Radial arteriovenous fistula after cardiac catheterisation

A 47-year-old man, 10 years after therapeutic cardiac catheterisation through the radial artery, appears with swelling on the right wrist, with growth evident over the last year and measuring about 3 cm. On examination there was evident thrill over the swelling.

An ultrasound with colour Doppler was performed and showed a fistulous connection (Fig. 1) with a 5,8mm neck and high output between the right radial artery and the adjacent vein (Fig. 2). The radial artery demonstrated a biphasic waveform with a low resistance flow (resistance index 0,45) and with a peak systolic velocity of 200 cm/s (Fig. 3). The adjacent vein shows a pulsatile arterial component (Fig. 4).

Cardiac catheterisation is the gold standard in treating and diagnosing of cardiac disease, that may be performed by femoral or radial approach. This last approach, described first in 1989 by Campeau, is increasingly being used due to numerous advantages, such as lower mortality or vascular complications and early patient ambulation, being, as such, associated with lower total hospital costs. [1-4]

Although very rare, the most frequent complications are associated with access site complications: bleeding, haematoma formation, pseudoaneurysm and arteriovenous fistula (AVF). [5]

The first case of iatrogenic AVF was published in 1973 by James and Myers. [6] It results from placement of the needle through a venous tributary which may lead to punctures in the shared arteries and veins. If this communication fails to heal, which happens rarely, a fistula is formed. So, AVF corresponds to an abnormal connection between the artery and the vein that results in increased flow across the connection, with a disruption of the normal blood flow pattern.

Various studies have shown that the frequency of AVF after radial catheterisation is very low, for example in one of the largest studies, published in 2015 and involving over 10000 patients, the frequency of AVF was only 0,04%. [7]

However, the risk of an iatrogenic AVF can still be minimised by using more experienced operators, limiting the number of times the same artery is accessed, using a sheath size smaller than the arterial diameter, using ultrasound-guided needle placement to provide anatomic information such as tortuosity, diameter and proximity of the radial artery to the vein. [8, 9]

Usually patients are examined by the clinician after catheterisation to detect signs of complication. Some signs may appear years after the procedure, such as in the case we present.

The clinical presentation of iatrogenic AVF can be varied, such as a pulsatile mass, thrill, pain, swelling, and varicose and dilated veins. However, in the particular case of radial AVF, it is usually asymptomatic and typically manifests as a palpable thrill and a continuous murmur on the wrist. They are usually associated with small volume shunts, so it is rare to condition significant haemodynamic changes.

In cases where there is clinical suspicion of an AVF, the diagnosis can be confirmed by complementary diagnostic tests that are useful to quantify the magnitude of the problem and estimate the overall impact of the AVF. The gray scale ultrasound combined with Doppler ultrasound is a good choice and is often used for this purpose. [10]

The characteristic findings are:

- The direct visualisation of a connection between the radial artery and an adjacent vein with a turbulent flow and pulsatile (arterialised) waveform at the fistula;

- Loss of normal triphasic waveform on the radial artery, proximal to the fistula with continuous and increased forward flow during diastole (and a corresponding decrease in resistance index);

- Decreased arterial flow in the arterial segments downstream of the fistula, better identified when compared to the opposite side, sometimes without a triphasic waveform;

- Increased and continuous venous flow upstream from the access site, with a lack of respiratory variation and often with a pulsatile arterial component (secondary sign of arterialisation of the veins). [10]

There is sufficient evidence in the literature to suggest that the prognosis of iatrogenic AVF is generally good, with about one-third of them closing spontaneously. Therefore, it can be managed as usual, with an appropriate follow-up, including clinical and ultrasound evaluation. [11] For this reason, some authors are of the opinion that when radial AVF is not inconvenient for the patient, does not enlarge and does not cause neurovascular impairment and / or heart failure, it can be treated conservatively without any intervention. [7,9]

Other therapeutic strategies have been reported for treating iatrogenic radial AVF, such as endovascular or surgical treatment, which are especially important in symptomatic cases or with haemodynamic repercussion. [11]

In the present case, given the recent evident growth, surgical closure of the AVF was proposed.

Take Home Message / Teaching Points

- Iatrogenic AVF is a very rare vascular complication of transradial cardiac catheterisation.

- The outcome of iatrogenic AVF is good.

- AVF treatment may be conservative, endovascular intervention or surgical intervention.

Written informed patient consent for publication has been obtained.