

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How does sodium thiosulfate contribute to treatment for cyanide toxicity?

It activates the enzymatic cycle. Rhodanese enzyme converts CN to SCN- (thiocyanate) which is renally excreted.

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What is another name for Vit B12a?

Hydroxocobalamin

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How does vitamin B12a contribute to the treatment for cyanide toxicity?

Vit B12a chelates cyanide to form cyanocobalamin (Vit B12), which is renally excreted.

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Where do angiotensin converting enzyme inhibitors (ACEIs) work in the renin-angiotensin-aldosterone pathway?

The inhibit the conversion of angiotensin I to angiotensin II in the lungs.

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How do ACEIs differ from other anti-hypertensive agents in terms of side effects?

ACEIs are free from many common side effects such as depression, insomnia, sexual dysfunction, electrolyte imbalances.

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What is used for first-line therapy for systemic hypertension and CHF?

ACEIs. They may reverse LV hypertrophy and decrease plasma aldosterone to reduce Na and water retention.

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In what patient population do ACEIs improve outcomes?

Diabetics

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What are examples of ACEIs?

Enalapril (Vasotec)
Quinapril (Accupril)
Lisinopril (Zestril)
Ramipril (Altace)

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What are side effects of ACEIs?

cough, allergic-like symptoms (due to bradykinin accumulation?) possibly causing angioedema, possible hyperkalemia due to decreased aldosterone

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What happens when ACEIs are given to patients with renal dysfunction?

Decreased glomerular filtration.

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How are ACEIs excreted?

Renally

Should ACEIs be discontinued prior to surgery?

You should consider holding ACEIs for 24+ hours before surgery to avoid prolonged hypotension under GA.

If a patient is on ACEIs during general anesthesia, how do we treat any prolonged hypotension that may result?

Vasopressin if unresponsive to fluid bolus of sympathomimetics (Epi, NE, dopa)

Where do A2RBs (Angiotensin II Receptor Blockers) work in the Renin-Angiotensin-Aldosterone pathway?

Later in the pathway, at the Angiotensin II receptors within the body to inhibit the hypertensive effect of Angiotensin II.

What is an example of an A2RBs?

Losartan (Cozaar)

How are A2RBs metabolized?

Hepatic metabolism -- with active metabolites!

Do you want to discontinue A2RBs prior to major surgery?

Consider to prevent resulting prolonged hypotension during GA.

Which shows less incidence of cough: ACEIs or A2RBs?

A2RBs

What is a side effect of A2RBs?

Hyperkalemia, especially when used with K-sparing diuretics

what type of drug are Phentolamine, phenoxybenzamine and prazosin

alpha antagonist

what drugs are used for management of pheochromocytoma ?

phentolamine, phenoxybenzamine, prazosin blocks action of catecholamines

a2 receptor blockade will ______ NE release and ______heart rate

a2 receptor blockade will Enhance NE release and Increase HR

side effects of A2 receptor blockade are

reflex tachycardia, orthostatic hypotension, cholinomimetic side effects , unrecognized volume depletion

what are cholinomimetic side effects?

hyperperistalsis , abdominal pain, diarrhea

how do you treat cholinomimetic side effects?

atropine and glycopyrrolate

alpha antagonist may lead to hypotension because...

unopposed stimulation of beta receptors . | beta stimulation decreases diastolic pressure

what drug is a non selective Beta antagonist

propranolol

what are side effects of propranolol or non selective Beta antagonist

bronchospasm and CHF

what are the B1 selective antagonist

metoprolol , atenolol, esmolol

which drug (metoprolol, atenolol, esmolol) is the shortest acting

esmolol

what are side effects of Beta 1 Antagonist

bradycardia av heart block hypotension

why do you get HoTN from Beta Antagonist

due to decreased myocardial contractility / decreased HR / decreased renin release

Beta Antagonist is good for pt with coronary artery disease because

it decreases the reduced myocardial O2 demand

which drug is a mixed alpha and beta antagonist ?

labetalol ( a:b = 1:7 )

cardedilol is a _______________ antagonist and a1______

cardedilol is a non selective B antagonist and an A1 antagonist

what is the advantage of using Labetalol ?

no reflex tachycardia as with pure alpha antagonists, and less bradycardia than with pure beta antagonists a- activity decreases peripheral vascular resistance and decrease renin

what is the result of cardedilol?

drops BP

which drug is a a centrally-acting a2 agonist

Clonidine

clonidine is a centrally acting a2 ________

agonist

clonidine decreases CNS sympathetic output at __________ a2 receptor

pre-synaptic

nitric oxide release inhibits...

platelet aggregation, activation, and adhesion

NO is rapidly inactivated by?

