How should the heart be positioned during obtuse marginal grafting?

Heart Positioning During Obtuse Marginal Grafting

For obtuse marginal (OM) grafting during minimally invasive or off-pump coronary artery bypass, the heart should be positioned using deep pericardial sutures to elevate and rotate the lateral cardiac surface, providing adequate exposure of the circumflex territory without requiring full sternotomy or cardiopulmonary bypass. 1

Positioning Technique

Deep Pericardial Suture Method

• Place deep pericardial sutures to manipulate and expose the lateral cardiac surface, allowing visualization and access to obtuse marginal branches without conversion to median sternotomy 1
• The pericardial stitches should be positioned to elevate the heart and rotate it medially, bringing the lateral wall into the operative field 1
• This technique has been successfully used in multivessel minimally invasive CABG with OM grafting in 20 of 24 cases (83%), demonstrating reliable exposure 1

Standard Patient Positioning for Lateral Access

• Position the patient supine with the right hemithorax elevated 30 degrees while keeping the hips flat when using right-sided approaches 2
• Place a small pillow or IV bag inferior to the scapula to open the axillary space and improve access 2
• The right arm should be fully supported by the table and slightly flexed to improve access to the anterior axillary line 2

Stabilization During Grafting

Mechanical Stabilization

• Use suction-based stabilization systems (such as the Octopus device) to create a motionless region encompassing the target OM coronary artery on the beating heart 3
• All anatomic regions including traditionally difficult locations such as obtuse marginal branches can be successfully grafted using mechanical stabilization without cardiopulmonary bypass 3
• This approach achieved successful multivessel grafting with remarkably low perioperative mortality (0.26%) in 374 patients 3

Critical Anatomical Considerations

Circumflex Territory Access

• The obtuse marginal branches originate from the left circumflex artery to supply the lateral wall of the left ventricle 2
• First, second, and third obtuse marginal branches may all require grafting depending on disease distribution 2
• Exposure of lateral and posterior cardiac surfaces requires careful manipulation as it is associated with some degree of cardiac instability during recovery 1

Common Pitfalls and How to Avoid Them

Inadequate Exposure

• Avoid insufficient pericardial retraction, which limits visualization and increases technical difficulty 1
• If exposure remains inadequate despite deep pericardial sutures, consider more posterolateral placement of camera and working ports in minimally invasive approaches 2
• Ensure the pericardial incision extends far enough inferiorly to "release" the posterior wall and prevent posterior atrial wall "tenting" 2

Hemodynamic Instability

• Anticipate some degree of cardiac instability when exposing lateral and inferior surfaces, particularly during positioning maneuvers 1
• Monitor for ventricular dysfunction and be prepared to adjust positioning if hemodynamic compromise occurs 1

Thrombotic Complications

• Be aware that OM grafts can occlude acutely due to thrombosis, particularly in patients with hypercoagulable states such as polycythemia vera 4
• Ensure adequate anticoagulation protocols are in place perioperatively 4