Infective endocarditis in patients after percutaneous pulmonary valve implantation with the stent-mounted bovine jugular vein valve: Clinical experience and evaluation of the modified Duke criteria

AIMS

Percutaneous pulmonary valve implantation (PPVI) has proven good hemodynamic results. As infective endocarditis (IE) remains a potential complication with limited available clinical data, we reviewed our patient records to improve future strategies of IE prevention, diagnosis and treatment.

METHODS

Medical records of all patients diagnosed with Melody® valve IE according to the modified Duke criteria were retrospectively analyzed in three Belgian tertiary centers.

RESULTS

23 IE episodes in 22 out of 240 patients were identified (incidence 2.4% / patient year) with a clear male predominance (86%). Median age at IE was 17.9 years (range 8.2-45.9 years) and median time from PPVI to IE was 2.4 years (range 0.7-8 years). Streptococcal species caused 10 infections (43%), followed by Staphylococcus aureus (n = 5, 22%). In 13/23 IE episodes a possible entry-point was identified (57%). IE was classified as definite in 15 (65%) and as possible in 8 (35%) cases due to limitations of imaging. Echocardiography visualized vegetations in only 10 patients. PET-CT showed positive FDG signals in 5/7 patients (71%) and intracardiac echocardiography a vegetation in 1/1 patient (100%). Eleven cases (48%) had a hemodynamically relevant pulmonary stenosis at IE presentation. Nine early and 6 late percutaneous or surgical re-interventions were performed. No IE related deaths occurred.

CONCLUSIONS

IE after Melody® valve PPVI is associated with a relevant need of re-interventions. Communication to patients and physicians about risk factors is essential in prevention. The modified Duke criteria underperformed in diagnosing definite IE, but inclusion of new imaging modalities might improve diagnostic performance.

CFD-based process optimization of a dissolved air flotation system for drinking water production

Dissolved air flotation (DAF) has received more attention recently as a separation technique in both drinking water as well as wastewater treatment. However, the process as well as the preceding flocculation step is complex and not completely understood. Given the multiphase nature of the process, fluid dynamics studies are important to understand and optimize the DAF system in terms of operation and design. The present study is intended towards a comprehensive computational analysis for design optimization of the treatment plant in Kluizen, Belgium. Setting up the modelling framework involving the multiphase flow problem is briefly discussed. 3D numerical simulations on a scaled down model of the DAF design were analysed. The flow features give better confidence, but the flocs escape through the outlet still prevails which is averse to the system performance. In order to improve the performance and ease of maintenance, design modifications have been proposed by using a perforated tube for water extraction and are found to be satisfactory. The discussion is further reinforced through validating the numerical model against the experimental findings for stratified flow conditions.

20 years of arterial switch operation for simple TGA

BACKGROUND

Arterial switch operation became the golden treatment for simple transposition of the great arteries (sTGA). We describe our experience with the arterial switch operation regarding long-term outcome and the need for re-intervention. Nevertheless, supravalvular pulmonary stenosis (SPS) remains a concern in the long run. We assess the evolution of SPS over time and evaluate the effect of technical modifications on SPS during our experience.

METHODS

We performed a retrospective study on 133 patients operated with ASO for TGA between October 1991 and November 2009. Last report method was used. We reviewed our pediatric cardiology and cardiac surgery database to examine the echocardiographic data and electrocardiograms. A mean follow-up of 9.2 years (+/- 5.83 SD) was reached.

RESULTS

One (0.8%) patient deceased postoperatively due to cardiogenic shock. The overall actuarial freedom from reoperation (open and percutaneous) was 88.1%, 78.5% and 76.9% at 1, 5 and 10 years. SPS needed to be treated in 17 patients. Valve regurgitation at final investigation was maximal moderate in 5 patients for the aortic valve, 10 for pulmonary valve and 3 in tricuspid valve.

CONCLUSIONS

ASO shows excellent long-term results in sTGA with a very low morbidity and mortality and is therefore the procedure of choice. Re-intervention rate is determined by SPS. Since the extensive mobilization of the pulmonary arteries and the creation of a longer neo-pulmonary root, reduction in SPS was seen with no re-interventions in the second half of the group. To obtain a final comparison with the atrial switch operation, a longer Follow-up is necessary.