Physiological responses to valvular disease

Question 1

The heart valves open and close because of

Answer 1

changes in pressure on either side of the valve

(they are not pulled by muscles)

Question 2

The heart sounds are due to

Answer 2

the turbulence that occurs as the valves close

Question 3

Systole occurs between which heart sounds?

Answer 3

S1 and S2

Question 4

What is the normal volume of the LV?

Answer 4

140mL

Question 5

What is the normal stroke volume?

Answer 5

70mL

Question 6

What is ejection fraction?

Answer 6

SV/EDV

~50% (lower in heart failure)

Question 7

What is valve stenosis?

Answer 7

• narrowing of valve
  
  • does not open fully
  • flow is restricted
  • creates a pressure gradient across the valve
    
    • need a higher pressure to overcome (see below)
  • creates higher pressure in chamber behind valve
    
    • LV in aortic stenosis
    • LA in mitral stenosis
  • leads to pressure overload

Question 8

What is valve incompetence?

Answer 8

• regurgitation or leaking back of blood
  
  • valve does not close fully
  • blood leaks back into previous chamber
  • heart required to pump greater SV to maintain SV and CO because part of the flow goes backwards
  • greater volume in the ventricule
    
    • increased EDV so SV can be larger
  • increased ejection fraction
  • leads to volume overload
    
    • problem is in the ventricle​ that contributes to heart failure

Question 9

Diastole occurs between

Answer 9

the second and first heart sounds

Question 10

What situations cause innocent flow murmurs?

Answer 10

• high flow
  
  • children, fever, anaemia, pregnancy

Question 11

Which part of the cardiac cycle is shortest?

Answer 11

systole (1/3rd)

diastole (2/3rds)

Question 12

Aortic stenosis murmur is heard

Answer 12

systole, between S1 and S2

Question 13

Mitral regurge murmur is heard

Answer 13

in systole between S1 and S2

Question 14

Aortic regurge murmur is heard during

Answer 14

diastole, between S2 and S1

Question 15

Mitral stenosis murmur is heard during

Answer 15

diastole, between S2 and S1

Question 16

Patent ductus arteriosus murmur is heard

Answer 16

continuously through diastole and systole

Question 17

Which murmurs are heard during systole?

Answer 17

aortic stenosis and mitral regurge

Question 18

Which murmurs are heard during diastole?

Answer 18

Aortic regurge and mitral stenosis

Question 19

What are the symptoms of mild and moderate valvular disease?

Answer 19

none - cardiac compensation is effective such that even severe lesions can be asymptomatic for many years, until the heart fails

Question 20

What is critical in the treatment of regurgitation?

Answer 20

• irreversible LV changes occur at the same time symptoms present
  
  • tf valves are operated on before symptoms appear

Question 21

What is the timing of treatment of aortic stenosis?

Answer 21

• LVH changes (concentric hypertrophy) are usually reversible even when symptomatic
• tf tend to wait until symtpoms appear before operating in stenosis

Question 22

What is the assessment of valvular disease?

Answer 22

• history (SOB)
• examination - murmur, pulse
• ECG
• echo
  
  • diagnosis, severity, ventricular size & function, atrial size, pulmonary artery pressure
  • can show LV changes before they are irreversible (trigger for intervention in regurge)

Question 23

What is aortic stenosis?

Answer 23

• progressive narrowing of the aortic valve
  
  • fibrosis, then calcification
• reduces valve area
  
  • normal > 2.5cm²
  • severe < 0.7cm²
• generates a pressure gradient across the valve (normally 0)
  
  • severe can be > 50mmHg
  • tf LVP can be 170mmHg if SBP is 120mmHg

Question 24

What is the left ventricular response to aortic stenosis?

Answer 24

• pressure overload
  
  • leads to concentric hypertrophy
• thicker, stiffer walls lead to decreased compliance
  
  • diastolic dysfunction bc harder to fill
  • need higher LA pressure and EDV
• incresed LVEDP to fill LV
• atrial contraction becomes crucial to LV filling (not normal)
• LV changes usually reversed after surgery
  
  • removes the pressure gradient
• LV can blow out and fail
  
  • tamponade, death

Question 25

What is the most common valve lesion?

Answer 25

Aortic stenosis

Question 26

What are the symptoms of aortic stenosis?

Answer 26

SOB, chest pain, blackouts

Question 27

Systolic murmurs are (sound)

Answer 27

systolic tf crescendo-decrescendo murmurs murmur gets louder as the gradient increases throughout the cardiac cycle

Question 28

Where are systolic murmurs best heard?

