Virtual implantation and patient-specific simulation for optimization of outcomes in ventricular assist device recipients.

BACKGROUND

Left ventricular assist devices (LVAD) are increasingly used for long-term mechanical circulatory support and are effective in improving survival and quality-of-life of patient with advanced heart failure. Nonetheless, they are associated with significant early and late morbidity rates (including pump thrombosis, thromboembolic events, and pump dysfunction). These complications are at least partially associated with suboptimal pump positioning. Currently, we are missing tools to further improve the positioning of LVAD devices in a patient-specific fashion.

METHODS AND EVALUATION OF THE HYPOTHESIS

We hypothesized that the analysis of the implanted device in patients presenting selected LVAD-related complications through segmentation and three-dimensional reconstruction of CT scans may provide patient-specific information into mechanical factors contributing to pump dysfunction and thromboembolic events, with potential to guide preventive interventions against development of new complications. We also hypothesized that preoperative virtual implantation and computer-assisted surgery in candidates to LVAD implantation may help in the customization of device positioning, with potential to minimize severe complications. The hypothesis was evaluated in a multidisciplinary fashion (cardiac surgeons, biomedical engineers and biomedical images processing experts). CT scans of 14 LVAD recipients were reconstructed through semi-automatic segmentation (including the whole heart, the implanted device and the chest wall). A coordinate system was built to quantify the coaxiality of the LVAD apical cannula with the mitral annulus. Patients were stratified into Group 1 (presenting complications such as thromboembolic events, pump dysfunction or thrombosis) and Group 2 (no complications). Group 1 patients presented significantly greater average rotation of the apical cannula towards the interventricular septum (p=0.015), although no difference was observed in terms of average rotation towards the anterior or posterior left ventricular wall.

CONCLUSIONS

Several patient-specific factors (including left ventricular morphology and chest wall conflict with the device after wound closure) may influence the effectiveness and safety of LVAD therapy, but they are difficultly managed through the current implantation techniques. We suggest that the clinical results of LVAD treatment can be improved through preoperative virtual implantation and computer-assisted surgery (in order to guide device selection, exact site of left ventricular wall coring site). Given these preliminary results, we are examining larger patient datasets in order to further test the hypothesis. Dedicated tools for virtual implantation are currently under development.