LVF - Physiology and Pathophysiology

Question 1

LVF - Heart as a pump

Answer 1

The heart is a muscular organ that pumps blood around the body.

On the right side it takes in deoxygenated blood from the superior and inferior vena cava and delivers it to the lungs for oxygenation.

Oxygenated blood returns to the left side of the heart before being pumped out of the aorta and into the various arteries which transport the blood throughout the body and into the various blood vessels.

Question 2

LVF - Cardiac output determined by:

Answer 2

HR
Preload
Contractility
Afterload

Question 3

LVF - Preload

Answer 3

is the degree of myocardial distension prior to shortening. Preload largely depends on the amount of ventricular filling

Question 4

LVF - Contractility

Answer 4

refers to the intrinsic strength of the ventricle, independent of loading conditions

Question 5

LVF - Aterload

Answer 5

is the force against which the ventricles must act in order to eject blood, and is largely dependent on the arterial blood pressure and vascular tone.

Question 6

LVF - Defn. of Heart failure

Answer 6

a condition caused by the heart failing to pump enough blood around the body at the right pressure

Question 7

3 main types of LVF

Answer 7

1. heart failure caused by left ventricular systolic dysfunction (LVSD) – left ventricle becomes weak (aka Systolic failure) - contractility
2. heart failure with preserved ejection fraction (HFPEF) – usually a result of the left ventricle becoming stiff, making it difficult for the heart chamber to fill with blood (aka Diastolic failure) - preload
3. heart failure caused by diseased or damaged heart valves -

Question 8

Causes of acute LVF

Answer 8

• Ischaemic Heat Disease /
• Myocardial Infarction
• Hypertension
• Aortic Stenosis
• Volume overload
• Drugs e.g. beta blockers
• Infection e.g. Myocarditis

Question 9

LVF - Cause of cardiogenic pulmonary oedema

Answer 9

As a result of the reduced cardiac output from the left ventricle, there becomes a back flow of blood back towards the lungs as the blood cannot return to the heart. This causes an increase in pressure on the pulmonary vascular system.
As the pressure in the pulmonary system rises, fluid from the vascular compartments is shifted across into the interstitial spaces and the alveoli.
The fluid in the alveoli then results in decreased gas exchange across the alveoli resulting in reduced oxygenation of the blood and potential for CO2 retention.