15.3 Indocyanine Green Angiography & Angiographic Complication Management

Indocyanine Green Angiography & Complication Management

Indocyanine green angiography complements fluorescein angiography by imaging the choroidal circulation. It is performed under an authorized order with patient identification, history review, venous access, image timing, monitoring, and emergency readiness.

Optical and pharmacokinetic features

ICG is excited near 790–805 nm and emits near 835 nm. Near-infrared light penetrates retinal pigment, xanthophyll, and some blood better than the visible wavelengths used for fluorescein. ICG is highly bound to plasma proteins, so it remains comparatively intravascular in the choroidal circulation. The liver removes it from plasma and excretes it into bile.

These properties help delineate branching vascular networks and polypoidal lesions, type 1 choroidal neovascularization beneath the RPE, pachychoroid disease, selected inflammatory choroidopathies, and some choroidal tumors. The ordering clinician determines whether the study is appropriate and interprets the images.

Label-based history screening

The current U.S. label for IC-GREEN states that the product contains not more than 5% sodium iodide and should be used with caution in a patient with a history of allergy to iodides because of the risk of anaphylaxis. Ask specifically about prior ICG exposure and reaction, iodide reactions, asthma or other severe allergic history under clinic protocol, pregnancy status when relevant, and hepatic disease. Route positive findings to the physician before preparation.

Do not use “shellfish allergy” as a proxy for iodide allergy. Shellfish reactions are caused by seafood proteins, and the current ICG label does not list shellfish allergy as a contraindication. Do not label pregnancy or liver dysfunction as automatic absolute contraindications; the clinician weighs indication, labeling, current evidence, and patient factors.

Anaphylactic and urticarial reactions have occurred in people with and without an allergy history. A negative history therefore does not replace monitoring.

Preparation and imaging

Verify patient, order, dose, product, lot, expiration, diluent, access patency, and emergency equipment. Reconstitute and administer only according to the current product labeling and clinic protocol. Start image capture at the ordered time and label eye, modality, and phase accurately. Early frames emphasize arterial and choroidal filling; later frames can demonstrate lesion architecture or persistent staining.

Adverse reactions

For nausea, warmth, sneezing, or a limited rash, stop or pause as protocol directs, observe vital signs, and notify the supervising clinician. Symptoms can progress.

For respiratory difficulty, stridor, wheeze, generalized hives with systemic symptoms, hypotension, collapse, or rapidly increasing facial or tongue swelling:

1. stop administration;
2. call for the physician and activate emergency medical response;
3. position and support airway, breathing, and circulation under protocol;
4. prepare or administer intramuscular epinephrine only within authorization and training;
5. monitor and document the event, medication, timing, vital signs, and transfer.

Do not rely on antihistamines or corticosteroids as first-line treatment for anaphylaxis; epinephrine is the essential first-line drug.

Extravasation

Pain, swelling, resistance, or loss of blood return can indicate infiltration. Stop the injection, leave or remove the catheter according to protocol, notify the clinician, elevate the limb when directed, and document site, estimated amount, symptoms, and follow-up instructions. ICG discoloration can persist temporarily. Severe pain, blistering, neurovascular change, or progressive swelling requires urgent evaluation.

After an uncomplicated study, remove the IV safely, apply pressure, inspect the site, and give the approved discharge instructions. Record any limitation in image quality or incomplete phases rather than hiding a failed acquisition.

Acquisition and documentation sequence

Obtain the ordered baseline and early, middle, and late frames with accurate elapsed time. Center and focus through the pupil, use the requested field, and note motion, media opacity, injection difficulty, or missed frames. ICG phase names and exact timing vary by protocol and circulation, so actual timestamps are more useful than a memorized second range.

Document the product, dose and route, lot when required, IV site, injection time, eye and fields, symptoms, interventions, and disposition. Preserve pre-injection frames because they help distinguish preexisting near-infrared reflectance from true dye fluorescence. A technician may recognize a safety problem or poor-quality study but leaves angiographic diagnosis and treatment choice to the clinician.

Quality review and patient handoff

Before the patient leaves, confirm that required fields and phases were captured, timestamps and laterality are correct, and any adverse symptom or IV-site problem was evaluated. Motion, blink, poor dilation, focus error, media opacity, or missed timing belongs in the record so the interpreting clinician does not mistake a technical limitation for absent pathology. If the study is incomplete, the clinician decides whether additional imaging is safe and useful; the technician does not repeat the injection independently.

Give only approved aftercare instructions. Explain whom to contact for worsening rash, breathing difficulty, dizziness, progressive swelling or pain at the IV site, or another delayed concern. Document the patient's condition, teaching, escort needs when relevant, and disposition.