What is the purpose of an angiogram test?

What an Angiogram Does

An angiogram is an invasive imaging procedure that visualizes blood vessels by injecting contrast dye and using X-ray imaging to create detailed pictures of arteries and veins, allowing physicians to identify blockages, narrowing, aneurysms, and other vascular abnormalities. 1

Primary Diagnostic Functions

Coronary Artery Assessment

• Visualizes coronary artery anatomy to identify the location, severity, and extent of blockages or stenoses (narrowing) in the heart's blood vessels 1
• Determines the cause of chest pain or anginal symptoms by revealing whether coronary artery disease is present 1
• Evaluates stenosis severity by comparing diseased segments to adjacent normal reference segments, though this has limitations in diffusely diseased vessels 1
• Assesses coronary blood flow patterns and identifies whether blood flow is restricted at rest or during maximal dilation 1

Vascular Abnormality Detection

• Identifies aneurysms (abnormal bulging of blood vessel walls) in various vascular territories 1
• Detects arterial dissections where the inner layer of an artery tears 1
• Visualizes emboli (blood clots or debris) within blood vessels 1
• Reveals stenoses and occlusions (complete blockages) in arteries throughout the body 1

Specialized Vascular Evaluation

• Assesses retinal and choroidal blood flow using fluorescein or indocyanine green angiography to evaluate delays in flow, ischemia, and the extent of retinal vascular involvement 1
• Evaluates gastrointestinal bleeding by detecting contrast extravasation into the bowel lumen when bleeding rates exceed 1 mL/min 1
• Identifies angiodysplasia (abnormal blood vessels) through characteristic findings like ectatic slow-emptying veins and early-filling veins 1

Functional Assessment Capabilities

Hemodynamic Evaluation

• Measures fractional flow reserve (FFR) to determine the functional significance of "intermediate" stenoses (those that appear 50-70% narrowed), helping decide whether intervention is needed 1
• Assesses aortic valve competency and evaluates for aortic regurgitation 1
• Evaluates branch vessel involvement including coronary arteries and other major arterial branches 1

Cardiac Function Assessment

• Performs left ventriculography to define ventricular function and identify regional wall motion abnormalities in patients with angina and ischemic heart disease 1
• Determines whether severe coronary disease is causing depressed left ventricular ejection fraction 1
• Assesses for ischemia-mediated ventricular arrhythmias 1

Therapeutic Guidance

Intervention Planning

• Defines coronary anatomy in patients with high-risk noninvasive stress test findings as a prerequisite for revascularization procedures 1
• Guides percutaneous coronary interventions (PCI) to the exact site of blockage during the same procedure 1
• Assesses suitability for revascularization in patients with unacceptable ischemic symptoms not controlled by medication 1
• Evaluates cardiovascular risk in solid-organ transplant candidates (both recipients and donors) 1

Therapeutic Interventions

• Enables intra-arterial vasopressin infusion to control gastrointestinal hemorrhage, achieving hemostasis in up to 91% of patients with lower GI bleeding 1
• Allows arterial embolization via the angiographic catheter to stop bleeding 1

Important Limitations and Risks

Technical Limitations

• Cannot assess plaque stability or identify "vulnerable" plaques likely to rupture and cause acute coronary syndrome 1
• Requires active bleeding at the moment of imaging to detect extravasation; intermittent bleeding may be missed 1
• Shows significant interobserver variability in grading coronary stenosis severity, with visual assessment often overestimating disease when stenosis is ≥50% 1
• May underestimate lesion severity in diffusely diseased arteries lacking a normal reference segment 1
• Cannot reliably predict hemodynamic significance from visual appearance alone—many stenoses appearing ≥70% do not restrict flow, while some <70% stenoses are hemodynamically significant 1

Procedural Complications

• Overall complication rate of 1.5% for diagnostic angiography based on 2012 registry data 1
• Serious complications include: death, stroke, myocardial infarction, bleeding, infection, contrast allergic/anaphylactoid reactions, vascular damage, contrast-induced nephropathy, arrhythmias, and need for emergency revascularization 1
• Higher risk in specific populations: age >70 years, severe functional impairment (CCS class IV angina or NYHA class IV heart failure), severe left ventricular dysfunction, left main coronary disease, severe valvular disease, severe comorbidities (renal, hepatic, pulmonary disease), bleeding disorders, or contrast allergy history 1
• Contrast-induced nephropathy risk is particularly elevated in patients with renal insufficiency or diabetes mellitus 1
• Fluorescein angiography carries rare but serious risks including death (approximately 1 per 200,000 patients) 1

Common Pitfalls to Avoid

• Do not rely solely on visual stenosis assessment without considering functional significance—use FFR for intermediate lesions to avoid unnecessary interventions or missed significant disease 1
• Do not perform angiography without informed consent that explicitly discusses risks, benefits, and alternatives with the patient 1
• Do not delay angiography for additional noninvasive testing in patients with clinical characteristics indicating high likelihood of multivessel or left main disease (large ischemic burden, long-standing diabetes with end-organ damage, severe peripheral vascular disease, prior chest radiation) 1
• Balance procedural risks against diagnostic yield in high-risk patients—the increased likelihood of finding critical disease must justify the elevated complication risk 1
• Recognize that normal or near-normal coronary arteries are found in a substantial proportion of patients undergoing angiography (21% in one Veterans Health Administration study), particularly women with microvascular disease 1