What key findings should be checked and reported on a CT scan for a patient post minimally invasive cardiac surgery (MICS) for aortic valve replacement?

Post-MICS Aortic Valve Replacement CT Reporting

For patients who have undergone minimally invasive cardiac surgery (MICS) for aortic valve replacement, CT imaging must systematically evaluate prosthetic valve function, position, and complications, along with assessment of surgical access sites and postoperative anatomic changes.

Prosthetic Valve Assessment

Valve Position and Integrity

• Assess valve positioning relative to the annulus, looking for gaps or spaces between the outer wall of the prosthesis and native valve annulus that may indicate paravalvular leak or dehiscence 1
• Evaluate leaflet motion and integrity using ECG-gated acquisitions to assess leaflets in fully open and fully closed positions, ensuring symmetrical motion 1
• For bioprosthetic valves, leaflets must appear smooth and symmetric with complete forward excursion during systole and complete coaptation during diastole 1
• For mechanical valves, measure leaflet opening and closing angles and compare to manufacturer specifications; deviation >4° suggests restricted motion 1

Valve Thrombosis and Pannus

• Screen for hypo-attenuated leaflet thickening (HALT), characterized by hypodense meniscoid thickening thickest at the base and thinnest at the leaflet tip 1
• Grade HALT extent along the curvilinear leaflet using a 4-tier scale: ≤25%, 25-50%, 50-75%, >75% 1
• Assess for restricted leaflet motion on cine reconstructions, which when present with HALT indicates leaflet thrombus formation 1
• Distinguish between thrombus and pannus formation, as pannus (composed of myofibroblasts and collagen) typically occurs >5 years post-implantation and requires surgical intervention rather than anticoagulation 1

Aortic Root and Ascending Aorta

Structural Complications

• Measure ascending aortic diameter and assess for aneurysmal dilatation, particularly in patients with bicuspid aortic valve history who may require concomitant aortic replacement 1
• Evaluate for aortic dissection, especially iatrogenic dissection related to cross-clamping or endoaortic balloon use 1
• Assess degree and location of aortic calcification, documenting any progression that could complicate future interventions 1

Perivalvular Findings

• Document periaortic soft tissue stranding, fluid, or air as normal early postoperative findings, though these can be difficult to differentiate from infection 1
• Identify suture pledgets appearing as small hyperdense foci in a circular pattern around the valve 1

Coronary Artery Assessment

• Evaluate coronary artery patency and ostial locations, as coronary obstruction risk is relevant for future valve-in-valve procedures 1
• Measure left main and right coronary artery heights from the annular plane, as low coronary heights (<10-12 mm) represent adverse features 2
• Assess for anomalous coronary anatomy including aberrant origins or courses 1
• While coronary stenosis assessment is challenging due to calcification and motion artifact, document any clearly visible significant stenoses 1

Surgical Access Site Evaluation

Chest Wall and Thoracic Anatomy

• Assess the right chest surgical access site (typically fourth intercostal space) for complications including lung herniation through the intercostal space 3
• Evaluate for chest wall deformities or rib abnormalities that may have complicated the surgical approach 1
• Document any pleural effusions or pneumothorax 1

Vascular Access Sites

• Examine femoral arterial cannulation sites for pseudoaneurysm, dissection, or hematoma formation 1, 4
• Assess iliac and femoral arteries for any iatrogenic injury, thrombosis, or stenosis related to cannulation 1, 4

Cardiac Chamber and Ventricular Function

• Report chamber sizes, particularly right ventricular dimensions, as RV dysfunction carries higher mortality risk in MICS patients 1
• Identify myocardial scar if present on contrast-enhanced imaging 1
• Assess for pericardial effusion and quantify if present 1

Other Valve Assessment

• Evaluate other cardiac valves for evidence of dysfunction, particularly mitral valve pathology and mitral annular calcification 1
• Document any paravalvular regurgitation by identifying gaps between prosthesis and native tissue 1

Preoperative Planning for Reoperation

If reoperation is being considered, the CT must specifically address:

• Distance between posterior sternum and right ventricle to assess risk of injury during re-do sternotomy 1
• Course and patency of any coronary bypass grafts to avoid injury during re-entry 1
• Peripheral artery disease in iliofemoral vessels that could affect peripheral cannulation strategy 1

Incidental Findings

• Report all relevant extra-cardiac pathologies including pulmonary nodules, mediastinal lymphadenopathy, or other incidental findings 1
• Clinical significance of incidental findings should be contextualized based on patient life expectancy and risk profile 1

Critical Pitfalls to Avoid

• Do not mistake normal early postoperative periaortic soft tissue changes for infection, though differentiation can be challenging 1
• Restricted valve motion without visible thickening should be reported with caution to avoid unnecessary treatment 1
• Ensure adequate temporal resolution for leaflet motion assessment; inadequate gating may miss subtle dysfunction 1
• Include multiplanar reformatted (MPR) reference images with cross-hairs in PACS to allow future reviewers to understand measurement orientation 1