MITRAL STENOSIS & REGURGITATION Pathophysiology & Anesthetic considerations for non-cardiac surgery

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MITRAL STENOSIS REGURGITATION Pathophysiolo
gy Anesthetic considerations for non-cardiac
surgery

• Presenter Dr Prashant Kumar

University College of Medical Sciences GTB
Hospital, Delhi
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Mitral Stenosis

• Mitral valve is present between LA LV
• Normal mitral valve orifice area (MVA) 4-6cm2
• MVA lt2.5cm2 leads to symptoms
• Decrease in Mitral valve orifice area leading to
  chronic fixed mechanical obstruction to LV
  filling is termed as MS.

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Causes

• Rheumatic Heart disease
• SLE
• Carcinoid syndrome
• Active Infective Endocarditis
• Left atrial myxoma
• Congenital mitral stenosis
• Massive Annular Calcification

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Rheumatic mitral stenosis

• More common in females (2/3rd of all pts)
• Symptoms occur two decades after onset of
  Rheumatic fever
• Age of presentation
• Earlier in 20s-30s
• Now in 40s-50s (slower progression)
• Isolated MS in 40 cases of RHD
• Remaining 60 cases associated with other
  valvular diseases- MR/AR

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Patho-physiology

• Immunological disorder initiated by Group A beta
  hemolytic streptococcus.
• Antibodies produced against streptococcal cell
  wall proteins sugars react with connective
  tissues heart result in rheumatic fever and
  symptoms like
• Carditis
• Arthritis
• Subcutaneous nodules
• Chorea
• Erythema marginatum

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• Chronic cardiac valvular inflammation leads to
  cardiac valvular pathology
• Valvular pathology
• Rheumatic fever involving mitral valves
• Valve leaflet thickening and fusion of
  commissures
• Increased rigidity of valve leaflets
• Thickening, fusion and contracture of chordae
  papillary heads
• Leaflet calcification (long standing MS)
• Progressive reduction in mitral valve orifice
  area
• Mitral Stenosis

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• Mechanical obstruction to left ventricular
  diastolic filling
• Adaptative ? in LAP to maintain LV filling
• ------------------------------------------------
  -------------------------
• LA enlargement ? in pulmonary venous pressure
  ? ? in pulmonary arterial pressure
• Atrial fibrillation Transudation of fluid into
  pulmonary interstitial space
• Thrombus formation
• Systemic thrombo-embolism ?ed pulmonary
  compliance ?Work of breathing
• Progressive dyspnoea on exertion/rest
• Acute conditions like AF, Pregnancy, Pain,
  sepsis
• (? HR/CO)
• Acute ? in LAP
• Pulmonary edema

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Effect of MS on left ventricle

• Pressure gradient between LA LV

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Effect of heart rate

• Gorlin formula
• Valve area Transvalvular flow rate (ml/s)
• K x PG1/2
• (PG Transvalvular pressure gradient, mmHg)
• (K is a hydraulic-pressure constant 38)
• Tachycardia shortens diastole more
  proportionately than systole
• Decreases the overall time for transmitral flow,
• In order to maintain CO, the flow rate per unit
  time must increase
• Pressure gradient increase proportionate to
  square of flow rate
• ?LAP ? Pulmonary venous congestion and symptoms.
• So, patients with MS do not tolerate tachycardia.

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Effect of Atrial fibrillation in MS

• Increased chances of thrombus formation
  systemic thrombo-embolism
• Normally effective atrial contraction is
  important in LV diastolic filling
• In presence of AF
• Loss of effective atrial contraction
• ?ed ventricular rate (?ed diastolic filling time)
• ?
• Impaired LV filling (?ed LV preload)
• ?
• decreased cardiac output

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Diagnosis

• Clinical presentation
• Dyspnea, fatigue, orthopnea, PND, cough,
  hemoptysis,.
• 10 patients have anginal type chest pain not
  attributable to CAD
• Systemic thromboembolism (first symptom in 20
  cases).
• Physical examination
• Low volume pulse
• Sign Symptoms of right sided heart failure -
  engorged neck veins, enlarged tender liver

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• Mitral facies
• Pink purple patches on the cheeks, cyanotic
  skin changes from low cardiac output
• Cardiac auscultation
• Opening snap
• Rumbling diastolic murmur best heard at apex
  radiating to the axilla
• Loud S2 pulmonary hypertension

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• ECG
• Broad notched P wave (left atrial enlargement)
• Atrial fibrillation

