ton mitral valve replacement

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MITRAL VALVE REPLACEMENT (PG1/2)MD 2 | PBL Case: #3, T

SaipaSony Ton | 10/11/201

LI Rationale :

Context: Patient Tui Saipaia (46 yo, Male, Samoan) is diagnosed with severe mitral-valveregurgitation (MR) and is scheduled for mitral-valve replacement surgery. The patient undergoessurgery and recovers uneventfully.

Purpose: Provide overview of the surgical procedure, indications, post-operative-management,and –complications.

Description:

Goal: to reduce the risk and/or symptoms of heart failure

Repair of mitral valve is recommended overvalve replacement, b/c of the diminished riskof thromboembolism. Repair may involvereshaping valvular leaflets, adding support tothe annulus, and/or attaching the valve to

chord-like structures (chordal transposition) Valve replacement is necessary in the

following situations: Extensive ballooning of the mitral valve Calcification of the valvular leaflets and/or

annulus Prolapse of the valve at the posterior leaflet Damage to the valve from infection (e.g.

endocarditis) Procedure: general anesthesia; blood is bypassed from the heart via heart-lung machine; 3-4

hr. procedure

Indications:

Class I (benefit >>> risk) Symptomatic patient with acute MR*

*Emergency situation = intolerable pulmonarycongestion and hemodynamic overload

Symptomatic (NYHA II-IV)*/asymptomaticpatients with chronic MR and mild/moderateleft-ventricle (LV) dysfunction**NYHA: New York Heart Association functionalclassification for extent of heart failure. II: milddyspnea/angina & slight limitation of physical activityIV: severe limitations and symptoms at rest*Ejection fraction (EF) between 30-60% and/or end-systolic dimension (ESD) <55 mm





Class II (benefit > risk) Asymptomatic patients with chronic MR and

preserved LV function* at an experiencedsurgical center with90% likelihood of

successful repair (not replacement)*EF > 60% and ESD < 40 mm

Asymptomatic patients with chronic MR,preserved LV function, and new onset of atrialfibrillation

Asymptomatic patients with chronic MR,preserved LV function, and pulmonaryhypertension†† Pulmonary artery systolic pressure > 50 mm Hg at rest;or > 60 mm Hg with exercise

Symptomatic patients (NYHA III-IV symptoms)with chronic MR due to severe LV dysfunction

(EF <30%), despite therapy for heart failureClass IV (risk < benefit) Asymptomatic patients with chronic MR and

preserved LV function**EF > 60% and ESD < 40 mm

Selection of Valve Prostheses for Mitral Valve Replacement:

Valves: Mechanical Tissue/Bio-prosthetic (e.g.porcine)

Advantages Excellent durability Low thromboembolic risk

Disadvantages

High thromboembolic risk Poor durability; earlydegeneration =>calcification (esp. in youngpts.)

Indications Patients (age <65) withlong-standing atrialfibrillation

Patients who cannothave warfarin therapy(Class I)

Patients (age >65) Patients (age <65) in

sinus rhythm who areaware of lifestyleconsiderations

Post-opmanagement

Heparin for initial 2 days Vitamin K antagonist

(VKA) therapy*, e.g.

warfarin

Heparin for initial 2 days VKA therapy for initial 3

months

Long-term aspirin therapy

Mechanical Heart (St. Jude Medical)

Bovine Tissue Valv(Carpentier-Edwards)





*Target INR based on type of mechanical valve

Aspirin supplementationfor high-riskthromboembolism*(exception: high risk tobleed)*Atrial fibrillation,hypercoagulable state, lowejection fraction

if patients are in sinusrhythm and have noindications for VKA (i.e.high-risk

thromboembolism*)*Atrial fibrillation,hypercoagulable state, low

ejection fraction

Complications: Operative mortality: 4-7% overall mortality for mitral valve replacement surgery

4% mortality for patients (<50 years) 17% mortality for patients (>80 years)

Post-operative risks: infection (both valve types), bleeding, intraoperative MI, and stroke Thromboembolism-related: risk to develop thrombotic/hemorrhagic stroke

Mechanical valves: 1-3% risk increase per year Tissue valves (w/o any anticoagulation): 1.5% risk increase per year

Endocarditis: cumulative incidence is estimated to be 1.4% to 3.1% at 1 year and 3.2% to5.7% at 5 years, which is the same for mechanical- and tissue-valves.

Left ventricular rupture: incidence < 1% undergoing mitral valve-replacement withposterior leaflet preservation/chordal-sparing techniques. Pathology consists of a dissectionpathway from the annulus or endocardial surface of the left ventricle myocardium. Overallmortality > 50% with aforementioned condition.

Prognosis: Survival rate: 50-60% in 10 years (long-term survival is almost identical between

mechanical- and tissue-valves) Congestive heart failure is the most common mode of death

References:1. ACC/AHA 2006 Guidelines for the Management of Patients with Valvular Heart Disease, a 2008 Focused Update

(2008). Journal of the American College of Cardiology, 52:1-142.2. ACCP Valvular and Structural Heart Disease Evidence-Based Clinical Guidelines, 8e (2008). Chest, 133(6).

3. Sellke: Sabiston and Spencer's Surgery of the Chest, 8e. Chapter 78: Acquired Disease of the Mitral Valve.(MDConsult)

4. Hanson, I., Afonso, L.C., (2010). Mitral Regurgitation. eMedicine.

ton mitral valve replacement

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