Coronary artery bypass grafting supported with intracardiac microaxial pumps versus normothermic cardiopulmonary bypass: a prospective randomized trial

Hemolysis and cardiopulmonary bypass: meta-analysis and systematic review of contributing factors

BACKGROUND

The use of cardiopulmonary bypass (CPB) is almost inevitable in cardiac surgery. However, it can cause complications, including hemolysis. Until now, there have not been any standards for reducing hemolysis from CPB. Therefore, this systematic review was conducted to determine the factors that increase or reduce hemolysis in the use of CPB.

METHODS

Keywords Earches (cardiac surgery AND cardiopulmonary bypass AND hemolysis) were done on PubMed databases and Cochrane CENTRAL from 1990-2021 for published randomized controlled trials (RCTs) that studied interventions on CPB, in cardiac surgery patients, and measured hemolysis as one of the outcomes. Studies involving patients with preoperative hematological disorders, prosthetic valves, preoperative use of intra-aortic balloon pumps and extracorporeal circulation, emergency and minimally invasive surgery are excluded RESULTS: The search yielded 64 studies that met the inclusion criteria, which involved a total of 3,434 patients. The most common surgery was coronary revascularization (75%). Out of 64 studies, 33 divided into 7 analyses. Remaining 31 studies were synthesized qualitatively. Significant decreases were found in centrifugal vs roller pumps for PFHb (p = 0.0006) and Hp (p < 0.0001) outcomes, separated vs combined suctioned blood (p = 0.003), CPB alternatives vs conventional CPB (p < 0.0001), and mini extracorporeal circulation (MiniECC) vs conventional CPB for LDH (p = 0.0008). Significant increases were found in pulsatility (p = 0.03) and vacuum-assisted venous drainage (VAVD) vs gravity-assisted venous drainage (GAVD) (p = 0.002).

CONCLUSION

The review shows that hemolysis could be caused by several factors and efforts have been made to reduce it, combining significant efforts could be beneficial. However, this review has limitations, such as heterogeneity due to no standards available for conducting CPB. Therefore, further research with standardized guidelines for CPB is needed to yield more comparable studies. Meta-analyses with more specific parameters should be done to minimize heterogeneity.

Temporary mechanical circulatory support prevents the occurrence of a low-output state in high-risk coronary artery bypass grafting: A case series

BACKGROUND

Coronary artery bypass grafting (CABG) is a durable treatment for coronary artery disease. Left ventricular dysfunction (LVD) (a division of cardiothoracic surgery) (ejection fraction < 35%) significantly elevates perioperative risk for patients pursuing surgical revascularization. Periprocedural support with temporary mechanical circulatory support (tMCS) has shown benefit in this patient population.

METHODS

Four patients with ischemic cardiomyopathy and LVD underwent CABG at our institution between 2017 and 2018. Each patient received perioperative ventricular support using a microaxial tMCS device (Impella 5.0®). The occurrence of a postoperative low-output state (LOS) was assessed for as well as postoperative morbidity and mortality, device-specific complications, and tMCS support duration.

RESULTS

All patients survived to device explant without device-related complications. Two patients required reoperation for nondevice-related bleeding. All patients were without an LOS at 24 h postoperatively with cardiac indices of 2.9-3.6 L/min/m² , normalized serum lactate, and vasoactive-inotrope scores of 0-12.0. There was a notably high incidence of acute renal failure (50%), which was observed in patients with preoperative cardiogenic shock. One patient died 10 days after the device explant. Of the three patients that survived to discharge, two were alive at the most recent follow-up. Postoperative device support varied widely (0-500 h).

CONCLUSION

Perioperative tMCS may be a viable strategy for preventing postoperative LOS in high-risk CABG patients with a low complication rate and acceptable morbidity. The application of microaxial tMCS devices in CABG is an area that warrants further investigation to delineate its impact on perioperative outcomes and potentially expand the indications for such devices.

