Heart Failure: Clinical Management

Question 1

What is heart failure?

Answer 1

inability to sustain a cardiac output sufficient to provide for their metabolic requirements are normal cardiac filling pressure

Question 2

What are some clinical signs of inadequate cardiac output?

Answer 2

• exercise intolerance
• syncope
• pallor
• cold extremities
• signs of hypotension (lethargy, depression)

Question 3

Whare are some clinical signs of excessive cardiac filling pressure?

Answer 3

signs of venous congestions
- tachypnea, dyspnea (pulmonary congestion, pleural effusion)
- ascites

Question 4

What’s the gold standard for diagnosing heart failure?

Answer 4

CXR
- cardiomegaly
- pulmonary venous congestion
- alveolar pattern

Question 5

How does heart failure affect the preload?

Answer 5

it may increase the preload due to fluid retention

Question 6

Which drugs would be beneficial in patients with signs of congestion?

Answer 6

• diuretics
• venodilators

Question 7

How does heart failure affect the afterload?

Answer 7

sympathetic nervous system and RAAS activation –> increase in afterload

Question 8

Which drugs would be beneficial in patients excessive afterload?

Answer 8

vasodilators

Question 9

Which drugs would be beneficial in patients with abnormal myocardial contractility?

Answer 9

positive inotrope

Question 10

What drugs can improve cardiac filling?

Answer 10

lusitropic drugs –> sympathomimetic agents and calcium channel blockers

Question 11

What are some clinical signs of patients with excessive preload?

Answer 11

• pulmonary edema (dyspnea)
• pleural effusion (dyspnea)
• ascites (respiratory compromise)

Question 12

What’s the first choice in diuretics?

Answer 12

furosemide

Question 13

If a patient is refractory to furosemide, what are the next options?

Answer 13

• can add in thiazide or spironolactone
• or switch to torsemide

Question 14

What’s the MOA of furosemide?

Answer 14

• acts at the Loop of Henle, ascending limb
• blocks the Na/K/2Cl co transporter
• up to 25% Na excretion

Question 15

What’s the MOA of thiazide?

Answer 15

• acts at the distal tubule and connecting segments
• blocks the Na/Cl carrier – ie. inhibits sodium reabsorption
• up to 5% Na excretion

Question 16

What’s the MOA of K-sparing diuretic?

Answer 16

• acts at the collecting tubules
• aldosterone antagonist
• up to 2% Na excretion

Question 17

What is a unique side of spironolactone in cats?

Answer 17

cutaneous adverse drug reactions

Question 18

How is spironolactone best used?

Answer 18

• by itself it’s not a very potent natriuretic
• best used along side a loop diuretic
• but it’s aldosterone antagonism has benefits beyond being a diuretic

Question 19

How is thiazide best used?

Answer 19

along side with loop diuretic and K-sparing diuretic to provide “sequential nephron blockade”

Question 20

What are the 3 common complications of diuretics?

Answer 20

1. volume depletion
2. reduction in cardiac output
3. electrolyte abnormalities – hypokalemia, hyponatremia

Question 21

How does hypokalemia develop in the face of diurectics?

Answer 21

the homeostatic mechanism in response to increased Na+ and water loss is more vigorous Na+ and water retention
- Na+ retention = K+ loss in the distal nephron
- therefore, hypokalemia develops, which is more common with the loop diuretics

Question 22

how does hyponatremia develop in the face of diurectics?

Answer 22

Vasopressin release
- free water retention = dilution of Na+ = hyponatremia

Question 23

How should abnormalities with diuretics be monitored?

Answer 23

baseline, and 10-14d later –> urea, creatinine, electrolyte levels

Question 24

What’s an example of a venodilator?

Answer 24

nitrate venous dilators: nitroglycerine
- cutaneous ointment
- gains tolerance quickly

Question 25

What are some complications of venodilator?

Answer 25

drop in blood pressure –> syncope, weakness, hypoperfusion
- watch in cats with hypertrophic cardiomyopathy

Question 26

How is nitroprusside used?

Answer 26

it’s a balanced vasodilator
- good for acute, ICU setting –> CRI, need to protect from light
- rapid, profound action –> need to monitor blood pressure
- gain tolerance quickly
- cyanide = metabolite, limits cumulative use

Question 27

How is angiotensin converting enzyme inhibitors (ACEi) used?

Answer 27

• usually alongside a diuretic to minimize the effects of RAAS activation
• not a very potent vasodilator
• more beneficial in chronic rather than acute setting

Question 28

How is amlodipine used?

Answer 28

it’s a calcium channel blocker
- good for cats with systemic hypertension
- may be beneficial for dogs with mitral valve regurgitation
- probably given as 2nd or 3rd line vasodilator if patient refractory to ACEi or pimobendan

Question 29

How is diltiazem used?

Answer 29

calcium channel blocker
- also a lusitrope in cats
- used as an antiarrhythmic in dogs

Question 30

Which drug can be used for pulmonary vasodilation? What’s the MOA?

Answer 30

Sildenafil
- it’s the phosphodiesterase V inhibitor
- reduces pulmonary vascular resistance
- can be used in dogs with severe degenerative mitral valve disease

• pimobendan can be used as well

Question 31

What’s the MOA of dobutamine?

Answer 31

It’s a inotrope and lusitrope
- block beta-1 receptor –>enhance myocardial contraction and rate of relaxation
- sympathomimetic agent
- only given as CRI – so in hospital use only
- high doses can lead to arrhythmia

Question 32

What’s the MOA of pimobendan?

Answer 32

Inodilator
- phosphodiesterase inhibition and calcium sensitization
- useful in DCM and DMVD
- may be helpful for cats with hypertrophic cardiomyopathy

Question 33

What’s the aim of resting respiration rate for dogs/ cats with heart failure?

Answer 33

<40 breaths per minute