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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

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Mitral stenosis l.jpg

MITRAL STENOSIS

Nick Tehrani, MD


Epidemiology of ms l.jpg

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 l.jpg

Clinical Diagnosis of Rheumatic Fever

  • Diagnosis of acute rheumatic fever

    • Two major Jones criteria, OR

    • One major criterion, and two minor criteria

      MajorMinor

      CarditisFever

      Erythema marginatumPR prolongation

      ChoreaESR elevation

      Subcutaneous nodulesHx of Rheumatic fever


Clinical diagnosis of acute rheumatic fever l.jpg

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 l.jpg

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 l.jpg

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 a normal mitral valve in diastole l.jpg

Flow Across a Normal Mitral Valve in Diastole


Flow across the stenotic valve l.jpg

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 l.jpg

Flow Across the Stenotic Valve

  • Note the “A” in patient who is in sinus


Diastolic transmitral pressure gradient due to limited lv filling l.jpg

Diastolic Transmitral Pressure Gradient due to Limited LV Filling


Pathophysiology l.jpg

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 l.jpg

  • Determinants of Transmitral Pressure Gradient

Increased Flow, OR

Decreased orifice size

Incr. Gradient.

Elevated LA pressure


Slide14 l.jpg

HR=72

HR=100


Variability l.jpg

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 l.jpg

Different ways of Measuring Mitral Valve Area

  • Echocardiographic:

    • PISA

    • 2-D

    • Pressure half-time

  • Cath:

    • Gorlin’s Equation

    • Pressure half time


The gorlin equation l.jpg

The Gorlin Equation

  • Torricelli’s Law:

  • Cc =Coefficient of

    • Orifice contraction

  • The Second Equation:

  • Cv=Coefficient of

  • Velocity


The gorlin equation18 l.jpg

The Gorlin Equation

  • Substituting for V, in Torricelli’s Eq.

C

44.3

Simplification of the above:

?


The numerator of the equation l.jpg

The Numerator of the Equation

  • Flow Across any Valve:

  • For Mitral (and Tricuspid) valve:


The gorlin equation20 l.jpg

The Gorlin Equation

  • Substituting for “Flow” and “h” in the first Eq.:


Gorlin s formula for mitral area l.jpg

Gorlin’s Formula for Mitral Area

  • The Gorlin Formula for Mitral Valve area:


Gorlin s formula for mitral area22 l.jpg

Gorlin’s Formula for Mitral Area

  • COCardiac output

  • DFPDiastolic Filling Period

  • HRHeart Rate

  • 44.3Derived Constant

  • CCorrection factor for valve type

    C=1.0 for all valves except Mitral

    C=0.85 for Mitral valve

  • PMean pressure gradient


How do you use this eqn l.jpg

Step 1: Figure out the Numerator First:

Dimensional analysis:

How Do you use this Eqn.?


Figure out the dfp l.jpg

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 l.jpg

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


Let s figure out the denominator l.jpg

Let’s Figure out the Denominator


Slide28 l.jpg

No Mitral Stenosis


Diastolic transmitral pressure gradient due to limited lv filling29 l.jpg

Diastolic Transmitral Pressure Gradient due to Limited LV Filling

Left Atrial

Tracing


Need to left shift the pcwp tracing l.jpg

Need to Left Shift the PCWP Tracing


Slide31 l.jpg

C

A

V

Planimeter

DFP

Shifted Over


Instrumentation l.jpg

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 l.jpg

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 l.jpg

How many tracings to Planimeter

  • If patient is in sinus =>5 tracings

  • If patient is in A-Fib.=>10 tracings


Putting things in perspective l.jpg

Putting things in Perspective

CC/Sec

cm2

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

mm Hg


Potential pitfalls l.jpg

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 l.jpg

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 l.jpg

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 l.jpg

Pulmonary Hypertension

  • This pulmonary hypertension has two components:

    • Reactive pulmonary arterial vasoconstriction,

    • Potentially Fixed resistance, secondary to morphologic changes in the pulmonary vasculature


How do you use this eqn41 l.jpg

Step 1: Figure out the Numerator First:

Dimensional analysis:

How Do you use this Eqn.?


Figure out the dfp42 l.jpg

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 l.jpg

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 l.jpg

C

A

V

Planimeter

DFP


From planimetered area to mean pressure gradient46 l.jpg

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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