Overview of the 2012 Food and Drug Administration circulatory system devices panel meeting on the reclassification of external counterpulsation, intra-aortic balloon pump, and non-roller-type cardiopulmonary bypass blood pump devices

The Food and Drug Administration held a Circulatory System Devices Advisory Panel meeting, December 5 and 6, 2012, to review the classification or potential reclassification of the following device types: external counterpulsation, intra-aortic balloon pump (IABP), and non-roller-type cardiopulmonary bypass blood pumps. These 3 devices are preamendment (Medical Device Amendments of 1976) class III devices. The advisory panel discussed the data and provided recommendations for reclassification of these devices. The panel recommended reclassification of ECP to class II for stable angina pectoris and to retain a class III for all other indications. For IABP, the recommendation was to reclassify IABP to class II for several indications (acute coronary syndrome, cardiac and noncardiac surgery, and heart failure complications) and remain class III for all other indications. As for non-roller type, the panel recommended that for cardiopulmonary bypass and temporary circulatory bypass, these devices should be reclassified to class II while retaining a class III device status for all other indications, including ventricular support both for hemodynamically unstable patients and for prophylactic support in high-risk percutaneous interventions.

Small pumps for ventricular assistance: progress in mechanical circulatory support

Compared with earlier models, current pumps are much smaller, simpler, and more efficient, offering long-term or even permanent support. They fit a wider size range of patients and are less invasive to implant. Because they have few moving parts, they are less susceptible to infection and failure. Additionally, they offer much greater patient comfort, allowing a relatively normal lifestyle. This article focuses on the current state of continuous-flow pumps for both temporary and long-term use in treating acute and chronic heart failure.

Emboli formation rather than inflammatory mediators are responsible for increased cerebral water content after conventional and assisted beating-heart myocardial revascularization in a porcine model

BACKGROUND AND PURPOSE

Emboli and proinflammatory mediators are suspected of generating cerebral edema after coronary surgery. In contrast to cardiopulmonary bypass (CPB), off-pump coronary artery bypass surgery (OPCAB) reduces microemboli count and proinflammatory mediator release but carries the risk of hemodynamic instability. A microaxial blood pump can augment cardiac output.

METHODS

Coronary bypasses were constructed in pigs with CPB and cardioplegia (n=9), OPCAB (n=9), or blood-pump support CAB (n=9). Nine animals underwent sham operation. Embolus count was monitored and regional cerebral blood flow was assessed with microspheres in 21 brain specimens per animal (n=189 per group). Interleukins 6 and 8 and tumor necrosis factor-alpha concentrations were determined. These variables were studied before, during, and for 4 hours after surgery. Finally, cerebral water content was determined.

RESULTS

During CPB and blood-pump CAB, a significant number of emboli were counted in contrast to OPCAB and controls (P<0.05). During CPB, regional cerebral blood flow was affected (32 of 189) and showed reactive hyperemia except in 10 specimens after aortic cross-clamp release. This impairment persisted in 20 specimens. During and after OPCAB, regional cerebral blood flow remained nearly unchanged but showed low flow during (58 of 189) and after (35 of 189) the blood-pump run. A significant increase in proinflammatory mediators was observed only in the CPB group. CPB and blood-pump CAB significantly increased cerebral water content (P<0.05). A strong correlation between embolic load and cerebral water content was observed in all groups. No correlation between proinflammatory mediator release and cerebral water content was detected.

CONCLUSIONS

Emboli formation rather than inflammatory mediators are responsible for increased cerebral water content after conventional and assisted beating-heart myocardial revascularization.

Experiencia inicial con la asistencia ventricular izquierda tipo «Impella» para el shock cardiogénico poscardiotomía y la angioplastia de tronco coronario izquierdo no protegido con baja fracción de eyección ventricular izquierda

Low-output syndrome is one of the leading causes of death following open-heart surgery or high-risk angioplasty. Ventricular assist devices have been used to treat patients who suffer from postoperative cardiogenic shock despite use of an intraaortic balloon pump and maximum inotropic support. The Impella pump (Impella Cardiosystems AG, Aachen, Germany) is a newly introduced left ventricular assist device that has been shown to reduce infarct size and to accelerate recovery of stunned myocardium. We report our initial experience using the Impella device for the treatment of cardiogenic shock following cardiopulmonary bypass and for maintaining hemodynamic stability in high-surgical-risk patients undergoing unprotected left coronary artery angioplasty.

