New Type Of Para-aortic Counterpulsation Device Preliminary Experimental Study

Party one:The para-aortic counterpulsation device and biocompatibility in vitro preliminary study[Abstract] Objective To test the hydrodynamic characteristics and biocompatibility of a new aortic counterpulsation device side (PACD) in vitro experiments and acute circulatory animal experiment. Materials and methods PACD, a monoport device, consists of a blood chamber (55ml) anastomosed to the descending aorta by means of a valveless graft and an air chamber connected to IABP machine by means of an adjustable volume amplifier. The device is separated by a movable polyurethane membrane, providing counterpulsation therapy by filling blood during systole and ejecting blood during diastole. The study was conducted to investigate acute hemodynamic responses to PACD. The air sac of PACD with 40ml,60ml and 80ml blood sac were connected to the IABP, blood sac connected to PVC pipe. The pressure load of PACD was set up 50 mmH20,100 mmH20 respectively by adjusting the vertical height. Then SV and EF were measured at different load conditions. In the acute animal-assisted study process, the level of plasma free hemoglobin was measured in support before, auxiliary 2 hours,4 hours,6 hours and 8 hours. The tissues and organs of experimental animals were observed in general samples, and were reserved for histological examination to observe the morphology change in microscopy, after the completion of the experimental animals. Results The EF of three kinds of devices were 95.5%,95.8%and 93.3%respectively, in the condition of 50mm-H2O pressure load, and when were confronted with 100mm H2O pressure load, the EF were 94.0%,92.0%and 90.4% respectively in those devices. The levels of plasma free hemoglobin increased from 3.92±1.70mg/dl to 9.36±2.68mg/dl gradually, during the whole assist period. The plasma free hemoglobin increased significantly (p<0.01) in the first four hours, and increased significantly (p<0.05) from the fourth to sixth hours. During the last two hours, the levels of plasma free hemoglobin showed an increasing. trend, but there was no statistically significant difference (p> 0.05). When the acute animal experiment was completed, there were no infarct ischemic, thrombosis change in organs of experimental animals, and was no thrombosis in mesenteric arterial system by the general observation. There were no organ infarction, edema, intravascular thrombosis and other pathological changes in microscopic histopathological observation. Conclusion The work of PACD showed good performance driven by IABP control instrument. The pressure load influenced values of SV and EF very little, the EF remained at least 90%. The biocompatibility of PACD is excellent, which has no adverse impact on organs. Part two:Early testing of a novel paraaortic counterpulsation device in sheep[Abstract] Objective To evaluate the hemodynamics characteristics of our new paraaortic counterpulsation device in animal experiment studies. Methods PACD, a monoport device, consists of a blood chamber (60ml) anastomosed to the descending aorta by means of a valveless graft and an air chamber connected to IABP machine by means of an adjustable volume amplifier. The device is separated by a movable polyurethane membrane, providing counterpulsation therapy by filling blood during systole and ejecting blood during diastole. Hemodynamic parameters during the PACD-assisted beats were compared with those during the unassist beats. Acute heart failure was induced in all animals by snaring the left anterior descending coronary artery and (or) branch of left circumflex artery. The hemodynamic effects PACD were then reassessed. Results We successfully induced all cases of heart failure, in the conditions of which CO and MAP decreased 17.6%(P<0.01), 27.7%(P<0.01) respectively, and PCWP increased 57.7%(P<0.01). All hemodynamics indexes, cerebral and herat perfusion improved significantly after PACD assisting. PACD activation increased significantly CO by 6.29%, from 3.18±0.34 to 3.38±0.28L/min(p< 0.01), and MAP by 2.04%, from 67.75±11.94 to 69. 