Gregory A. Fleming, MD, MSCI, FSCAI; Jayant Bagai, MD, FSCAI; Faisal Latif, MD, FSCAI

Femoral artery injury is a common complication of cardiac catheterization in pediatric patients, with femoral artery thrombosis being the most common form of injury. Femoral artery thrombosis often presents with the loss of distal pulse and/or a cool, pale extremity; however, subclinical femoral artery thrombosis and occlusion may also occur. The diagnosis is often confirmed with a vascular ultrasound. In this Tip of the Month, we will summarize the significance of this problem, review quality measures that may reduce the risk of developing this complication, and discuss management strategies for femoral artery thrombosis following cardiac catheterization in pediatric patients.

Incidence, Risk Factors, and Consequences of Femoral Artery Injury

The incidence of femoral artery thrombosis following pediatric cardiac catheterization is up to 9.6 percent when detected by clinical signs, and infants are at the highest risk.^1–4 Use of routine ultrasound in infants following cardiac catheterization likely picks up many subclinical cases of femoral arterial thrombosis, with one study reporting an increase in the detection rate of arterial thrombosis from 8.3 percent to 23.4 percent following implementation of routine ultrasound in all patients less than six months of age.³ Risk factors associated with femoral artery injury include a lower weight (weight < 4 kg), a younger age, an increased sheath diameter, an arterial sheath exchange, a final activated clotting time (ACT) of less than 250 seconds, and a longer procedural time.^1–5 Limb-threatening ischemia can occur with femoral artery thrombus and requires aggressive medical, surgical, and/or interventional management to prevent limb loss.⁶ However, collateralization around the occluded vessel more often results in adequate blood flow that prevents this kind of complication. Subclinical femoral artery thrombosis may present later in life with symptoms of claudication, leg length discrepancy, and/or the inability to cannulate the occluded artery at a follow-up cardiac catheterization.^{3, 4, 6}

Quality Measures for Prevention/Management of Femoral Artery Injury

1. Adjust for modifiable risk factors:
   1. Consider alternate access sites if feasible (i.e., umbilical artery or a prograde approach from the femoral vein), especially in infants < 4 kg.
   2. Use the smallest sheath possible; consider the 3.3 Fr Mongoose^â Pediavascular sheath in infants < 4 kg.
   3. Avoid sheath exchanges if possible.
   4. Heparinize after the arterial access is obtained and ensure the ACT is >250 seconds if there are no contraindications. 

2. Consider using ultrasound-guided vascular access routinely, as it:
   1. Avoids access of the superficial or profunda femoral artery¹
   2. Allows for the visualization of the common femoral artery as the desired point of access¹
   3. Allows for the measurement of the vessel diameter prior to sheath placement¹

3. Use post-procedural ultrasound, as it:
   1. Allows for the assessment of any patient with a loss of pulse or signs of limb ischemia after cardiac catheterization
   2. Should be considered a routine ultrasound assessment in all infants < 4 kg after cardiac catheterization³
   3. Allows for the early detection of arterial injury and/or thrombus and the early initiation of anticoagulation

4. Develop an institutional protocol for management of post-catheterization arterial thrombus. Some examples are:
   1. Duke University Vascular Access Protocol (Unpublished) (Table 1)
   2. CHOP Clinical Practice Strategy (Table 2)⁵
   3. UC San Diego – Use of Low-Dose Tissue Plasminogen Activator (tPA) for Vascular Thrombosis in Pediatric Patients⁷
      1. Start heparin infusion with a target activated partial thromboplastin time (aPTT) 65–80 seconds for 12 hours → if there is no evidence of recanalization of the vessel by exam or ultrasound → start tPA administration at 0.05 mg/kg/h for 30 minutes. The dose is increased to 0.1 mg/kg/h if there are no signs of bleeding. Closely monitor vital signs and pulses. The tPA should be stopped once the pulse returns or after four hours. Heparin is continued after the tPA is stopped, and patients are discharged on Lovenox and aspirin.⁷

Conclusion

Femoral artery injury and/or thrombosis following cardiac catheterization in pediatric patients is a significant complication with several identified pre-procedural risk factors. In the event of a cold or ischemic extremity, urgent surgical or interventional management for thrombus extraction may be necessary. When there is adequate blood flow from collateralization, early detection and initiation of a management protocol may lead to resolution of the thrombus and avoid the long-term consequences of an occluded femoral artery.

Table 1: Duke University Vascular Access Protocol (Unpublished)

Table 2: CHOP Clinical Practice Strategy⁵

1. Alexander J, Yohannan T, Abutineh I, et al. Ultrasound-guided femoral arterial access in pediatric cardiac catheterizations: A prospective evaluation of the prevalence, risk factors, and mechanism for acute loss of arterial pulse. Catheter Cardiovasc Interv. 2016 Dec.;88(7):1098-1107.
2. Glatz AC, Shah SS, McCarthy AL, et al. Prevalence of and risk factors for acute occlusive arterial injury following pediatric cardiac catheterization: a large single-center cohort study. Catheter Cardiovasc Interv. 2013 Sep 1;82(3):454-62.
3. Kamyszek RW, Leraas HJ, Nag UP, et al. Routine postprocedure ultrasound increases rate of detection of femoral arterial thrombosis in infants after cardiac catheterization. Catheter Cardiovasc Interv. 2019 Mar 1;93(4):652-659.
4. Kim J, Sun Z, Benrashid E, et al. The impact of femoral arterial thrombosis in pediatric cardiac catheterization: a national study. Cardiol Young. 2017 Jul;27(5):912-917.
5. Glatz AC, Keashen R, Chang J, et al. Outcomes using a clinical practice pathway for the management of pulse loss following pediatric cardiac catheterization. Catheter Cardiovasc Interv. 2015 Jan 1;85(1):111-7.
6. Andraska EA, Jackson T, Chen H, et al. Natural History of Iatrogenic Pediatric Femoral Artery Injury. Ann Vasc Surg. 2017 Jul;42:205-213.
7. Bratincsak A, Moore JW, and El-Said HG. Low dose tissue plasminogen activator treatment for vascular thrombosis following cardiac catheterization in children: a single center experience. Catheter Cardiovasc Interv. 2013 Nov 1;82(5):782-5.