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SpC Surgery > Interactive Tutorial: Surgery Treatment Of Coronary Artery Disease And Heart Transplant > Flashcards

Interactive Tutorial: Surgery Treatment Of Coronary Artery Disease And Heart Transplant Flashcards

1
Q

CAD

A

Types:

  1. Stable angina
  2. ACS
    - Unstable angina
    - Non-STEMI
    - STEMI
  3. Sudden death
5-year survival of CAD:
- Left main: 50%
- 3 vessel: 70%
- 2 vessel: 88%
- 1 vessel: 90-95%
—> Other interfering risk factors: LV function, extent of Ischaemia, anatomy of lesion, arrhythmia, DM, recent MI etc.

Diagnosis:
- History, P/E —> Determine Low, Intermediate, High risk patient of having CAD
- Low / Intermediate risk:
—> Able to exercise —> **Stress test / Exercise ECG (aka treadmill)
—> Not able to exercise —> **CT coronary (Iodine contrast), **MRI (Gadolinium contrast) / **Stress Echo, **Perfusion study (Thallium contrast)
- High risk:
—> **Catheter coronary angiogram (still Gold standard) —> Vessels narrowed >50% diameter considered significant

Other classification:

  1. Perfusion study and Viability study
    - SPECT scan (aka Thallium scan —> Perfusion study)
    - PET scan
    - MRI
    - Stress Echo
  2. Anatomical study
    - CT coronary angiogram
    - Catheter coronary angiogram with functional flow reserve
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2
Q

Treatment options of Stable angina

A
  1. Medical treatment
    - ABCDE
    —> Aspirin + Anti-anginal
    —> Beta blocker + BP control
    —> Cholesterol + Cigarette control
    —> Diet + DM
    —> Exercise + Education
  2. PCI
  3. CABG

Choice: Balance between risks + benefits
Benefits: Relieve symptoms + Improve survival
Risks: Morbidity + Mortality

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3
Q

Indications for Revascularisation

A

2 Determining factors:

  1. Symptom
    - Not controlled by optimum medical therapy
  2. Prognosis
    - Anatomy (Left main / 3 vessel)
    - Ischaemic region
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4
Q

PCI vs CABG

A

CABG:
- **Left main
- **3 vessel disease with LV dysfunction
(- In reality: CABG > PCI if more risk factors)

Risk factors:

  1. Impaired ventricular function (EF <50%)
  2. DM
  3. Difficult coronary anatomy (e.g. proximal lesions, total occlusion, diffuse disease, calcified vessel)

Efficacy:
- CABG > PCI in 10 years
—> PCI has higher rate of recurrence angina, reoperation rate (∵ in stent re-stenosis)
—> PCI has slightly higher risk of MI / death in 10 years

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5
Q

***CABG

A

Area of Grafts:

  1. Aorta —> Posterior descending artery from RCA
  2. Aorta —> LAD
  3. Aorta —> Obtuse marginal branch from LCx

Conduit:

  1. ***Left internal mammary artery (LIMA)
    - “best” conduit
    - underneath left side of sternum
    - patency >90% in 10 years
    - usually anastomosed to LAD (∵ cover most area of myocardium)
  2. ***Radial artery
    - arterial graft theoretically more patent than venous graft
    - patency ~70% in 10 years
    - can be harvested by minimally invasive method
  3. ***Long saphenous vein
    - most commonly used
    - patency ~50% in 10 years
    - can be harvested by minimally invasive method
  4. Other less commonly used conduits
    - Right internal mammary artery (RIMA)
    - Gastroepiploic artery
    - Inferior epigastric artery
    - Short saphenous vein
    - Homograft (very poor patency rate)

Approach:

  1. Open: Median sternotomy (still most frequently used)
  2. Minimally invasive surgery (MIS)
    - MIDCAB (Minimally invasive direct CA bypass) —> harvest LIMA and directly graft onto LAD
    - Robotic

Anastomosis:

  1. Distal anastomosis
    - End to side
    - Sequential graft (一條graft配給兩條CA —> end to side + side to side)
  2. Proximal anastomosis (LIMA graft no need proximal anastomosis, branch from left subclavian artery)
    - Aorta
    - Y-graft
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6
Q

Cardiopulmonary bypass

A
  • Stop heart from beating —> But have to do Myocardial protection
  • Aim: Bloodless + Motionless surgical field
Off pump CABG (without Cardiopulmonary bypass) —> Use in high risk patients (e.g. atherosclerotic aorta —> cannot find site to cannulate for cardiopulmonary bypass):
Pros:
- Less bleeding
- Less renal failure
- Less stroke in atherosclerotic aorta

Cons:

  • Less no. of grafts
  • Less long term patency
  • Technical demanding
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7
Q

