Complications of opening a redo and the planning of bypass equipment to handle complications
Various cannulation techniques for redos
Cannula made especially for redos
Autotransfusion in relation to redos
The varying surgical incisions relating to redos
1. Reoperative cardiac surgery
a) With sternal opening, existing grafts or myocardium my be damaged
i) The heart or vein graft may be adherent to the sternum and can be torn with sternotomy
ii) An oscillating saw is used to decrease the likelihood of damage to the soft tissues
b) Care should be taken when entering the chest of patients with mitral valve disease and associated right heart enlargement
c) If previous operation the pericardium was not closed, see adherence of RV to sternum
d) Atheroma
i) Concern during aortic root pleging: debris, atheroma entering coronaries or brain
ii) Source of atheroma etc within previous grafts
iii) Use retrograde pleging to flush out of coronaries
iv) Head down to remove X-clamp with redos
2. Contingency planning
a) The femoral vessels are always identified, prepared & draped and consideration given to femoral artery cannulation prior to sternotomy
b) If the RA, RV or great vessels are cut, emergent CPB can be initiated by using:
i) ‘Sucker bypass’ with a femoral artery or aortic cannula and the cardiotomy suckers used as the venous return line
ii) Complete femoral artery-femoral vein bypass
c) It is mandatory to have at least 2 units of blood in the theatre ready for administration
d) The prolonged surgical dissection increases the risk of dysrhythmias:
i) Defibrillation may be necessary prior to exposure of heart; use of ‘redo plate’ (external defibrillator pad attached to a sterile paddle placed on chest wall)
1. If the right atrium, right ventricle or great vessels are cut, emergent CPB can be initiated by using:
a) ‘Sucker bypass’ with a femoral artery or aortic cannula and the cardiotomy suckers used as the venous return line
b) Complete femoral artery-femoral vein bypass
2. Old vein grafts may make insertion of the aortic cannula difficult; may choose to feed in the narrower descending aorta cannula (but not necessarily all the way into the descending aorta)
3. Aorta
a) Usually the old aortic cannulation site is adherent to the undersurface of the innominate vein
b) Entering into the previous aortic cannulation site may be difficult due to previously used Teflon pledgets and scar tissue, and manipulation of this area may increase the risk of embolisation of intraluminal debris
c) The new site is usually lateral or just distal to the old site
d) If the new cannulation site does not provide enough room for application of X-clamp distal to origin of old vein grafts or leave enough room for new grafts, then femoral cannulation should be considered
4. Atria
a) Right atrial cannulation can be difficult because the atrial tissue is usually thinned and friable after dissection of the pericardial adhesions
b) Teflon or pericardial pledgets can be used to reinforce a thinned atrial cannulation site
c) May occasionally need to drain from left atrium or pulmonary vein
5. Femoral vessel cannulation should be considered if aortoatria vessel canulation for reoperation becomes difficult
i) Descending aorta cannula
a) Inserted just distal to left subclavian or distal ascending aorta
b) When problems for X-clamping due to prox grafts
ii) Femoral cannulation
a) May be indicated from X-ray
b) Need to drain heart - collapses - decreases danger of trauma during sternotomy
c) For reasons as above plus unable to dissect aorta out plus possibility of entering heart/major vessels upon entering/sternotomy
iii) Percutaneous femoral
a) Difficulty in cannulating femoral artery or vein
iv) Soft Flow ascending aortic cannula
a) Reduced sandblasting effect
v) Axillary cannula
1. Cell saver (as opposed to cell washing)
a) Salvaging operative blood during dissection prior to systemic heparinisation
b) Heparinisation will exacerbate bleeding & is therefore given as late as possible by some surgeons
2. Cardiotomy sucker
a) Subsequent to heparinisation
b) Some surgeons may prefer to heparinise early; salvaged blood enters CPB circuit
c) If the RA, RV or great vessels are cut, emergent CPB can be initiated by using:
i) ‘Sucker bypass’ with a femoral artery or aortic cannula and the cardiotomy suckers used as the venous return line
1.
Mitral valve redo
a) Concern is enlarged right atrium; danger of entering on sternotomy
b) Right lateral thoracotomy
i) Approach left atrium inferiorly
ii) Right atrial — femoral artery cannulation
iii) Hypothermic VF arrest; no venting or cardioplegia or X-clamp
a) However, left heart is open and is passively venting
2.
Aortic valve redo
a) Median sternotomy
3.
CABG redo
a) Median sternotomy
4. Right thoracotomy
a) Anterolateral thoracotomy at 5th rib
b) Good access to atria
c) Favoured for MVR especially with previous median sternotomy
d) Access to ascending aorta is difficult
e) Access to left ventricle impossible
f) Cardioplumonary circulation from right atrium to ascending aorta or femoral artery
5. Left thoracotomy
a) Anterolateral thoracotomy at 5th rib
b) Applications:
i) Partial left heart CPB during surgery on descending thoracic aorta
a) Left atrial to aorta or femoral
ii) Left sided accessory pathway ablation with CPB
iii) Redo CABG where only circumflex system involved eg descending aorta to cx using saphenous vein conduit
Note: < 6 weeks post primary op – dependent on
pericardium – not too complex
6 weeks
– 6 months + increased vascularisation of scar tissue
> 1-2 years – reduced vascularity of scar tissue
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