Cardiology Flashcards
What are the Class III antiarrythmics?
-“tilide” drugs (dofetilide, ibutilide)
Sotalol
Amiodarone
What are some of the MANY side effects of amiodarone?
Pulmonary fibrosis Hypo OR hyper thyroidism Hypersensitivity hepatitis Risky in heart failure patients Grey corneal deposits Grey-blue skin discoloration in sun CYP450 inhibitor LOW incidence of torsades (sotalol and the ilide drugs have a higher risk)
What is the action of class III antiarrhythmics?
Block K+ channels that depolarize the myocardium thereby causing prolonged depolarization (prolonged action potential) and prolonged refractory period
How is Digoxin cleared/metabolized? What are signs of toxicity?
Renally
Toxicities: yellow tinting, anorexia, n/v, abdominal pain
Although digoxin can cause _____kalemia, toxicity is actually exacerbated by _____kalemia because it increases Digoxin binding to the Na/K ATPase pump.
Digoxin can cause hyperkalemia (blocked pump prevents sodium coming out and thus exchange for K in).
However hypokalemia increases Digoxin binding so it can make toxicity (yellow tinted vision and GI disturbances) worse.
What are the most common causes of nonbacterial thrombotic endocarditis (NBTE)?
- Advanced malignancy
- Chronic inflammatory diseases (SLE, antiphospholipid syndrome, DIC)
NBTE is characterized by sterile platelet-rich thrombi on the valves
Although Digoxin is primarily used to increase contractility, it may also be used for rate control. What is the mechanism by which Digoxin slows ventricular rate during atrial fibrillation?
Increasing parasympathetic tone via the Vagus nerve -> ultimately inhibits AV nodal conduction
What is the mechanism of action of dobutamine? What is the signaling cascade?
Beta 1 agonist:
Gs signaling -> increased cAMP -> calcium channel activation -> increased Ca2+ = increased contractility and heart rate (and thus cardiac output overall)
What cardiac defects result from doxorubicin (or other anthracyclines like daunorubicin)?
What can be co-administered to prevent these effects?
Dilated cardiomyopathy due to formation of iron-containing complexes that produce DNA-damaging free radicals.
Dexrazoxane is a chelating agent that can block the free radicals.
Which organ is most likely to suffer from infarction/thromboembolism in emboli generated in Afib?
Kidneys due to higher perfusion rate
Infarction will appear as a wedge-shaped lesion on CT
What is the classic triad of physical exam findings seen in cardiac tamponade?
- Muffled heart sounds
- JVD
- Hypotension (+ pulsus paradoxus!)
How does Digoxin increase myocardial contractility?
Competes for the Na/K ATPase, reducing its activity. This prevents Na efflux (and K influx).
Na builds up but then escapes through another Na/Ca2+ exchanger. This floods the cell with calcium, causing increased contractility.
(+) Inotropy will increase cardiac output INDEPENDENT of ______.
EDV (cardiomyocyte stretching)
Total peripheral resistance is MOSTLY determined by what vessels?
Arterioles
In what situations will you often see a decrease in TPR?
i.e. arteriolar dilation
Exercise
Arterio-venus shunts
An S4 heart sound is a sign of ______ dysfunction.
Diastolic
It occurs due to a sudden rise in end-diastolic ventricular pressure caused by atrial contraction against a stiff ventricle.
Occurs in any condition that reduces ventricular compliance (e.g. hypertensive heart disease, aortic stenosis, hypertrophic cardiomyopathy).
What causes the S3 heart sound?
Rapid passive filling of ventricles in diastole.
Sudden cessation of filling as ventricle reaches elastic limit.
Occurs in systolic heart failure, mitral regurg, and high-output states
Think of lots of blood sloshing around slamming against the wall
What is the major determining factor of severity of a case of Tetralogy of Fallot?
Degree of RVOT obstruction
What compensatory mechanisms are initiated by the kidneys in response to decreased renal perfusion (e.g. as in CHF)?
- RAAS activation: sodium retention, aldosterone production, vasoconstriction
- Sympathetic output: epinephrine and norepinephrine increase HR and contractility and increase in peripheral arterial resistance increasing afterload.
Class IB antiarrhythmics are useful for treating _____-induced ventricular arrhythmias.
Ischemia-induced
Class IC antiarrhythmics have the strongest binding to sodium channels and thus are slowest to dissociate causing cumulative effects, thus they are especially useful in treating what type of arrhythmia?
Tachyarrhythmia
Aortic regurgitation murmur is best heard in which position?
Sitting up and leaning forward with breath held at end-expiration
Midsystolic click followed by a Mid- to late systolic murmur = ?
Mitral valve prolapse with mitral regurgitation
The click results from the sudden tensing of the chordae tendineae as they are pulled taut by the ballooning valve leaflets
What are the only two murmurs that DECREASE with increased preload/venous return?
Mitral valve prolapse
Hypertrophic cardiomyopathy systolic murmur at cardiac apex
Which class of anti-arrhythmics work by blocking voltage-dependent sodium channels (i.e. depolarization) of the cardiac AP?
Class I
What do endothelial cells secrete to prevent platelet aggregation and adhesion to the vascular endothelium?
Prostacyclin
Damaged endothelial cells lose the ability to synthesize prostacyclin, predisposing them to the development of thrombi and hemostasis.
What are the 2 main effects of milrinone (a PDE3 enzyme inhibitor)?
- Positive inotropy
2. Vasodilation (arterial AND venous)
Nesiritide and is a synthetic form of what endogenous peptide?
BNP
thus causes naturesis and arteriolar and venous dilation
Due to the very high myocardial oxygen extraction (up to 75%), what vessel in the body has the absolute lowest oxygen saturation?
The coronary sinus (drains the venous blood of the heart itself)
What are the actions of nitroprusside?
Short-acting arteriolar and venous dilation
As such, it decreases both preload and afterload, allowing adequate CO to be delivered at lower LVEDPs.
What pathologies can cause wide splitting (i.e. P2 heart sound, delayed pulmonary valve closing)?
Right bundle branch block
Pulmonic valve stenosis
What pathologies can cause fixed splitting (i.e. P2 heart sound, delayed pulmonary valve closing that doesn’t change with inspiration/expiration)?
ASD
What pathologies can cause paradoxical splitting (i.e. P2 heart sound pulmonic valve closing before A2 aortic valve)?
What will bring them back closer together?
Increase in left ventricular volume
Left bundle branch block)
Aortic valve stenosis
Inspiration will bring them back together (though P2 will still occur before A2, you just won’t be able to hear it).
Hand grip increases ___load. It therefore increases the intensities of which murmurs?
Afterload
MR
AR
VSD
Rapid squatting increases ______ and _____. Ultimately what murmurs are decreased
Preload AND afterload
AS
MR
VSD
Valsalva decreases ____load.
Preload by increasing thoracic pressure
Decreases most murmurs but NOT MVP or HCM
New onset mitral valve regurgitation may be due to an infarct in _______ because it supplies the _____ valve leaflet.
RCA
Posterior valve leaflet
In what part of systole does mitral and tricuspid regurg present?
All of it! (they are holosystolic)
Patients with what type of diseases are predisposed to mitral valve prolapse?
Connective tissue diseases
VSD and tricuspid regurgitation are both holosystolic murmurs heard best at the LSB…so how can you tell them apart?
Tricuspid regurg will radiate to the right shoulder