Cardiovascular Flashcards
What is the function of the late I-Na?
maintaining plateau of action potential
What ion antiporter can excessive inward flux of Na+ activate? What can this lead to?
Na+-Ca2+ Exchanger
after-depolarizations
When is enhanced late I-Na+ found?
CV pathologies
Regarding the ERP/APD, what do most anti-arrhythmics attempt to do?
prolong refractoriness
Where are EADs most easily brought about?
Purkinje cells
Are DADs more common during a fast heart rate or a slow heart rate?
fast
Overload of what ion causes a DAD?
calcium
What is the etiology of a re-entry circuit?
existence of conduction routes with different velocities
What is the most common cause of re-entry tachycardia?
AVNRT
Which has a higher rate, PSVT or Nodal Tachycardia?
PSVT
Which two arrhythmias are associated with thrombus formation?
atrial fibrillation
atrial flutter
What do class Ia drugs do to the height of Phase 2 of AP?
lower
What do class Ia anti-arrhythmics do to the length of the refractory period?
increase
What do class Ia anti-arrhythmics do to the slope of Phase O?
decrease the slope
What ion channel do class Ia anti-arrhythmics block to prolong the AP?
potassium channels
What channel do Class Ia anti-arrhythmics block at high doses?
calcium channels
Which two autonomic receptors can quinidine block?
muscarinic and alpha
What are the two uses of quinidine?
convert refractory Afib and Aflutter
What is the most common side effect of quindine?
nausea and vomiting
Can quinidine cause TdP? Why?
yes
blockade of potassium channels
What cytochrome enzyme degrades quinidine?
CYP 3A4
What drug inhibits CYP3A4 that can lead to the increased metabolism of quinidine?
cimetidine
What three drugs can inhibit the clearance of quinidine based on their ability to increase CYP3A4?
phenytoin, rifampicin, phenobarbital
Which cytochrome enzyme is quinidine a potent inhibitor of?
CYP2D6
What CV drugs toxicity is increased with co-administration of quinidine?
digoxin
Which has a higher likihood of causing TdP, quinidine or procainamide? Why?
quindine
procainamide doesnt block potassium channels as much
What are the two differences between quinidine and procainamide regarding their effects on autonomic nervous sytsem?
- little effect on M
2. no effect on alpha
In what three conditions would the use of procainamide be contraindicated?
hypokalemia
long QT
history of TdP
What are the two common side effects of procainamide?
nausea and vomiting
What systemic reaction can be caused by procainamide?
drug induced lupus
What do class Ib anti-arrhythmics do to the slope of Phase O?
decrease
What do class Ib anti-arrhythmics do to the slope of Phase O?
decrease
What do class Ib anti-arrhythmics do to the action potential duration?
Ib = shortened AP duration
Class Ib anti-arrhythmics are effective in the Tx of two pro-arrhythmic states?
digitalis and MI
What type of tissue is lidocaine most effective in?
ischemic
Why is lidocaine ineffective in atrial tissues?
AP of atrial muscle is too short
Why must lidocaine be used IV?
undergoes extensive first pass metabolism
What is the most notable MOA of Class Ic anti-arrhythmics?
potent fast Na+ channel inhibitors
What part of the action potential do Class Ic anti-arrhythmics most effect?
major decrease in Phase O upslope
Other than the effects on sodium channels, what else can propafenone do? WHy?
β-blockade
similarity in structure to propranalol
Which two patient characteristics must be met in order to begin treatment with propafanone?
no/minimal heart disease
preserved Ventricular function
Which class of anti-arrhythmics are proven to reduce sudden death due to sudden or previous MI?
class II
What three ion channels can amiodarone block?
Na+
K+
Ca2+
What two drugs does amiodarone have structural similarity to?
thyroxine and procainamide
What is the main endocrine side effect of amiodarone?
“cardiac hypothyroidism”
Which anti-arrhythmic is highly lipid soluble?
amiodarone
Which anti-arrhythmic has a very high Vd?
amiodarone
What is amiodarone commonly metabolized to?
desethyl amiodarone
Why can poor amiodarone administration result in reoccurence of arrhythmias?
diffuses out of myocardium easily if all tissues are not saturated
What is the most common side effect of amiodarone?
interstitial pneumonitis
What two endocrine side effects is amiodarone most notable for causing?
hypothyroidism or hyperthyroidism
Which anti-arrhythmic can cause photosensitivity?
amiodarone
Which anti-arrhythmic can increase hepatic enzyme levels?
amiodarone
What are the four subunits of L-type Ca2+ channels? Which subunit contains the pores for binding of Ca2+?
α1-α2-β-γ
α1
What two isoforms of calcium channel do CCBs block?
L-type and T-type
What is the main Dihydropyridine CCB?
