Introduction
Non-invasive imaging techniques that may obviate the need for catheter-directed angiography. Catheter-directed angiography may be necessary for diagnosis of intracerebral pathologies, renovascular hypertension, gastrointestinal vascular pathologies, and in the context of trauma. In the majority of cases, arteriography is combined with therapeutic interventions. 

Contraindication 
  • When the desired information can be acquired noninvasively 
  • The majority of contraindications are relative: renal insufficiency, severe hypertension, contrast allergy, coagulopathy, volume restrictions, metabolic disease, skin infections at the access site and sepsis 
  • Patients with vasculitis may be more prone to vascular injury and ideally treated prior to angiography to achieve remission before intervention. 
  • Hypertensive crisis may occur in patients with pheochromocytoma during angiography.

Pre-Procedure
  • Allergies, renal function, and laboratory parameters should be optimized as in the adult population 
  • Normal laboratory values can vary in the pediatric population and treating physicians should be familiar with these variations 
  • Neonates (age < 28 days), tend to be hypercoagulable but angiography is typically considered safe in those with a platelet count greater than 50,000/µl, prothrombin time of less than 18 s, partial thromboplastin time of less than 32 s, and an International Normalized Ratio of less than 1.2 for elective cases and 1.5 for urgent cases 
  • Coagulopathies may require treatment with fresh frozen plasma, vitamin K, or platelet transfusion.  
  • Most pediatric patients will require general anesthesia for angiography with conscious sedation used more frequently in older patients 

Technique
  • Vessels tend to be more superficial in neonates and infants as well as more likely to vasospasm, thrombosis, and occlusion. 
  • Ultrasound should be used as pediatric patients should not be stuck more than once due to risk of arterial damage (pseudoaneurysm formation, etc.).
  • Additional sites for access include axillary, brachial and umbilical arteries.
  • The umbilical artery is an effective alternative to femoral access as it avoids potential access site complications and can be used for up to 5 days after birth.  
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  • Starting with a smaller gauge needle and a flexible wire, eg., 21-Ga/ 0.018-in. can be advantageous in smaller patients. The system can then be converted to a 0.035-in. system with a 4- or 5-Fr micropuncture sheath depending on the size of the patient.
  • Vascular sheaths should be used if multiple catheter exchanges will be required, but left to operator discretion.
  • Vascular sheaths come as small as 3-Fr and can be useful in patients under 10 kg.
  • Microcatheters can be inserted directly through the indwelling 3- or 4- Fr vascular sheath and if the purpose of the procedure is to perform an embolization a 4-Fr 0.038-in. inner diameter catheters are widely available to accommodate a coaxially placed microcatheter thereby keeping the vascular sheath to 4-Fr.
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  • Patients weighing less than 15 kg tend to be hypercoagulable and intraprocedural systemic heparin therapy should be given to prevent thrombosis at the access site.
  • Doses of 75-100 IU/kg are typically used and in prolonged cases activated clotting time can be a useful measure for titration of anticoagulants.
  • The vessels of the pediatric population tend to be less tortuous than adults making catheter selection and advancement easier.
  • Pediatric vessels are more prone to vasospasm and it is suggested that the operator lead with the wire. 
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  • The volume of flushes and contrast should be carefully monitored to avoid volume-overload.
  • It is recommended that the volume of contrast used in neonates should be less than 5 mL/ kg and 6– 8 mL/ kg in patients outside the neonatal age group.
  • Contrast injection rates vary based on the weight of the patient and anatomical location; see Angiographic Rates.
  • Note: values presented are in mL/ s and total volumes in mL. There is no consensus on the values given, but it may serve as a guide to an interventionalist with the knowledge that improvements in imaging, contrast agents, injector pumps, and medication use (e.g. vasodilators), may significantly alter injection parameters.
  • Pump injectors are used in regions requiring high flow rates; however, many pediatric angiographers prefer hand injections for selective arteriography, or in the contexts of neonatal and small infant arteriography to maximize control of arterial bed opacification and minimize contrast agent reflux.
  • Arterial phase frame rates are suggested to be 3-4 frames per second whereas venous phase can be 1 frame per second by hand injection.

Complications
  • While the rate of complications tends to be low, the rate increases in patients weighing less than 15kg. 
  • Smaller devices help to improve complication rates; however, rates can be as high as 10% in pediatrics and especially those less than 1 year of age making the procedures riskier than that of their adult counterparts where the complication rate is below 1%.  
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  • Puncture site complications may be as high as 25% in patients less than 15 kg who undergo arterial interventions, which includes hematomas, dissections, thrombosis, occlusion, pseudoaneurysm, and arteriovenous fistula formation.
  • The majority of access site complications are self-limiting and will not require treatment.
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  • Pediatric populations can be treated with adult doses of nitroglycerin (1– 3 μg/ kg) administered intra-arterially in 1 μg/ kg aliquots to treat or prevent vasospasm.
  • Administration of systemic heparin dosed at 75– 100 μg/kg will prevent thrombosis in patients weighing less than 15kg.
  • If arterial thrombosis occurs, it may be treated by keeping the extremity warm and heparin infusion to keep PTT double the normal value.
  • Neonates are at higher risk for hypoglycemia and hypothermia especially in premature patients. Hypoglycemia can be treated by giving boluses of intravenous glucose at 5-10%.
  • Hypothermia can be addressed in a number of ways but those include covering the patient with blankets, warming lamps, and warming fluids given intravenously.​ ​
  • The risk of contrast nephropathy can be significant based on preexisting conditions in adults, but the risk can be decreased as in the adult populations with use of low osmolar or diluted contrast medium, preprocedural hydration, and use of alternative contrast agents such as carbon dioxide.

Post-Procedure
  • Peripheral pulses 
  • In-patients should be reexamined the next day 
  • Out-patients should be called the following day. 
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