MITRAL STENOSIS Anesthetic considerations

Dr.Harshil Joshi

DM Cardiac Anesthesia Resident

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.

Natural History- untreated MS• Progressive, lifelong disease• Usually slow & stable in the early years• Progressive acceleration in the later years• 20-40 year latency from rheumatic fever to symptom onset in

developed countries• After symptoms-- additional 10 years before disabling

symptoms

Causes

• Rheumatic Heart disease

• SLE

• Carcinoid syndrome

• Active Infective Endocarditis

• Left atrial myxoma

• Congenital mitral stenosis

• Massive Annular Calcification

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

Rheumatic fever- Jones criteria

Major criteria • Carditis• Arthritis• Subcutaneous nodules• Chorea• Erythema marginatum

Minor CriteriaClinical • Fever• Arthralgia• P/H rheumatic fever / RHDLaboratory• Acute phase reactants:

leucocytosis, ESR, CR proteins

• Prolonged PR interval

RF - Essential criteria

• Evidence for recent streptococcal infection as indicated by

– Increased anti streptococcal antibody titers

– Positive throat cultures

– Recent scarlet fever

Symptoms

• Valve area > 1.5 cm2 usually does not produce symptoms at rest

• Dyspnoea in patients with mild MS usually precipitated by – Exercise– Emotional stress– Fever, Infection– Anaemia – Pregnancy– Atrial fibrillation with rapid ventricular response– Thyrotoxicosis

Symptoms…• Dyspnoea

• PND

• Orthopnea

• Palpitations

• Fatigue

• Chest pain (RVH,CAD)

• Cough

• Hemoptysis

• Atrial fibrillation• Systemic embolism• Pulmonary infection• Right sided failure

– Hepatic Congestion– Edema

General examination

• Mitral facies

‘Pink purple patches on the cheeks, cyanotic skin changes from low cardiac output’

• Pulse – low volume pulse

• Blood pressure

Examination

Inspection• Engorged vein in neckPalpation:• Tapping apex beat• Palpable S1• Parasternal heave• Palpable S2• Diastolic thrill

Auscultation:• S1 is short, sharp , accentuated

(loud, snapping) • S2 audible• Opening snap after S2• A2 to OS interval inversely

proportional to severity• Diastolic rumble: length

proportional to severity• In severe MS with low flow-

S1, OS & rumble may be inaudible

Features of PHT

Palpation:

• Parasternal heave• Palpable S2

Auscultation:• ESM over pulmonary area• SM which increases on

inspiration heard along the left sternal border -Functional TR

• Graham Steel murmur – pulmonary Regurgitation

Complications• Atrial dysrhythmias• Systemic embolization (10-25%)

– Risk of embolization is related to age, presence of atrial fibrillation, previous embolic events

• Congestive heart failure • Pulmonary infarcts (result of severe CHF)• Endocarditis• Pulmonary infections

Normal mitral valve

• MVA > 4 cm2 (4- 6 cm2)

• Diastolic mitral valve flow of 150- 200 ml/ sec/ diastole

• Diastolic transvalvular pressure gradient of less than 2 mmHg

Classification

Mild Moderate Severe

Mean gradient (mm Hg) < 5 5- 10 > 10

Pulmonary artery systolic pressure (mm Hg)

< 30 30- 50 > 50

Valve area (cm2) > 1.5 1.0- 1.5 < 1.0

Pre-operative Optimization of patient Atrial fibrillationSinus 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

– Pulmonary HTN/Edema/RVF

1. Oxygen

2. Diuretic

Loop diuretics

High dose deleterious

Combine with vasodilator

3. Digitalis

4. Morphine (0.1mg/kg)

5. Vasodilators (NTG)Pulmonary vasodilation (↓PAP) Start from small dose (0.5–10

μg/kg/min)S/E: systemic hypotension

6. NesiritideRecombinant BNP Arterial & venous dilatationControls dyspnoea in Acute heart

failure7. Myofilament calcium sensitizer

(Levosimendan) Inodilators (↑es myocardial

contractile strength, dilatation of systemic, pulmonary & coronary artery)

8. Inotropic agents

Norepinephrine

Dopamine

Dobutamine

9. Inodilators

Amrinone

Milrinone

• ANAESTHETIC MANAGEMENT

medications to continue intra operatively

• Diuretics- Evaluate fluid status Check electrolytes on day of surgery

• Drugs to control AF ( Digoxin, beta blockers, Amiodarone) Continue in perioperative period

• Patients on pulmonary vasodilators (sildenafile,bosentan)

• Watch serum potassium- in patients receiving digoxin and diuretics

• Warfarin- switch to heparin perioperative for better control. Titrate to APTT 1.5-2 times normal Continue post op.

