Module 2 - Heart Failure

Question 1

Cardiac Output

Answer 1

the amount of blood pumped out of the left ventricle in one minute

HR X SV = CO

litres/min

Question 2

Heart Rate is determined by ?

Answer 2

pacemaker cells
sns
pns
circulating hormones

Question 3

Stroke volume

Answer 3

the amount of blood pumped from the ventricle in a single beat

Question 4

Stroke volume calculation

Answer 4

SV = EDV - ESV

Question 5

Cardiac index

Answer 5

used to compare cardiac output of different individuals

Cardiac output (L/min) / body surface area (m^2)

Question 6

Cardiac index is abnormal outside of what range?

Answer 6

2.5 - 5.0

Question 7

Stroke volume is determined by 3 variables

Answer 7

preload, afterload and myocardial contractility

Question 8

preload

Answer 8

passive tension created in the myocardium before contraction

depends primarily on venous return
represented by atrial pressure

Question 9

afterload

Answer 9

the resistance against which the heart must push blood out and into the arteries

Question 10

myocardial contractility

Answer 10

the tension that is developed within the muscle on contraction independent of it’s original length (at the end of diastole)

Question 11

ejection fraction

Answer 11

the proportion of the end diastolic volume (EDV) expelled in each beat

usually this varies between 55-75%
mean = 65%

Question 12

CHF

Answer 12

a complex of signs and symptoms that arrises when HF occurs

Question 13

Causes of HF (6)

Answer 13

1) heart cannot pump hard enough to overcome (incr afterload)
2) increase in volume of blood to be pumped (incr preload)
3) impairment of atrial emptying
4) reduced myo contractility - impaired systolic function
5) reduced myo relaxation - impaired diastolic function
6) incr. demand for blood by tissues (high output failure)

Question 14

Classifications of HF

Low Output Failure

Answer 14

most common
output falls below normal and can’t meet minimum criteria for body, even at rest

causes: arrhythmias, myo ischemia, and MI

Question 15

Classifications of HF

High Output Failure

Answer 15

body requires more oxygen and heart can’t provide enough oxygenated blood

causes: pregnancy, exertion at high altitudes

Question 16

Classifications of HF

Forward Failure

Answer 16

explains the effects of heart failure by the reduced tissue perfusion that occurs and by the adaptations that are brought into play to compensate for it.

Question 17

Classifications of HF

Backward Failure

Answer 17

heart cannot efficiently pump the blood delivered to it

ie: broken mitral valve? blood backs up in LA - signs of backward failure

Question 18

Classifications of HF

Left Heart Failure

Answer 18

most common; b/c this is a higher pressure/work zone

common causes: MI, hypertension, and valve disease

blood backs up in LA and in to pulmonary system

Question 19

pulmonary capillary wedge pressure (PCWP)

Answer 19

catheter is placed in pulmonary artery circulation to measure the pressure

this pressure is approx LA pressure

Question 20

orthopnea

Answer 20

difficulty breathing when lying down

Question 21

cheyne stokes respiration

Answer 21

alternating periods of apnea and hyperventilation

Question 22

Classifications of HF

Right Heart Failure

Answer 22

very rare to occur on it’s own

most frequent cause is cor pulmonale (hypertrophy of the RV associated w/ primary lung disease)
2nd most freq cause: pulmonary emboli (block)

Question 23

Causes of High Output Failure

Answer 23

hyperthyroidism
Paget’s disease
chronic anemia
renal failure
arteriovenous shunts

Question 24

arteriovenous shunts

Answer 24

an abnormal connection between an artery and a vein

Question 25

Clinical presentation of Right Heart Failure

Answer 25

not much pulmonary edema/congestion
systemic venous congestion
hepatic and splenic enlargement
peripheral edema (swelling in tissues)
ascites