Nifedipine
What are the non-Dihydropyridine CCBs?
verapamil
diltiazem
Do CCBs produce vasodilation more in the arterioles or veins?
arterioles
What direct cardiac effect can DHP CCBs produce?
direct negative inotropy
Which specific cardiac disease would the use of CCBs be contraindicated in?
WPW
Which isoform of the adenosine receptor is activated by adenosine in the heart? What G-protein?
A1
Gi
What is the MOA for how adenosine effects myocardiocytes?
increased potassium efflux
Which isoform of the adenosine receptor is activated by adenosine in the vasculature? What ion is increased in its flux?
A2
potassium
What is adenosine particularly useful in the treatment of?
PSVT
Would acetazolamide result in an acidosis or alkalosis?
acidosis
Do CA Inhibitors increase or decrease intraocular pressure?
decrease
Where in the brain is carbonic anhydrase located?
choroid plexus
What two mechanisms can CAI aid in the treatment of elevation sickness?
decrease CSF production
decrease pH of CSF
What do CAIs do to ventilation rate?
increase
What do CAIs do to the pH of urine?
increase pH
What type of kidney stone is relatively insoluble at low pH?
calcium stone
CAIs can result in the loss of what ion?
potassium
When are CAIs contraindicated? Why?
hepatic encephalopathy
decrease urinary excretion of ammonium
In what two segments of the nephron would osmotic diuretics produce their effects?
proximal tubule and descending loop
Do osmotic diuretics expand or shrink the ECF volume?
expand
Where in the nephron do osmotic diuretics function?
thin limbs
What do loop diuretics do to calcium excretion?
increase
What do loop diuretics do to magnesium excretion?
increase
What type of diuretic is used to treat acute pulmonary edema?
loop
What type of diuretic is used to treat acute CHF?
loop
What type of diuretic is used to treat nephrotic syndrome?
loop
Which four ions can loop diuretics deplete?
Na, Mg, Ca and K
In addition to their intended action, what drug can thiazide diuretics mimmic?
CAIs
What can thiazide diuretics do to calcium excretion?
decrease calcium excretion
Most thiazide diuretics are ineffective when the GFR is between which two levels?
30-40 ml/min
What CNS effects can loop diuretics induce?
ototoxicity
Why can thiazides be useful in the treatment of calcium nephrolithiasis?
thiazides decrease calcium excretion
Which class of diuretics can be used to treat diabetis insipidus?
nephrogenic
Can thiazides produce hypokalemia or hyperkalemia?
hypokalemia
Can thiazides produce an increase or decrease in levels of uric acid?
increase
What can thiazides do to glucose metabolism? Why?
impaired glucose metabolism
thiazides decrease pancreatic insulin production
What do thiazides do to lipid levels?
increase lipid levels
Thiazides can produce an allergic reaction in patients who are also allergic to what other type of drug?
sulfonamides
How strong is amiloride as a single use diuretic?
quite weak
Amiloride spares which ion?
potassium
Which ion can amiloride cause an increase in?
potassium
Amiloride is contraindicated in patients with what two conditions?
hyperkalemia
propensity to develop hyperkalemia
What does amiloride do to glucose profile?
glucose tolerance
What type of inflammation can amiloride produce?
interstitial nephritis
Can amiloride produce renal stones?
yes
What two drugs does spironolactone have to be used in combination with to reduce LV modeling?
ACE or ARB
Spironolactone increases the bioavailability of what substance?
nitrous oxide
What electrolyte defect can spironolactone produce?
hyperkalemia
Which drug can produce metabolic acidosis in cirrhotic patients?
spironolactone
What is the systolic and diastolic criteria for a HTN urgency? Is end organ damage present during hypertensive urgency?
systolic greater than 180
diastolic greater than 120
no
Resistant HTN is defined by what?
HTN than cannot be controlled by three or more drugs one of which is a diuretic
What blood pressure does a physician work to attain in a patient with diabetes or CKD?
less than 130/80
Sulfhydrl containing ACE inhibitors are structurally related to what drug?
captopril
Dicarboxyl containing ACE inhibitors are structurally related to what drug?
enalapril
Phosphorus containing ACE inhibitors are structurally related to what drug?
Fosinopril
What type of anti-HTN drug is used in good combination with ACE inhibitors?
ACEI and diuretics
Which anti-HTN meication is contraindicated in pregnancy?
ACE Inhibitors
Which population group generally responds poorly to ACE Inhibitors?
Elderly african americans
What are the only two CCBs that can be used during LV failure?
amlodipine and felodipine
Which anti-HTN medication can be used to treat Reynaud syndrome?
CCBs
Which anti-HTN medication is particularly useful during cyclosporin induced HTN?
CCBs
In a patient without a sulfa allergy, what situation would the use of a thiazide diuretic be contraindicated?
gout
Which endocrine disorder could β-blockers be used to treat?
Hyperthyroidism
