Species: Feline   |   Classification: Techniques

Introduction Requirements Preparation Procedure Aftercare Outcomes Further Reading

Introduction

  • Injection of positive contrast into circulation allows visualization of vascular system.

Uses

  • Investigation of:
    • Cardiac chamber size.
    • Cardiac wall thickness.
    • Position of blood vessels.
    • Suspected shunts in heart, liver Congenital portosystemic shunt (CPSS) or circulation.
    • Thromboembolic disease aortic or pulmonary
  • Assessment of perfusion.

Advantages

  • Relatively simple procedure.
  • Equipment available in general practice.
  • Good anatomical detail.

Disadvantages

  • General anesthesia required (and patient may be severely compromized).
  • Fluoroscopy required for selective angiography.

Alternative Techniques

  • Scintigraphy (allows assessment of vascular perfusion and ventilation perfusion ratio).
  • Ultrasonography for measurement of cardiac chamber size, presence of vascular shunts and thrombotic disease.
  • Fluoroscopy gives better visualization of dynamic lesions.

Time Required

Preparation

  • 15 min.

Procedure

  • 10 min.

Decision Taking

Criteria for choosing test

  • Is the examination appropriate?
  • Can you make the diagnosis without it?
  • Will your management of the case be affected by the outcome of the examination?

Risk assessment

  • For many conditions where vascular contrast studies are indicated the patient is likely to be clinically ill, eg pulmonary thromboembolism therefore careful assessment of risks of anesthesia/sedation should be made.

Requirements

Materials Required

Minimum equipment

  • X-ray machine that allows rapid multiple exposures to be made.
  • Cassette.
  • Processing facilities.
  • Protective clothing (lead apron) for radiographer.
  • Positioning aids (sandbags, cradle and ties).
  • Method of labeling film.
  • Cassette tunnel.

Ideal equipment

  • Rapid cassette changer to allow multiple exposures to be made.
  • Ability to process films during procedure so that repeat radiographs can be taken during course of study if required.
  • High output X-ray machine.
  • High definition screen.

Minimum consumables

  • Radiographic film.
  • Intravenous catheter (20G).
  • Contrast agent (water soluble iodine-based).

Ideal consumables

  • Ideally non-ionic, low osmolar water soluble contrast is used, eg iohexol as this is less likely to cause circulatory disturbances.

Preparation

Restraint

  • General anesthesia.

Other Preparation

  • Pre place catheter in peripheral vein (for non-selective angiography) usually jugular or cephalic .
  • Catheterization of specific region requires more experience and may need fluoroscopic guidance.

Procedure

Approach

Step 1 - Control Films

  • Check exposure settings and processing.
  • Confirm positioning adequate.
  • Confirm diagnosis not apparent without contrast study.

Core Procedure

Step 1 - Non-selective angiography

  • Inject contrast agent 200 mg iodine/0.45 kg as rapidly as possible.

Step 2 - Selective angiography

  • Introduce bolus of contrast agent at specific site eg cardiac chamber, renal artery.
    Fluoroscopy may be required to ensure catheter in correct site at time of injection.

Step 3 - Make exposure

  • Make exposure immediately after injection.
  • Exposure multiple films in rapid succession.

Exit

Step 1 - Assess radiographs

  • Has structure of interest been exposed during time of contrast presence?
  • If not repeat films after second contrast injection.

Aftercare

Outcomes

Further Reading

Publications

Refereed papers

Other sources of information

  • Fox P R & Bond B R (1983) Non-selective angiocardiography. Vet Clin North Am Small Anim Pract 13, 259-272.