Cardiac Imaging

What Imaging Is Best for Pre-Op Planning in Adults with Prior Cardiac Surgery?

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What Imaging Is Best for Pre-Op Planning in Adults with Prior Cardiac Surgery?

A 68-year-old male with a history of coronary artery bypass grafting (CABG) a decade ago now presents with recurrent, disabling angina. A cardiac catheterization confirms new severe disease in a native vessel and identifies a patent but stenotic left internal mammary artery (LIMA) graft. The cardiothoracic surgery team is planning a redo CABG, but the prior sternotomy introduces significant risks, particularly during sternal re-entry. You need to order imaging that will precisely map his current anatomy to help the surgeon plan the safest approach. This article details the clinical workflow for preprocedural imaging in an adult with a history of cardiothoracic surgery who is scheduled for repeat coronary surgery.

For this specific scenario, the American College of Radiology (ACR) Appropriateness Criteria rate several studies as valuable, with US echocardiography transesophageal being designated Usually appropriate for its ability to assess cardiac function and aortic anatomy without radiation.

Who Fits This Clinical Scenario?

This guidance applies to a specific and high-risk patient population: adults with a history of any prior cardiothoracic surgery who are now being evaluated for a repeat coronary cardiac surgery, such as a redo CABG. The key elements are the history of a previous operation involving the chest or heart and the planned procedure being coronary-focused. The goal of imaging in this context is not diagnosis but preprocedural planning to mitigate the risks associated with re-operation.

This workflow is distinct from several similar-sounding but clinically different scenarios:

  • First-time coronary surgery: Patients with no history of cardiothoracic surgery have a different risk profile and anatomical considerations. Their pre-operative imaging needs are covered in a separate ACR variant.
  • Noncoronary cardiac surgery: If the planned procedure is for a valve replacement, aortic repair, or congenital defect correction (even with a prior surgical history), the specific anatomical questions change, and imaging priorities may shift.
  • Non-cardiac thoracic surgery: Patients undergoing procedures like a lobectomy or esophagectomy, even with a prior cardiac surgery, require a different imaging workup focused on pulmonary and mediastinal structures unrelated to coronary anatomy.

Correctly identifying your patient within this specific context ensures the imaging ordered directly answers the critical questions facing the surgical team.

What Anatomic and Pathologic Features Are You Assessing?

In preprocedural planning for repeat coronary surgery, imaging is used to identify potential hazards and inform surgical strategy. The “differential” is less about diagnosing a new condition and more about characterizing known postsurgical changes and comorbidities that impact operative risk.

Mediastinal Adhesions and Structural Relationships: The primary concern in a redo sternotomy is inadvertent injury to vital structures adherent to the posterior sternum. This most commonly includes the right ventricle, ascending aorta, or, critically, a patent bypass graft. Imaging aims to measure the distance between the sternum and these structures to guide the surgeon’s entry.

Bypass Graft Location and Patency: Identifying the precise location and patency of prior bypass grafts, especially an internal mammary artery (IMA) graft, is paramount. An IMA graft often crosses the midline and can be directly in the path of the sternal saw. Knowing its course allows the surgeon to potentially modify the incision or dissection technique to avoid catastrophic bleeding.

Aortic Atherosclerosis (e.g., “Porcelain Aorta”): Severe calcification or mobile atheroma in the ascending aorta significantly increases the risk of embolic stroke during aortic cannulation, cross-clamping, or manipulation. Preoperative imaging is essential to evaluate the aortic wall and guide the surgeon toward alternative cannulation sites or “no-touch” aortic techniques.

Concurrent Valvular and Myocardial Pathology: The patient’s cardiac function and valvular integrity may have changed since their last operation. Identifying new or worsened valvular stenosis or regurgitation, or a decline in ventricular function, may lead to an expanded surgical plan that addresses these issues concurrently with the coronary revascularization.

Why Is Transesophageal Echocardiography a Key Recommended Study?

For preprocedural planning in a patient with prior cardiothoracic surgery undergoing a repeat coronary procedure, the ACR rates US echocardiography transesophageal (TEE) as Usually appropriate. This recommendation is based on its unique ability to provide high-resolution, real-time functional and anatomical information without exposing the patient to ionizing radiation (0 mSv).

TEE offers a superior acoustic window compared to transthoracic echo, providing detailed views of posterior cardiac structures, the thoracic aorta, and heart valves. It is particularly effective for assessing the severity and location of aortic atherosclerosis, a critical factor in preventing intraoperative stroke. It can also precisely evaluate valvular function and detect intracardiac thrombus, helping to finalize the scope of the surgical plan. While TEE may not visualize the full course of a retrosternal bypass graft as clearly as other modalities, its functional and aortic assessment is invaluable.

Several other imaging studies are also rated Usually appropriate and are often used in a complementary fashion:

  • CTA chest with IV contrast (☢☢☢ 1-10 mSv): This is the gold standard for anatomical mapping. It provides an exquisite, three-dimensional view of the relationship between the sternum, heart, great vessels, and, most importantly, the prior bypass grafts. It is the best test to answer the question, “How close is the patent LIMA graft to the sternum?”
  • Radiography chest (☢ <0.1 mSv): A standard chest X-ray is a fundamental baseline study. It provides a quick overview of cardiac size, pulmonary status, and the position of sternal wires and other hardware. However, it lacks the detail needed for strategic surgical planning.