Answer 28

over the upper R sternal edge | (crescendo-decrescendo)

Question 29

What causes aortic regurgitation?

Answer 29

* damage to the aortic leaflets or dilated aortic root * damage by: * endocarditis (staph or strep viridans on valve leaflets), rheumatic fever (strep pyrogenes outside heart) * leaflets cannot seal * dilation by: * Marfan's syndrome (mutation in fibrillin, a CT protein), aortic dissection (media, can split to aortic valve and root or dissect completely), collagen vascular disorders (ankylosing spondulitis), syphilis * leaflets do not close

Question 30

How does the heart adapt to aortic regurgitation?

Answer 30

* portion of SV leaks back into the LV during diastole * tf to maintain CO, LV pressure increases to pump **greater SV** * leads to volume overload * **there is no pressure gradient generated** * maintenance of CO achieved by: * increased EDV * increased EF * normal ESV * can be effective in mild to severe AR for some time * **diastolic BP drops** (~30mmHg) as blood flows back into ventricle from aorta through the leaky valve * crashing/collapsing pulse * tf **pulse pressure is increased (e.g. 150/30mmHg)** * **​generates 'bounding' pulse**

Question 31

What determines diastolic pressure?

Answer 31

* systolic pressure * peripheral run-off * where the blood goes out of the aorta * how stretchy/stiff the aorta is * if aortic valve does not shut, get backflow into the LV * decreases DBP * increases pulse pressure

Question 32

What is the sound of the aortic regurgitation murmur?

Answer 32

* lub-woosh instead of lub dub * don't hear S2 because the aortic valve is not closing

Question 33

What are the effects of prolonged severe aortic regurgitation?

Answer 33

* decompensation (irreversible) of eccentric/dilated LV hypertrophy * ++LV diastolic volume * -LV function * +LV systolic volume * when symptoms appear, these changes are irreversible

Question 34

What causes mitral regurgitation?

Answer 34

* myxomatous degeneration (mitral prolapse, doesn't close) * ruptured chordae tendinae (flail leaflet, severe) * infective endocarditis (strep or staph viridans) * MI --\> ruptured papillary muscle (acute, surgical emerge) * rheumatic fever (strep pyrogenes) * collagen vascular disease (Marfan's) * cardiomyopathy (change in ventricular shape)

Question 35

What are the consequences of mitral regurgitation?

Answer 35

* portion of SV ejected into LA * to maintain CO, LV must pump greater SV per beat * leads to volume overload * increased EDV * increased EF * normal ESV * **increased LA volume and pressure due to LA dilation** * **​affecting ventricle and atrium; in aortic just ventricle**

Question 36

What are the consequences of prolonged severe mitral regurge?

Answer 36

* eventual decomponsation * ++LV diastolic volume * -EF * +LV systolic volume * changes coincide with symptoms, irreversible * tf operate earlier to repair valve instead of replacing it

Question 37

What are the additional risks associated with mitral regurgitation?

Answer 37

* due to increased LA pressure and volume (dilation): * atrial fibrillation due to electrical instability * thrombus formation, embolism to brain, heart kindey, limbs * increased pulmonary venous pressure (due to +LAP) * pulmonary congestion and oedema, causing hypoxia * hypoxia stimulates pulmonary arteriole vasoconstriction * PA hypertension, can cause failure of RV

Question 38

What is the sound of the mitral regurge murmur?

Answer 38

pansystolic 'woosh-woosh' constant throughout systole due to the pressure gradient between LV and LA

Question 39

What causes mitral stenosis?

Answer 39

* almost always previous rheumatic fever, esp. in women

Question 40

What is mitral stenosis?

Answer 40

* fibrotic, narrowed mitral valve * generates pressure gradient across mitral valve * reduces LV filling * LV atrial contraction becomes imporant to filling, CO * LV systolic function unaffected

Question 41

What are the consequences of mitral stenosis?

Answer 41

* increased LA pressure and volume * atrial fibrillation due to electrical instability * risk of thrombus formation in LA, can embolise * cause of thromboembolism and stroke * increased pulmonary venous pressure * pulm congestoion (interstitium) and oedema (alveoli) causing hypoxia * leads to PA hypertension through PA vasoconstriction response * normal LV pressure, normal aortic pressure

Question 42

What is the trigger for intervention in mitral stenosis?

Answer 42

* well tolerated if mild to moderate * development of symtoms or PA hypertension is trigger for tx

Question 43

What are the interventions for mitral stenosis?

Answer 43

* valvotomy - surgical or balloon dilation * valve replacement