Development of "plug and play" TransApical to aorta VAD

Our TransApical to Aorta pump, a simple and minimally invasive left ventricular (LV) assist device, has a flexible, thin-wall conduit connected by six struts to a motor with ball bearings and a turbine extending into the blood path. Pulsatile flow is inherent in the design as the native heart contraction preloads the turbine. In six healthy sheep, the LV apex was exposed by a fifth intercostal left thoracotomy. The pump was inserted from the cardiac apex through the LV cavity into the ascending aorta. Aortic and LV pressure waveforms, pump flow, motor current, and pressure were directly measured. All six cannula pumps were smoothly advanced on the first attempt. Pump implantation was <15 minutes (13.6 +/- 1.8 minutes). Blood flow was 2.8 l/min to 4.4 l/min against 86 +/- 8.9 mm Hg mean arterial blood pressure at maximum flow. LV systemic pressure decreased significantly from 102.5 +/- 5.55 mm Hg to 58.8 +/- 15.5 mm Hg at the fourth hour of pumping (p = 0.042), and diastolic LV pressure decreased from 8.4 +/- 3.7 to 6.1 +/- 2.3 mm Hg (p > 0.05). The pump operated with a current of 0.4 to 0.7 amps and rotation speed of 28,000 to 33,000 rpm. Plasma free hemoglobin was 4 +/- 1.41 mg/dl (range, 2 to 5 mg/dl) at termination. No thrombosis was observed at necropsy.A left ventricular assist device using the transapical to aorta approach is quick, reliable, minimally invasive, and achieves significant LV unloading with minimal blood trauma.

A New Minimized Perfusion Circuit Provides Highly Effective Ultrasound Controlled Deairing

Minimized perfusion circuits (MPCs) have been criticized for insufficient air elimination. The deairing capabilities of a new MPC, including an ultrasound controlled deairing unit, were compared to a standard extracorporeal circuit (ECC) in a laboratory setup. During blood flow of 4.0l/min, we injected 30-cc air over a period of 30 s into the venous line of both systems (n = 10 measurements/15-min intervals). Air was detected during the first 2 min post injection using a dual-channel ultrasound bubble counter. Venous air bubble measurements were made after the MPC bubble trap and the ECC hard-shell reservoir, respectively. Arterial air bubble data were obtained after the arterial filters (40 microm). Venous bubble count was significantly (P < 0.01) reduced in the MPC group (5-250 microm, 681 +/- 177; >40 microm, 288 +/- 92) compared with the ECC group (5-250 microm, 19 272 +/- 682; >40 microm, 7642 +/- 520). After the arterial filter, minimal numbers of air bubbles (5-250 microm, 172 +/- 59; >40 microm, 0) could be detected in the MPC group, but large amounts of air (5-250 microm, 16 194 +/- 1072; >40 microm, 3732 +/- 997) were measured in the ECC group. The air elimination of the modern MPC is superior to conventional ECC, which may result in a reduction of neurological complications.

Left ventricular mechanical support with the Impella Recover left direct microaxial blood pump: a single-center experience

The Impella Recover left direct (LD) is a new intravascular microaxial blood pump, intended as a short-term mechanical support especially in case of acutely reduced left ventricular function. From September 2002 to October 2004, Impella was used to support 12 patients: six patients were supported as bridge-to-heart transplant (HTx); three patients were treated for fulminant acute myocarditis, and three patients for postcardiotomy low-output syndrome. Mean support time was 8.8 +/- 2.3 days. Overall mortality was 50%. Four patients were successfully HTxed; two patients supported as bridge-to-HTx died on left ventricular assist device. Two patients with myocarditis died of septic shock; two patients in the group of postcardiotomy died of multiorgan failure. The latter two patients were slowly weaned from the device, and at 3-months follow-up showed good improvement of the left ventricular function. Our initial experience with Impella Recover LD as mechanical support for patients in cardiogenic shock of various etiology is promising, yielding a good survival in a population of particularly compromised patients.

