Interactive Tutorial: Surgery For Heart Valve Disease

Question 1

Heart valve problem in general

Answer 1

1. Stenosis
   - Limited blood pass through —> Pressure overload
2. 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.

Question 2

1. Chronic rheumatic heart disease

Answer 2

• Group A beta haemolytic streptococcal pharyngeal infection
• Ab cross-reactivity attacking body own tissue
• Fibrosis of leaflet, ***Commissural (connection points between leaflets) fusion + annulus

Question 3

2. Degeneration

Answer 3

• Actual pathophysiology pathway unknown (Multifactorial)
  —> Degeneration of leaflet + chordae
  —> Aging
  —> ?Genetic
  —> ?Same process of atherosclerosis of vessels

Question 4

3. Infective endocarditis

Answer 4

Usually in patients with predisposed valve problem

Causative agents:

• Streptococcus viridans
• Staphylococcus aureus / epidermidis
• Enterococci

Diagnosis:
- Modified Duke’s criteria

Question 5

4. IHD

Answer 5

• 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

Question 6

5. Congenital disease

Answer 6

1. Marfan syndrome
   - Aortic problem (e.g. dissection / aneurysm) —> number 1 cause of death
   - Valvular problem (e.g. AV / MV regurgitation)
2. Bicuspid aortic valve
   - common in chinese: 2-3% normal population
   - sustain higher pressure —> earlier degeneration
3. Mitral valve prolapse syndrome
   - longer mitral valve leaflet —> easier prolapse
4. Ebstein’s anomaly (Atresia of tricuspid leaflet + Atrialised RV)
5. Others

Question 7

Natural history of heart valve disease

Answer 7

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

Question 8

Symptoms of Heart valve disease

Answer 8

1. SOB (esp. on exertion)
2. Tiredness, dizziness, LOC
3. Chest tightness, discomfort, pressure
4. Edema (from foot —> knee —> abdomen)

Question 9

Diagnosis of Heart valve disease

Answer 9

1. Stethoscope
2. CXR
3. ECG
4. Echocardiogram (gold standard, easy, non-invasive, accurate)
5. Angiogram
6. MRI
   Etc.

Question 10

Treatment of Heart valve disease

Answer 10

1. Medical (Palliative)
   - ACE inhibitors
   - Diuretics
   Etc.
2. Trans-catheter treatment
3. Surgery
   - Valve repair
   - Valve replacement

Question 11

Valve repair vs replacement

Answer 11

Native valve ***better than Artificial valve —> Repair first before replacement whenever possible

1. ***Less endocarditis
2. ***Less affect heart function
3. Better QoL
   - no need long term anticoagulant if in sinus rhythm
   - less risk of thromboembolism / bleeding
   - less risk of prosthetic endocarditis
4. 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)

Question 12

Mechanical vs Tissue heart valve

Answer 12

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)

Question 13

Atrial Fibrillation

Answer 13

• 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)

2. Long term risk
   - Blood clot —> Stroke (5x)
   - Poor control can lead to cardiomyopathy
3. 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

Question 14

Common valve diseases

Answer 14

1. Mitral regurgitation
2. Mitral stenosis
3. Aortic stenosis
4. Aortic regurgitation

Prognosis: AS > AR > MS/MR

Question 15

1. Mitral regurgitation

Answer 15

• 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:

1. Severe MR + symptom
2. Severe MR + LV dysfunction but asymptomatic
3. Severe MR + asymptomatic
   - if valve likely repairable
   - unfavourable features present: AF, pulmonary HT

Question 16

2. Mitral stenosis

Answer 16

• 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

2. Surgery (repair / replacement —> repair treatment of choice for all etiologies)
   - More severe cases

Question 17

Mitral repair / replacement techniques

Answer 17

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

Question 18

Open heart surgery

Answer 18

1. Median sternotomy
   - Most common approach to perform MVR / MR repair
2. Cardiopulmonary bypass
   - Motionless + Bloodless surgical field

Potential problem:

1. Need 10 weeks for bone healing —> No weight bearing exercise
2. Larger wound
3. Wound infection

Question 19

General results after MV surgery

Answer 19

• 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

Question 20

Transcatheter treatment for mitral valve

Answer 20

• Developing stage
• Mainly for high risk patients / research purpose
• Repair / Replacement

Question 21

3. Aortic stenosis

Answer 21

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:

1. Severe AS + symptomatic
2. Severe AS + LV dysfunction
3. Severe AS + asymptomatic / normal LV
   - Heavily calcified
   - Vmax >4m/s
   - Rapid rate of deterioration

Question 22

4. Aortic regurgitation

Answer 22

• 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:

1. Severe AR + symptoms
2. Severe AR + LV dysfunction
   - EF <50% / ESD >55mm / EDD >75mm

Question 23

Treatment options for Aortic valve disease

Answer 23

1. **Aortic valve replacement (vs Mitral: **repair mainly) (∵ mainly stenosis —> valve too calcified to be repaired)
2. Aortic valve repair
3. Pulmonary valve autotransplant
4. Homograft
5. LV to descending aorta shunt

Question 24

General results after AV surgery

Answer 24

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

Question 25

New treatment options for AV valve

Answer 25

1. Surgical AVR - Small incision: Hemisternotomy / Thoracotomy 2. 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

Question 26

Summary

Answer 26

- 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