Aorto-ventricular tunnel

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

Founder mutation in N-terminus of cardiac troponin I causes malignant hypertrophic cardiomyopathy

Background - Cardiac troponin I (TNNI3) gene mutations account for 3% of hypertrophic cardiomyopathy and carriers have a heterogeneous phenotype, with increased risk of sudden cardiac death. Only one mutation (p.Arg21Cys) has been reported in the N-terminus of the protein. In model organisms, it impairs protein kinase A phosphorylation, increases calcium sensitivity, and causes diastolic dysfunction. The phenotype of this unique mutation in hypertrophic cardiomyopathy patients remains unknown. Methods - We sequenced 29 families with hypertrophic cardiomyopathy enriched for pediatric-onset disease and identified 5 families with the TNNI3 p.Arg21Cys mutation. Using cascade screening, we studied the clinical phenotype of 57 individuals from the 5 families with TNNI3 p.Arg21Cys-related cardiomyopathy. We performed survival analysis investigating the age at first sudden cardiac death in carriers of the mutation. Results - All five families with TNNI3 p.Arg21Cys were from south Lebanon. TNNI3 p.Arg21Cys-related cardiomyopathy manifested a malignant phenotype - sudden cardiac death occurred in 30 (53%) of 57 affected individuals at median age of 22.5 years. In select carriers without left ventricular hypertrophy on echocardiogram, sudden cardiac death occurred, myocyte disarray was found on autopsy heart, and tissue doppler and cardiac magnetic resonance imaging identified subclinical disease features such as diastolic dysfunction and late-gadolinium enhancement. Conclusions - The TNNI3 p.Arg21Cys mutation has a founder effect in south Lebanon and causes malignant hypertrophic cardiomyopathy with early sudden cardiac death even in the absence of hypertrophy. Genetic diagnosis with this mutation may be sufficient for risk stratification for sudden cardiac death