Main pulmonary artery dilation in association with congenital bicuspid aortic valve in the absence of pulmonary valve abnormality.

BACKGROUND: Main pulmonary artery (MPA) dilation is reported to occur in association with pulmonary valve (PV) abnormalities and in genetic diseases of connective tissue. AIM: To determine whether MPA dilation occurs with bicuspid aortic valve (BAV) in the absence of PV abnormality.
METHODS: MPA and aortic dimensions were investigated in 194 subjects with BAV and 178 controls matched for age, sex and body surface area (BSA) using transthoracic two-dimensional echocardiography. Using control measurements, linear regression of each parameter versus age, gender, and BSA(2/3) provided expected values. For each subject with BAV, the percentage divergence from expected value ((observed--expected value)/expected value) for each dimension was analysed.
RESULTS: MPA and aortic measurements showed normal distribution in all subjects. PV annulus and MPA were larger in BAV; 17.7% positive divergence of MPA dimension from expected was found in diastole, and 16.7% in systole. Aortic dimensions at all levels measured were larger in BAV; divergence was greater distally than proximally (10% divergence at annulus, 31% at ascending aorta). In BAV, divergence of ascending aortic dimensions from expected values increased with age (r(2)=0.142, p=0.02), but MPA divergence from expected values did not increase with age (r(2)=0.001, p=0.296).
CONCLUSIONS: MPA dilation occurs in association with BAV in the absence of PV abnormality, suggesting primary vessel wall pathology predisposing to arterial dilation. A systemic abnormality of connective tissue common to both arteries may be responsible, or the dilation may result from a common developmental exposure as both originate from the embryologic cono-truncus.