UWorld-Cardiology

Question 1

what drug would you use to treat beta blocker overdose and why

Answer 1

glucagon; it activates GPCRs in cardiac myocytes leading to increased adenylyl cyclase activity –> increased cAMP leading to increased contractility and heart rate in cardiac myocytes

Question 2

tetralogy of Fallot, transposition of the great vessels and truncus arteriosus all result from what impaired process during embryologic development

Answer 2

migration of the neural crest cells into the truncus arteriosus and bulbus cordis in preparation to grow in spiraling fashion and separate the aorta from the pulmonary artery

Question 3

which artery usually supplies the diaphragmatic surface of the heart

Answer 3

the right coronary artery (b/c it usually supplies the PDA and the PDA supplies the inferior left ventricle, which lies against the diaphragm)

Question 4

name the four features of Tetralogy of Fallot

Answer 4

pulmonic stenosis, RVH, overriding aorta, and VSD

Question 5

how long after onset of total ischemia does cardiac myocyte contraction cease

Answer 5

less then 60 seconds

Question 6

explain the mechanism of action by which NO causes relaxation of smooth muscle

Answer 6

NO activates guanylate cyclase leading to increased cGMP, cGMP downregulates intracellular calcium, which decreases myosin light chain kinase activity leading to myosin dephosphorylation and consequent relaxation of smooth muscle

Question 7

what is the equation for the maintenance dose

Answer 7

maintenance dose= (steady state plasma conc.) X (clearance) / (bioavailability)

Question 8

which cardiac disease is characterized by an opening snap followed by a low-pitched late diastolic rumble

Answer 8

mitral stenosis (opening snap= abrupt halting of mitral valve leaflets due to fusion of the valve tips)

Question 9

which cardiac disease is characterized by a mid-systolic click followed by a crescendo murmur

Answer 9

mitral valve prolapse

mid-systolic click= sudden tensing of chordae tendinae

Question 10

which anti-arrhythmic drug used to treat ventricular tachycardia is most selective for ischemic myocardium over normal cardiac tissue

Answer 10

lidocaine suppresses rapidly depolarizing and depolarized cells (though it is being replaced by amiodarone for management of v. tach)

Question 11

explain pulsus paradoxus, what it is and when you would see it

Answer 11

pulsus paradoxus is a decrease in SBP during inhalation that is greater than 10mmHg; this occurs in disease that impair right heart expansion into the paricardial space; the right ventricle must instead push the interventricular septum into the left ventricular side decreasing EDV and thereby decreasing SBP

Question 12

what does an S3 indicate

Answer 12

left ventricular failure or increased left end systolic volume

Question 13

what is milrinone and what effect does it have in the heart vs. vascular smooth muscle

Answer 13

milrinone is a phosphodiesterase isoenzyme 3 inhibitor;

it increases cAMP to increase contractility in the heart and vasodilation in vascular smooth muscle

Question 14

what is the main way that nitrates work to treat angina pectoris

Answer 14

nitrates decrease preload (thereby lowering ventricular work and O2 demand)

Question 15

which of these three tissues have beta-1 receptors:
cardiac muscle
vascular smooth muscle
juxtaglomerular cells

Answer 15

beta-1 receptors are found in cardiac muscle, juxtaglomerular cells and vascular smooth muscle

Question 16

what keeps a patent ductus arteriosus open?

what closes a patent ductus arteriosus?

Answer 16

prostaglandins keep a PDA open

indomethacin or NSAIDS close a PDA

Question 17

what is amyl nitrite and why isn’t it used anymore

Answer 17

a volatile inhalant historically used to treat angina pectoris;
discontinued because of side effects of cutaneous flushing and postural hypotension

Question 18

bounding femoral and carotid pulses with head bobbing indicates what cardiac abnormality

Answer 18

aortic regurgitation
(note:  head bobbing due to bounding carotid pulse= de Musset's sign

Question 19

what are the resting potentials for cardiac vs. skeletal myocytes

Answer 19

cardiac myocytes: -90mV

skeletal myocytes: -75mV

Question 20

which bacteria synthesize dextrans from glucose

Answer 20

strep viridans bacteria;

this enables them to colonize enamel and valves

Question 21

what reaction is catalyzed by endothelial nitric oxide synthase (eNOS)

Answer 21

in response to ACh, bradykinin or shear stress, intracellular calcium increases triggering eNOS to catalyze this reaction:
Argining + O2 —-> NO + citrulline

Question 22

what is the commonest cause and location of aortic rupture

Answer 22

motor vehicle accident;
aortic isthmus: the connection between the ascending and descending, just distal to the branch point of the left subclavian arterty

Question 23

what group of drugs and what particular drug from that class has been proven to slow progression and lower mortality for CHF

Answer 23

beta blockers; particularly carvedilol

Question 24

what is seen under the microscope for cardiac tissue 3 hours after myocardial infarction

Answer 24

trick question! minimal change is detectable before 4 hours

Question 25

what is Trousseau’s syndrome

Answer 25

migratory thrombophlebitis due to hypercoagulability (often seen in patients with disseminated cancers)

Question 26

list the ventricular muscle, atrial muscle, AV node and Purkinje system in order from fastest to slowest in terms of action potential velocity

Answer 26

Purkinje system is fastest (2.2 m/sec), then the atrial muscle (1.1 m/sec), then ventricular muscle (0.3 m/sec), and the AV node is slowest (0.05 m/sec)

Question 27

which drug for MRSA has a side effect of myopathy and increased Cr kinase;
how does it work?

Answer 27

daptomycin can cause myopathy and increased creatinine kinase;
it works by depolarizing the bacterial cellular membrane

Question 28

best indicator of severity of mitral regurgitation =?

Answer 28

audible S3 (suggests high volume of regurgitant flow into LV)

Question 29

name the proteins associated with the following types of amyloidosis:

• localized cardiac atria (isolated atrial amyloidosis)
• localized thyroid gland
• localized pancreatic
• localized pituitary gland
• Alzheimer’s and Cerebral Amyloid Angiopathy
• systemic amyloidosis

Answer 29

• cardiac atria: atrial natriuretic peptide
• thyroid gland: calcitonin
• pancreatic: amylin
• pituitary gland: prolactin
• Alzheimer’s and CAA: beta-amyloid
• systemic amyloidosis: immune globulin light chain

Question 30

in the lung, a cavitary lesion with an air-fluid level =?

Answer 30

lung abscess (most common cause is aspiration => abscess with normal mouth flora)

Question 31

why should you advise your patient to take 8-10 hour breaks from taking their nitroglycerin

Answer 31

nitroglycerine (much like nasal decongestants) exhibit tachyphylaxis; after prolonged use buildup of the chemical mediator (NO) feeds back negatively on the system

Question 32

why would an anti-anginal drug seek to inhibit fatty acid oxidation

Answer 32

fatty acid oxidation is a major source of energy, but it utilized more oxygen per ATP generated and so it would be better to shift ATP production to more glycolysis and oxidative phosphorylation

Question 33

differentiate valve findings for infective endocarditis vs. rhematic fever

Answer 33

infective endocarditis causes larger vegetations and degeneration of the valve;
rhematic fever causes smaller vegetations and thickening or fibrosis of the valve