04.16 - Heart Failure

Question 1

What causes dyspnea BEFORE transudation of fluid into the lungs in heart failure?

Answer 1

Increased pulmonary venous pressure

Question 2

What is central venous pressure, and how is it related to heart failure?

Answer 2

• INC = volume overload; DEC = volume depletion
• Wide range of normal values and pressures, but normal is from about 2 - 8 mm Hg
  1. 6 mm Hg NORMAL CVP -> can be estimated from physical exam or measured from tip of central venous catheter in SVC
• EXAMPLE: if CVP is 5, may have been 2, then pt had heart failure, or 8 and occult intestinal bleeding caused MI precipitating heart failure -> give pt a bolus of fluid via central line
  1. CVP goes up, stays up, NOT volume depletion
  2. CVP goes up transiently, falls back down, the pt may have heart failure AND volume depletion
• Volume depletion could be due to: 1) intestinal hemorrhage due to ischemia due to the heart failure, or 2) painless spontaneous retroperitoneal hemorrhage from anticoagulation

Question 3

What are LVEDP, LDEDV, SV, EF, and LVESV? What are the “normal” values?

Answer 3

• LV end diastolic pressure (LVEDP): 4-12 (10) mm Hg
• LV end diastolic volume (LVEDV): 65-240 (120) mL
• LV end systolic volume (LVESV): 15-145 (50) mL
• Stroke volume (SV): amount of blood pumped per heartbeat; 55-100 (70) mL
  1. SV = LVEDV- LVESV
• Ejection fraction: % LVEDV pumped per heartbeat; 50-75% (60%)

Question 4

How do the LVEDP, LVEDV, SV, EF, and LVESV compare for the two hearts shown? Why?

Answer 4

• Failing heart will have:
  1. Higher LVEDP
  2. Higher LVEDV
  3. Lower SV
  4. Lower EF
  5. Higher LVESV

Question 5

What are the 7 general principles of heart failure?

Answer 5

1. Initial symptom is dyspnea (usually only w/exertion)
2. Most pts have both left AND right heart failure
3. 25% reduction in forward stroke volume OFTEN a threshold -> pts begin to have symptoms
4. Severe, acute, uncompensated aortic regurgitation is a sx emergency
5. Mitral valve regurgitation can be cause OR effect
6. Mitral regurgitation causes murmur during systole; mitral stenosis causes heart murmur in diastole
7. Aortic regurgitation causes murmur during diastole; aortic stenosis causes murmur during systole

Question 6

What are the symptoms of left VS. right heart failure?

Answer 6

• Left: dyspnea on exertion, progressing to dyspnea at rest
  1. Orthopnea (dyspnea when lying flat)
  2. Paroxysmal nocturnal dyspnea (PND)
  3. Fatigue
• Right: edema of feet, then ankles, then legs
  1. Abdominal distention
• NOTE: be careful not to confuse PND with PNH

Question 7

What are the signs of left VS. right heart failure?

Answer 7

• Left: bibasilar (bottom) pulmonary crackles
  1. Tachycardia
  2. S3
  3. Pedal, ankle, or leg edema
• Right: pedal, ankle, or leg edema
  1. Jugular venous distention
  2. Hepatomegaly
  3. Ascites
• NOTE: right heart failure causes peripheral edema via buildup of venous back pressure; left heart failure causes peripheral edema via mechs in image on card

Question 8

How does left heart failure cause pulmonary edema?

Answer 8

• By causing a buildup of pressure in left ventricle, left atrium, pulmonary veins, and pulmonary capillaries
• When pulmonary capillary pressure INC from upper limit of normal (10mmHg) to 2x that, fluid starts to transudate into interstitium -> INTERSTITIAL PULM EDEMA
• When pulm cap pressure >25mmHg, fluid starts to transudate into alveoli -> ALVEOLAR PULM EDEMA, associated with wet pulmonary crackles

Question 9

What else can cause pulmonary edema? How might you differentiate between all of these potential causes?