13±10.95mmHg(p< 0.05). Both of SAP and DAP decreased significantly from 85.00±13.83,59.63±12.00 to 81.88±14.68 mmHg(p<0.01),54.63±12.39(p<0.01) respectively, at the same time, MADP increased 19.4%, from 65.0±12.3 to 77.6±11.6mmHg(p<0.01), after PACD assist. With the assist of PACD the PADP is 97.25±13.67mmHg, which higher significant than the SAP before PACD assist. The value of MDLMF,LMF and CSF increased by 14.0%(P<0.01), from 89.00±8.09 to 101.50±6.41ml/min(P< 0.01),13.8%, from 66.63±7.78 to 75.88±8.03ml/min(P<0.01),11.6%, from122.75±15.06 to 137.13±15.78 ml/min (P<0.01) respectively. Both of EVR and LCAF increased by 35.9%, from 1.03±0.13 to 1.40±0.11(P<0.01), by 11.23%, from 187.88±23.67 to 208.00±19.88 ml/min (p<0.01) respectively after PACD assist. Conclusion The PACD was an effective counterpulsator, providing cardiac assist that may be provid long-term circulation assist to heart failure patients. Part three:Circulatory Assisting by Para-aortic Counterpulsation Device in Sheep Model with Low cardiac output syndromeObjective:To evaluate the hemodynamic efficacy of a para-aortic counterpulsation device (PACD) in assisting circulation in sheep model with different degree of low cardiac output syndrome. Materials and methods:PACD, a monoport device, consists of a blood chamber (60ml) anastomosed to the descending aorta by means of a valveless graft and an air chamber connected to IABP machine by means of an adjustable volume amplifier. The device is separated by a movable polyurethane membrane, providing counterpulsation therapy by filling blood during systole and ejecting blood during diastole. The study was conducted to investigate acute hemodynamic responses to PACD, which lasted for 8 hours, in eight sheep (44.8±3.8kg) with different degree of low cardiac output syndrome. The model was developed by ligating the left anterior descending coronary artery and/or branches of circumflex coronary artery, that induced different levels of low cardiac output syndrome with relatively stable CVP at 4-10mmHg. The low cardiac output syndrome was defined as mild (CO:3.74±0.28 L/min, MAP:70～85 mmHg), medium (CO:2.95±0.30 L/min, MAP:50～69 mmHg) and severe (CO:2.13±0.24 L/min, MAP:30-49 mmHg). PACD was used to assist circulation in these three groups. Hemodynamic data were collected to evaluate the efficacy of circulatory assisting by PACD. Results:1) Mild low cardiac output syndrome (n=5) There was no significant difference in CO, MAP, and LCAF with/without the device on. The LV+dp/dtmax showed a slight increase from 2113±221mmHg/sec to 2238±275mmHg/sec, and the LV-dp/dtmax showed a slight decrease from-974±120mmHg/sec to-1068±195mmHg/sec. PACD decreased significantly SAP and DAP by 1.94%and 6.34%respectively, and MADP increased from 71.20±3.42 to 82.40±5.41 mmHg significantly. CSF and LMF increased significantly from 135.00±11.58ml/min,68.40±5.50 ml/min to 148.40±16.18 ml/min,77.80±7.53 ml/min respectively, after the assist circulation by PACD. EVR and CS-SO2 increased significantly from 1.24±0.18,55.04±4.24%to 1.56±0.19,62.62±2.71%respectively, and CO2a-v decreased from 4.58±0.43ml/dl to 3.86±0.30 ml/dl significantly.2) Medium low cardiac output syndrome (n=8) With the assist of PACD, CO and MAP increased significantly from 2.95±0.30L/min,58.63±5.71 mmHg to 3.19±0.33L/min,60.63±4.87 mmHg respectively. The LV+dp/dtmax showed a slight increase from 1313±398 mmHg/sec to 1332±387 mmHg/sec, and the LV-dp/dtmax showed a slight decrease from-730±290 mmHg/sec to-765±243 mmHg/sec. PACD decreased significantly SAP and DAP by 4.70% and 11.44%respectively, and MADP increased from 55.63±5.97 to 69.75±8.38 mmHg significantly. CSF, LMF and LCAF increased significantly from 114.63±12.69 ml/min, 61.25±9.08ml/min and 173.75±15.77ml/min to 130.75±14.11 ml/min,71.75±10.26ml/min, 184.38±16.43 ml/min respectively, after the assist circulation by PACD. EVR and CS-SO2 increased significantly from 0.95±0.08,40.54±5.20%to 1.36±0.12,51.40±5.86% respectively. CO2a-v and MCO decreased significantly from 5.82±0.77ml/dl,3.83±0.43 ml/min/100g to 4.75±0.52 ml/dl,3.64±0.37 ml/min/100g respectively.3) Severe low cardiac output syndrome (n=8) With the assist of PACD, CO and MAP increased significantly from 2.13±0.24L/min,39.00±7.98 mmHg to 2.39±0.29L/min,42.63±7.63 mmHg respectively. The LV+dp/dtmax showed a slight increase from 749±270mmHg/sec to 826±396 mmHg/sec, and the LV-dp/dtmax showed a slight decrease from-512±105 mmHg/sec to-550±70 mmHg/sec. PACD decreased significantly SAP and DAP by 9.39% and 20.34%respectively, and MADP increased from 35.75±7.92 to 56.75±9.36 mmHg significantly. CSF, LMF and LCAF increased significantly from 86.63±7.73 ml/min, 46.25±5.50 ml/min and 141.63±7.25 ml/min to 113.00±13.64 ml/min,62.13±7.79 ml/min, 148.63±8.38 ml/min respectively, after the assist circulation by PACD. EVR and CS-SO2 increased significantly from 0.93±0.13,22.84±3.20%to 1.44±0.24,44.51±7.03% respectively. CO2a-v and MCO decreased significantly from 6.67±1.12 ml/dl,3,46±0.25 ml/min/100g to 4.67±0.40 ml/dl,3.09±0.11 ml/min/100g respectively. Conclusions:The experiment demonstrated that PACD significantly improved hemodynamics, as evidenced by augmented MADP, CSF, CO, LVEW and EVR. The advantages of PACD include low cost, adjustable volume, more effective circulatory support compared to IABP and easy to implant, making it, as a bridge to transplantation or myocardial recovery,:a desirable alternative mechanical support device for the patients with different degree of heart failure.