mitral stenosis regurgitation pathophysiology anesthetic considerations for non cardiac surgery
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MITRAL STENOSIS & REGURGITATION Pathophysiology & Anesthetic considerations for non-cardiac surgery. Presenter: Dr Prashant Kumar. University College of Medical Sciences & GTB Hospital, Delhi. Mitral Stenosis. Mitral valve is present between LA & LV

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mitral stenosis regurgitation pathophysiology anesthetic considerations for non cardiac surgery

MITRAL STENOSIS & REGURGITATIONPathophysiology & Anesthetic considerations for non-cardiac surgery

Presenter: Dr Prashant Kumar

University College of Medical Sciences & GTB Hospital, Delhi

mitral stenosis
Mitral Stenosis
  • Mitral valve is present between LA & LV
  • Normal mitral valve orifice area (MVA): 4-6cm2
  • MVA <2.5cm2 leads to symptoms
  • Decrease in Mitral valve orifice area leading to chronic & fixed mechanical obstruction to LV filling is termed as MS.
causes
Causes
  • Rheumatic Heart disease
  • SLE
  • Carcinoid syndrome
  • Active Infective Endocarditis
  • Left atrial myxoma
  • Congenital mitral stenosis
  • Massive Annular Calcification
rheumatic mitral stenosis
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
patho physiology
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
slide6
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

slide7
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

↑ in pulmonary arterial pressure*--------→ Pulmonary arterial hypertrophy (Pulmonary HTN)

RV hypertrophy and dilatation

RV failure

effect of heart rate
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.
effect of atrial fibrillation in ms
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

diagnosis
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
slide13
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
slide14
ECG

Broad notched P wave (left atrial enlargement)

Atrial fibrillation

slide15
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

LAA: Left atrial appendages, MPA: Main pulmonary artery, LPA: left pulmonary artery, RPA: Right pulmonary artery, Ao- Aortic knuckle (Ao)

slide16
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
guidelines
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
slide19
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 <60bpm- Stop)

2. CCB (verapamil/diltiazem: 0.075-0.15mg/kg IV)

3. β-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

slide20
Pulmonary HTN/Edema/RVF

1. Oxygen

2. Diuretic

Loop diuretics

High dose deleterious

Combine with vasodilator

3. Digitalis

4. Morphine (0.1mg/kg)

slide21
(Pre-operative Optimization of patient> Pulmonary HTN/Edema/RVF continued…)

5. Vasodilators (NTG)

Pulmonary vasodilation (↓PAP)

Start from small dose (0.5–10 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)

slide22
(Pre-operative Optimization of patient> Pulmonary HTN/Edema/RVF continued…)

8. Inotropic agents

Norepinephrine

Dopamine

Dobutamine

9. Inodilators

Amrinone

Milrinone

slide23
Elective surgery
    • Mild/ moderate MS
      • Proceed with surgery after evaluation
      • Continue medications
    • Severe MS
      • Cardiology referral/surgical correction
      • Patients taken in optimized condition
pre medication
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: Miller’s Anesthesia, 7th edition)
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

Monitoring
post operative
Management

Monitoring

Oxygen

Pain relief: multimodal including neuroaxial opioids

Intravenous fluids

Anticoagulants

Complication

Pulmonary congestion/edema

Thrombo-embolism

Heart failure

Post-operative
congestive heart failure
Congestive Heart Failure
  • Diuretics: loop diuretics (furosemide 20-40mg IV); S/E: Hypokalemia
  • Digoxin:

Therapeutic plasma concentration level: 0.5-2.0ng/ml

slide35
Clinical manifestation of digitalis toxicity
  • Plasma level > 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
anticoagulant therapy
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 <1.5
    • Elective surgery
        • Stop 3 days preoperatively
        • monitor INR daily
        • Give heparin when INR <1.5
slide37
Stop heparin 6 hours prior to surgery
  • Check INR
  • Accept for surgery if INR <1.5
  • Restart heparin post-operatively as soon as possible
  • Both to be given for 2 – 3 days, stop heparin if INR 1.5 – 2.0.
slide38
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 <1.5
      • Restart heparin in post-op as soon as possible

If patient is on LMWH, we rarely need to stop it.

summary of ms
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
slide41
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
slide42
Functional

Structurally normal leaflets and chordae tendineae

    • Ischemic heart disease (Ischemic MR)
    • Idiopathic dilated cardiomyopathy
    • Mitral annular dilatation
pathophysiology of mr
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

acute mr
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

chronic compensated mr
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

decompensated phase
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/HTN

Atrial Fibrillation RV dysfunction/failure

pathophysiology of ms with mr
Pathophysiology of MS with MR

MSMR

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 COLA dilatation

↑PVP/PAP

(LV size/function: N)

RV dysfunction

diagnosis1
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
slide50
ECG

Non-specific findings

Atrial fibrillation

LA enlargement/LV hypertrophy

Chest X-ray

Left heart chamber enlargement

Pulmonary congestion

slide51
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
management of anesthesia
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
slide54
Anesthetic goals in MR Primary goals - Maintain forward systemic flow - Decrease the regurgitant fraction - Optimize RV function
technique of anesthesia in mr
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
monitoring1
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

Monitoring
maintenance
Maintenance

Narcotic oxygen relaxant technique

Use of N2O – declined

summary of mr
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
summary
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.
references
References
  • Kaplan’s Cardiac Anesthesia; 5th edition
  • Miller’s Anesthesia; 7th edition
  • Clinical Anesthesia; Barash, Cullen, Stoelting, 5th edition
  • Stoelting’s Anesthesia & Co-existing Disease; 5th edition
  • Harrison’s Internal Medicine; 17th edition
  • Wylie & Churchill- Davidson’s A Practice of Anesthesia; 7th edition
  • Clinical Anesthesia; Morgan 4th edition
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