mitral stenosis
Post on 07-Aug-2015
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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)
• 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 ↓ ↔/ ↓ ↔ ↔/↑ ↔
• 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
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