Maternal Physio - Cardiovascular

Question 1

Cardiac output changes

• AOG
• Why

Answer 1

• CO ↑ at 5th week AOG due to:
  
  • ↓ systemic vascular resistance plus ↑ heart rate
• Memory aid:*
• In Buntis, Both SVR and HR are affected

Question 2

A pregnant woman’s CXR has a slightly enlarged cardiac silhouette. What is a possible explanation?

Answer 2

Some degree of benign pericardial effusion may increase the cardiac silhoutte

Question 3

A pregnant woman has a diastolic murmur on auscultation. Is this normal?

Answer 3

• No
  
  • Diastolic murmurs are never normal and should be evaluated by a cardiologist
  • Systolic murmur in 90% of pregnant patients due to ↑ flow across aortic and pulmonic valves

Question 4

Plasma volume changes

• AOG
• Change
• Effect

Answer 4

• Between 10-20 weeks AOG
  
  • Plasma volume expands
  • ↑ preload

Note:

• Increase preload due to plasma volume expansion
• Decrease in afterload due to decreased vascular resistance

Question 5

Heart position

• Changes
• CXR finding

Answer 5

• Changes
  
  • Displaced to the left and upward
  • Rotated somewhat on its long axis
• CXR finding
  
  • Apex is somewhat lateral from its usual position
  • Larger cardiac silhoutte on chest radiograph
    
    • some degree of benign pericardial effusion may increase the cardiac silhoutte
• Note:*
• This is best imagined!

Question 6

ECG change

Answer 6

No characteristic ECG changes other than slight left-axis deviation as a result of the altered heart position

• Note:*
• Again, imagine and correlate!

Question 7

Cardiac sounds

Answer 7

• Exaggerated splitting of the 1st heart sound with increased loudness of both components
• Systolic murmur in 90% of pregnant patients due to ↑ flow across aortic and pulmonic valves
  
  • intensified during inspiration
  • disappears shortly after delivery
• Diastolic murmurs are never normal and should be evaluated by a cardiologist

Memory aid:

• Splitting and
• Systolic murmur are normal

Question 8

BP changes

Answer 8

• Arterial pressure usually decreases to a nadir at 24 to 26 weeks

Question 9

How many percent of women experience supine hypotensive syndrome?

Answer 9

About 10%

Question 10

RAA component changes and why

Answer 10

• Increased on normal pregnancy
  
  • Renin
    
    • produced by kidney and placenta
  • Angiotensinogen
    
    • produced by maternal and fetal liver and influenced by estrogen
• Memory aid:*
• Vowels; so it is not progesterone

Question 11

If angiotensin is increased, why is there no BP elevation in normal pregnancy?

Answer 11

Because of prostacyclin, which is implicated in the angiotensin resistance characteristic of normal pregnancy

• Therefore:*
• Prostacyclin is decreased in preeclampsia

Question 12

Diastolic decreases ____ [less/more] than systolic

Answer 12

More

• Memory aid:*
• SBP/DBP → DBP decreased to a greater extent

Question 13

Prostaglandin E2 synthesis

• Where synthesized
• Increased/decreased release and when

Answer 13

• Where synthesized
  
  • Renal medulla
• Increased/decreased release
  
  • Increased markedly in late pregnancy

Question 14

Principal prostaglandin of endothelium

Answer 14

Prostacyclin

Question 15

Potent vasoconstrictor in endothelial and vascular smooth muscle cells which also stimulates secretion of ANP, aldosterone and catecholamines

Answer 15

Endothelin

Question 16

Fetal oxygen saturation is approximately ____% ____ (higher/lower) in a labouring woman

Answer 16

10% higher

Question 17

Potent vasodilator released by endothelial cells and have important implication for modifying vascular resistance during pregnancy

Answer 17

Nitric oxide