Interactive Tutorial: Surgery For Heart Valve Disease Flashcards
Heart valve problem in general
- Stenosis
- Limited blood pass through —> Pressure overload - Regurgitation
- Large amount of blood going back —> Volume overload
Causes of Valve disease: 1. Chronic rheumatic heart disease (2nd most common) 2. Degeneration (most common) 3. Infective endocarditis 4. IHD 5. Congenital disease Etc.
- Chronic rheumatic heart disease
- Group A beta haemolytic streptococcal pharyngeal infection
- Ab cross-reactivity attacking body own tissue
- Fibrosis of leaflet, ***Commissural (connection points between leaflets) fusion + annulus
- Degeneration
- Actual pathophysiology pathway unknown (Multifactorial)
—> Degeneration of leaflet + chordae
—> Aging
—> ?Genetic
—> ?Same process of atherosclerosis of vessels
- Infective endocarditis
Usually in patients with predisposed valve problem
Causative agents:
- Streptococcus viridans
- Staphylococcus aureus / epidermidis
- Enterococci
Diagnosis:
- Modified Duke’s criteria
- IHD
- Mainly cause problem of ***Mitral valve (particularly posterior LV —> ischaemic LV distortion —> papillary muscle displacement —> tethered chordae —> restricted leaflet closure of MV + annular dilation of AV)
- ?AV, TV
- Congenital disease
- Marfan syndrome
- Aortic problem (e.g. dissection / aneurysm) —> number 1 cause of death
- Valvular problem (e.g. AV / MV regurgitation) - Bicuspid aortic valve
- common in chinese: 2-3% normal population
- sustain higher pressure —> earlier degeneration - Mitral valve prolapse syndrome
- longer mitral valve leaflet —> easier prolapse - Ebstein’s anomaly (Atresia of tricuspid leaflet + Atrialised RV)
- Others
Natural history of heart valve disease
Normal heart function
—> Dilated atrium / ventricle
—> AF (worsening of all symptoms ∵ drop in 20% CO) + Other valves affected
—> Heart failure (∵ Volume / Pressure overload)
—> Life-threatening events
Symptoms of Heart valve disease
- SOB (esp. on exertion)
- Tiredness, dizziness, LOC
- Chest tightness, discomfort, pressure
- Edema (from foot —> knee —> abdomen)
Diagnosis of Heart valve disease
- Stethoscope
- CXR
- ECG
- Echocardiogram (gold standard, easy, non-invasive, accurate)
- Angiogram
- MRI
Etc.
Treatment of Heart valve disease
- Medical (Palliative)
- ACE inhibitors
- Diuretics
Etc. - Trans-catheter treatment
- Surgery
- Valve repair
- Valve replacement
Valve repair vs replacement
Native valve ***better than Artificial valve —> Repair first before replacement whenever possible
- ***Less endocarditis
- ***Less affect heart function
- Better QoL
- no need long term anticoagulant if in sinus rhythm
- less risk of thromboembolism / bleeding
- less risk of prosthetic endocarditis - Repair as first choice
Replacement:
- Require cutting out major native heart tissues
—> Including chordae, papillary muscle (subvalvular apparatus)
—> Alter LV **geometry (Elliptical to Spherical shape) + **function
—> Change LV **outflow direction + **Larger size (Laplace’s law: greater volume of ventricle —> more energy required for contraction)
Mechanical vs Tissue heart valve
Long term complication rate:
- SAME
Mechanical:
- More durable (>20 years)
- Require life long warfarin (X NOAC)
- Risks: Bleeding due to warfarin
Tissue:
- Less durable (~15 years —> 50% chance to re-do)
- Only need short period of warfarin (~3 months)
- Risks: Redo operation
Choice depends on patient preference: Towards Tissue valve: - Pregnancy (∵ warfarin: teratogenic in 3rd trimester, high abortion rate in 1st trimester —> need to switch to heparin) - Old age patient (>65) - History of severe bleeding
Towards Mechanical valve:
- Mechanical valve in-situ
- Long term renal replacement therapy (esp. peritoneal dialysis ∵ ***HyperCa in renal failure patients —> tissue valve calcify much faster)
Atrial Fibrillation
- Rhythm + Rate problem
- Most have no cause ?Degeneration
- Can due to IHD, valve disease, infection, thyroid problem
- Longer time having valve disease —> higher chance of AF
- ~30% of patient have AF before valve operation
Problems:
1. Additional symptom to valve problem (∵ decreased in CO)
- Long term risk
- Blood clot —> Stroke (5x)
- Poor control can lead to cardiomyopathy - Impact on cardiac surgery
- Higher risk for surgery
- Higher early + late mortality
- Only a small proportion of patient can converted back to sinus after surgery if they have AF pre-op
Concomitant AF surgery:
- Maze procedure
—> break down “reentry wave form” + “ectopic foci” by RFA / Cryo
—> allow normal signal run in near normal manner
—> highest success rate 65-90% in literatures (better than Drugs, Catheter ablation)
—> confirmed long term benefits: less stroke, better QoL, less cardiac complications, probably better survival
—> recommended as a ***concomitant procedure to cardiac surgery
Common valve diseases
- Mitral regurgitation
- Mitral stenosis
