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MITRAL STENOSIS . Nick Tehrani, MD. Epidemiology of MS. Hx of Rheumatic fever is elicited in only 50\% of path proven cases Other causes Severe MAC Congenital MS. Clinical Diagnosis of Rheumatic Fever. Diagnosis of acute rheumatic fever Two major Jones criteria, OR

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mitral stenosis

MITRAL STENOSIS

Nick Tehrani, MD

epidemiology of ms
Epidemiology of MS
  • Hx of Rheumatic fever is elicited in only 50% of path proven cases
  • Other causes
    • Severe MAC
    • Congenital MS
clinical diagnosis of rheumatic fever
Clinical Diagnosis of Rheumatic Fever
  • Diagnosis of acute rheumatic fever
    • Two major Jones criteria, OR
    • One major criterion, and two minor criteria

MajorMinor

Carditis Fever

Erythema marginatum PR prolongation

Chorea ESR elevation

Subcutaneous nodules Hx of Rheumatic fever

clinical diagnosis of acute rheumatic fever
Clinical Diagnosis of Acute Rheumatic Fever
  • Additionally, serologic evidence of recent streptococcal infection is needed:
    • Positive bacteriologic culture
    • Increase in ASO titers
    • Increase in anti-DNAse B titers
histopathology
Histopathology
  • The acute valvular pathology caused by Rheumatic fever is:

Mitral Regurgitation

  • Over the next several decades stenosis accrues by:
    • Thickening of the leaflets
    • Fusion of the commisures
    • Fusion or shortening of the chordae
definitions of severity of mitral stenosis
Definitions of severity of Mitral Stenosis
  • Valve Area:
    • <1.0 cm2  Severe
    • 1.0-1.5 cm2  Moderate
    • >1.5-2.5 cm2  Mild
  • Mean gradient:
    • >10 mmHg  Severe
    • 5-10 mmHg  Moderate
    • <5 mmHg  Mild
flow across the stenotic valve
Flow Across the Stenotic Valve
  • Persistent LA-LV gradient in diastole  sustained flow throughout diastole
  • The slope of the envelope is proportional to the severity of stenosis
flow across the stenotic valve10
Flow Across the Stenotic Valve
  • Note the “A” in patient who is in sinus
pathophysiology
Pathophysiology
  • Limited flow into the LV has 3 major sequale:
    • Elevation of Lt. Atrial pressure
    • Secondary RV pressure overload
    • Reduced LV ejection performance
      • Due to diminished preload
      • Tachycardic response to compensate to decreased SV worsens the transmitral gradient
slide13
Determinants of Transmitral Pressure Gradient

Increased Flow, OR

Decreased orifice size

Incr. Gradient.

Elevated LA pressure

slide14
HR=72

HR=100

variability
Variability

Problems are

Introduced by:

  • The three inter-related parameters are:
    • HR
    • CO
    • Trans-mitral gradient

 Mitral valve area

Heart rate variability

CO measurement and reproducibility

different ways of measuring mitral valve area
Different ways of Measuring Mitral Valve Area
  • Echocardiographic:
    • PISA
    • 2-D
    • Pressure half-time
  • Cath:
    • Gorlin’s Equation
    • Pressure half time
the gorlin equation
The Gorlin Equation
  • Torricelli’s Law:
  • Cc =Coefficient of
    • Orifice contraction
  • The Second Equation:
  • Cv=Coefficient of
  • Velocity
the gorlin equation18
The Gorlin Equation
  • Substituting for V, in Torricelli’s Eq.