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• Chest X-ray
• Normal to ?ed cardiac shadow
• Straightening of the left heart of border and
  elevation of left main bronchus (left atrial
  enlargement)
• mitral calcification
• Evidence of pulmonary edema/ HTN

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• Echocardiography
• Anatomy/size of mitral valve its appendages
• severity of MS (area of orifice)
• Size function of ventricles
• Estimation of pulmonary artery pressure
• Cardiac catheterization and invasive measurement
• Are almost never necessary
• Reserved for situations ECHO sub-optimal/conflict
  with clinical presentation

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Severity of MS
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Guidelines

• Symptomatic MS (progressive dyspnoea on
  exertion, exertional pre-syncope, heart failure)
  is an active cardiac condition pt should
  undergo evaluation treatment before non cardiac
  surgery
• Emergency surgery
• Mild / Moderate MS
• High risk
• Continue medication
• Proceed with surgery
• Severe MS
• Very high risk consent
• Post- op ventilatory consent

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• Pre-operative Optimization of patient
• Atrial fibrillation
• Sinus rhythm/control of ventricular rate
• 1. Digoxin (emergent IV digitalization-
  loading dose 0.25mg iv over 15 minutes
  followed by 0.1mg every hour till response
  occur or total dose of 0.5-1.0mg. Monitor
  ECG, BP, CVP HR lt60bpm- Stop)
• 2. CCB (verapamil/diltiazem 0.075-0.15mg/kg
  IV)
• 3. ß-blocker (esmolol 1mg IV)
• 4. Amiodarone (loading 100mg IV, infusion
  1mg/min IV for 6 hrs. 0.5mg/min for next 18
  hrs)
• 5. Cardioversion in hemodynamic unstable
  patients

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• Pulmonary HTN/Edema/RVF
• 1. Oxygen
• 2. Diuretic
• Loop diuretics
• High dose deleterious
• Combine with vasodilator
• 3. Digitalis
• 4. Morphine (0.1mg/kg)

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• (Pre-operative Optimization of patientgt
  Pulmonary HTN/Edema/RVF continued)
• 5. Vasodilators (NTG)
• Pulmonary vasodilation (?PAP)
• Start from small dose (0.510 µg/kg/min)
• S/E systemic hypotension
• 6. Nesiritide
• Recombinant BNP (Brain natriuretic peptide)
• Arterial venous dilatation
• Controls dyspnoea in Acute heart failure
• 7. Myofilament calcium sensitizer
  (Levosimendan)
• Inodilators (?es myocardial contractile
  strength, dilatation of systemic, pulmonary
  coronary artery)

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• (Pre-operative Optimization of
  patientgt Pulmonary HTN/Edema/RVF continued)
• 8. Inotropic agents
• Norepinephrine
• Dopamine
• Dobutamine
• 9. Inodilators
• Amrinone
• Milrinone

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• Elective surgery
• Mild/ moderate MS
• Proceed with surgery after evaluation
• Continue medications
• Severe MS
• Cardiology referral/surgical correction
• Patients taken in optimized condition

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Management of Anesthesia Anesthetic goals
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Pre medication

• To decrease anxiety any associated likelihood
  of adverse circulatory responses produced by
  tachycardia
• Drug to control heart rate
• Antibiotics (prophylaxis for infective
  endocarditis is no longer recommended) (Ref
  Millers Anesthesia, 7th edition)

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Monitoring

• Asymptomatic
• Standard non-invasive
• ECG,
• HR
• NIBP
• Pulse-oxymetry
• Capnograph
• Temperature

• Symptomatic pts or major surgery
• Standard non-invasive
• Serial ABG
• Invasive monitoring
• IBP
• CVP/PAC
• Echocardiography (TTE/TEE)
• Cardiac catheterization

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Intra-operative management
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Non-opioid induction agents
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Muscle Relaxants
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Post-operative

• Management
• Monitoring
• Oxygen
• Pain relief multimodal including neuroaxial
  opioids
• Intravenous fluids
• Anticoagulants

• Complication
• Pulmonary congestion/edema
• Thrombo-embolism
• Heart failure

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New York Heart Association functional
classification of patients with heart disease
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Congestive Heart Failure

