Physio- Heart Failure.

Question 1

List the causes of heart failure.

Answer 1

1. Loss of muscle
2. Loss of contractility
3. Pressure overload
4. Volume overload
5. Restrictive filling

Question 2

List the symptoms of backward heart failure mechanism.

Answer 2

Reduced cardiac output
Elevated LV diastolic pressure
Elevated pulmonary wedge pressure
Fluid transsudation to alveoli
Shortness of breath, rales, cough

Notes- acronym - REEFS.

Question 3

List the symptoms of forward heart failure mechanism.

Answer 3

Reduced cardiac output
Reduces renal perfusion
RAAS activated
Increased Na and water reabsorption
Increases capillary pressure
Fluid transsudation in interstitium
Anasarka, ankle swelling ascites

RRRIIFA
FRIRIRA

Question 4

What is the mechanisms for contractile dysfunction in systolic HF?

Answer 4

— reduced shortening on cardiac myocyte.
— reduced SR Ca2+ release and storage
— Leaky Ryanodine Receptor
— increase SERCA

Question 5

What is the mechanisms for contractile dysfunction in diastolic HF?

Answer 5

— decrease in LV diastolic pressure
— decrease in LV filling
— increase is myocardial stiffness
— myocardial fibrosis

Question 6

In which direction does the Frank Starling curve shift in response to heart failure?

Answer 6

It shifts downward

Note: compensatory mechanism in heart failure.

Question 7

Explain the neurohormonal activation mechanism in heart failure.

Answer 7

1. Sympathetic overactivation — a decrease in LV cardiac output > lesser stimulation to the aortic baroreceptors > sends signals to increase the sympathetic outflow.
2. RAAA overactivation — A decrease in cardiac output > decrease in blood to kidney > leads to an increase in renin which activates the RAAS.

Question 8

How does the neurohormonal activation help to compensate for cardiac dysfunction in HF?

Answer 8

— Sympathetic outflow increase cardiac contractility
— RAAS activation increases Na+ reabsorption, increase blood volume, cardiac output and venous return due to frank starling mechanism

Question 9

How does the myocardial structural remolding helps to compensate for cardiac dysfunction in HF?

Answer 9

1. Cardiac Hypertrophy - thickening of the LV wall generates a greater contractile force.
2. Cardiac dilatation — dilation of the LV wall leads to a greater blood volume in diastole
3. Myocardial fibrosis — LV wall has a greater tolerance to deformities.

Question 10

List the compensatory mechanisms in hypovolemic shock and explain each.

Answer 10

Atrial baroreflex- BP drop
Activation of RAAS
Release of ACH
Thirst
Chemoreflex - stimulates peripheral and central chemoreceptors. Cerebral ischemia.
Transcapillary refill - shift of fluid from interstitium to blood.
Redistribution of blood flow from non vital to vital organs
Blood release from storage in liver