C

44.3

Simplification of the above:

?

the numerator of the equation
The Numerator of the Equation
  • Flow Across any Valve:
  • For Mitral (and Tricuspid) valve:
the gorlin equation20
The Gorlin Equation
  • Substituting for “Flow” and “h” in the first Eq.:
gorlin s formula for mitral area
Gorlin’s Formula for Mitral Area
  • The Gorlin Formula for Mitral Valve area:
gorlin s formula for mitral area22
Gorlin’s Formula for Mitral Area
  • CO Cardiac output
  • DFP Diastolic Filling Period
  • HR Heart Rate
  • 44.3 Derived Constant
  • C Correction factor for valve type

C=1.0 for all valves except Mitral

C=0.85 for Mitral valve

  • P Mean pressure gradient
figure out the dfp
DFP in Sec/beat

Measure the Distance in mm from MV opening to MV closing in one beat

Convert distance to time

100 speed= 100 mm/sec, makes life easy

50 speed= 50 mm/sec, tough life

Figure out the DFP
figure out the heart rate
Assuming Patient is in Sinus

Measure the RR interval in mm

Convert to Beats/min by…

In 100 speed just divide 6,000 by the RR in mm

Figure out the Heart Rate
slide31
C

A

V

Planimeter

DFP

Shifted Over

instrumentation
Instrumentation
  • The trickiest part is to set up the instrument correctly:
  • The reading must be adjusted to
  • 0.0000
from planimetered area to mean pressure gradient
From Planimetered Area to Mean Pressure Gradient
  • Area as provided by the instrument is in (in)x(in)
  • Must convert to (cm)x(cm)
    • Multiply by 6.45 cm2/In2
  • To obtain mean Area under the curve
    • Divide the Area by the DFP in cm
  • To convert cm of pressure to mm of Hg
    • Multiply the above # in cm, by the “scale factor”
    • Get “Scale factor” from the tracing: mm Hg/cm
how many tracings to planimeter
How many tracings to Planimeter
  • If patient is in sinus => 5 tracings
  • If patient is in A-Fib.=> 10 tracings
putting things in perspective
Putting things in Perspective

CC/Sec

cm2

CC/sec.cm2.(mm Hg)P0.5

mm Hg

potential pitfalls
Potential Pitfalls
  • Wedge vs. LA Pressure
    • Stiff End-hole catheter: Cournand
    • Verify true wedge by checking O2 Sat
    • Mean Wedge should be less than Mean PA
  • Cardiac Output
    • True Fick vs. Thermodilution vs. Green dye
  • Concurrent MR with MS:
    • Gradient across the valve reflects forward and regurgitant flow
    • CO reflects the net forward flow only
      • Likely underestimation of the true valve area
mitral stenosis and the la
Mitral Stenosis and the LA
  • Even in sinus rhythm, the low velocity flow predisposes to formation of atrial thrombi.
  • Low flow pattern is seen as spontaneous contrast on echocardiography
  • 17% of patients undergoing surgery for MS have LA thrombus
    • In one third of cases thrombus restricted to the LAA
pulmonary hypertension
Pulmonary Hypertension
  • Normal pressure drop across pulmonary bed:

10-15 mm Hg

  • Expected mean PA in Mitral Stenosis:

Mean LA (elevated of course) + (10-15 mm Hg)

  • In MS, Mean PA pressure often exceed the expected.
pulmonary hypertension39
Pulmonary Hypertension
  • This pulmonary hypertension has two components:
    • Reactive pulmonary arterial vasoconstriction,
    • Potentially Fixed resistance, secondary to morphologic changes in the pulmonary vasculature
figure out the dfp42
DFP in Sec/beat

Measure the Distance in mm from MV opening to MV closing in one beat

Convert distance to time

100 speed= 100 mm/sec, makes life easy

50 speed= 50 mm/sec, tough life

Figure out the DFP
figure out the heart rate44
Assuming Patient is in Sinus

Measure the RR interval in mm

Convert to Beats/min by…

In 100 speed just divide 60,000 by the RR in mm

Figure out the Heart Rate
slide45
C

A

V

Planimeter

DFP

from planimetered area to mean pressure gradient46
From Planimetered Area to Mean Pressure Gradient
  • Area as provided by the instrument is in (in)x(in)
  • Must convert to (cm)x(cm)
    • Multiply by 6.45 cm2/In2
  • To obtain mean Area under the curve
    • Divide the Area by the DFP in cm
  • To convert cm of pressure to mm of Hg
    • Multiply the above # in cm, by the “scale factor”
    • Get “Scale factor” from the tracing: mm Hg/cm
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