Unicuspid aortic valve replacement with development of complete heart block: a case report.

Background: Aortic stenosis is a progressive disease that frequently remains undiagnosed until late in the disease course. In patients that present with symptoms of heart failure and a systolic murmur at a young age, a congenital valvular abnormality must be on the differential. With patients that have accelerated symptoms of aortic stenosis and valvular dysfunction, a unicuspid aortic valve (UAV) could be present. A UAV is often difficult to distinguish from a bicuspid aortic valve (BAV) on transthoracic echocardiography. In patients with congenital valvular abnormalities an ascending aortic aneurysm can also be present. Aortic stenosis changes the jet of fluid emerging from the aortic valve leading to an increased risk for aortic aneurysm dissection and rupture. The gold standard treatment for aortic stenosis secondary to a congenital valvular abnormality is valve replacement. A known risk of aortic valve replacement is conduction abnormalities. In this case, we present a patient with a unicuspid valve who postoperatively develops complete heart block leading to pacemaker implantation.

Case Summary: We present a case of a 46-year-old Caucasian male with no prior medical history who presented with progressively worsening exertional dyspnoea and palpitations for 7 months. Transthoracic echocardiogram showed a BAV, however, further work up confirmed a unicommissural aortic valve with severe aortic stenosis and moderate regurgitation along with an ascending aortic aneurysm. Aortic valve replacement and aortic aneurysm repair via the Bentall procedure was successfully completed with postoperative course being complicated by a complete heart block and subsequent permanent pacemaker placement.

Discussion: When assessing patients with symptoms of heart failure with a systolic murmur that suggests aortic stenosis at a young age, a UAV must be kept on the differential. The symptoms of aortic stenosis and valvular dysfunction are accelerated in UAVs when compared with BAVs. Currently, the treatment for patients with congenital valvular abnormalities presenting with aortic stenosis is aortic valve replacement using traditional open surgery. A known sequelae of isolated aortic valve replacement is conduction abnormalities that can sometimes lead to permanent pacemaker placement. After the confirmation of unicuspid or bicuspid valve postoperatively, it is important to report any postoperative conduction abnormalities. This is because, currently, there is no literature that compares the incidence of conduction abnormalities after unicuspid replacement to that of other BAV syndromes.