• Diuretics loop diuretics (furosemide 20-40mg
  IV) S/E Hypokalemia
• Digoxin

Therapeutic plasma concentration level
0.5-2.0ng/ml
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• Clinical manifestation of digitalis toxicity
• Plasma level gt 3ng/ml
• Extra Cardiac Anorexia, nausea, vomiting
  abdominal pain (CTZ stimulation)
• Cardiac any type of atrial or ventricular
  arrhythmia, delayed conduction through AV
  Junction.
• Atrial tachycardia with AV block is most common
  arrhythmia
• Ventricular fibrillation is most frequently cause
  of death.
• Treatment of digitalis toxicity
• Stop further dose
• Correction of hypokalemia, hypomagnesemia,
  arterial hypoxemia
• Drugs
• Phenytoin (0.5-1.5mg/kg IV over 5min), lidocaine
  (1-2mg/kg IV), atropine (35-70µg/kg IV) for
  cardiac dysarrhythmia
• Digiband (digoxin specific antibodies, Fab
  portion, IV preparation 40mg vial)
• Insertion of a temporary artificial transvenous
  cardiac pacemaker

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Anticoagulant therapy

• Management of Patients on warfarin
• Emergency surgery
• Discontinue warfarin
• Give vitamin K 0.5 2.0 mg IV
• FFP 15 ml/kg repeat if necessary
• Accept for surgery if INR lt1.5
• Elective surgery
• Stop 3 days preoperatively
• monitor INR daily
• Give heparin when INR lt1.5

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• Stop heparin 6 hours prior to surgery
• Check INR
• Accept for surgery if INR lt1.5
• Restart heparin post-operatively as soon as
  possible
• Both to be given for 2 3 days, stop heparin if
  INR 1.5 2.0.

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• Management of Patients on Heparin
• Emergency surgery
• Consider reversal with IV protamine 1 mg for
  every 100 IU of heparin
• Elective Surgery
• Stop heparin 6 hours prior to surgery
• Check INR, accept for surgery if INR lt1.5
• Restart heparin in post-op as soon as possible
• If patient is on LMWH, we rarely need to stop it.

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Summary of MS

• Is a low fixed cardiac output condition
• Stress condition like pregnancy, labour sepsis,
  condition become worst- CHF, pulmonary edema, AF
• Patients may be on diuretics, digitalis
  anticoagulant therapy
• Peri-operatively these patients have to be
  managed as per medications guidelines
• Tachycardia has to be avoided at any cost
• Pulmonary vasculature resistance has to be
  reduced
• Preload afterload both should be maintained
• NYHA I II - Epidural block or GA
• NYHA III IV - GA preferred over epidural block

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Mitral Regurgitation
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• Retrograde flow of blood from LV to LA through
  incompetent mitral valve during systolic phase
• Causes
• MR is almost always (90) associated with MS in
  RHD
• Degenerative processes of leaflets and chordal
  structures
• Infective endocarditis
• Mitral annular calcification

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• Functional
• Structurally normal leaflets and chordae
  tendineae
• Ischemic heart disease (Ischemic MR)
• Idiopathic dilated cardiomyopathy
• Mitral annular dilatation

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Pathophysiology of MR

• Mitral regurgitation
• Systolic (Retrograde) ejection into LA
• Acute Chronic
• Volume overload in LA LV ?ed LV afterload
  (into LA)
• ?ed LA, LV Pressure ?ed LA/LV size/ compliance
• Pulmonary edema ?ed Cardiac output LA
  dilatation ?ed contractility
• AF ? CO
• Pulmonary congestion

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Acute MR

• Sudden onset MR
• Sudden increase in LV preload
• Enhanced LV contractility ?ed LAP (acute)
• (LV size N) (LA size N)
• Ejection into LA ?ed Pulm vascul pressure
• systemic circulation
• ? cardiac output Pulmonary congestion/edema

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Chronic compensated MR

• Slow development of MR
• Chronic LV overloading
• Eccentric LV hypertrophy LA dilatation
• ?LV radius, ?ed wall tension Maintenance of LAP
• Maintenance of LV systolic function Change in LV
  compliance
• (LVEDP maintained)
• After load/CO maintained
• Gradual decline in LV systolic function
• Decompensated phase

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Decompensated phase

• Progressive LV dilatation
• Mitral annular dilatation ?ed wall
  stress/afterload
• Increased regurgitation deteoration in LV
  syslolic
• diastolic function
• ?ed LAP
• Atrial enlargement Pulmonary congestion/edema/HT
  N
• Atrial Fibrillation RV dysfunction/failure

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Pathophysiology of MS with MR

