cardiac anatomy and dynamics

Question 1

What is the flow of blood through the heart?

Answer 1

Vena Cava, RA, Tricupside valve, RV, pulmonic valve, pulmonary artery, pulmonary vascular bed, pulmonary veins, LA, Mitral valve, LV, aortic valve, aorta, systemic vasculature

Question 2

Cardiac output

Answer 2

• Normal: 5-8 LPM
• the amount of blood pumped from the left heart in one minute
• CO=HRxSV

Question 3

What is stroke volume?

Answer 3

• The amount of blood pumped out with eat beat
• Governed by:
  
  • preload
  • afterload
  • contractility

Question 4

What is pre-load?

Answer 4

• Stretch on cardiac muscle before contraction(systole) due to volume or stretch on muscles at end-diastole
• stretching pre-contraction
• equivalent to LVENDP- left ventricular end-diastolic pressure
• increased filling pressure will increase the stroke volume and increase LVENDP

Question 5

What is afterload?

Answer 5

• pressure heart must work against to eject blood during systole(contraction)
• force heart works against to remove the blood
• vascular resistance indirectly proportional to stroke volume (SV)
• increased afterload causes decreased SV
• if veins narrowed SV would be decreased

Question 6

What is SVR and PVR and what do they reflect?

Answer 6

• SVR-systemic vascular resistance
  
  • Left ventricular afterload
• PVR- pulmonary vascular resistance
  
  • right ventricular afterload

Question 7

What is contractility?

Answer 7

• Force of ventricular contraction ejecting blood
• strength of the heart- how hard it works
• contractility directly proportional to stroke volume
• inotropic medications increase contractility

Question 8

What are the two types of heart failure and how are they different?

Answer 8

• Diastolic HF- impaired filling
  
  • heart muscle is thick and stiff- less blood can enter the ventricle and it can’t relax normally
• Systolic HF- impaired contractility
  
  • heart muscle is weak and cannot pump normally

Question 9

What is an intra-aortic balloon pump and how does it work?

Answer 9

• A balloon is inserted into the aorta to assist the heart
• inflates during diastole- increases coronary perfusion
• deflates during systole- decreases LV afterload

Question 10

What are non-invasive ways to assess cardiac status?

Answer 10

• Peripheral skin temp
• capillary refill tone
• cyanosis
• urine output
• LOC
• pulses
• Arterial pressure
• ECG
• auscultate heart sounds

Question 11

What are invasive ways to assess cardiac status?

Answer 11

• arterial pressures
• CVP
• PAP
• PCWP
• CO

Question 12

What are compensatory mechanisms to maintain blood pressure?

Answer 12

• Increase cardiac output (increase HR and SV)
• Vasoconstriction