Aortico-left ventricular tunnel is a rare defect and accounts for 0.001% of all congenital cardiac defects.Reference Okoroma, Perry, Scott and McClenathan 1 Martins et alReference Martins, Sherwood, Mayer and Keane 2 described this defect among 0.05% of the 17,381 patients who underwent cardiac catheterisation over 35 years at the Boston Children's Hospital. It is an abnormal channel that begins in the ascending aorta, bypasses the aortic valve, and leads into the left ventricular cavity. These tunnels bypass the normal ventriculoarterial junction but do not penetrate the septal musculature.Reference Ho, Muriago, Cook, Thiene and Anderson 3 Reports on device closure of aortico-left ventricular tunnel are scarce. This is the first report of device closure of aortico-left ventricular tunnel using an Amplatzer vascular plug III.
Case report
A 4.5-year-old boy was referred to the paediatric cardiology clinic for cardiac murmur noted as an incidental finding at the peripheral health centre. This child remained completely asymptomatic since birth. His clinical examination revealed regular high-volume radial pulses at a rate of 110/min, right arm supine blood pressure of 101/56 mmHg, grade 3/6 ejection systolic murmur, and grade 3/4 early diastolic murmur audible best at the aortic areas.
Transthoracic echocardiogram revealed a sigmoid tract arising superior to the sinotubular junction and traversing antero-lateral to the right coronary cusp assuming an oval shape in the short-axis enface view venting inferiorly into the left ventricular ouflow tract. This aortico-left ventricular tunnel measured about 8.5 mm in length, and the width measured 4.5 mm, 6 mm, and 3.6 mm at the superior ostium at the aortic end, mid-portion, and inferior ostium at the left ventricular end, respectively. There were no associated aortopulmonary anomalies. Coronary arteries and both the ventricular outflow tracts were normal. We could demonstrate pan-diastolic flow reversal in the descending aorta on colour and pulse wave Doppler interrogations. There was mild left ventricular dilatation, with the left ventricular end-diastolic dimension measuring 41 mm (Z-score = +2.29).
This child underwent successful device closure of the aortico-left ventricular tunnel under trans-oesophageal and biplanar fluoroscopic guidance. Immediate pre-procedural trans-oesophageal echocardiogram assessment demonstrated the tunnel to be of 4.5 mm width and about 8 mm length (Fig 1). A minor aneurysmal bulge of the intracardiac portion of the tunnel into the right ventricular outflow tract was also noted with no obstruction. After securing a 5 F sheath in the right femoral artery, an aortic root angiogram using a 4 F pigtail catheter demonstrated the dye filling the left ventricle via the tunnel in diastole. Coronary arteries were normal. We positioned a 014 extra-stiff cross-it 300 coronary wire into the left ventricle via the tunnel through a 5 F right Judkin's catheter to aid the threading of Tyshak II (B. Braun International Systems Inc., Bethlehem, PA, United States of America), 8 mm/4 cm balloon. This was inflated slowly to conform to the course and shape of the tunnel. The dimensions further measured with the balloon inflated in situ revealed the tunnel length to be 5.3 mm and diameter 4.3 mm. We then exchanged the coronary wire for 035 Amplatzer extra-stiff wire over which a 7 F Mullin's sheath was positioned in the left ventricle through which we advanced 10 mm/5 mm Amplatzer Vascular Plug III (St. Jude Medical, Inc., St. Paul, Minnesota, United States of America). Under trans-oesophageal and fluoroscopic guidance, we initially positioned the device to be seated entirely in the tunnel with inferior lobe optimally placed at the left ventricular end and the waist sitting in the body of the tunnel and the superior lobe closing the aortic end. We repeated aortic and left ventricular angiograms with a 4 F pigtail catheter advanced through a 4 F sheath secured in the left femoral artery, with the device fully deployed and not released. These angiograms and the trans-oesophageal echocardiogram did not reveal any antegrade or retrograde flow through the tunnel. The coronaries’ filling was normal and there was no demonstrable aortic regurgitation. These findings were further confirmed on repeating the angiographic study after the release of the device (Fig 2). We administered intravenous bolus dose of unfractionated heparin, 100 units/kg at the beginning of the procedure. The child received aspirin at 5 mg/kg/day starting from 1 day before the procedure for the following 6 months duration.
Figure 1 Mid oesophageal long-axis view (trans-oesophageal echocardiogram) demonstrating aortic regurgitation through the aortico-left ventricular tunnel adjacent to the right coronary cusp
Figure 2 Mid-oesophageal long-axis view (trans-oesophageal echocardiogram) and aortic root angiogram showing the device well placed in the aortico-left ventricular tunnel (ALVT) with no residual regurgitation and aortic valve integrity well preserved.
Electrocardiogram monitoring during the entire procedure did not reveal any ischaemic changes.
We performed a transthoracic echocardiogram recently at 4 months after the device closure. This showed the device positioned well with no residual shunt and no aortic regurgitation (Fig 3).
Figure 3 Follow-up transthoracic echocardiogram after 4 months, revealing the device effectively closing the aortico-left ventricular tunnel with no evidence of aortic valve compromise.