hemoglobin

inhaled nitric oxide can be used as a

selective pulmonary vasodilator, bronchodilator, and can improve V/Q mismatch

inhaled nitric oxide can be used to treat:

pulmonary hypertension, persistent pulmonary HTN of newborn, adult respiratory distress syndrome/acute lung injury

nitric oxide combines with Hgb to make...

met-Hgb

Isosorbide Mononitrates (Imdur) is used in the prevention of

angina pectoris

Isosorbide Dinitrates (Isordil) is used in the prevention of _______ and the treatment of ______

angina pectoris; CHF

What are side effects of oral nitrates?

headache, orthostatic hypotension

Nitroglycerin is a long acting or short acting drug?

short acting

Nitroglycerin mainly causes

venous dilation

NO is released through what pathway?

glutathione-dependent

nitroglycerin causes cerebral vasodilation which in turn increases...

ICP and CBF, which can cause headaches

NTG is less potent than

SNP (sodium nitroprusside)

NTG can be used for

controlled hypotension, uterine relaxation

the risk of metHgb-emia is rare with the use of NTG because

of rapid hepatic metabolism

NTG can be given

sublingually, transmucosally, and transdermally, IV

What is the benefit of giving NTG sulingually or transmucosally

avoids 1st pass effect and goes right into the superior vena cava

dosing for sublingual NTG in treatment of angina pectoris

0.3 mg

dosing for NTG ointment for treatment of angine pectoris

NTG increases coronary perfusion to what layer of the heart?

ischemic subendocardium

IV dosing for NTG

10-100 mcg IV

infusion rate of NTG

0.5-2 mcg/kg/min

tolerance for nTG develops with how many hours of sustained treatment?

24 hours

SNP causes direct

arterial and venous vasodilation

What is Fe-(CN)5(NO)

SNP

SNP is used for

controlled hypotension, hypertensive emergencies, cardiac disease

SNP can cause

reflex tachycardia

Does SNP increase or decrease cerebral blood flow?

increase

SNP ___________ (increases or decreases) hypoxic pulmonary vasoconstriction

decreases (attenuates)

What is the concentration of SNP?

50 mg per 250 ml = 200 mcg/ml

What is the starting dose of SNP?

0.3-0.5 mcg/kg/min = ~10 mL/hr

What is the onset of SNP?

almost instant

What is the duration of SNP?

1-10 minutes

Titrate SNP up by what increment?

0.2-0.5mcg/kg/min

Common dose of SNP?

~3 mcg/kg/min

What is the max dose of SNP for less than 10 minutes?

10 mcg/kg/min

What is the max dose of SNP for long term purposes?

2 mcg/kg/min

Why dose SNP need to be wrapped in foil or black plastic?

it breaks down in light

continuous arterial BP monitoring is necessary for what drug?

SNP

what happens at 10 mcg/kg/min of SNP?

CN toxicity

in nitroprusside mtabolism, what percentage of Hgb is naturally met-Hgb?

CN + et-Hgb =

cyanmet-Hgb

the rhodanese enzyme converts CN to ________ in the liver/kidney

thiocyanate

what happens to the remaining CN that is not converted by the rhodanese enzyme?

causes toxicity

what should be a concern if you discontinue the use of clonidine?

rebound hypertension

how do you treat rebound hypertension cause by discontinuation of clonidine ?

treat with vasodilator

what are other use of clonidine?

analgesia, pre- anesthetic medication, regional anesthesia, treatment of opioid, withdrawal syndrome , post operative shivering

methyldopa ( he said he wont test over this)

a parkinson drug that treats HTN, especially in pregnancy induced HTN inhibits DOPA dedcarboxylase which converts dopa into dopamine > NE > epi thus low catocholaines >> lowers BP metabolize into a2 agonist ( similar to clonidine)

hydralazine directly cause ______________ relaxation

vascular smooth muscle ( arterioles > veins )

hydralazine has its largest effect in which part of the body

coronary , cerebral, renal, splanchnic circulation

hydralazine decrease _____ more than _____

hydralazine decreases DBP more than SBP

what is the dose of hydralazine

2.5-10 mg IV

effect of hydralazine starts in ______ minutes

10-20 min. not a fast acting drug

how is hydralazine metabolized and excreted ?

liver metabolism and renal excretion

what is an side effect of hydralazine ?

reflex tachycardia

what is an oral medication with action like hydralazine?

minoxidil

when do you use minoxidil?

used for the most severe forms of hypertension

what are the effects of minoxidil?

fluid retention, edema, pericardial effusion

what is hypertricchosis

hair growth

minoxidil is also known as

rogaine