Heart Failure Therapy

Question 1

What are the goals of Heart Failure Therapy?

Answer 1

1. Relieve Congestion/Effusion
(decrease ventricular filling pressure)
-decrease blood volume (preload) - diuretics
-decrease venous return (preload) - venodilators
-increase forward flow

2. Improve CO
(Dz-specific)
-systolic: contractility —>positive inodilators: dec. afterload
-diastolic: lusitropy—>chronotropy; improve ventricular relaxation

Question 2

How is heart failure defined?

Answer 2

as a syndrome in which the heart is unable to meet metabolic needs of tissue despite ADEQUATE VENOUS RETURN

Question 3

How can we define Low Output Heart Failure?

Answer 3

as severe ventricular systolic dysfunction

Question 4

Congestive Heart Failure is specifically cardiac malfunction resulting in what?

Answer 4

increased pulmonary return and/or systemic venous pressures

(edema/effusion, “wet”)

Question 5

Which type of structural remodeling pathophysiological mechanism is caused by increased systolic ventricular pressure (pressure overload)?

Give example(s)…

Answer 5

Concentric Hypertrophy
sarcomeres replicate side-by-side (in parallel) resulting in wider cells and a thicker, “stiffer” ventricular wall. This loss of distensibility makes the ventricle less able to dilate in diastole (lysotropy). Decreased filling in diastole—>increased preload—>potential lung edema and signs of Left HF

For example: with Aortic Stenosis or Systemic Hypertension…

Question 6

Which type of structural remodeling pathophysiological mechanism is caused by chronic increased diastolic pressure (volume overload) and is characterized by cells elongating by the addition of sarcomeres end-to-end (in series)?

Give example(s)…

Answer 6

Eccentric Hypertrophy
​This usually results in normal contractility but the end-diastolic volume is increased to accommodate the larger volume of blood that needs to be ejected to maintain blood pressure and forward stroke volume.

For example: Endocardiosis, Dilated Cardiomyopathy…

Question 7

Emergency doses for furosemide in dogs and cats?

Answer 7

K9: 2-4 mg/kg

Fel: 1-3 mg/kg
(IV or IM)

*remember furosemide activates RAAS and can cause decreased CO, hypotension, dehydration, azotemia, and electrolyte imbalances*

Question 8

How does pimobendan work?

Answer 8

Phosphodiesterase inhibitor which causes arterio- and veno-dilation. Positive inotrope that sensitizes troponin to Ca2+—>creates a stronger contraction

*also increases cAMP—>vasodilates arteries*

Question 9

One of the goals of HF therapy is to relieve congestion and effusion.
Besides drawing fluid (thoraco/abdomino-centesis), we can target relief by decreasing ventricular filling pressure. What are the 2 ways we can achieve this and the respective drug classes we use to do so?

Answer 9

1. Decrease blood volume (Preload) —> diuretics
2. Decrease venous return to the heart (Preload) —> venodilators

Question 10

One of the goals of HF therapy is to improve cardiac output.
In the case of systolic dysfunction, how can we achieve this and what respective drugs would we use to do so?

Answer 10

1. Increase ventricular contractility (inotropy) —> positive inotropes
2. *Decrease afterload —> arteriodilators*

Question 11

One of the goals of HF therapy is to improve cardiac output.
In the case of diastolic dysfunction, how can we achieve this and what drugs would we use to do so?

Answer 11

1. Improve ventricular relaxation (lusitropy) —> positive lusitropes
2. Decrease HR (to allow more time in diastole) —> negative chronotropes

Question 12

What is the emergency dose for Diltiazem in dogs and cats?

Answer 12

0.1 mg/kg IV SLOW over 5 min

Question 13

Emergency dose for lidocaine in DOGS?

Answer 13

2mg/kg SLOW over 2-3 min

Question 14

Emergency dose for lidocaine in CATS?

Answer 14

0.2 mg/kg SLOW…