Answer 9

• Acute lung injury
  1. Cardiogenic: high cap pressure (heart failure)
  2. Septic shock: normal capillary pressure
  3. Hemorrhagic shock: low cap pressure
• Balloon-tipped, Swan-Ganz catheter: pass catheter w/pressure monitor through SVC, right atrium, right ventricle and pulmonary artery until wedged into smallest artery it will fit into, and inflate balloon
  1. Pulmonary capillary wedge pressure (PCWP) approx same as the left atrial pressure & LVEDP
  2. Can also be used to measure mixed venous oxygen saturation and cardiac output (CO)

Question 10

How common are the various signs of heart failure?

Answer 10

• Pretty common -> in a study of over 500 patients hospitalized for heart failure, reported symptoms:
  1. 77% dyspnea on exertion, 47% at rest,
  2. 41% orthopnea,
  3. 37% fatigue,
  4. 30% paroxysmal nocturnal dyspnea
  5. Signs: 64% pulmonary crackles, 60% edema, 11% an S3
• DO NOT MEMORIZE THESE #’s (appreciate them)

Question 11

What is diastolic heart failure?

Answer 11

• Many elderly pts devo heart failure w/dyspnea, orthopnea, PND and bibasilar pulmonary crackles, but have normal or near normal ejection fraction
• Most of these pts have long-standing HTN, often with obesity, & concentric left ventricular hypertrophy
• These pts have noncompliant, stiff left ventricles with impaired diastolic function and filling
• Condition is called diastolic heart failure or heart failure with preserved ejection fraction

Question 12

What are the pathophysiologic mechanisms of the tachycardia experienced by heart failure pts?

Answer 12

1. SNS stimulation
2. N and NE from adrenal

Question 13

Why do heart failure patients have elevated B-type natriuretic peptide?

Answer 13

• Released due to stretch or increase in cardiac chamber volume (precipitated by the heart failure)
• COUNTER-REGULATORY

Question 14

Why is it important to not confuse cor pulmonale with right heart failure?

Answer 14

• Most patients with cor pulmonale are compensated; they do not have heart failure
• Many more patients with right heart failure have it because of left heart failure than cor pulmonale
• There is only a small group of patients with right heart failure due to cor pulmonale

Question 15

What is the most common clinical scenario for heart failure with preserved ejection fraction?

Answer 15

• Elderly patient with long-standing HTN, often obesity too, and concentric left ventricular hypertrophy, now with impaired compliance

Question 16

What are the 4 hemodynamic profiles for acute heart failure? Why is this relevant?

Answer 16

• Cold = low perfusion; wet = pulmonary edema (spectrum of dyspnea due to high LV filling pressures)
• You can strategize therapy based on hemodynamic profile:
  1. Warm and dry (10% die)
  2. Warm and wet
  3. Cold and dry
  4. Cold and wet (40% die)

Question 17

What are the 3 general principles of heart failure?

Answer 17

1. Heart failure incl. pump failure, causing inadequate perfusion, or requiring abnormally high volumes or pressures to pump adequately
2. Morbid obesity can cause heart failure by itself
3. Like shock, heart failure is not defined by a number

Question 18

What are the 4 categories of shock?

Answer 18

• Distributive: blood volume distributed to widely (i.e., due to INC vasodilation, making capacitance of vascular system too big for amount of blood volume)
• Hypovolemic: e.g., loss of plasma or blood volume
• Cardiogenic: e.g., ventricular failure
• Obstructive: i.e., large pulmonary thromboembolus or cardiac tamponade

Question 19

Appreciate this distribution of the types of shock, and their various signs and symptoms.

Answer 19

Good job!

Question 20

What are the biochemical and hemodynamic signs of shock?

Answer 20

• Dx of shock is based on clinical, hemodynamic, and biochemical signs (clinical signs on another card)
• Biochemical sign: elevated serum lactate from anaerobic metabolism required b/c body is not adequately perfused
• Hemodynamic sign: hypotension, although what would be a normal BP for a healthy person may be hypotension for a patient with chronic HTN

Question 21

What are the clinical signs of shock?

Answer 21

• Behavior: disorientation, confusion, obtundation, and worse
• Skin: mottled, cold, clammy, pale, or cyanotic
• Urine: decreased output