management of congestive heart failure

Question 1

what is CHF?

Answer 1

a condition in which the heart is unable to pump sufficient amount of oxygenated blood to meet the metabolic demands of the body. edematous state produced by the fluid retention leading to pulmonary as well as peripheral congestion with decreased cardiac output

Question 2

what are the symptoms of CHF?

Answer 2

peripheral and pulmonary edema, fatigue, diminished exercise capacity, decreased cardiac output, shortness of breath/dyspnea, cough, tachycardia(what is tachycardia) hepatomegaly

Question 3

what are the causes of CHF?

Answer 3

myocardial infraction, hypertension, angina, ventricular tachycardia, diabetes mellitus, anemia, hyperthyroidism. left side/right side heart failure or both

Question 4

what are the compensatory responses of CHF?

Answer 4

increased sympathetic activity; activiation of RASa. Ventricular remodeling: important myocardial hypertrophy, cardiomegaly. on a long term these changes rather increase work load of heart and cause worsening of cardiac performance

Question 5

what are the drugs used in CHF with positive inotropic effects?

Answer 5

Cardiac glycosides: digoxin, digitoxin, ovabain
B-adrengeric agonists: dopamine, dobutamine
Phosphodiesterase inhibitors: Amrinone, Milrinone
(These are all used only in emergency)

Question 6

What are the drugs used in CHF without positive inotropic effects?

Answer 6

Diuretics: Furosemide, hydrochlorthiazide
ACE inhibitors: L Enalapril, Lisinopril
B1 (or a+B1) adrenoceptor antagonists: Metoprolol, bisoprolol
Vasodilators: Hydralazine, nitrates
(These are all used for chronic cases of CHF)

Question 7

where are digitoxin, digoxin, ovabain obtained from?

Answer 7

obtained from leaves of fox glove (digitalis)

Question 8

what is the mechanism of action of cardiac glycosides?

Answer 8

by inhibiting the NA+/K+ ATPase enzyme, digoxin reduces the ability of the myocyte to actively pump Na+ from the cell. Digoxin causes dose dependent positive inotropic effect

Question 9

what are the adverse effects of digoxin?

Answer 9

bradycardia, partial / complete heart block, coupled beats, GI effects (nausea, vomiting, anorexia, diarrhea)

Question 10

What is the toxicity margin of digoxin?

Answer 10

The toxicity margin of safety is low (0.5 to 0.8 ng/mL effective, 2ng/mL toxicity appears)

Question 11

what is mechanism of action of beta agonists?

Answer 11

They lead to increase in intracelluar cAMP, which results in the activation of protein kinase. protein kinase then phosphorylates slow calcium channels, thereby increasing entry of Ca2+ into the myocardial cells and enhancing contraction

Question 12

How is dopamine and dobutamine is given?

Answer 12

given by i.v infusion. primiarly used in the short term treatment of acute HF in the hospital setting.
(Most commonly used inotrpic agent other than digoxin)

Question 13

What are adverse effects of beta agonists?

Answer 13

Arrhythmias, tachycardia

Question 14

what is the use of phospdiestrase inhibiotors (amrinone and milrinone)?

Answer 14

only short term I.V in severe and refractory CHF as an additional drug to conventional therapy. long term milrinone therapy may be associated with a substantial increased risk of mortality

Question 15

What are the adverse effects of phoshodiesterase inhibitors?

Answer 15

thrombocytopenia (transient), diarrhea, abdominal pain, nausea, liver damage and fever

Question 16

What is the preferred phoshodiesterase inhibitor?

Answer 16

Milrinone, more potent, short acting, thrombocytopenia less significant hence preferred