Mitral Regurgitation Flashcards
Causes of chronic mitral regurgitation
Marfan’s
Cardiomyopathy
Lupus etc
Rheumatic fever
Causes of acute mitral regurgitation
Ischemia of papillary muscles/chordate tendinea
Endocarditis
Symptoms of mitral regurgitation
Systolic murmur
Weakness
The magnitude of regurgitation with MR is influenced by what 2 things?
HR
SVR
What is the primary pathophysiology with MR?
Decreased SV
How is MR classified?
By regurgitant fraction of SV
What is mild MR
< 30%
What is moderate MR?
30-60%
What is severe MR?
> 60%
What are the secondary compensation mechanisms of MR?
Increased blood volume
LA overload
What consequence occurs from MR’s compensatory mechanisms?
Left atrial enlargement eventually can’t accommodate more volume and pulmonary edema develops
Explain the difference between chronic and acute MR
With chronic MR the LA has time to dilate and accommodate volume giving long term compensation
With acute MR there is a sudden overload of the LA without time for compensation and pulmonary congestion is likely
How does LA overload eventually lead to LV failure?
The volume gets recirculated over repetitive cardiac cycles and eventually the LV has too much volume, becomes compliant, eccentric hypertrophy occurs, and eventually LV failure
With MR LA overload leads to LV failure, how does the LV at first compensate, and what shows LV failure
As the volume in the LV increases, it becomes compliant and eccentric hypertrophy occurs to compensate for the additional volume. Eventually compensation fails and the pressure also increases
What are V waves?
V waves are an abnormal wave on a PCWP that result from regurgitant flow through the mitral valve
What does the sign of a V wave mean?
The size of the V wave correlates to the severity of MR regurg
What does a sudden onset of V waves mean?
Acute MR
-may be from ischemia of papillary muscles
What are the anesthesia goals for MR and HR?
Modest increase in HR
Why is a modest increase in HR best for MR?
SV is rate dependent
Sudden bradycardia causes abrupt LV overload
What are the anesthesia goals for preload and MR?
Maintain of increase preload
What are the anesthesia goals for SVR and MR?
Decrease SVR
Why is is good to decrease SVR with MR?
Less resistance promotes forward flow
What are the anesthesia goals for contractility and MR?
Maintain contractility to keep volume moving forward
Goals are more manageable with what anesthetic technique?
General
-regional may be tolerated, but anticoagulation may be an issue
Induction drugs and MR
Any
Ketamine increases HR which is good, but increases SVR which is bad
Muscle relaxant and MR
Any
Pancuronium increases HR which is good
Volatile anesthetics and MR
Isoflurane is ideal because it is the strongest vasodilator (good), and has a modest increase in HR (good)
SEVO and DES are good too
Monitoring and MR
5 lead to monitor for ischemia
PAC may be useful for titration of vasodilators
What information can a PAC help obtain
Adequate preload - which is essential to maintain net forward volume
Failing ventricle benefits from afterload reduction
Over aggressive vasodilation risks preload reduction
Helps find optimal filling pressure
Does stenotic or regurgitant valve disease lead to more hemodynamic changes?
Stenotic leads to more hemodynamic changes