• MS MR
• Obstruction of blood flow systolic
  (retrograde) ejection into LA
• from LA to LV during diastole
• Volume overload in LA Volume
  overload in LV
• ?ed LV filling ? LAP LV dysfunction
• ?ed CO
• ?ed CO LA dilatation
• ?PVP/PAP
• (LV size/function N)
• RV dysfunction

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MR MS
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Diagnosis

• Clinical presentation
• Fatigue, dyspnoea, orthopnoea/Systemic
  thrombo-embolism
• Physical examination
• Arterial pressure N/?
• Pulse (Water Hammer pulse- ?DBP, ? SBP)
• Signs of RVF like ? JVP
• Systolic thrill at apex (hyperdynamic
  circulation)
• Cardiac auscultation
• Holosystolic murmur
• S1 is absent, soft or buried in the systolic
  murmur

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• ECG
• Non-specific findings
• Atrial fibrillation
• LA enlargement/LV hypertrophy
• Chest X-ray
• Left heart chamber enlargement
• Pulmonary congestion

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• Echocardiography
• Diagnosis/mechanism/severity of MR/MS
• Impact on cardiac chamber size, pressure
  function
• Pulmonary artery pressure
• Presence of thrombus
• Cardiac catheterization with left
  ventriculography
• invasive
• Reserved for pts in whom ECHO is sub-optimal

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• Severity of MR

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Management of Anesthesia

• Problems to be anticipated
• Pulmonary congestion/ edema
• Atrial fibrillation/ thrombo-embolism
• LV dysfunction ? CO
• Acute ? in afterload following ET intubation
  surgical stimulation ? acute decompensation of LV
• Bradycardia - ? time for retrograde blood flow
• Drug induced myocardial depression

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Anesthetic goals in MR Primary goals -
Maintain forward systemic flow - Decrease the
regurgitant fraction - Optimize RV function
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Anesthetic Goals in MS and MR
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Technique of anesthesia In MR

• Regional vs General Anesthesia in MR
• Peripheral nerve blocks
• Safe
• Avoid intravascular drug injections
  (ultrasound/nerve stimulator guided blocks)
• Central neuraxial blocks
• Preload ? HR ?/ ?/ ?, Contractility ?
• Afterload ? Pulmonary vasculature ?
• Mild/ Moderate MR (NYHA class I II) SAB and
  epidural are well tolerated (avoid bradycardia)
• Severe MR (NYHA class III IV) Prefer GA over
  SAB and epidural

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Monitoring

• Asymptomatic
• Standard non-invasive
• ECG,
• HR
• NIBP
• Pulse-oxymeter
• Capnograph
• Temperature

• Symptomatic pts or major surgery
• Standard non-invasive
• Serial ABG
• Invasive monitoring
• IBP
• CVP/PAC
• Echocardiography (TTE/TEE)
• Cardiac catheterization

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Management of GA
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Non-opioid induction agents
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Muscle Relaxants
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Maintenance
Narcotic oxygen relaxant technique Use of N2O
declined
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Summary of MR

• 90 of Rheumatic MR are associated with MS
• LV has to deal with large volume- only a fraction
  goes to systemic circulation
• Patient may present with CHF, pulmonary edema
  LV dysfunction
• Patients may be on diuretics, digitalis
  anticoagulants- to be managed as per patients
  condition and guidelines.
• Bradycardia has to be avoided at any cost
• Systemic vascular resistance (afterload) should
  be kept slightly low
• Preload should me maintained
• NYHA I II - neuraxial block or GA
• NYHA III IV - GA preferred over neuraxial
  block

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Summary

• Valvular heart disease poses challenge during
  anesthesia
• We should know pathophysiology of each valvular
  heart diseases
• Most of the time, valvular heart diseases occur
  in combination
• Our aim is to maintain normal cardiac output
  tissue perfusion by regulating heart rate/rhythm,
  preload, afterload, myocardial contractility.
• Use of regional anesthesia is not contraindicated
  in theses patients, but proper patients selection
  precaution are must.

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References

• Kaplans Cardiac Anesthesia 5th edition
• Millers Anesthesia 7th edition
• Clinical Anesthesia Barash, Cullen, Stoelting,
  5th edition
• Stoeltings Anesthesia Co-existing Disease 5th
  edition
• Harrisons Internal Medicine 17th edition
• Wylie Churchill- Davidsons A Practice of
  Anesthesia 7th edition
• Clinical Anesthesia Morgan 4th edition

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Thank you