• Management of anticoagulation perioperatively should balance risks of bleeding with the risk of thrombosis and systemic embolization

Management of Anesthesia Anesthetic goals

Heart rate/

rhythm

Sinus rhythm, control ventricular rate (70-90bpm)

Avoid tachycardia

Preload Normal or increased Avoid under-load/ overload

After-load Maintain normal after load

Avoid sudden increase/reduction in afterload

Contractility Usually LV systolic function: N

But may be reduced in long history

Avoid cardio-depressant drugs

Pulmonary HTN/RV dysfunction

Normal oxygenation, acid base status

Avoid hypoxia, hypercarbia, acidosis

• ANAESTHETIC MANAGEMENT

• Premedication

• Adequate dose prevents anxiety and tachycardia. While overdose cause hypoventilation & hypotension(↑pvr &↓c.o.) exacerbate pulmonary hypertension.

Morphine 0.1-0.2mg/kgClonidine 30ug iv 30 min before surgerySmall dose Benzodiazepenes can be given ( reduce dose of morphine)

• Anticholinergics- avoided as they increase heart rate

Pre medication• To decrease anxiety & any associated likelihood of adverse

circulatory responses produced by tachycardia

Class Drug Dose (mg/kg) Route

BZPs Diazepam 0.1-0.15 PO, IMLorazepam 0.03-0.06 PO, IMMidazolam 0.03-0.07 IM

Opioids Morphine 0.2 IMMeperidine 1.0-1.5 IM

• Monitoring• ECG, BP, Spo2, capnography, temperature • Invasive monitoring-

-Direct arterial pressure -CVP- measure loading conditions and means of transfusing inotropes/dilators -Pulmonary artery catheter- - Monitor Pulmonary Artery Pressure ( PAP)- useful in PAH

- Helpful for confirming the adequacy of cardiac function, intravascular fluid volume, ventilation, and oxygenation.

- PCWP reflect LA pressure but not LVEDP because of mitral stenosis.

2- D ECHO 2- D ECHO

Mitral valve areaMitral valve areaMV characteristics ( Wilkins score )MV characteristics ( Wilkins score )LA – LV gradientLA – LV gradientMitral regurgitationMitral regurgitationDimensions of LA , LA clot from TEEDimensions of LA , LA clot from TEEPulmonary hypertensionPulmonary hypertensionOther valvular pathologyOther valvular pathologyLV functionLV function

• ANAESTHETIC MANAGEMENT

• Induction

• Etomidate best for hemodynamic stabilty .

• Any intravenous induction drug except ketamine( H.R.)

• Should be double diluted and given slowly.

• Midazolam,Narcotic( morphine 0.5mg/kg or Fentanyl 5-10 ug/kg)

• Avoid Propofol- direct and indirect effects on ventricular preload

• Muscle relaxants Vecuronium + Narcotics- dangerous bradycardia. Hence pancuronium preferred unless basal heart rate is highRocuronium- vagolytic. Hence slightly HR and PAP↓

• Avoid atracurium- histamine release

• Benzodiazepenes (midazolam) – use cautiously as can cause profound vasodilatation with narcotics.

Non-opioid induction agents

Thiopentone Propofol Etomidate Ketamine BZP

MAP ↔

HR ↔

CO ↔

SVR ↔/↓

PVR ↔ ↔/↓ ↓ ↑ ↔

contr ↓ ↔/ ↓ ↔ ↔/↑ ↔

Muscle Relaxants

Pan Vec Roc Atra Miv Sch

MAP -

HR -

CO - -

SVR - - - -

Histamine - - - + + -

• Maintainence• A balanced anesthesia that includes low

concentrations of a volatile anesthetic is desirable.Avoid halothane- arrythmogenic

• Isoflurane(tachy cardia),Sevoflurane(ideal).• Nitrous oxide – Increases PVR . Best avoided in PAH• Vasodilator therapy ( NTG/ Nitroprusside 0.5-1

ug/kg/min)- desirable in severe PAH• Intraoperative fluid replacement must be carefully

titrated• Reversal- slowly to help ameliorate any drug-induced

tachycardia caused by the anticholinergic drug in the mixture.

• Post operative management• MV replacement-improves hemodynamics , obstruction to

LV filling resolved• Mean gr. 4-7 mm hg across prosthetic valve remain.• If pulmonary hypertension & rv failure – support of

choice is milrinone, dobutamine , nitricoxide & pg E1• Inotropic support and vasodilator therapy should be

continued for prolonged ( 24-48 hrs) in patients with severe PAH.

• May require a period of mechanical ventilation:- avoid Pain and hypoventilation(PVR)

• Relief of postoperative pain with neuraxial opioids useful

Post-operative

Management

• Monitoring

• Oxygen

• Pain relief: multimodal including neuroaxial opioids

• Intravenous fluids

• Anticoagulants

Complication

• Pulmonary congestion/edema

• Thrombo-embolism

• Heart failure

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

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

• 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

THANK YOU