Post-op medications

A
  1. GTN infusion
    - Prevent spasm of ***IMA
    - No specific duration, usually stop next day
  2. Diltiazem infusion
    - Prevent spasm of ***RA
    - Usually stop when oral Diltiazem started
    - Last for 3-6 months
  3. Aspirin
    - Early aspirin improve early vein graft patency —> best to take within 6 hours post-op, no benefit if >48 hours
    - Life long for post-CABG
  4. Beta blocker
    - Early resume beta blocker reduce post-op AF + decrease cardiac workload
  5. Lipid lowering drugs
    - Improve vein graft long term patency
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8
Q

Complications of CABG

A
  • Risk stratification according to EuroScore: Most 1-2%

Major risk:

  • Bleeding
  • CVA
  • MI
  • Arrhythmia
  • Infection
  • Acute renal failure (requiring temporary renal replacement therapy)
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9
Q

Complication: Peri-operative MI

A

Causes:

  1. Poor myocardial protection techniques
  2. Graft occlusion
  3. Emboli to grafts / native coronary arteries

Diagnosis:

  1. Chest pain (NOT accurate ∵ concomitant chest wall wound pain)
  2. Cardiac enzyme
    - CKMB >5x normal
    - Tnl >10x normal
  3. ECG
    - New Q wave, ST changes (compare to previous ECG!!!)
  4. Echo
    - New regional wall movement abnormality

Treatment (depend on Haemodynamic status):
Stable / Suspicious:
1. LMWH

Unstable:

  1. IABP (intra-aortic balloon pump)
  2. Coronary angiogram
  3. ?Redo
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10
Q

Complication: AF

A
  • Up to 40% of patient will have post-op AF

Risk factors:

  • Old age
  • COAD
  • Withdrawal of Beta blocker

Problems:

  • Loss of 20% CO
  • Risk of thromboembolism (esp. >48 hours)

Preventive measures:

  • Keep K, Mg normal
  • Resume Beta-blocker
  • Amiodarone, Sotalol, Mg supplement

Treatment
Stable:
1. Pharmacological cardioversion
2. Rate control + Anticoagulation (if AF is chronic / >48 hours, difficult in Pharmacological cardioversion)

Unstable:
1. DC cardioversion

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11
Q

Complication: Stroke

A
  • 3% risk in CABG patients
  • Prolonged hospital stay, increase morbidity + mortality

Risk factors:

  1. History of stroke
  2. Old age
  3. Carotid artery disease
  4. Emergency operation
  5. Atherosclerotic aorta

Diagnosis:
1. CT brain (diagnosis + treatment if haemorrhage)

Prevention:

  1. Off pump CABG
  2. Alternative cannulation sites (avoid dislodging atherosclerotic plaques when cannulating ascending aorta)
  3. Special device
  4. Circulatory arrest
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12
Q

Special situations in Surgical management of IHD

A
  1. Primary CABG for STEMI
  2. Shock due to MI (Post-MI shock)
  3. Acute post-MI mechanical complications
    - MR
    - VSD
  4. Chronic post-MI mechanical complications
    - Aneurysm of LV
    - Heart failure
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13
Q
  1. Primary CABG for STEMI
A
  • Less common
  • Golden period usually passed when arrive OT
  • Advance of primary ***PCI

Post-MI CABG:

  • Best to delay 3-7 days if stable and pain free
  • Possibly due to ***reperfusion injury
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14
Q
  1. Shock due to MI (Post-MI shock)
A
  • 0.2% of MI
  • ***>40% myocardium is loss before developing shock
  • High 30-day mortality ~70%
  • SHOCK trial: CABG would have better 1 year survival compared to medical treatment
  • Surgical mortality ~50%
  • Tendency is stabilise —> CABG later
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15
Q
  1. Acute post-MI mechanical complications: MR
A
  • Papillary muscle dysfunction / rupture ***after 3-5 days (muscle slowly necrosis)
  • Usually postero-medial papillary muscle due to sole blood supply by 1 coronary artery

Clinical features:

  1. SOB, Shock (~***day 3-5 post-MI)
  2. New Pan-systolic murmur
  3. Congested lung field on CXR

Diagnosis:
1. Echo

Treatment:

  1. Support by Inotropes + IABP
  2. Urgent operation
    - MV repair / MVR
    - +/- CABG
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16
Q
  1. Acute post-MI mechanical complications: VSD
A
  • Mortality >50% in first day
  • Most common ***Anterior VSD from LAD infarct

Clinical features (~MR):

  1. SOB, Shock (~***day 3-5 post-MI)
  2. New Pan-systolic murmur
  3. Congested lung field on CXR

Diagnosis:
1. Echo

Treatment:

  1. Support by Inotropes + IABP
  2. Delayed operation if stable until fibrosis around VSD
    - ∵ myocardium is fragile after MI —> early operation cannot close defect effectively
17
Q
  1. Chronic post-MI mechanical complications: Aneurysm of LV
A
  • Success of primary PCI —> reduce incidence of acute mechanical complication post-MI
  • Patient survive longer after IHD / MI
  • Translate to more chronic problem

Aneurysm of LV:

  • Affect LV efficiency
  • LV clots (more stagnant blood flow in hypokinetic aneurysm area)
  • Patient may have SOB (∵ lower LV efficiency)