Cardiac failure: Mechanical support strategies

OBJECTIVE

Mechanical support of the circulation is necessary when heart failure becomes refractory to medical support and is typically applied when organ dysfunction occurs as a result of hypoperfusion. However, in timing the intervention, it is important to apply mechanical support before multiple organ failure occurs. The objective of this work is to review the current strategies for mechanical circulatory support in patients with refractory cardiac failure.

DESIGN

A review of the use of mechanical circulatory support is presented for patients with refractory cardiac failure.

PATIENTS

Data are taken from human studies that were selected to best exemplify the results that may be obtained from various forms of mechanical circulatory support.

INTERVENTIONS

Commonly applied forms of mechanical support include mechanical ventilatory support, intraaortic balloon counterpulsation, and hemodialysis or ultrafiltration. If these measures fail, mechanical support of the circulation with ventricular assist devices is possible in specialized centers with expertise in the implantation and management of these devices. The decision to pursue mechanical circulatory support in the critically ill patient is based on the cause of acute decompensation, the potential reversibility of the condition, and the possibility for other treatments to improve the underlying condition or, in highly selected cases, heart transplantation. Newer forms of ventricular assistance that require less surgery are becoming available and may allow use in a broader range of critically ill patients.

MAIN RESULTS

There is a range of means to mechanically support the circulation in patients with advanced heart failure.

CONCLUSIONS

A variety of means to support the circulation have found application in the treatment of patients with refractory heart failure. More work is required to best identify populations who will benefit from the therapy and to refine the therapy to reduce associated risks.

Transradial unprotected left main coronary stenting supported by percutaneous Impella® Recover LP 2.5 assist device

Percutaneous coronary intervention (PCI) has been increasingly applied to patients with severely depressed left ventricular function and complex coronary lesions. The availability of hemodynamic support devices offers a promising option to reduce PCI-related complications in high-risk procedures. We report the case of a 79-year-old man who suffered from unstable angina. The coronary angiogram revealed multivessel disease including a significant distal left main (LM) stenosis. Additionally, the patient had a history of chronic lymphatic leukemia with immune hemolysis. Therefore, the patient was considered to be at exceptionally high mortality risk in case of cardiac surgery. We decided to perform a percutaneous revascularization of the LM supported by the Impella Recover LP 2.5 assist device. This case report discusses the principles of indications, technique and complications of this new addition to interventional cardiology.

Ventricular unloading with a miniature axial flow pump in combination with extracorporeal membrane oxygenation

OBJECTIVE

ECMO for acute cardiorespiratory failure is an established therapeutic option. Persistent insufficient unloading of the left ventricle (LV) can compromise recovery of ventricular function. We decided to insert a miniature rotary blood pump (Impella) for decompression of the LV. In contrast to previous experience with this new device, where it was generally used for postcardiotomy heart failure or cardiogenic shock and inserted in the operating room or the catheter laboratory, this is the first report describing the potential of this technology in the intensive care unit, in a patient on ECMO and the value of echocardiography guidance.

PATIENT

A 13-year-old boy with a history of congenital heart disease was admitted to the ICU with acute cardio-respiratory failure.

INTERVENTIONS

On day 2 venoarterial ECMO was instituted because of worsening cardiorespiratory insufficiency refractory to conventional treatment. On day 5 a percutaneous rotary blood pump was inserted to decompress the LV.

CONCLUSIONS

A percutaneous miniature rotary blood pump can be an alternative to decompress a failing LV in the setting of VA-ECMO. Echocardiography can avoid the use of fluoroscopy and the transport to a catheter laboratory to insert the rotary pump.

Different applications for left ventricular mechanical support with the Impella Recover 100 microaxial blood pump

The "Impella Recover 100" (IR100) is a new intravascular microaxial blood pump for use as short-term mechanical support for cases of acutely reduced left ventricular function. From September 2002 to April 2003, we used the IR100 to support 5 patients: 2 patients were bridged to heart transplant; 2 were being treated for fulminant acute myocarditis; and 1 for post-cardiotomy low-output syndrome. Only 1 patient with myocarditis died of septic shock, 2 had successful heart transplants; and the latter 2 were slowly weaned from the device and, at 3-month follow-up, showed moderate improvement of left ventricular (LV) function. Our initial experience with the IR100 as mechanical support for patients in cardiogenic shock of varying etiology has been positive, yielding good survival in a population of particularly compromised patients.

