5.2 Off Pump Bypass

Question 1

Q2 — Off-pump bypass
a) List four theoretical advantages of ‘off-pump’ coronary artery bypass (OPCAB) grafting compared with an ‘on-bypass’ technique.

Answer 1

● Reduction in neurological complications.

● Less need for transfusion.

● Reduction in renal failure.

● Fast-track surgery.

● Cost benefits.

● Reduced postoperative temperature fluctuations and associated complications.

Question 2

b) What are the four potential mechanisms of haemodynamic instability during OPCAB grafting?

Answer 2

● Placement of stabilisers reduces
contractility and thus stroke volume.

● Change in anatomical position
of the heart chambers
(e.g. verticalisation).

● Change in anatomical position of heart
valves thus altering flow through the chambers.

● Reduced venous return.

● Ischaemia during the anastomosis.

● Arrhythmias.

Question 3

c) List any three anaesthetic strategies that help to minimise this haemodynamic instability.

Answer 3

● Careful assessment, selection
and optimisation of patients.

● Close monitoring.

● Maintenance of coronary supply/demand balance.

● Maintenance of optimal core body temperature.

Question 4

d) List three important mechanisms to maintain coronary perfusion during off-pump CABG.

Answer 4

● Heart rate control (supply/demand balance).

● Maintain coronary perfusion with fluids (optimal preload) and vasopressors.

● Close communication with surgeons.

● Intracoronary (vessel) shunts.

Question 5

e) What are the potential disadvantages of OPCAB grafting?

Answer 5

● Potential for inadequate revascularisation.

● Inadequate data to compare with
on-pump surgery on long-term results.

● Haemodynamic instability during surgical manipulation.