Cardio/Renal Flashcards
Drug added to regimen for stable angina (with atenolol and aspirin) causes hypotension and bradycardia. What drug was it?
Non-hydropyridine CCB (verabamil, diltiazam) –> additive negative chronotropic effects (slows HR) when combined w/ b blocker
5 groups of drugs w/ negative chronotropic effects (slow HR)
b blockers non-hydropyridine CCB cardiac glycoside (digoxin) amiodarone and sotalol cholinergic agonists
Graph showing dissociation of described class I antiarrhythmics being faster than quinidine. What could that antiarrhythmics be?
Class IB so lidocaine or mexiletine This is because Na+ channel binding strength for class I antiarrhythmics is IC > IA > IB, so IB dissociates fastest IC dissociates slowest, so it demonstrates most "use dependence" (higher rates of depolarization leads to increased Na+ channel blockade)
What’s a coronary steal? What drugs do this? And what do you wanna chieve instead?
In ischemia, collateral circulation maintains perfusion to areas distal to occluded vessel
Drugs that cause CORONARY ARTERIOLAR dilation exacerbate ischemia by causing the already well-perfused vessels (nonischemic) to dilate and steal blood from that collateral circulation
Adenosine and dipyridamole (selective vasodilators) do this
What you wanna achieve instead in this scenario is systemic venous & arterial dilation
Microelectrodes placed in cardiac muscle cells detect rapid decrease in cytoplasmic calcium level immediately preceding relaxation. What mediates this?
Na+/Ca2+ exchange mechanism (sarcolemmal, doesn’t need ATP)
The answer is NOT calmodulin, which stimulates plasma membrane Ca2+-ATPase (indirect contributor of efflux)
NE administered to correct hypotension. What’s the cellular/messenger changes?
Increase in cAMP in CARDIAC MUSCLE CELL (B1 receptors work thru increase in cAMP)
NOT cAMP increase in vascular smooth muscle cell, whose a1 receptors work thru increase in IP3 (and DAG)
NOT cAMP increase in bronchial smooth muscle cell, whose b2 receptors aren’t stimulated by NE
a2 receptor works thru decrease in cAMP (decreases NE release and insulin release)
Where are the 3 leads of biventricular pacemakers?
1) RA (from -> SVC -> RA)
2) RV (same as 1)
3) Left ventricular coronary sinus, which lies in the artrioventricular groove in the posterior aspect of the heart (from left subclavian -> SVC -> RA -> coronary sinus ostium -> left ventricular coronary sinus -> lateral tributaries to regulate LV)
What class of drugs is CI in low level C1 esterase inhibitor?
ACEi (side effect of angioedema from bradykinin accumulation)
Low level of C1 esterase inhibitor -> hereditary angioedema (AD condition)
C1 esterase inhibitor normally inhibits classical complement pathway and kallikrein (normally kallikrein increases bradykinin level by converting it from kininogen)
Pt w/ preexisting atherosclerotic plaque. What increased intraplaque activity will predispose to MI?
Metalloproteinases (destabilizes fibrous cap by degrading collagen)
Get a rise in creatinine after starting ACEi. What structure is involved?
Efferent arteriole
B/c ACEi reduces Ang II, which normally constricts efferent arteriole and thus increases GFR
If less Ang II, GFR decreases
What are the 4 components of crescent formation in RPGN?
1) Fibrin - essential pathologic step, shows up on IF
2) Plasma protein (C3b, NO C4)
3) Parietal cells
4) Monocytes & macrophages
A substance inhibits glucose carrier in proximal tubule. Glucose clearance will now resemble the clearance of what substance?
Inulin, because its filtered amount is now equal to the excretion amount (glucose is not reabsorbed or secreted anywhere else)
Inulin is freely filtered and neither reabsorbed nor secreted = so approximate GFR
What heart sounds are you trying to listen to in LLD position?
S3, S4, MS
What maneuvers make S3 easier to hear?
Make pt fully exhale while lying LLD -> heart closer to chest wall b/c of decreased lung volume
What does use-dependence mean in the context of antiarrhythmics? What’s reverse use-dependence?
Use-dependence: effects exaggerated with increased HR -> Na+ channel blockers, esp class IC (flecainide and propafenone) -> QRS interval more prolonged w/ increased HR Reverse use-depdendence: effects exaggerated with decreased HR -> class III antiarrhythmics (K+ channel blockers - amiodarone, ibutilide, dofetilide, sotalol) -> QT interval more prolonged w/ slower HR
What antiarrhythmic drug prolongs QRS interval during immediate recovery period after stress test?
Flecainide and propafenone (class IC aniarrhythmics) -> strongest use-dependence (the higher the HR, like immediately after exercise test, the more prolonged QRS)
What nitrate agent has the highest bioavailability PO?
Isosorbide mononitrate (metabolite of isosorbide dinitrate) Both nitroglycerin and isosorbide dinitrate undergo extensive 1st pass in liver
Tamponade triad?
Severe hypotension
Muffled heart sounds
Elevated JVP
32-yo healthy male passed a stone in his urine. What abnormalities are you likely to find in his blood and urine?
Normocalcemia and hypercalciuria -> bc calcium stone is the most common kidney stone and it’s idiopathic hypercalciuria half the time
3 ways to get normocalcemia and hyperoxaluria?
Diets high in oxalate such as chocolate, nuts, spinach
Diets low in calcium (so more free oxalate around)
Crohns and other intestinal malabsorptions
How do you get normouricemia w/ hyperuricosuria? How about hyperuricemia w/ hyperuricosuria?
High protein diet
If high both in blood and urine, it’s something more systemic (tumor lysis, myeloproliferative disorders, gout, lesch-nyhan, etc)
What are the characteristics of PSGN deposits under EM?
subEPITHELIAL deposits of immune complex -> lumpy bumpy IgG, IgM, C3 along GBM and mesangium
How do you prevent paradoxical increase in MVO2 demand when using nitrates?
Prescribe B-blocker w/ it (prevents reflex tachycardia) -> prevents catecholamine from stimulating B1 receptors on myocardium -> slows conduction thru AV node & cardiac conduction system in general
How does chronic kidney disease result in increased bone resorption?
By decreasing phosphate excretion -> more phosphates complex w/ calcium -> body thinks you’re low on serum calcium and starts producing more PTH -> “renal osteodystrophy” -> bone pain/osteopenia/sign of soft tissue calcification on X-ray
Also by decreasing calcitriol (less a1 conversion of vit D)