Control of Cardiac Output

Question 1

Regarding the PV loop of the normal left ventricle (true or false):

In the PV loop the ejection phase is represented by a vertical ascending segment

Answer 1

False. The ejection phase is represented by the top segment of the loop which passes from right to left. The vertical ascending segment represents the isovolumic contraction.

Question 2

Regarding the PV loop of the normal left ventricle (true or false):

It is not possible to calculate SV from a PV loop

Answer 2

False. From the PV curve we can calculate SV= EDV-ESV.

Question 3

Regarding the PV loop of the normal left ventricle (true or false):

The steeper gradient of the EDPVR represents the lower compliance of the ventricle during filling

Answer 3

True. Poor compliance, i.e. diastolic function, is represented by up and left shift, i.e. the steeper section, of the EDPVR curve.

Question 4

Regarding the PV loop of the normal left ventricle (true or false):

The gradient of the ESPVR represents the elastance of the ventricle during filling

Answer 4

False. ESPVR relates the pressure and volume during systole and not during the ventricle filling, i.e. diastole.

Question 5

Regarding the PV loop of the normal left ventricle (true or false):

Isovolumetric relaxation is represented by a vertical descending segment of the loop

Answer 5

True

Question 6

Regarding Laplace’s Law (true or false):

Intraventricular pressure is proportional to wall tension

Answer 6

True

Question 7

Regarding Laplace’s Law (true or false):

It applies to both elastic and nonelastic spheres

Answer 7

False. Laplace’s law applies to elastic spheres.

Question 8

Regarding Laplace’s Law (true or false):

For physiological purposes the ventricle is considered as a sphere

Answer 8

True

Question 9

Regarding Laplace’s Law (true or false):

P = 2Tr/h

Answer 9

False. P = 2Th/r

Question 10

Regarding Laplace’s Law (true or false):

Intraventricular pressure is a direct index of wall tension

Answer 10

False. Intraventricular pressure is an indirect index of wall tension.

Question 11

Regarding the Frank-Starling law (true or false):

As initial fibre length increases from resting value, the tension developed during contraction increases and reaches a maximum

Answer 11

True

Question 12

Regarding the Frank-Starling law (true or false):

The law applies only to cardiac muscles and not to skeletal muscles

Answer 12

False. The Frank-Starling law applies to both skeletal and cardiac muscles.

Question 13

Regarding the Frank-Starling law (true or false):

CVP and RVEDP are indices of resting fibre length

Answer 13

True

Question 14

Regarding the Frank-Starling law (true or false):

SV and LVEDP are indices of contractility

Answer 14

False. CVP, RVEDP, LVEDP, RVEDV, LVEDV are indices of resting fibre length. SV, SW, RVESP and LVESP are indices of contractility.

Question 15

Regarding the Frank-Starling law (true or false):

Intravenous fluid bolus in a failing heart may decrease the contractility

Answer 15

True

Question 16

Cardiac contractility is (true or false):

Increased by parasympathetic stimulation

Answer 16

Cardiac contractility is increased by sympathetic stimulation, parasympathetic blockade (not stimulation) and increased Ca2+

Question 17

Cardiac contractility is (true or false):

Increased by sympathetic stimulation

Answer 17

Cardiac contractility is increased by sympathetic stimulation, parasympathetic blockade (not stimulation) and increased Ca2+

Question 18

Cardiac contractility is (true or false):

Decreased by most of the inhalational anaesthetics

Answer 18

True. Most inhalational anaesthetics decrease the cardiac contractility.

Question 19

Cardiac contractility is (true or false):

Not influenced by serum levels of Ca2+

Answer 19

Cardiac contractility is increased by sympathetic stimulation, parasympathetic blockade (not stimulation) and increased Ca2+

Question 20

Cardiac contractility is (true or false):

Affected by changes in preload and afterload

Answer 20

True