Chapter 16 - Management of heart failure

Question 1

list common pathophysiological mechanisms of congestive heart failure

Answer 1

primary myocardial failure
volume (flow) overload
systolic pressure overload
reduced ventricular compliance (impaired filling)

Question 2

what is laplace’s law?

Answer 2

wall stress is directly related to ventricular pressure and internal dimensions (radius) and inversely related to wall thickness

Question 3

pressure loading stimulates ___ hypertrophy, volume loading stimulates ___ hypertrophy and chamber dilation

Answer 3

concentric, eccentric

Question 4

myocardial oxygen demands are more severe with pressure loading than volume loading T/F

Answer 4

T

Question 5

describe how chronic sympathetic stimulation adversely effects the heart

Answer 5

detrimental effects occur due to greater myocardial afterload stress and oxygen demand, cellular damage, myocardial remodeling and fibrosis and enhanced potential for cardiac arrhythmias. norepi increases automaticity and oxidative stress and, through beta1 receptor activation, increases cAMP production and intracellular Ca2+, leading to calcium overload and cell necrosis. chronic catecholamine exposure leads to myocardial beta1-receptor down-regulation and decreased sensitivity to changes in adrenergic tone due to altered cell signalling

Question 6

spironolactone MOA

Answer 6

competitive aldosterone antagonist

Question 7

contraindications to spironolactone use

Answer 7

hyperkalemia (care if patient is receiving ACE inhibitors

or K+ supplementation)

Question 8

what is aldosterone escape?

Answer 8

where aldosterone release occurs despite ACE inhibitor use, resulting in Na+ and water retention (a good reason to add spironolactone if needed)

Question 9

4 adverse effects of ACE inhibitors

Answer 9

hypotension, azotemia, AKI, hyperkalemia, (cough)

Question 10

how do ACE inhibitors cause cough

Answer 10

thought to be via inhibited bradykinin degradation or increased NO generation - inflam on bronchial cells

Question 11

pimobendan drug class

Answer 11

phosphodiesterase III inhibitor - inodilator, benzimidazole derivative

Question 12

digoxin drug class

Answer 12

digitalis glycoside

Question 13

monitoring while on digoxin

Answer 13

monitor digoxin levels 7-10d after starting and after dose changes, monitor renal function and electrolytes

Question 14

how does potassium concentration affect likelihood of digoxin toxicity

Answer 14

hypokalemia promotes myocardial toxicity by leaving more membrane Na/K-ATPase binding sites available; conversely, hyperkalemia displaces digitalis from those binding sites

Question 15

signs of digoxin toxicity

Answer 15

GI, myocardial (arrhythmias, can lead to collapse and death), CNS (depression, disorientation)

Question 16

drug of choice after accidental oral digoxin overdose

Answer 16

cholestyramine (steroid-binding resin), can also use digoxin-specific antigen-binding fragments (digoxin-immune Fab)

Question 17

amlodipine MOA

Answer 17

dihydropyridine L-type calcium channel-blocker, peripheral vasodilation outweighs negative inotropism