A new rotary blood pump for versatile extracorporeal circulation: the DeltaStream™

Hemocompatibility of new magnetically-levitated centrifugal pump technology compared to the CentriMag adult pump

The specific hemocompatibility properties of mechanical-circulatory-support (MCS)-pump technologies have not previously been described in a comparable manner. We thus investigated the hemocompatibility-indicating marker of a new magnetically-levitated (MagLev) centrifugal pump (MT-Mag) in a human, whole-blood mock-loop for 360 min using the MCS devices as a driving component. We compared those results with the CentriMag adult (C-Mag) device under the same conditions according to ISO10993-4. Blood samples were analyzed via enzyme-linked-immunosorbent-assay (ELISA) for markers of coagulation, complement system, and the inflammatory response. The time-dependent activation of the coagulation system was measured by detecting thrombin-anti-thrombin complexes (TAT). The activation of the complement system was determined by increased SC5b-9 levels in both groups. A significant activation of neutrophils (PMN-elastase) was detected within the C-Mag group, but not in the MT-Mag group. However, the amount of PMN-elastase at 360 min did not differ significantly between groups. The activation of the complement and coagulation system was found to be significantly time-dependent in both devices. However, coagulation activation as determined by the TAT level was lower in the MT-Mag group than in the C-Mag group. This slight disparity could have been achieved by the optimized secondary flow paths and surface coating, which reduces the interaction of the surface with blood.

Intermediate Coronary Revascularization using the Deltastream Blood Pump: Results from an Experimental Study

Background

Myocardial revascularization using a complete heart-lung machine may involve many problems, as do complete off-pump attempts. Thus, it was the aim of this study to evaluate the effects of intermediate on-pump/off-pump myocardial revascularization using the miniaturized Deltastream blood pump, on ischemia and hemolysis, in comparison with standard myocardial revascularization.

Methods

In a group of 8 mini-pigs, combined on-pump/off-pump myocardial revascularization was performed using the Deltastream blood pump as beating-heart support for the on-pump part of the operation (group A). Seven other animals served as controls and underwent standard myocardial revascularization with the same device as integrated pump of a complete heart-lung machine (group B). Blood samples for blood gas metabolism, creatine kinase (CK), troponin I, lactate dehydrogenase (LDH), and hydroxybutyrate dehydrogenase (HBDH) were taken before and after the entire operation.

Results

Comparing the baseline values, the increase of CK was more pronounced in group B than in group A (176.4 ± 41.2 to 279.7 ± 29 U/L vs. 274 ± 142.7 to 288.1 ± 118.6 U/L, respectively; p=0.0006). Increase of troponin I was significantly higher in group B than in group A (1 ± 0.3 to 2.9 ± 1 ng/mL vs. 1.1 ± 0.9 to 3 ± 3.8 ng/mL, respectively; p=0.002). LDH increase was also more pronounced in group B (231.7 ± 54.3 to 299.9 ± 39.8 U/L vs. 274.9 ± 59.7 to 263.8 ± 57.9 U/L, respectively; p=0.01). HBDH values increased significantly in group B after the operation (group A: 215.9 ± 34.7 to 200 ± 39.2 U/L vs. group B: 195.4 ± 41.7 to 274.9 ± 51.6 U/L; p=0.02). Hemodynamic measures and LDH values under luxation (group A: 1.9 ± 0.6 U/L; B: 3.5 ± 1 U/L, p=0.001) were also superior in the study group.

Conclusion

The current set-up might be superior to conventional extracorporeal circulation and thus be an alternative for high-risk candidates to avoid the adverse events of a complete heart-lung machine, when they are scheduled for complete myocardial revascularization.

