Department of Cardiovascular Surgery, Children's National Medical Center, Washington, DC.
Department of Anesthesiology, Children's National Medical Center, Washington, DC.
J Thorac Cardiovasc Surg. 2014 Apr;147(4):1271-5. doi: 10.1016/j.jtcvs.2013.12.018. Epub 2014 Jan 2.
Previous attempts to support single ventricle circulation mechanically have suggested that a custom-built assist device is needed to push, rather than pull, through the pulmonary circulation. We hypothesized that using a conventional ventricular assist device, with or without conversion of a total cavopulmonary connection to a bidirectional Glenn cavopulmonary connection, would allow assistance by pulling blood through the circuit and improve the cardiac index (CI).
Cavopulmonary connections were established in each of 5 Yorkshire pigs (25 kg) using ePTFE conduits in a Y configuration with appropriate clamping of the limbs of the Y to achieve a total cavopulmonary Fontan connection (TCPC), superior vena cava cavopulmonary connection (SVC Glenn), and inferior vena cava cavopulmonary connection (IVC Glenn). A common atrium had been established previously by balloon septostomy. Mechanical circulatory assistance of the single systemic ventricle was achieved using a centrifugal pump with common atrial inflow and proximal ascending aortic outflow. The CI was calculated using an ultrasonic flow meter placed on the distal ascending aorta and compared between the assisted and nonassisted circulation for 3 conditions: TCPC, SVC Glenn, and IVC Glenn. The mean pulmonary artery pressure, common atrial pressure, arterial oxygen saturation, partial pressure of arterial oxygen, and oxygen delivery were calculated.
The unassisted SVC Glenn CI tended to be greater than the TCPC or IVC Glenn CI. Significant augmentation of total CI was achieved with mechanical assistance for SVC Glenn (109% ± 24%, P = .04) and TCPC (130% ± 109%, P = .01). The assisted CI achieved at least a mean baseline biventricular CI for all 3 support modes. Oxygen delivery was greatest for assisted SVC Glenn (1786 ± 1307 mL/L/min) and lowest for TCPC (1146 ± 386 mL/L/min), with a trend toward lower common atrial and pulmonary artery pressures for SVC Glenn.
SVC bidirectional Glenn circulation might allow optimal augmentation of the CI and oxygen delivery in a failing single ventricle using a conventional pediatric ventricular assist device. The results from our model also suggest that the Fontan circulation itself can be supported with systemic ventricular assistance of the single ventricle.
之前支持单心室循环的尝试表明，需要使用定制的辅助设备来推动，而不是拉动肺循环。我们假设使用传统的心室辅助设备，无论是否将全腔肺连接转换为双向 Glenn 腔肺连接，都可以通过拉动血液通过回路来辅助，并提高心指数（CI）。
在 5 只约克夏猪（25 公斤）中，使用 Y 形配置的 ePTFE 导管建立腔肺连接，适当夹闭 Y 形的四肢以实现全腔肺 Fontan 连接（TCPC）、上腔静脉腔肺连接（SVC Glenn）和下腔静脉腔肺连接（IVC Glenn）。先前通过球囊房间隔造口术建立了共同心房。通过离心泵实现单系统心室的机械循环辅助，泵的共同心房流入和近端升主动脉流出。使用放置在远端升主动脉上的超声流量计计算 CI，并在 3 种情况下比较辅助和非辅助循环的 CI：TCPC、SVC Glenn 和 IVC Glenn。计算平均肺动脉压、共同心房压、动脉血氧饱和度、动脉血氧分压和氧输送。
未辅助的 SVC Glenn CI 倾向于大于 TCPC 或 IVC Glenn CI。机械辅助 SVC Glenn（109%±24%，P=.04）和 TCPC（130%±109%，P=.01）可显著增加总 CI。所有 3 种支持模式的辅助 CI 均至少达到平均基线双心室 CI。辅助 SVC Glenn 的氧输送最大（1786±1307 mL/L/min），TCPC 的氧输送最低（1146±386 mL/L/min），SVC Glenn 的共同心房和肺动脉压力有下降趋势。
SVC 双向 Glenn 循环可能允许使用传统儿科心室辅助设备对衰竭的单心室进行 CI 和氧输送的最佳增强。我们模型的结果还表明，Fontan 循环本身可以通过单心室的系统性心室辅助来支持。
