Patient Size Parameters to Guide Use of the Impella Device in Pediatric Patients

Background
There are few options for minimally invasive circulatory support in children, and there are no data on minimum patient size requirements for placement of the Impella 2.5 device. This study defines patient and ventricular size parameters to guide Impella device (Abiomed Inc, Danvers, MA) placement for temporary circulatory support in smaller pediatric patients (10-30 kg).

Methods
This was a multicenter study of echocardiographic and MRI derived dimensions of the left ventricle (LV) length and ascending aorta used to define minimum size parameters that are necessary for the placement of the Impella catheter.

Results
Data were collected from 44 cardiac MRIs conducted in healthy pediatric patients and 39 echocardiograms conducted in pediatrics patients with cardiomyopathy prior to ventricular assist device (VAD) placement. From the MRI studies, the mean LV apical length was 6.4 ± 0.9 cm and the mean ascending aortic length was 3.9 ± 0.7 cm. From the echocardiograms, the mean LV parasternal length was 6.4 ± 1.6 cm in systole and 6.8 ± 1.5 cm in diastole. The length of the Impella 2.5 device from the pigtail to the aortic valve marker is 7.5 cm. In the cohort of patients undergoing consideration for VAD placement a minimum LV length of 7.5 cm corresponded to a height of 122 cm, weight of 23 kg and BSA of 0.89 m². In the MRI cohort a minimum LV length of 7.5 cm corresponded to a height of 121 cm, weight of 23.9 kg and BSA of 0.89 m².

Conclusions
Temporary circulatory support with Impella devices is feasible in pediatric and adolescent patients. This study defines anthropomorphic and anatomic measurements to guide providers in patient selection for mechanical support using the Impella devices.