A 45-year-old male with a background of VSD repair as a child. He was thought to have a biscuspid aortic valve and a degree of aortic coarctation presented with a 4-week history of headaches, malaise, and productive cough. He had been prescribed several antibiotic courses by his general practitioner with no improvement in his symptoms. He was found to have and elevated D-dimer which prompted a computed tomography (CT) pulmonary angiogram. This suggested an abnormal appearance to the aortic valve and convex indentation of the anterior wall of the aortic sinus into the RVOT, this was confirmed to be a fistula between the aortic root and RVOT on a gated CT aorta (Fig. 1). On examination, a continuous murmur could be heard throughout the precordium on auscultation. A transthoracic echocardiogram (TTE) showed severe aortic stenosis (AS) with heavy calcification. A subsequent trans-oesophageal echocardiogram (TOE) showed confirmed a mass attached to the aortic valve (1.6cm x 1.5cm). A diagnosis of sub-acute bacterial endocarditis was made, with negative blood cultures and a raised white cell count of 16.1x109/L. MRI of the brain was also positive for scattered microhaemorrhages suggesting likely dissemination of infective detritus. The patient was prepared and consented for urgent inpatient surgery.
Figure 1 (a) Axial CT of the aorta showing fistula arising from the aortic root outpouching towards the right ventricular outflow tract (RVOT), (b) CT showing the fistulous communication in the RVOT, (c) Coronal CT imaging showing the relationship between the aortic root and the fistula, (d) 3D reconstruction showing the fistula.
Redo-sternotomy was performed and the heart circumferentially freed of adhesions. Heparin was administered and routine central cannulation achieved with insertion of a right superior pulmonary vein vent. Cardiopulmonary bypass was successfully commenced, cross clamp applied and antegrade and retrograde cold blood cardioplegia administered. There was a palpable thrill in the RVOT secondary to the fistula. An oblique aortotomy was performed. The right coronary cusp sinus was eroded with communication into the RVOT with necrotic and disrupted edges of the ventricular septum measuring 3.5cm x 2 cm (Fig. 2): The aortic valve was found to be unicuspid. The valve was extensively calcified, with thrombus and vegetation noted.
Figure 2. Intraoperative image demonstrating the fistula.
The native valve was excised, which helped to identify the fistula’s origin at the right coronary sinus with erosion of the aorto-ventricular region. This was extensively debrided of infected and necrotic tissue and washed out. The defect was closed with an oval bovine pericardial patch using a double suture line, initially with interrupted pledgeted 4 − 0 prolene followed by 6 − 0 prolene suture in a continuous fashion circumferentially (Fig. 3). Routine aortic valve replacement with a 21mm mechanical prosthesis in the intra-annular position was completed with a continuous suture technique and the aortotomy closed using a bovine pericardial patch. The cross clamp was removed, with direct current cardioversion required and the heart returning to sinus rhythm with a bundle branch block that subsequently resolved. The patient was weaned slowly from cardiopulmonary bypass and routine decannulation and closure completed.
Figure 3. This diagram shows the way in which the fistula closure was undertaken. The red is representative of the aortic side and the blue of the pulmonary artery side. A single pericardial patch closure was undertaken initially with interrupted plegeted 4 − 0 prolene sutures (orange arrow) with an additional 6 − 0 prolene suture run continuously over that area (green arrow).
The patient progressed well post-operatively with TTE showing no residual flow across the previous fistula site, there was narrowing of the main pulmonary trunk but no significant increase in velocities. Peak forward velocity across pulmonary valve ~ 1.8m/s and RVOT Vmax ~ 1.4m/s. Tissue sample from theatre grew staphylococcus sp. And targeted antibiotic therapy was commenced. The patient completed a full 6-week course of post-operative antibiotic therapy prior to safe discharge home. Post-operative gated CT scan confirmed there was no recurrence of the fistula (Fig. 4). He continues to do well six months after surgery and will continue long term imaging surveillance.
Figure 4. A) 3D reconstruction showing repaired fistula, B) no contrast flow was detected across the repair indicating a competent repair, this was validated by TTE doppler.