Treatment:

  1. LV Aneurysmectomy / Ventriculoplasty
    - improve in EF + symptom of SOB but NOT survival
18
Q
  1. Chronic post-MI mechanical complications: Heart failure
A
  • Repeated MI —> progressive deterioration of function

Treatment:

  1. Mechanical support (can be bridging therapy to heart transplant)
    - ECMO
    - LVAD
  2. Heart transplant
19
Q

***Summary

A

Indication of CABG

  1. Symptom
  2. Prognosis

Common conduits and patency rate

  1. LIMA (90%)
  2. RA (70%)
  3. Long saphenous vein (50%)

Major risks of CABG:

  1. Peri-operative MI
  2. AF
  3. Stroke

Complications from AMI:

  1. Acute
    - MR
    - VSD
  2. Chronic
    - Aneurysm of LV
    - Heart failure
20
Q

Success of Heart transplant

A
  1. Advance in immunosuppressant
    - Cyclosporine
  2. Advance in endomyocardial biopsy
    - Transvenous endomyocardial biopsy —> reliable mean for monitoring allograft rejection
21
Q

Indications of Heart transplant

A
  • **End stage cardiac disease
  • Mostly end stage heart failure
    1. **Dilated cardiomyopathy
    2. **    Ischaemic cardiomyopathy
    3. Valvular cause
    4. Hypertrophic cardiomyopathy

Recipient selection:

  1. Relatively healthy patients with end-stage heart disease
  2. Refractory to other appropriate medical + surgical therapies
  3. Possess potential to resume a normal active life
  4. Ability to maintain compliance with a rigorous medical regimen after cardiac transplantation
22
Q

Relative CI for Heart transplant

A
  1. Recent malignancy
  2. COPD
  3. Recent + Unresolved pulmonary infarction / PE
  4. DM with end-organ damage (neuropathy, nephropathy, retinopathy)
  5. Peripheral vascular / cerebrovascular disease
  6. Active peptic ulcer disease
  7. Current / Recent diverticulitis
  8. Other systemic illness likely to limit survival / rehabilitation
  9. Sever obesity / cachexia
  10. Severe osteoporosis
  11. Active alcohol / drug abuse
  12. History of non-compliance / psychiatric illness likely to interfere with long-term compliance
  13. Absence of psychosocial support
23
Q

Recipient prioritisation for Heart transplant

A

More urgent:

  • less life expectancy
  • more mechanical support
24
Q

Donor selection

A 
Suggested criteria:
- Age <55
- Absence of following:
—> Prolonged cardiac arrest
—> Septicaemia
—> Extracerebral malignancy
—> Positive serologies for HIV, HBV, HCV
—> Haemodynamic stability without high-dose inotropic support

Workup for Cardiac donor:

  1. Past medical history + P/E
  2. ECG
  3. CXR
  4. ABG
  5. ABO compatibility, HIV, HBV, HCV
  6. **Echo, Pulmonary artery catheter evaluation, **Coronary angiogram

Process:
- Echo
—> Good LVEF >45% —> Proceed
—> Poor LVEF <45% —> Hormonal resuscitation (T3, Vasopressin, Methylprednisolone, Insulin) —> Haemodynamic management (Fluid status, Inotropic support) —> Ok —> Proceed

25
Q

Procedure of Harvest heart

A
  1. Heparin
  2. Aortic cross clamp
  3. Cardioplegic solution to stop + protect heart (diffuse into myocardium via coronary artery)
  4. Left + Right heart decompression (ligate LA + RA)
  5. Cardiectomy

Organ preservation:

  • Current graft preservation techniques —> Safe ischaemic period 4-6 hours
  • Single flush of cardioplegic solution —> Static hypothermic storage at 4-10oC

Orthotopic Implantation technique:

  1. Biatrial technique (suture donor RA with recipient RA)
  2. Bicaval technique (RA is entirely donor’s)
26
Q

Immunosuppressants in Heart transplant

A

Triple therapy:

  1. CNI
    - Cyclosporine
    - Tacrolimus
  2. Anti-Proliferative agent
    - AZA
    - MMF
    - Cyclophosphamide (rare)
  3. Corticosteroid
    - Prednisone / Prednisolone

Recent:
- Sirolimus (Rapamycin), Everolimus —> block downstream of IL2 receptor

27
Q

Complications of Heart transplant

A

Early:

  1. Infection
  2. Rejection

Chronic:

  1. Cardiac allograft vasculopathy (~CAD)
  2. Renal dysfunction
  3. Malignancy (∵ prolonged immunosuppressants)
28
Q

Future of heart transplant

A

Improvement in:

  1. Immunosuppressant strategies (decrease rejection + infection)
  2. Organ preservation techniques (prolong safe ischaemic time, prevent ischaemic damage)
  3. Mechanical assist devices
  4. Ventricular restoration surgeries
  5. Possibility of donor pool expansion

SpC Surgery (11 decks)

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