MR

Question 1

Regurgitant orifice area and MR severity depends on

Answer 1

o Severity of valve damage
o Chordal integrity
o LA/annular/LV dilation

Question 2

How changes in BP affects MR

Answer 2

• Pressure gradient LV → LA
  o ↑ afterload (BP) → ↑ PG → ↑ regurgitant volume
  o ↓ afterload (BP) → ↓ PG → ↓ regurgitant volume + ↑ forward flow

Question 3

Regurgitant volume depends on 3 factors

Answer 3

• Regurgitant orifice area
• Pressure gradient LV → LA
• Duration of systole

Question 4

Drugs that may influence regurgitant volumes

Answer 4

o Diuretics → ↓LV size and ROA → ↓ regurgitant volume
o Vasodilators → ↓ afterload → ↓ PG
o Inotropes → ↑ rate of fiber shortening → ↓ systole duration → ↓ regurgitant volume

Question 5

Pathophysiology of MR

Answer 5

ventricular unloading
* Normally, no blood ejection during IVCT
* Hemodynamic change with MR
o Early systole: LOW pressure and wall stress → EASY contraction
 LV ejects blood → LA
 Up to 50% of LV SV before AoV opening
 ↓LV size
o AoV opening: NORMAL systolic pressure and ↑ wall thirckness → NORMAL contraction

Question 6

Mild MR: pathophys

Answer 6

• Regurgitant fraction <50%

↓SV = hypoperfusion + ↑LA volume
o Primary compensation: ↓SV → ↓BP and renal perfusion → baroR stimulation + ∑ activation → ↑ SA node rate + contractility (β1) + vasoconstriction → ↑SV and BP
 Β1-R ↓ rapidly (3days) → ↓ contractility → ↓ SV
o Secondary compensation: ↓SV → ↓BP and renal perfusion → RAAS stimulation → ↑Na+/H2O retention → ↑ venous return to  → L sided volume overload → eccentric hypertrophy → normalize SV

Question 7

Mild MR: final outcome

Answer 7

o ↑ end diastolic volume but normal end systolic volume, ↑FS%
o Total SV ↑ but normal forward SV
o Normal LAP

Question 8

Moderate MR: pathophys

Answer 8

• Regurgitant fraction 45-75%

o ↑FS% NOT indicate ↑ contractility
 2nd to ↑ end diastolic volume
 Normal end systolic volume

Question 9

Moderate MR: final outcome

Answer 9

o Progressed ↑ end diastolic volume, still normal end systolic volume, progressive ↑FS%
o Progressive total SV ↑ but normal forward SV
o Mild ↑ LAP

Question 10

Severe MR

Answer 10

• Regurgitant fraction >75%
• Final: similar progression
  o ↑ LAP → ↑ pulmonary capillary pressure → pulmonary edema

Question 11

Very severe MR

Answer 11

• Progressive ↑ end diastolic volume, ↑ end systolic volume, progressive, ↓FS% (but normal range)
• Progressive total SV , ↓ forward SV
• Maximal LAE with progressive ↑ LAP

Question 12

Causes of MR from dynamic LVOTO

Answer 12

o HCM + SAM
 Basal septal bulge can worsen obstruction
o Hypertension with LVH
o Exercise
o Inotropic agents
 Hyperadrenergic state 2nd to CHF → hyperdynamic contractility can worsen LVOTO
o Vasodilators/Valsalva maneuvers

Question 13

Pathophys of MR 2nd to dynamin LVOTO

Answer 13

o Mild to severe MR
o Obstruction worsened by (↑MR)
 ↑ afterload
 ↑ inotropy