Discussion
Ever since the first description by Levy et al in 1963,Reference Levy, Lillehei, Anderson, Amplatz and Edwards 4 there have been many reports of aortico-left ventricular tunnel focussing mainly on its surgical management. The exact aetiology and embryology of aortico-left ventricular tunnel still remain largely speculative. Suggested explanations include an anomalous coronary artery, possibly the conal vessel, opening in the left ventricle,Reference Levy, Lillehei, Anderson, Amplatz and Edwards 4 rupture of a sinus of Valsalva aneurysm,Reference Turley, Silverman, Teitel, Mavroudis, Snider and Rudolph 5 an anterior aortic wall abnormality with communication into the left ventricle,Reference Ho, Muriago, Cook, Thiene and Anderson 3 defective incorporation of the distal end of the bulbus cordis,Reference Somerville, English and Ross 6 persistence of embryonic crests of the fifth aortic arch,Reference Palacio, Peralta, Sanchez and Alperovich 7 and early aortic dissection similar to Marfan's syndrome.Reference Cooley, Harris and Rodin 8 Hovaguimian et al in 1988 attempted to describe four types of aortico-left ventricular tunnel with their attendant implications on the surgical approach: type 1, a simple tunnel with a slit-like opening at the aortic end and no aortic valve distortion; type II, a large extracardiac aortic wall aneurysm of the tunnel with an oval opening at the aortic end with or without valvular distortion; type III, intracardiac aneurysm of the septal portion of the tunnel, with or without right ventricular outflow tract obstruction; and type IV, types II and III combined.Reference Hovaguimian, Cobanoglu and Starr 9 In our patient, the tunnel had an oval opening at the aortic end with no aortic wall aneurysm or any aortic valve distortion. There is in addition a minor aneurysmal bulge of the intracardiac septal portion of the tunnel, thus categorising this into type III.
Generally, aortico-left ventricular tunnel presents in childhood or infancy, and the natural course depends on the degree of aortic regurgitation. Recognition of aortic incompetence in a neonate or young infant should suggest aortico-left ventricular tunnel as a possible diagnosis. Other lesions that must be differentiated are ruptured aneurysm of the sinus of Valsalva, coronary cameral fistula, congenital isolated aortic incompetence, and aortic incompetence with ventricular septal defect.
Transthoracic echocardiography can identify the aortico-left ventricular tunnel and associated lesions. Associated cardiac anomalies are present in about 45% of these patients.Reference Martins, Sherwood, Mayer and Keane 2 Coronary artery anomalies are commonly encountered in the form of complete absence of right or left coronary arteries, ostium of right coronary artery lying within the tunnel and right coronary artery to distal tunnel fistula. Critical aortic stenosis, bicommissural aortic valve, unicommissural aortic valve, sub-aortic stenosis, aortic incompetence, leaflet perforation of the aortic valve from haemodynamic trauma of the unsupported right coronary cusp, pulmonary valvar stenosis, right ventricular outflow tract obstruction and left ventricular non-compaction, ventricular septal defect, atrial septal defect, and patent ductus arteriosus are among the other reported associations.Reference Horvath, Balaji, Skovranek, Hucin, de Leval and Stark 10 – Reference McKay 12 Our patient did not have any other significant associated cardiac lesion.
Catheterisation should be reserved for patients with unclear non-invasive findings or for transcatheter closure. Other imaging modalities like trans-oesophageal echocardiography, foetal echocardiography, and magnetic resonance imaging are also helpful in defining the details in various clinical settings.Reference Singh, Reinhardt, Desai and Rasiah 13 , Reference Kakadekar, Sandor, Patterson and LeBlanc 14
There are very few reports of successful percutaneous closure of aortico-left ventricular tunnel.Reference Chessa, Chaudhari and De Giovanni 15 , Reference Vijayalakshmi, Chitra and Prabhu Deva 16 The varied nature of the anatomy, close proximity of the tunnel to the coronary arteries, the necessity to improvise devices that are designed for other defects, and the potential deformation complications of the aortic valve annulus resulting in aortic regurgitation can all dissuade the interventionist. Transcatheter closure of the aortico-left ventricular tunnel may be attempted in all the four types when there is no associated lesion amenable only to surgical repair and when the device itself is not going to compromise the coronary arteries. Significant right ventricular and left ventricular outflow obstructions, more than mild aortic valve regurgitation, other aortic and pulmonary valve abnormalities and coronary artery abnormalities requiring surgery should be considered as contraindications for device closure.
Almost all the reports of device closures in the literature used Amplatzer duct occluder devices. These nitinol-based devices owing to their flexible nature conform to the shape of the aortico-left ventricular tunnel plugging the defect effectively. However, their retention skirt protruding into the left ventricular outflow tract can exert shearing stress on the red blood cells leading to haemolytic anaemia and hyperbilirubinaemia.Reference Vijayalakshmi, Chitra and Prabhu Deva 16 In this context, Amplatzer vascular plugs, which come in more suitable lengths and diameters, prove to be the better option. We used Amplatzer vascular plug III in our patient. The Amplatzer family of Vascular Plugs have four different types with a flexibility to select the correct vascular plug for the procedure based on vessel type, blood flow, and the available landing zone. The Amplatzer Vascular Plug III, with oblong cross-sectional shape, multiple nitinol mesh layers, and extended rims, provides the fastest occlusion of all Amplatzer Vascular Plugs and is ideal for high-flow situations. There is a small platinum marker on the distal rim centred in the long axis that further aids to improve visualisation for device orientation. In addition, 155 cm-long delivery wire accommodates a greater range of procedures for easy device delivery.
We feel that percutaneous device closure of aortico-left ventricular tunnel has the inherent advantage of plugging both ends of the tunnel, obviating the potential aneurysm formation noted in the earlier surgical methods of closing only the aortic end. It is also unlikely for aortic regurgitation to occur in future if no such problem is evident during the procedure itself. This presumption is nevertheless unsubstantiated as there are no long-term follow-up reports in these patients with device closure. On the contrary, regardless of the surgical technique used, valvar aortic regurgitation is a major concern in these patients, and despite successful surgical repair the incidence of aortic regurgitation ranges from 16% to 60%.Reference Horvath, Balaji, Skovranek, Hucin, de Leval and Stark 10 , Reference Sreeram, Franks, Arnord and Walsh 17
