Aorto-ventricular tunnel

Last revised by Yuranga Weerakkody on 6 Nov 2022

Aorto-ventricular tunnel (AVT) is an extremely rare form of congenital heart disease, representing an anomalous extracardiac communication between the ascending aorta and the left or right ventricles.

In most cases the anomalous communication is between the aorta and the left ventricle and therefore the term aorto-left ventricular tunnel (ALVT) is used. Rarely the abnormal connection is with the right ventricle, in which case the term aorto-right ventricular tunnel (ARVT) is used instead.

Approximately 130 cases have been described in the literature, with an estimated prevalence ranging from ~0.001% to ~0.1% of all cases of congenital heart disease 1,4. There is a clear male predilection of 2:1, male: female cases. Very few cases have been seen in those with African or Asian ethnicity 4
In ~90% of cases, the connection is between the aorta and the left ventricle; a right ventricle connection only occurs in ~10%.

The anomaly usually occurs in isolation, and does not seem to be part of a syndrome.

It can be diagnosed antenatally on routine ultrasonography.

On physical examination, a "to-and-fro" murmur may be appreciated on precordial auscultation, along with an easily palpable pulse (due to rapid aortic runoff).

The commonest presentation is heart failure in the first year of life although there is a wide spectrum of severity, from in utero death, to rapid postnatal heart failure, and even some adults who are entirely asymptomatic.

Congenital communication between the ascending aorta, distal to the sinotubular junction, and the left or right ventricles. The communication usually occurs distal to the right sinus of Valsalva.

The anomaly typically occurs in isolation, independent of other anomalies.

The spectrum of severity of the condition is related to the size of the anomalous connection and the degree of aortic incompetence.

Transthoracic echocardiography (both 2-D and 3-D have been used) is the modality of choice, with prenatal diagnosis also described in a similar manner with fetal echocardiography.

Parasternal long and short axis views (at the base/aortic valve level) may demonstrate a dilated left ventricle, increased wall thickness, with a normal or decreased ejection fraction/global systolic function. Modification of the scanning plane may be necessary to fully visualize the aortic root which is often dilated; the origin of the tunnel is most commonly cephalad to the right sinus of valsalva. The tunnel will most commonly travel anteriorly, just deep to the RVOT and the pulmonary arteries before diving into the outlet portion (i.e. supra-cristal) of the interventricular septum becoming contiguous with the left ventricular outflow tract just below the annulus of the aortic valve. The tunnel (less commonly) may also drain into the right ventricle (particularly the outflow tract) 9.

Color flow and spectral Doppler are essential to define the direction, velocity and magnitude of blood flow, especially the diastolic regurgitation jets flowing from the tunnel into the LVOT with or without aortic valvular regurgitation. Quantification of severity (e.g. by pressure half time) should be noted. Apical 5 chamber and long axis views are complimentary, and may provide more optimal Doppler alignment with regurgitation jets to enhance detection and quantification 8.

Associated anomalies of the aortic valve, coronary origins, and ventricular septal defects should also be noted; the membranous ventricular septum may be posteriorly deviated forming a malalignment VSD with right ventricular outflow tract obstruction 7.

MRA has been used with some success, but is of course, not widely available. 

Rarely used any more in view of its invasive nature and ionizing radiation. It is reserved for the trickier cases, in which non-invasive modalities have been equivocal.

It can be diagnosed antenatally after gestation week 18. 
In 2015 a new sonographic finding, the cockade sign was described for the antenatal diagnosis of aorto-left ventricular tunnel 2.

In the majority of cases, even when the patient is asymptomatic, early surgical intervention is required to prevent permanent left ventricular dysfunction.

The first case, an aorto-left ventricular tract, was reported in 1957 by Jesse E Edwards (1912-2008), American cardiac pathologist 5, and Howard B Burchell (1908-2009), American cardiologist 4.

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