Echocardiographic imaging of the Medtronic Micro Vascular Plug™ during off label placement in the premature infant with patent ductus arteriosus.

OBJECTIVES: To report the usefulness of harmonic imaging in echocardiography to visualize and direct the implantation of the Medtronic micro vascular plug (MVP). BACKGROUND: Off label use of the MVP was reported for transcatheter occlusion of patent ductus arteriosus (PDA) in premature infants. The device is poorly visible on fluoroscopy and echocardiography. METHODS: In 9 consecutive premature infants, the MVP was used for transcatheter closure of the PDA. In each, the ability of conventional echocardiographic imaging was compared to harmonic imaging, and the device was deployed in the PDA using echocardiography. RESULTS: In each subject, harmonic imaging proved superior to conventional echocardiography to visualize the MVP in premature infants using 12 and 8 MHz probes. Once the delivery, catheter was across the PDA into the descending aorta, and the MVP advanced to the catheter tip, positioning, and deployment of the device was possible without fluoroscopy. All devices were deployed appropriately with immediate occlusion and no obstruction to the left pulmonary artery or aorta. CONCLUSIONS: The MVP can be accurately imaged using harmonic imaging, even in the near field in premature infants. Precise implantation of the MVP in the PDA of premature infants is possible with echocardiographic imaging of the device and vascular structures.

Validation of a Simple Score to Determine Risk of Early Rejection After Pediatric Heart Transplantation.

OBJECTIVES: This study aimed to develop a reliable and feasible score to assess the risk of rejection in pediatric heart transplantation recipients during the first post-transplant year. BACKGROUND: The first post-transplant year is the most likely time for rejection to occur in pediatric heart transplantation. Rejection during this period is associated with worse outcomes. METHODS: The United Network for Organ Sharing database was queried for pediatric patients (age <18 years) who underwent isolated orthotopic heart transplantation from January 1, 2000 to December 31, 2012. Transplantations were divided into a derivation cohort (n = 2,686) and a validation (n = 509) cohort. The validation cohort was randomly selected from 20% of transplantations from 2005 to 2012. Covariates found to be associated with rejection (p < 0.2) were included in the initial multivariable logistic regression model. The final model was derived by including only variables independently associated with rejection. A risk score was then developed using relative magnitudes of the covariates' odds ratio. The score was then tested in the validation cohort. RESULTS: A 9-point risk score using 3 variables (age, cardiac diagnosis, and panel reactive antibody) was developed. Mean score in the derivation and validation cohorts were 4.5 ± 2.6 and 4.8 ± 2.7, respectively. A higher score was associated with an increased rate of rejection (score = 0, 10.6% in the validation cohort vs. score = 9, 40%; p < 0.01). In weighted regression analysis, the model-predicted risk of rejection correlated closely with the actual rates of rejection in the validation cohort (R(2) = 0.86; p < 0.01). CONCLUSIONS: The rejection score is accurate in determining the risk of early rejection in pediatric heart transplantation recipients. The score has the potential to be used in clinical practice to aid in determining the immunosuppressant regimen and the frequency of rejection surveillance in the first post-transplant year.