Early outcomes of heart transplantation in critical patients: single center experience of Fuwai Hospital / 器官移植

Objective To analyze the early outcomes of heart transplantation in critical patients and its significance in donor allocation decision. Methods Clinical data of 449 recipients undergoing heart transplantation were retrospectively analyzed. According to preoperative status, all patients were divided into the critical status group (n=64) and general status group (n=385). The incidence of critical status was summarized. Clinical data of recipients were statistically compared between two groups. Postoperative survival and causes of death in recipients between two groups were analyzed. Perioperative results of critical recipients undergoing different mechanical circulation support as a bridge to heart transplantation were compared. Results Critical patients accounted for 14.3% of the total number of transplant recipients. The proportion of critical patients gradually increased in recent 5 years. Compared with the general status group, the recipients in critical status group had a lower proportion of smoking history, a higher proportion of cardiac surgery history, a higher serum level of creatinine, and a higher proportion of primary diseases of heart failure before heart transplantation(all P≤0.01). The proportion of undergoing mechanical circulation support was higher, the incidence of complications was higher, the stay time in intensive care unit (ICU) was longer and the in-hospital fatality was higher after heart transplantation in the critical status group (all P≤0.01). The 1-year survival rate of recipients in critical status group was significantly lower than that in general status group (83% vs. 95%, P < 0.01). The fatality of recipients due to infection and multiple organ failure in critical status group was higher than that in general status group. Among 64 critical recipients, 1 recipient received ventilator alone, and 63 recipients underwent mechanical circulation support devices as a bridge to heart transplantation. Among them, intra-aortic balloon pump (IABP) alone was applied in 49 cases (77%), 8 cases (13%) of extracorporeal membrane oxygenation (ECMO) combined with IABP, 4 cases (6%) of ECMO alone, and 2 cases (3%) of left ventricular assist device (LVAD) alone. Critical patients who received preoperative ECMO and ECMO combined with IABP bridging to heart transplantation have a higher proportion of postoperative complications, a longer ICU stay time, a longer mechanical ventilation time, and a higher proportion of hospital deaths. Conclusions The overall prognosis of critical patients undergoing heart transplantation is relatively poor. Effective preoperative management may reverse the high-risk status of critical patients in a certain extent. The limited quantity of donor heart should be allocated to the most urgent patients who can obtain the greatest benefit from heart transplantation.

Hemodynamic Analysis on Meglev Left Ventricular Assist Device of a New Generation / 医用生物力学

Objective To reduce the thrombosis probability and hemolysis risk of the meglev left ventricular assist device (LVAD), so as to increase the efficiency of blood supply. Methods The influences of the pump outlet diameter, exit angle, fillet size between the outlet and the inner wall of the pump, as well as gap between the rotor and the shell on internal flow field of the pump were studied by using the computational fluid dynamics (CFD) method, so as to optimize the internal structure and improve the hydrodynamic performance of the pump. Results Compared with pump of the previous generation, the maximum wall shear stress (WSS) of the pump inner wall, the maximum WSS of the pump rotor, the area with WSS >200 Pa were reduced by 23.6%, 47.4%, 76.2%, respectively, while the outlet flow was increased by 14.4%. Conclusions For the meglev LVAD of the new generation, its internal blood flow tended to be smooth, and the hemodynamic performance of blood flow was improved comprehensively. The research findings provide references for optimization design of the meglev LVAD and related experimental researches in the future.

Exercise Therapy for an Older Patient With Left Ventricular Assist Device

A left ventricular assist device (LVAD) is a mechanical circulation support implanted for patients with end-stage heart failure. It may be used either as a bridge to cardiac transplantation or as a destination therapy. The health of a 75-year-old man with a medical history of systolic heart failure worsened. Therefore, he was recommended to have implanted a LVAD (Thoratec Corp.) as a destination therapy. After the surgery, he was enrolled in patient cardiac rehabilitation for the improvement of dyspnea and exercise capacity. In results, there is an improvement on his exercise capacity and quality of life. For the first time in Korea, we reported a benefit of exercise therapy after being implanted with a LVAD.

Theoretical Estimation of Cannulation Methods for Left Ventricular Assist Device Support as a Bridge to Recovery

Left ventricular assist device (LVAD) support under cannulation connected from the left atrium to the aorta (LA-AA) is used as a bridge to recovery in heart failure patients because it is non-invasive to ventricular muscle. However, it has serious problems, such as valve stenosis and blood thrombosis due to the low ejection fraction of the ventricle. We theoretically estimated the effect of the in-series cannulation, connected from ascending aorta to descending aorta (AA-DA), on ventricular unloading as an alternative to the LA-AA method. We developed a theoretical model of a LVAD-implanted cardiovascular system that included coronary circulation. Using this model, we compared hemodynamic responses according to various cannulation methods such as LA-AA, AA-DA, and a cannulation connected from the left ventricle to ascending aorta (LV-AA), under continuous and pulsatile LVAD supports. The AA-DA method provided 14% and 18% less left ventricular peak pressure than the LA-AA method under continuous and pulsatile LVAD conditions, respectively. The LA-AA method demonstrated higher coronary flow than AA-DA method. Therefore, the LA-AA method is more advantageous in increasing ventricular unloading whereas the AA-DA method is a better choice to increase coronary perfusion.