Long Aorta

Overview

• Objective: Obtain long-axis views of the abdominal aorta (proximal, mid, distal) and its bifurcation into iliac arteries.

• Goal: Optimize image quality, stabilize for measurements, and localize key landmarks.

Equipment & Settings

• Transducer Placement: Start between ribs (near heart), then move down (caudally) to find proximal aorta.

• Visual Cue: Look for the left liver lobe near the proximal aorta.

• Imaging Adjustments:

  • Apply Time Gain Compensation (TGC) to darken the aorta for contrast.

  • Use freeze frame for measurements.

  • Adjust depth to balance near and far fields; lighten image bottom to match.

• Breathing Protocol: Deep breath and hold to reduce motion; allow slow breathing if unstable, then re-hold.

Anatomical Landmarks

• Proximal Aorta: Above the celiac trunk and Superior Mesenteric Artery (SMA) origins.

• Mid Aorta: After the SMA origin, centered on the screen.

• Distal Aorta: Follow until it appears "stump-like" before bifurcation.

• Coronal Bifurcation: Where aorta splits into iliac arteries, ~$2 \text{ inches}$ from the side of the belly button.

Step-by-Step Imaging

1. Proximal Aorta:

   • Patient holds breath. Slide transducer caudally from heart view.

   • Confirm location (above celiac/SMA, near liver).

   • Adjust depth, darken with TGC. Freeze and measure.

2. Mid Aorta:

   • Slide down to place SMA origin near top of screen; center aorta view.

   • Reduce depth to balance fields, darken. Freeze and measure.

3. Distal Aorta:

   • Rock/twist transducer to follow aorta until "stump-like" end.

   • Darken, freeze, and measure.

4. Coronal Bifurcation (Iliac Arteries):

   • Move ~$2 \text{ inches}$ from side of umbilicus.

   • Push in and angle toward belly button to image distal aorta and iliac split.

   • Identify, label, and document.

Measurements & Documentation

• Proximal: Above celiac/SMA origin.

• Mid: After SMA origin, center screen.

• Distal: At stump-like end.

• Coronal Bifurcation: Approx. $2 \text{ inches}$ from umbilicus.

• All measurements taken on frozen frames with stable transducer.

Practical Implications

• Segmentation: Defines specific areas for consistent measurement.

• Landmarks: Celiac trunk, SMA, and liver are crucial for orientation.

• Technical Considerations: Proper depth, stable imaging (via breathing), and the distal "stump" are key for accuracy.

• Relevance: Essential for assessing aortic size and potential aneurysmal disease.

Tips & Pitfalls

• Always verify proximal view (celiac/SMA, liver).

• Use patient breathing for image stability during measurement.

• If unstable, pause, allow breathing, then re-attempt adjustments.

• Keep aorta centered for mid/distal views.

• For bifurcation, approach laterally towards umbilicus.

• Document exact location and distance from landmarks.

Definitions (Common Terms)

• Aorta: Main artery from heart.

• Proximal/Mid/Distal Aorta: Segments of the abdominal aorta.

• Coronal Bifurcation: Aorta split into iliac arteries.

• Celiac Trunk (celiac) / Superior Mesenteric Artery (SMA): Major abdominal aorta branches.

• Near field / Far field: Image regions closer/further from transducer; should be balanced.

• TGC: Time Gain Compensation for depth brightness adjustment.

Summary Takeaways

• Perform long-axis ultrasound of abdominal aorta, identifying proximal, mid, distal, and coronal bifurcation (approx. $2 \text{ inches}$ from umbilicus) using celiac/SMA as guides.

• Proper technique (breathing, probe, depth, TGC) is vital for reliable measurements.

• Measurements taken on frozen frames, with clear documentation of location.