Prenatal Diagnosis of Aorto-Left Ventricular Tunnel With Dysplastic Bicuspid Aortic Valve: From Fetal Cardiac Failure to Favorable Outcome

The purpose of this study was to review our 35 years of experience with aortico-left ventricular tunnel (ALVT), with emphasis on diagnosis, surgical details, and follow-up. Aortico-left ventricular tunnel is a rare congenital anomaly. Neonatal surgery has been advocated in all due to long-term concern of valvar aortic regurgitation (AR). We identified 11 patients from 1963 to August 2002. Clinical, echocardiographic, catheterization, and surgical details were reviewed. Eight of 11 patients presented at less than six months old (six with congestive heart failure) and three later with a murmur, all with clinical evidence of AR. Associated lesions, most commonly aortic valve and coronary artery anomalies, were present in 45%. Catheter occlusion was considered but not performed in five. Spontaneous occlusion was documented in one. Ten had surgery (nine in our institution), seven with direct suture and two by patch closure of the aortic end of the AVLT. At follow-up (median, 5 years; 1 month to 35 years), all were asymptomatic; three had residual ALVT (one moderate, two small/trivial), with at most mild AR. Aortico-left ventricular tunnel is a rare cardiac malformation with a good post-operative long-term outcome. Associated lesions occurred in 45%. Catheterization should be reserved for patients with unclear non-invasive findings or transcatheter closure. We recommend surgery for most patients. We report spontaneous closure in one patient, prompting consideration of conservative follow-up in rare small, asymptomatic AVLT.

Aorto-ventricular tunnel is a congenital, extracardiac channel which connects the ascending aorta above the sinutubular junction to the cavity of the left, or (less commonly) right ventricle. The exact incidence is unknown, estimates ranging from 0.5% of fetal cardiac malformations to less than 0.1% of congenitally malformed hearts in clinico-pathological series. Approximately 130 cases have been reported in the literature, about twice as many cases in males as in females. Associated defects, usually involving the proximal coronary arteries, or the aortic or pulmonary valves, are present in nearly half the cases. Occasional patients present with an asymptomatic heart murmur and cardiac enlargement, but most suffer heart failure in the first year of life. The etiology of aorto-ventricular tunnel is uncertain. It appears to result from a combination of maldevelopment of the cushions which give rise to the pulmonary and aortic roots, and abnormal separation of these structures. Echocardiography is the diagnostic investigation of choice. Antenatal diagnosis by fetal echocardiography is reliable after 18 weeks gestation. Aorto-ventricular tunnel must be distinguished from other lesions which cause rapid run-off of blood from the aorta and produce cardiac failure. Optimal management of symptomatic aorto-ventricular tunnel consists of diagnosis by echocardiography, complimented with cardiac catheterization as needed to elucidate coronary arterial origins or associated defects, and prompt surgical repair. Observation of the exceedingly rare, asymptomatic patient with a small tunnel may be justified by occasional spontaneous closure. All patients require life-long follow-up for recurrence of the tunnel, aortic valve incompetence, left ventricular function, and aneurysmal enlargement of the ascending aorta.

To investigate the echocardiographic, morphological, and histological appearances of aorto-left ventricular tunnel observed in four fetal hearts and compare the findings with those reported in older patients with the malformation. Previous studies have concentrated on clinical features of the malformation from birth to adult life and have speculated on either its embryological formation or its acquisition during late intrauterine life. The presentation of a large series of cases in fetal life is a unique opportunity to study the malformation at an early stage in its natural course. A retrospective study was performed of four cases of aorto-left ventricular tunnel discovered among 872 cases of congenital abnormalities diagnosed at a tertiary centre for fetal echocardiography. Detailed echocardiographic and anatomical observations were made of the malformation as identified during fetal life. The precise anatomical arrangement was determined and compared with previous descriptions found in journals published in English. In fetal life, as after birth, the malformation is characterised by enlargement and hypertrophy of the left ventricle, enlargement of the aortic root, and free regurgitation at the level of the aortic valve. Anatomical abnormalities are found at the aortic ventriculoarterial and sinutubular junctions as well as in the intervening aortic wall. These are unrelated to necrosis, ischaemia, or the presence of mucopolysaccharides. The lesion is a developmental abnormality that should be reliably diagnosed by fetal echocardiography combined with colour flow Doppler echocardiography during the mid-trimester. The exact anatomical relations clarified by this study are pertinent to diagnosis and subsequent surgical correction.