- Aortic stenosis
- Aortic regurgitation
Prognosis: AS > AR > MS/MR
- Mitral regurgitation
- Volume overload —> Higher requirement for EF to be normal (>60% ∵ higher preload)
- Dilatation of LA + LV —> Increased C:T ratio
Natural history: - Asymptomatic for many years - Progression is slow - Once become severe —> NOT benign —> Develop symptoms —> AF —> Mortality / Surgery in 10 years
Indications for surgery:
- Severe MR + symptom
- Severe MR + LV dysfunction but asymptomatic
- Severe MR + asymptomatic
- if valve likely repairable
- unfavourable features present: AF, pulmonary HT
- Mitral stenosis
- Pressure overload of LA —> LA enlargement —> Pulmonary HT —> Dilated pulmonary artery (shown on CXR) —> Early TR
Causes:
- Rheumatic (99%)
- Congenital
Natural history:
- Progression from Rheumatic fever to Symptomatic MS require 20-40 years
- Asymptomatic: Good survival >80% at 10 years
- Symptomatic: Poor survival 10% at 10 years
- Pulmonary HT: <3 year survival
Treatment:
1. Percutaneous mitral balloon valvuloplasty (PMBV)
- Less severe cases
- Less calcified
- No MR
—> will still progress + need surgery eventually due to ongoing autoimmune disease process
- Surgery (repair / replacement —> repair treatment of choice for all etiologies)
- More severe cases
Mitral repair / replacement techniques
Repair: Treat: Annulus + Leaflet + Chordae 1. Quadrangular resection 2. Annuloplasty 3. Triangular resection 4. Chordal shortening 5. Chordal transfer 6. Chordal replacement 7. Double orifice technique 8. Leaflet extension
Replacement:
- Excise all leaflets + chordae —> Larger space for prosthesis
- Preserving leaflets (esp. posterior leaflet): To preserve LV geometry + function
Open heart surgery
- Median sternotomy
- Most common approach to perform MVR / MR repair - Cardiopulmonary bypass
- Motionless + Bloodless surgical field
Potential problem:
- Need 10 weeks for bone healing —> No weight bearing exercise
- Larger wound
- Wound infection
General results after MV surgery
- Mortality: 1-5%
- Morbidity: 5%
—> General: severe infection, bleeding, multi-organ failure, CVA
—> Specific: heart block (require pacemaker), heart failure (require inotropic support), peri-op MI - Progressive improvement of symptom + heart function after 3 months of surgery
Transcatheter treatment for mitral valve
- Developing stage
- Mainly for high risk patients / research purpose
- Repair / Replacement
- Aortic stenosis
Pressure overload —> LV hypertrophy
Natural history: - Most lethal - Prolong latent period + slow progression - Asymptomatic: Good prognosis - Symptomatic: 2-3 year survival + high risk of sudden death - Poor prognostic factor: —> Heavily calcified valve —> Jet velocity >4m/s
Symptoms:
- SOB
- Chest pain
- LOC
Indications for surgery:
- Severe AS + symptomatic
- Severe AS + LV dysfunction
- Severe AS + asymptomatic / normal LV
- Heavily calcified
- Vmax >4m/s
- Rapid rate of deterioration
- Aortic regurgitation
- Volume overload —> LV dilatation —> Increased C:T ratio
Natural history:
- Mild / Moderate: Progress slowly + unlikely to have symptoms
- Severe:
—> Asymptomatic: Progression to symptom / LV dysfunction 5% per year
—> Symptomatic / LV dysfunction: 10-20% per year of mortality
Indications of surgery:
- Severe AR + symptoms
- Severe AR + LV dysfunction
- EF <50% / ESD >55mm / EDD >75mm
Treatment options for Aortic valve disease
- **Aortic valve replacement (vs Mitral: **repair mainly) (∵ mainly stenosis —> valve too calcified to be repaired)
- Aortic valve repair
- Pulmonary valve autotransplant
- Homograft
- LV to descending aorta shunt
General results after AV surgery
Operative mortality:
- 1-5% depending on pre-morbid, cardiac, operative condition
Complications:
- ~5%
- General: bleeding, infection, multi-organ failure, CVA
- Specific: heart block, heart failure, peri-op MI
New treatment options for AV valve
- Surgical AVR
- Small incision: Hemisternotomy / Thoracotomy - Transcatheter AVR (TAVI)
- Femoral approach
- Transaortic / Transapical approach
—> patients with access problem
How to choose between treatments?
- Low risk patients (young, good past health) —> Surgical AVR
- Moderate risk patients (some comorbidities, older age) —> Surgical AVR
- High risk patients —> TAVI
- Inoperable patients —> TAVI
Surgical AVR: Higher durability
Summary
- Increasing patients with valve disease, esp. AS, MR
- Key symptoms: SOB, Chest discomfort, Dizziness, Tiredness, Edema
- Once symptomatic —> most valve problem have ***poor prognosis
- Treatment: Surgery / Transcatheter based
- General indication for surgery: **Severe valve problem + **Symptom / ***Ventricular dysfunction
- Surgery for valve disease: Repair > Replacement
- Traditional approach: Median sternotomy
- Recent development of surgery for valve: Minimally invasive surgery, Robotic assisted surgery, TAVI, Other trans-catheter instruments
