mitral stenosis regurgitation pathophysiology anesthetic considerations for non cardiac surgery n.
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Presenter: Dr Prashant Kumar

Presenter: Dr Prashant Kumar

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  1. MITRAL STENOSIS & REGURGITATIONPathophysiology & Anesthetic considerations for non-cardiac surgery Presenter: Dr Prashant Kumar University College of Medical Sciences & GTB Hospital, Delhi

  2. 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.

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

  4. 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

  5. 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

  6. 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

  7. 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

  8. Pressure gradient between LA & LV Effect of MS on left ventricle

  9. 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.

  10. 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

  11. 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

  12. 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

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

  14. 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)

  15. 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

  16. Severity of MS

  17. 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

  18. 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

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

  20. (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)

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

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

  23. Management of Anesthesia Anesthetic goals

  24. 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)

  25. 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

  26. Intra-operative management

  27. Non-opioid induction agents

  28. Muscle Relaxants

  29. Management Monitoring Oxygen Pain relief: multimodal including neuroaxial opioids Intravenous fluids Anticoagulants Complication Pulmonary congestion/edema Thrombo-embolism Heart failure Post-operative

  30. New York Heart Association functional classification of patients with heart disease

  31. Congestive Heart Failure • Diuretics: loop diuretics (furosemide 20-40mg IV); S/E: Hypokalemia • Digoxin: Therapeutic plasma concentration level: 0.5-2.0ng/ml

  32. 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

  33. 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

  34. 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.

  35. 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.

  36. 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

  37. Mitral Regurgitation

  38. 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

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

  40. 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

  41. 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

  42. 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

  43. 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

  44. 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

  45. MR MS

  46. 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

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