De Paulis R, Engelhardt H, Chiariello L, Reul H, Morea M
Cattedra di Cardiochirurgia, 2nd University of Roma, Italy.
Int J Artif Organs. 1990 Apr;13(4):237-46.
The possibility of achieving effective mechanical ventricular assistance without the need for thoracotomy provides great clinical advantages. Two in vitro systems were used to assess left ventricular unloading by means of a small-diameter cannula inserted retrograde into the left ventricle by cannulation of the femoral artery. This cannula is connected to the inlet of a centrifugal blood pump (CP) that delivers the blood into the contralateral femoral artery. Steady-flow test circulation was used to pump fluid in a closed loop from a reservoir through the test cannula back into the reservoir. Pressure drops over cannulae with inner diameters of 4, 5, 6, 7, and 8 mm at flows of 2, 2.5, 3 L/min, against a pressure of 60, 80, 100, and 120 mmHg were calculated. A stationary pressure drop of 120 mmHg was measured at a flow of 3 L/min through a 100 cm cannula with an inner diameter of 6 mm. The second system was a pulsatile mock circulation composed of an atrial and an arterial reservoir linked by a pneumatic prosthetic ventricle. This system was coupled with a 100 cm cannula, 6.1 mm inner diameter, which was passed across the outflow valve of the pulsatile prosthetic ventricle and connected to a CP. Fluid was withdrawn from the ventricle and pumped back into the arterial reservoir. Pulsatile pressure drop over the cannula was measured at different CP flows for increasing systolic ventricular pressure; heart unloading was quantified as a function of CP flow under baseline and failing conditions of the prosthetic left ventricle model. At a constant CP flow the pressure drop over the cannula increased with the pulsatility inside the ventricle. The work of the prosthetic ventricle was reduced by more than 50% when the CP pump was set to 3 L/min; at the same flow setting, when the situation of a failing left ventricle was simulated, the CP was able to take over all the work of the prosthetic ventricle, establishing a stationary flow and a 25% higher mean aortic pressure. This approach to left ventricular assistance may have significant clinical relevance.
无需开胸就能实现有效的机械性心室辅助，这具有很大的临床优势。使用了两种体外系统，通过经股动脉插管将小直径套管逆行插入左心室来评估左心室卸载情况。该套管连接到离心血泵（CP）的入口，血泵将血液输送到对侧股动脉。使用稳流测试循环从储液器通过测试套管以闭环方式将液体泵回储液器。计算了内径分别为4、5、6、7和8毫米的套管在流量为2、2.5、3升/分钟、对抗60、80、100和120毫米汞柱压力时的压力降。在流量为3升/分钟时，通过内径为6毫米、长度为100厘米的套管测得的固定压力降为120毫米汞柱。第二个系统是由一个心房储液器和一个动脉储液器通过一个气动人工心室连接而成的搏动性模拟循环。该系统与一个内径为6.1毫米、长度为100厘米的套管相连，该套管穿过搏动性人工心室的流出阀并连接到一个CP。液体从心室抽出并泵回动脉储液器。在不同的CP流量下，随着收缩期心室压力的增加，测量套管上的搏动性压力降；在人工左心室模型的基线和衰竭状态下，将心脏卸载量化为CP流量的函数。在CP流量恒定的情况下，套管上的压力降随着心室内的搏动性增加而增大。当CP泵设置为3升/分钟时，人工心室的工作量减少了50%以上；在相同的流量设置下，当模拟左心室衰竭情况时，CP能够承担人工心室的所有工作，建立稳定的血流并使平均主动脉压升高25%。这种左心室辅助方法可能具有重要的临床意义。
