The adjustment of the location of the anastomosis of the LVAD outflow cannula as well as its angle of incidence plays a significant role in the level of thromboembolisms. By proper adjustment in this CFD study of a synthetic model of an aortic arch bed, we found that nearly a 50% reduction in cerebral embolism could be achieved for a configuration consisting of a shallow angle of implantation over a baseline normal incidence of the LVAD cannula. Within the limitations of our model, we have established that the LVAD implantation geometry is an important factor and should be taken into consideration when implanting an LVAD. It is possible that other parameters such as distance of the LVAD outflow cannula to the root of the IA could affect the thrombi embolisation probabilities. However, the results of this study suggest that the risk of stroke may be significantly reduced by as much as 50% by tailoring the VAD implantation by a simple surgical manoeuvre. The results of this line of research may ultimately lead to techniques that can be used to estimate the optimal LVAD configuration in a patient-specific manner by pre-operative imaging.
We found that a 4-mm × 21-mm RBTS completely compensated for the effects of a 90% discrete stenosis of the distal aortic arch in the HN. Placed preventatively, the RBTS and arch displayed zones with thrombogenic potential showing recirculation and stagnation that persist for a substantial fraction of the cardiac cycle, indicating that anticoagulation should be considered with a prophylactic RBTS.
This study suggests that SPS decreases CBF, especially in the presence of a higher Qp/Qs and epinephrine. The mechanism is largely due to the decrease in diastolic pressure and the inability of the coronary arteries to compensate with vasodilation.
Infantile scimitar syndrome (SS) carries significant mortality. Consistent management guidelines have not been well established, and outcomes continue to be disappointing. We present our experience managing an SS patient with complex anatomy who developed stenosis of the pulmonary veins contralateral to the hypoplastic lung.
Presently, mechanical support is the most promising alternative to cardiac transplantation. Ventricular Assist Devices (VADs) were originally used to provide mechanical circulatory support in patients waiting planned heart transplantation (“bridge-to-transplantation” therapy). The success of short-term bridge devices led to clinical trials evaluating the clinical suitability of long-term support (“destination” therapy) with left ventricular assist devices (LVADs). The first larger-scale, randomized trial that tested long-term support with a LVAD reported a 44% reduction in the risk of stroke or death in patients with a LVAD. In spite of the success of LVADs as bridge-to-transplantation and long-term support. Patients carrying these devices are still at risk of several adverse events. The most devastating complication is caused by embolization of thrombi formed within the LVAD or inside the heart into the brain. Prevention of thrombi formation is attempted through anticoagulation management and by improving LVADs design; however there is still significant occurrence of thromboembolic events in patients. Investigators have reported that the incidence of thromboembolic cerebral events ranges from 14% to 47% over a period of 6–12 months. An alternative method to reduce the incidence of cerebral embolization has been proposed by one of the co-authors, namely William DeCampli M.D., Ph.D. The hypothesis is that it is possible to minimize the number of thrombi flowing into the carotid arteries by an optimal placement of the LVAD outflow conduit, and/or the addition of aortic bypass connecting the ascending aorta (AO) and the innominate artery (IA), or left carotid artery (LCA). This paper presents the computational fluid dynamics (CFD) analysis of the aortic arch hemodynamics using a representative geometry of the human aortic arch and an alternative aortic bypass. The alternative aortic bypass is intended to reduce thrombi flow incidence into the carotid arteries in patients with LVAD implants with the aim to reduce thromboembolisms. In order to study the trajectory of the thrombi within the aortic arch, a Lagrangian particle-tracking model is coupled to the CFD model. Results are presented in the form of percentage of thrombi flowing to the carotid arteries as a function of LVAD conduit placement and aortic bypass implantation, revealing promising improvement.
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