Miniature Intracardiac Assist Device Provides More Effective Cardiac Unloading and Circulatory Support During Severe Left Heart Failure Than Intraaortic Balloon Pumping

BACKGROUND

Hemodynamic assistance with a miniature intracardiac pump may fill the treatment gap between use of an intraaortic balloon pump (IABP) and the current, more invasive ventricular assist devices. The objective of this study was to compare the hemodynamic efficacy of a miniature intracardiac pump device with that of IABP.

METHODS AND RESULTS

Reversible acute mitral regurgitation (AMR) was induced in eight calves by stenting the mitral valve using a vena cava filter. Full and partial AMR assist were compared with maximum IABP support in each animal. In full-support mode, both assist systems increased cardiac output (miniature intracardiac pump, 13% [p < 0.05]; IABP, 3% [p < 0.05]), mean aortic pressure (miniature intracardiac pump, 13% [p < 0.05]; IABP, 8% [p < 0.05]), carotid artery flow (miniature intracardiac pump, 29% [p < 0.05]; IABP, 5% [difference not significant]), and coronary blood flow (miniature intracardiac pump, 25% [difference not significant]; IABP, 34% [p < 0.05]). Again in full-support mode, both systems reduced left atrial pressure (miniature intracardiac pump, 2.4 mm Hg [p < 0.05]; IABP, 0.7 mm Hg [p < 0.05]), peak left ventricular (LV) pressure (miniature intracardiac pump, 13% [p < 0.05]; IABP, 5% [p < 0.05]), and external LV work (miniature intracardiac pump, 29% [p < 0.05]; IABP, 3% [p < 0.05]). Only full miniature intracardiac pump support reduced both end-diastolic LV volume (7%; p < 0.05) and end-systolic LV volume (10%; p < 0.05). IABP mainly improved coronary perfusion, while the miniature intracardiac pump proved more capable of genuinely unloading the LV.

CONCLUSIONS

We conclude that during severe acute LV failure, the miniature intracardiac pump is capable of more effective cardiac unloading and circulatory support than IABP.

Echocardiographic approach in a new left ventricular assist device: impella recover 100

Echocardiographic evaluation represents a basic tool for the treatment of patients undergoing ventricular assist device implant. Impella Recover 100 is a new left intraventricular assist device proposed for short-term mechanical circulatory support to be implanted without cardiopulmonary bypass. We report our experience with echocardiographic monitoring on a patient with ischemic cardiomyopathy who underwent Impella Recover 100 implant as a bridge to heart transplant. During the surgical procedure echocardiography had an essential role for anatomic evaluation of the heart and correct intraventricular positioning of the device. Moreover, during the whole period of assistance, echocardiography contributed to assessment of patient-device interaction and to check the device when malfunction was suggested.

Impella recover 100 microaxial left ventricular assist device: the Niguarda experience

BACKGROUND

The Impella Recover 100 (IR100) is an intravascular microaxial blood pump used to support blood circulation for a maximum of 7 days in cases of reduced left ventricular function, for example in postcardiotomy low output syndrome or in cardiogenic shock after acute myocardial infarction.

MATERIALS AND METHODS

We supported five patients with the IR100. The mean age, cardiac index (CI), and ejection fraction (EF) of our population were 42 years, 1.83 L/min/m(2), and 20%, respectively. Two patients (group A) with ischemic dilated cardiomyopathy were bridged to heart transplant. Two patients (group B) with fulminan myocarditis and septic shock were bridged to recovery. One patient, with severe valvular cardiomyopathy who underwent aortic valve replacement and mitral valve annuloplasty, was supported to weaning from ECC.