Studies like MRA chest are rated May be appropriate. While MRA avoids ionizing radiation, it can be limited by metallic artifact from sternal wires and surgical clips, and it is generally less effective than CTA for visualizing coronary graft anatomy and aortic calcification.

What’s Next After Imaging? Downstream Workflow

The results of preprocedural imaging directly shape the operative plan, creating a clear decision tree for the surgical team. The goal is to transform unknown risks into known anatomical challenges that can be proactively managed.

  • Finding: Patent Graft Adherent to Sternum. If CTA reveals a patent bypass graft (especially an IMA) is directly behind or adherent to the sternum, the surgeon may alter the approach. This could involve initiating peripheral (femoral) cardiopulmonary bypass before opening the chest, allowing for safe cardiac decompression. In some cases, a right thoracotomy may be used to avoid the midline sternotomy altogether.
    • Finding: Severe Aortic Atherosclerosis. If TEE or CTA identifies a “porcelain aorta” with heavy, circumferential calcification, the standard plan for aortic cannulation and cross-clamping is abandoned. The surgeon will pivot to an alternative strategy, such as axillary artery cannulation and performing the surgery off-pump or using a “no-touch” technique with an aortic clamping device.
  • Finding: Unexpected Severe Valvular Disease. If TEE reveals previously unrecognized severe aortic stenosis or mitral regurgitation, the surgical plan will likely be expanded. The patient will be counseled, and the procedure will be modified to include a concomitant valve repair or replacement, addressing all critical pathology in one operation.
  • Finding: Reassuring Anatomy. If imaging shows adequate space between the sternum and underlying structures, a non-calcified aorta, and no other significant pathology, the team can proceed with a standard median sternotomy with a higher degree of confidence.

Pitfalls to Avoid (and When to Get Help)

Navigating preprocedural imaging for redo cardiac surgery requires careful planning and communication. Here are common pitfalls to avoid:

  • Relying on a Single Modality: TEE and CTA provide complementary information. TEE excels at functional assessment and aortic atheroma, while CTA excels at pure anatomical mapping of grafts and retrosternal space. The best plan often integrates findings from both.
  • Ordering a Non-Gated CT Scan: A standard, non-gated CT of the chest is insufficient. A cardiac-gated CTA with a specific timing protocol is required to minimize motion artifact and optimally opacify the coronary arteries and bypass grafts.
  • Poor Communication with the Surgeon: The radiologist’s report is most useful when it directly answers the surgeon’s questions. Ensure the imaging requisition clearly states the clinical concern (e.g., “redo CABG, assess LIMA to sternum distance”).
  • Overlooking Renal Insufficiency: This patient population often has comorbidities, including chronic kidney disease. The need for iodinated contrast for a CTA must be weighed against the risk of contrast-induced nephropathy. Pre-procedural hydration and consideration of alternative non-contrast studies (like MRA, if appropriate) are essential.

If imaging reveals anatomy that makes the planned surgery prohibitively high-risk, escalate the discussion to a multidisciplinary heart team meeting to consider alternative revascularization strategies, such as high-risk percutaneous coronary intervention (PCI).

Related ACR Topics and Tools

For a comprehensive overview of imaging recommendations across all cardiothoracic surgery scenarios, please consult the parent topic article. For additional tools to refine your imaging orders and discuss them with patients, see the resources below.

Frequently Asked Questions

Why is CTA also ‘Usually Appropriate’ if TEE is recommended?

TEE and CTA provide complementary information and are often both used. TEE is excellent for assessing aortic atherosclerosis and cardiac function without radiation. CTA is superior for creating a 3D anatomical map, especially for visualizing the precise course of bypass grafts and their distance from the sternum. The choice often depends on the specific primary question; if the main concern is the LIMA graft’s location, CTA is the preferred study.

Is a transthoracic echocardiogram (TTE) sufficient for this scenario?

While a resting transthoracic echocardiogram (TTE) is also rated ‘Usually Appropriate’ by the ACR for a baseline assessment of ventricular function, it often provides limited views of the aorta and posterior structures, especially in postoperative patients. A transesophageal echo (TEE) offers far superior image quality for the specific pre-procedural questions about aortic disease and detailed valve morphology that are critical in this high-risk setting.

What if my patient has severe renal dysfunction and cannot receive IV contrast for a CTA?

In cases of severe chronic kidney disease, a non-contrast CT chest can still provide valuable information about the proximity of the heart and great vessels to the sternum and can identify heavy calcification. For assessing graft anatomy, a Magnetic Resonance Angiography (MRA) without contrast may be considered, though it can be limited by artifact from sternal wires. A TEE, which requires no contrast, becomes an even more critical component of the workup.

Does the type of prior surgery (e.g., valve vs. CABG) change the imaging recommendation for a new coronary surgery?

No, for the purposes of this ACR scenario, any history of cardiothoracic surgery qualifies. The key risk is from the prior sternotomy and resulting adhesions, regardless of the original procedure. The imaging goals—mapping adhesions, grafts, and aortic integrity—remain the same when planning a repeat sternal entry for coronary surgery.

How soon before the surgery should this imaging be performed?

The imaging should be performed close enough to the surgery date to accurately reflect the patient’s current condition, typically within a few weeks. However, it must be done with enough lead time to allow the surgical team to analyze the results and make any necessary, significant changes to the operative plan, such as arranging for alternative cannulation equipment or expanding the scope of the procedure.

Reviewed by Pouyan Golshani, MD, Interventional Radiologist — May 30, 2026