Beating Heart Surgery - Preoperative Planning

PREOPERATIVE PLANNING

Beating heart CABG requires a preoperative plan for the revascularization procedure that is different from CABG with CPB. In CABG with CPB, global ischemia is caused by aortic cross-clamping and cardioplegic arrest. Global ischemia is then managed by decreasing myocardial oxygen demand. In beating heart CABG, normothermic regional ischemia is managed by minimizing the area of ischemia. It is therefore critical to have a preoperative grafting strategy to minimize the amount of myocardium subjected to each ischemic episode.

Angiogram review:

Locate the perforators in order to prevent performing an arteriotomy over a perforator. Avoiding the perforators prevents persistent bleeding into the arteriotomy.
Identify the specific location of the arteriotomy to avoid plaque and small-diameter vessels.

Minimize normothermic regional ischemia:

Establish distal blood flow as soon as possible:
- Perform the IMA graft first.
- Perform the proximal anastomosis first.
- Use a multivessel cannula to perfuse the constructed SVG (e.g., Medtronic Multiple Perfusion Set).
Graft collateralized vessels before collateralizing vessels. Collateralizing vessels should be occluded only after collateralized vessels are bypassed.
Attempt to occlude the artery distal to major branch arteries.

Figure 1. Coronary and graft placement

CASE STUDY

62-year-old white male status post MI and angioplasty in 1988 presents with increasing fatigue upon exertion.

Cardiac Catheterization Results (Figure 1)

EF = 70% and LVEDP = 11 mmHg
99% occluded proximal RCA with very large PDA and PLB
90% occluded proximal LAD prior to take-off of first diagonal artery
100% occluded mid LAD (distal vessel fills by collateral flow)
90% occluded OM-1

Beating Heart Grafting Sequence

1. LIMA to LAD: Occlusion time – 8 minutes

Relatively easy exposure
Low-risk occlusion (collateralized vessel)
Immediate blood flow stabilizes the anterior wall and septum.

2. RIMA to OM-1 via the transverse sinus: Occlusion time – 11 minutes

Vessel is already partially exposed.
Immediate blood flow stabilizes the lateral wall.

3. SVG to diagonal artery: Occlusion time – 8 minutes

Vessel is already exposed.

4. Proximal grafts for the diagonal and PDA

Single placement of partial occlusion clamp on aorta
Establishes blood flow in the diagonal

5. SVG to PDA: Occlusion time – 8 minutes

Occlude only the PDA to keep the large PLB patent and minimize ischemia.
The anterior wall is no longer dependent on collateral flow originating from the posterior vessels because it has already been revascularized with the LIMA.
Immediate blood flow is established because the proximal graft is already constructed

"Anterior wall vessels are usually grafted first. If both the LAD and diagonal grafts are planned, the diagonal is grafted first, followed by the LIMA to LAD. Following anterior grafting, usually right coronary branches are approached next. Last but not least, the marginal branches of the circumflex artery are grafted. I do the proximals after all of the distals are completed."¹² -James C. Hart, M.D. Surgeon

The general concepts presented above are guidelines and can be adapted to meet surgeon preferences.