RESULTS

Mean support time was 9.8 +/- 2.3 days. Only one acute myocarditis patient died from a severe vasoplegic syndrome despite maximal inotropic and vasoactive support. Both group A patients were successfully transplanted. Among group B, the second patient resolved the septic status and was slowly weaned from the device and discharged home with moderate improvement of LV function (EF = 40%). Patient C was weaned from the IR100 and electively placed on the heart transplant recipient list.

CONCLUSIONS

IR100 is a device that in our experience can be utilized for various indications for short-term support. In compromised patients where a traditional LVAD is contraindicated, the IR100 showed good results, for it is minimally invasive and does not need ECC or systemic anticoagulation.

New strategies to control the inflammatory response in cardiac surgery

PURPOSE OF REVIEW

To present and interpret data from recent clinical studies (July 2002-August 2003) of strategies to control the inflammatory response after cardiac surgery.

RECENT FINDINGS

Off-pump coronary artery bypass techniques, which avoid the need for extracorporeal circulation, attenuate the inflammatory response and appear to confer clinical benefit. Concerns regarding the quality of the revascularization after off-pump coronary artery bypass appear to have been allayed. At present, ventricular assist devices do not enhance the efficacy of off-pump coronary artery bypass. In patients undergoing cardiopulmonary bypass, heparin-coated circuits, hypothermic pulmonary perfusion, normoxic reperfusion after aortic unclamping, and modified ultrafiltration hold promise. Strategies to maintain perioperative haemodynamic stability, such as enoximone therapy, may be beneficial, particularly in elderly patients. Aprotinin may have important beneficial anti-inflammatory actions in higher-risk adult and paediatric patients. The therapeutic potential of corticosteroids, particularly when administered in multiple dosages is increasingly clear. Direct anti-mediator therapies that focus upon key effector molecules and pathways of the inflammatory response offer future therapeutic options.

SUMMARY

The potential for strategies that inhibit the inflammatory response to improve outcome after cardiac surgery is clear. Large-scale multicentre trials investigating the most promising strategies, including off-pump coronary artery bypass, heparin-coated circuits, and perioperative corticosteroid and aprotinin therapy, are urgently needed. These trials need to be restricted to the high-risk patient groups most likely to experience benefit. In the interim, the optimal strategy to minimize the inflammatory response to cardiac surgery will remain elusive.

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.

Left ventricular support by catheter-mounted axial flow pump reduces infarct size

OBJECTIVES

We sought to investigate the effect of a catheter-mounted microaxial blood pump (Impella, Aachen, Germany) on myocardial infarct size.

BACKGROUND

The small rotary blood pump Impella provides unloading of the left ventricle and is introducible via the femoral artery.

METHODS

Myocardial infarction was induced by occlusion of major branches of the left anterior descending coronary artery for 60 min followed by 120 min of reperfusion in 26 sheep. The animals were allocated to four groups: group 1 had no support; group 2 was fully supported with the pump during ischemia and reperfusion; group 3 was supported during reperfusion only; and group 4 was partially supported during reperfusion. Infarct size, hemodynamics, myocardial oxygen consumption, lactate extraction, and myocardial flow were analyzed.

RESULTS

Infarct size was significantly reduced in the pump-supported animals (percent area at risk in group 1: 67.2 +/- 4.6%; group 2: 18.1 +/- 10%; group 3: 41.6 +/- 5.8%; group 4: 54 +/- 8%; p = 0.00001). The pump produced 4.1 +/- 0.1 l/min at full support and 2.4 +/- 0.1 l/min at partial support. The pump significantly increased the diastolic and mean blood pressures (groups 2, 3, and 4) and significantly decreased the left ventricular end-diastolic pressure (groups 2 and 3). During ischemia, myocardial flow was not influenced by pump support. At reperfusion, the fully supported group had significantly higher myocardial flow. Pump support reduced myocardial oxygen consumption significantly, and this reduction correlates strongly with the reduction in infarct size (r = 0.9).

CONCLUSIONS

Support by a microaxial blood pump reduces myocardial oxygen consumption during ischemia and reperfusion and leads to a reduction of infarct size. This reduction in infarct size correlates with the degree of unloading during reperfusion.