Cardiac Cycle: Mechanical Events

Question 1

what is systole?

Answer 1

contraction

Question 2

diastole is what ?

Answer 2

relaxation

Question 3

what is the normal duration of the cardiac cycle?

Answer 3

0.8 sec. resulting in a resting heart rate of 72 beats/min

systole/contraction = 0.3 sec

diastole/relaxation = 0.5 sec

Question 4

if you shorten the diastole time what happens?

Answer 4

you have less blood filling into the ventricle - therefore you have less blood available to the body - therefore you have less blood flow profusing the heart = vicious cycle

• the heart pumps everywhere including to the heart -

Question 5

what portion of the heart is responsible for the unidirectional flow of the heart?

Answer 5

the heart valves

Question 6

the mitral valve connects which two chambers?

Answer 6

mitral valve is between the left atrium and left ventricle

Question 7

when the atriums fill with blood, what valve is closed?

Answer 7

the AV valves are closed

Question 8

when the ventricles are filled, what valves are closed?

Answer 8

the semi-lunar vavles are closed (to the aorta or pulmonary arteries)

Question 9

pressure on what side of the heart is higher?

Answer 9

the pressure on the left side of the heart is higher than the right side

Question 10

the 1st and second heart sounds are associated with what events?

Answer 10

first = AV valve closure (tricuspid/mitral)

second = outflow valve closure (pulmonary /aortic)

Question 11

What is associated with the 3rd anf fourth heart sounds?

Answer 11

third= filling of ventricles - benign in youth, some trained athletes, and pregnancies - though sometimes it can be indicative of a pathology

4th = atrial contraction

Question 12

what is a murmer?

Answer 12

most common cause is an aortic regurgitation and mitral stenosis

regurgitation = valvular incompetence

stenosis = valvular narrowing

Question 13

when in the heart sound does a murmer occur?

Answer 13

depends on type of murmer

diastolic murmur = occurs after S2 and before S1 - due to aortic regurgitation/mitral stenosis

systolic murmur= occurs between S1 and S2 - due to mitral regurgitation/aorticc stenosis- or non-pathological reasons

Question 14

what is a cystolic murmer?

Answer 14

quite common - often “innocent functional” flow murmurs

• common pathological cuasese are mitral regurgitation, aortic stenosis, and tricuspid regurgitation

Question 15

REVIEW THE LEFT VENTRICULAR PRESSURE VOLUME RELATIONSHIP GRAPH

Answer 15

Question 16

What is the left ventricular en diastolic pressure?

Answer 16

left ventricular pressure just before onset of left ventricular systolic indicative of haemodynamic health of left ventricle - normally less than 12 mmHg

Question 17

what is the ejection fraction?

Answer 17

it is the percentage of blood that is ejected by the ventricle relative to its end

Question 18

what is a normal ejection fraction?

Answer 18

55-70%

during exercise it could increase to more than 90%

Question 19

explain what occurs at each indicated letter in this jugular venous pressure wave form

Answer 19

c= rise in atrial pressure- right vent. contraction causes tricuspid valve to bulge towards the right atrium

x= fall in atrial pressure- atrial relaxation and rapid atrial filling due to low pressure

v= rise in atrial pressure- venous filling when the tricuspid valve is closed

y = fall in atrial pressure- rapid emptying of the atrium into the ventricle following the opening of the tricupsid valve