Decomponsation HEart

Question 1

What does long term inc atrial pressure lead to?

Answer 1

1. stretch of atrial chamber
2. muscle becomes thinned and stretched
3. active filling of ventricles less effective, reducing CO
4. Enlarged atria compress the tracheal bifurcation causing the animal to cough

Question 2

What does long term activation of angiotensin 2 result in? What nervous protion is this?

Answer 2

SYMPATHETIC

sympathetic action Ag2 contributes to vasoconstriction in the non-essential organs which aims to preserve blood supply to essential organs and improve preload
Designed to cope short term losses e.g. haemorrhages

Prolonged
vasoconstriction means a sustained reduction in perfusion of organs such as the kidneys and the
gastrointestinal tract and increases the afterload on the failing heart.

Question 3

Ling term Ag2 = reduced perfusion kidneys. What does this cause?

Answer 3

Decreased perfusion of the kidney leads to reduced filtration of blood, which causes build-up of
electrolytes and toxic metabolic waste products such as urea and creatinine in the bloodstream
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(azotaemia). This can lead to the serious clinical syndrome uraemia, which further reduces
myocardial contractility. Persistently reduced blood supply to the kidney can end in irreversible
damage to the nephrons, leaving the animal with renal failure which is often in itself terminal.

Question 4

Long term Ag2 = reduced perfusion to GI, what deos this result in?

Answer 4

Decreased gastrointestinal perfusion can lead to the mucosa of the intestine becoming ischaemic
which breaks down the barrier between the bacteria-laden contents of the intestine and the blood
stream. This can lead to septic shock

Question 5

Backward heart failureleads to increased venous pressure. What does this cause?

Answer 5

o filtration of water out of the circulation and
development of oedema and/or effusions. Small volumes of oedema are managed by increasing
interstitial hydrostatic pressure which reduces the drive for filtration, increases lymph flow from the
area affected and reduces interstitial protein concentration reducing the oncotic drive for further
filtration. The lymphatic system becomes overwhelmed by the volume of fluid entering the ISF in
congestive heart failure, and oedema/effusions build up.
Pulmonary oedema reduces efficacy of oxygen exchange at the lungs, resulting in reduced blood
oxygenation (hypoxia) which further reduces myocardial (and other organ) function. Effusions may
also affect respiratory function: severe ascites can raise abdominal pressure to the point that the
diaphragm is compromised and breathing becomes laboured, or a pleural effusion prevents the
lungs from expanding effectively (see respiratory lectures).