CV Function in Pathology - Nordgren

Question 1

What is circulatory shock?

Answer 1

Generalized, severe reduction in blood supply to the body tissues.

• metabolic needs of tissues not met
• arterial pressure usually low

Question 2

What are the primary disturbances that can account for cariogenic, hypovolemic, anaphylactic, septic, and neurogenic shock states?

Answer 2

• Severely depressed myocardial functional ability
  
  • cardiogenic shock
• Grossly inadequate filling due to low mean circulatory filling pressure
  
  • hypovolemic shock
• Profound systemic vasodilation
  
  • anaphylatic shock
  • septic shock
  • neurogenic shock

Question 3

What are the compensatory processes that may arise during various types of circulatory shock?

Answer 3

• Greatly increased sympathetic nerve activity
  
  • pallor, cold/clammy skin, rapid HR, muscle weakness, venous restriction
• Abnormally low arterial pressure, reduced cerebral perfusion –> dizziness, confusion, LOC
• Rapid/shallow breathing –> increase VR (respiratory pump)
• Increased levels of epinephrine
• Reduced capillary hydrostatic pressure resulting from intense arteriolar constriction –> reabsorption
• Increased glycogenolysis in the liver (via Epi/NE)

Question 4

What are the renal compensatory processes that may arise during various types of circulatory shock?

Answer 4

• Increased RENIN release →
  
  • increased TPR via formation of angiotensin II (vasoconstriction)
• Increased circulating levels of ADH →
  
  • increased TPR (fluid retention)
• Increased circulating levels of Aldosterone →
  
  • Na⁺ & fluid retention

Question 5

What are the decompensatory processes that may arise during shock and describe how these lead to irreversible shock states?

Answer 5

• Arteriolar vasoconstriction
  
  • can lead to severely reduced perfusion of other tissues → possibly damage organs
• Bodily homeostasis deteriorates with prolonged reductions in organ flow
  
  • adversely impacts CV system → further reduces flow

Question 6

How may coronary artery disease lead to abnormal cardiac function?

Answer 6

• Atherosclerosis of the large coronary arteries leads to:
  
  • permanently increased vascular resistance → reduced coronary flow
  • arrhythmias
  • heart failure
  • MI

Question 7

What is the difference between Progressive shock and Irreversible shock?

Answer 7

• Progressive:
  
  • general CV situation progressively degenerates
• Irreversible:
  
  • no intervention can halt the ultimate collapse of the CV system → DEATH

Question 8

Define the term “heart failure”.

Answer 8

Depressed ventricular function due to myocardial damage, insufficient coronary flow, or anything that directly impairs mechanical performance.

Question 9

What is the difference between systolic and diastolic failure?

Answer 9

• Systolic:
  
  • Left ventricular EF <40% (reduced CO at any given filling pressure)
  • Reduced myocyte function
  • 1° disturbance = decreased CO → decreased arterial pressure
  • cause edema & congestion
• Diastolic:
  
  • stiffened heart during diastole
  • increases in cardiac filling pressure do not produce normal increases in EDV

Question 10

What are the short-term and long-term compensatory processes that accompany chronic systolic heart failure?

Answer 10

• Short-term:
  
  • Increased sympathetic activity
  • Rapid breathing
• Long-term:
  
  • Rise in blood volume (renin release)→ increased mean circulatory filling pressure
  • Fluid retention causes increased peripheral and central venous pressures
    
    • cardiac dilation → increased myocardial O₂ demand

Question 11

What are the advantages and disadvantages of the fluid accumulation that accompanies systolic heart failure?

Answer 11

• Pro:
  
  • ↑sympathetic activity (short-term) → ↑blood volume → ↑mean circulatory filling pressure
  • ↑CO closer to normal and allows reduction of sympathetic activity
    
    • when enough fluid has been retained, normal CO can be achieved with normal sympathetic nerve activity
• CON:
  
  • fluid retention → ↑ peripheral and central venous pressure → chronically high EDV
    
    • causes excessive cardiac dilation → impairs function due to ↑ total wall tension/stress required to generate adequate pressure
    • increased myocardial O₂ demand

Question 12

What is the difference between pulmonary and systemic arterial hypertension?

Answer 12

• Pulmonary:
  
  • pulmonary artery pressure >20mmHg
  • systemic edema, chest pain, fatigue
  • linked to chronic hypoxia (COPD, cystic fibrosis)
• Systemic:
  
  • elevation of mean systemic arterial pressure > 140/90 mmHg
  • >20% of adult western world pop’n
  • increased risk of CAD, MI, heart failure, stroke, etc.
  • primary OR essential