CVS AND HEART FAILURE

Question 1

what does an athletes heart look like

Answer 1

1. increased left ventricular dilation
2. thickening of the left ventricular wall
3. increased heart mass
4. increased cardiac function

Question 2

what is ficks principle

Answer 2

CO=VO2/Ca-Cv

Question 3

what changes to the heart occur with endurance/isotonic exercise

Answer 3

this leads to VOLUME OVERLOAD which with healthy exercise is good
1. increased lusitropy
2. increased inotropy
3. increased frank starling effect ie; stroke volume
4. peripheral vascular dilation- increase blood flow to the periphery
5. venous constriction ie; increased venous compliance to promote venous return to the heart
6. increased skeletal muscle and abdominothoracic pumps

Question 4

what changes to the heart occur with isometric/strength training

Answer 4

leads to PRESSURE OVERLOAD
1. minimal increase in cardiac output
2. decrease in pump activity
3. increased peripheral resistance

Question 5

define heart failure

Answer 5

the heart has the inability to produce a sufficient cardiac output

Question 6

what is the main cause of heart failure

Answer 6

myocardial infarction ie; heart attack which damages the heart leading to heart failure

Question 7

explain how a myocardial infarction occurs

Answer 7

1. plaque builds up in the coronary arteries
2. this forms a blockage as it thickens
3. so part of the heart no longer receives blood
4. call this the perfusion area
5. if this area remains without blood for long enough then necrosis/tissue death is going to occur which leads to an infarct

Question 8

in the diagram of the heart why where some areas near the perfusion area protected/ still receiving blood

Answer 8

because these myocytes lie close to the left ventricle and so they are still receiving blood from this area via diffusion

Question 9

what can a myocardial infarction lead to

Answer 9

dyskinesis

Question 10

what is dyskinesis

Answer 10

this is when the heart structure changes in response to damage
- so in the case of an infarct forming(area of dead tissue); this causes dyskinesis to occur
-dyskinesis is where the damaged area will bulge outwards upon contraction; causing the blood to pool in this bulge instead of being pumped out of the heart
-thus; dyskinesis results in a decreased stroke volume

Question 11

what compensatory mechanism does the heart use to counteract the decline in stroke volume caused by the damage to myocytes

Answer 11

so the damage caused decreasing pumping capacity of the heart right and so increased preload occurs to try and compensate for the decline in stroke volume from the heart upon damage to the heart
-but this then puts increased workload on the surviving myocytes so although it is a compensatory mechanism against the decline in cardiac output; it inevitably leads to heart failure

Question 12

what are other causes of heart failure

Answer 12

1. valvular disease
2. cardiomyopathies
3. myocarditis
4. hypertension

Question 13

explain the pressure volume loop

Answer 13

pressure on the y axis and volume on the x axis
A= ESV
A-B= ventricular filling so mitral valves must open at A
B=EDV and slight increase in pressure to force the mitral valves close
B-C= then pressure rapidly increases to open the aortic valves
C-D= the blood leaves the heart and so volume drops
D= the aortic valves close as pressure drops slightly
D-A= large drop in pressure so the mitral valves can open

Question 14

what is preload

Answer 14

initial stretching of the cardiomyocytes prior to contraction thus; the more blood present at EDV the more they are going to stretch
-the more they stretch the greater the tension they generate in systole
- it is an initial compensatory mechanism to try and increase the stroke volume in heart damage

Question 15

how does preload change the pressure volume loop

Answer 15

EDV will be greater but all the rest will be the same
-thus SV will increase

Question 16

what is afterload

Answer 16

load against which cardiomyocytes must contract to eject blood

Question 17

what are the 2 main contributors to afterload

Answer 17

1. wall stress
2. blood pressure outside the heart
   -an example of afterload is hypertension

Question 18

how does increased afterload influence the heart

Answer 18

the greater the afterload; the shorter the myocytes become ie; their contractility declines and so does the tension they generate and thus; decreases stroke volume
- so the heart works harder to maintain cardiac output which can lead to hypertrophy and thus heart failure

Question 19

how does afterload influence the pressure volume loop

Answer 19

it causes the ESV to increase because less blood can be pumped out
- also see increase in the height of loop ie; increased arterial pressure

Question 20

define inotropy

Answer 20

cardiomyocyte contractility

Question 21

how does inotropy influence the the pressure volume loop

Answer 21

1. increased inotropy means the ESV is going to be less
2. decreased inotropy means the ESV is going to be more

Question 22

what are the 3 types of heart failure

Answer 22

1. systolic dysfunction
   2.diastolic dysfunction
   3.systolic and diastolic dysfunction

Question 23

explain what systolic dysfunction is

Answer 23

1. decrease inotropy
   2.increased ESV
   3.increased EDV but by less than the ESV so SV declines
2. increased EDP
3. increased venous pressure
4. edema

Question 24

explain what diastolic dysfunction is

Answer 24

impaired filling of the ventricles
-can be caused by hypertension(hypertrophy)
- cardiomyopathies
1.decreased venous compliance
2. decreased SV
3. Increased EDP
4. decreased EDV and increased ESV

Question 25

diastolic and systolic dysfunction

Answer 25

-result of a large heart attack because the heart attack can cause hypertrophy of the surviving myocytes that are working extra hard
-and they cause loss of inotropy

Question 26

what is the bodies systemic response to heart failure

Answer 26

1. the baroreceptors will sense the drop in cardiac output and secrete norepinephrine to do the following:
   a. increase inotropy
   b. increase lusitropy
   c. increase heart rate
   d. increase preload and mean arterial pressure
   e. increase workload of the heart
   f. then later the RAAS kicks in to firther increase preload and mean arterial pressure and to retain fluid from the kidneys to increase the volume of the blood

Question 27

what are therapeutics used in heart failure

Answer 27

1. diuretics to reduce edema
2. vasodilators
3. B blockers

Question 28

how can volume overload lead to pathological hypertrophy

Answer 28

it can cause eccentric hypertrophy where the cardiac walls thin ie; enlarged ventricular chamber