Normothermic Beating Heart Surgery with Assistance of Miniaturized Bypass Systems: The Effects on Intraoperative Hemodynamics and Inflammatory Response

The use of miniaturized cardiopulmonary bypass (CPB) circuits and avoidance of cardioplegic arrest are attempts to reduce the inflammatory response to cardiac surgery. We studied the effects of beating heart surgery (BHS) with assistance of simplified bypass systems (SBS) on global hemodynamics, myocardial function and the inflammatory response to CPB. We hypothesized that the use of SBS was associated with less hemodynamic instability after CPB resulting from attenuation of the inflammatory response when compared with surgery performed with a conventional CPB (cCPB) circuit. Forty-five patients undergoing coronary artery bypass grafting were prospectively studied. Fifteen patients were randomized to the use of a cCPB circuit, cold crystalloid cardioplegia, and moderate hypothermia. Two groups of 15 patients underwent BHS during normothermia with assistance of two different SBS consisting of only blood pump and oxygenator. Hemodynamic variables were assessed with transpulmonary thermodilution and transesophageal echocardiography. Plasma levels of proinflammatory and antiinflammatory mediators were measured perioperatively. After CPB, variables of global hemodynamics and systolic ventricular function did not differ among groups. Left ventricular diastolic function was impaired after CPB equally in all groups (P < 0.01 versus pre-CPB). At the end of surgery, there was more need for vasopressor (norepinephrine) support in both SBS groups than in the cCPB group (P < 0.01). After CPB, the release of interleukin (IL)-6 did not differ significantly among groups, whereas plasma levels of IL-10 were higher in the cCPB group (P < 0.01 versus SBS). The extent of myocardial necrosis (Troponin T) was comparable in all groups. We conclude that in our study, miniaturizing bypass systems and avoidance of cardioplegic arrest were not effective in improving hemodynamic performance and in attenuating the proinflammatory immune response after CPB.

Hemodynamic Modes of Ventricular Assist with a Rotary Blood Pump: Continuous, Pulsatile, and Failure

Pulsatile operation of rotary blood pumps (RBPs) has received interest due to potential concern with nonphysiological hemodynamics. This study aimed to gain insight to the effects of various RBP modes on the heart-device interaction. A Deltastream diagonal pump (Medos Medizintechnik GmbH) was inserted in a cardiovascular simulator with apical-to-ascending aorta cannulation. The pump was run in continuous mode with incrementally increasing rotating speed (0-5000 rpm). This was repeated for three heart rates (50-100-150 bpm) and three levels of left ventricular (LV) contractility. Subsequently, the Deltastream was run in pulsatile mode to elucidate the effect of (de)synchronization between heart and pump. LV volume and pressure, arterial pressure, flows, and energetic parameters were used to evaluate the interaction. Pump failure (0 rpm) resulted in aortic pressure drops (17-46 mm Hg) from baseline. In continuous mode, pump flow compensated by diminished aortic flow, thus yielding constant total flow. High continuous rotating speed resulted in acute hypertension (mean aortic pressure up to 178 mm Hg). In pulsatile mode, unmatched heart and pulsatile pump rates yielded unphysiologic pressure and flow patterns and LV unloading was found to be highly dependent on synchronization phase. Optimal unloading was achieved when the minimum rotating speed occurred at end-systole. We conclude that, in continuous mode, a perfusion benefit can only be achieved if the continuous pump flow exceeds the preimplant (baseline) cardiac output. Pulsatile mode of support results in complex pressure and volume variations and requires accurate triggering to achieve optimal unloading.

Priming Reduced Extracorporeal Circulation Setup (PRECiSe) with the DeltaStream diagonal pump

Different systems for beating heart procedures and low priming systems limited to coronary artery bypass grafting (CABG) have been introduced. We describe Priming Reduced Extracorporeal Circulation Setup (PRECiSe), a new low priming system which sup-plies all the features of cardiopulmonary bypass (CPB). PRECiSe incorporates the DeltaStream diagonal pump, which pumps blood from the right atrium to the aorta via a membrane oxygenator and a filter; the system is placed beneath the patient's head resulting in extremely short tubing. A reservoir allows the use of suckers and vents. Autologous blood priming furthers reduces hemodilution. In a safety study the system was used for extracorporeal circulation in 11 patients undergoing CABG without adverse effects. By use of PRECiSe mean priming was reduced to 268.5 ml resulting in minimal hemo-dilution and transfusion requirements.