Impact of microaxillar mechanical left ventricular support on renal resistive index in patients with cardiogenic shock after myocardial infarction: a pilot trial to predict renal organ dysfunction in cardiogenic shock

The Role of Impella in Cardiogenic Shock Complicated by an Acute Myocardial Infarction: A Meta-Analysis

Background: Emerging evidence suggests the role of mechanical circulatory support (MCS) devices in the therapy of refractory cardiogenic shock (CS). However, largerandomized trials addressing the role of Impella in the therapy of infarct-associated CS are sparse. As such, evidence coming from comprehensive retrospective studies or meta-analyses is of major importance in order to clarify the role of the Impella device in this setting. Methods: Only clinical trials involving patients receiving Impella 2.5 and Impella CP for treatment of CS caused in terms of acute coronary syndrome (ACS) were included in this meta-analysis. The primary endpoint was 30-day mortality, with major bleeding and ischemic vascular complications serving as secondary endpoints. Results: A total of 18 observational retrospective studies (2617 patients with CS and Impella implantation) were included in this analysis. The mean age of the total participants was 64.7 ± 2.93 years. A mean mortality incidence of 45% was found between all included participants. The ischemia rate was in total 8.5 ± 4.4%, and the incidence of bleeding was 13.9 ± 5.6%. Conclusions: The 30-day mortality rate for patients with ACS-associated CS treated with Impella remains high. The high complication rates underline the importance of Impella use in only a very well-selected population of patients.

Mechanical circulatory support reduces renal sympathetic nerve activity in an ovine model of acute myocardial infarction

PURPOSE

The use of circulatory assist devices has been shown to improve glomerular filtration rate and reduce the incidence of acute kidney injury in patients following acute cardiac pathology. However, the mechanisms of improvement in kidney function are not clear. We tested the hypothesis that mechanical circulatory support would result in a decrease in directly recorded renal sympathetic nerve activity (RSNA) and mediate the improvement in renal blood flow (RBF) in a setting of acute myocardial infarction (AMI)-induced left ventricular systolic dysfunction.

METHODS

An anaesthetized ovine model was used to induce AMI (n = 8) using injections of microspheres into the left coronary artery in one group. The second group did not undergo embolization (n = 6). The effects of mechanical circulatory support using the Impella CP on directly recorded renal sympathetic nerve activity were examined in these two groups of animals.

RESULTS

Injection of microspheres resulted in a drop in mean arterial pressure (MAP) of 21 ± 4 mmHg compared to baseline values (p < 0.05; n = 8). This was associated with a 67% increase in renal sympathetic nerve activity (RSNA; from 16 ± 5 to 21 ± 5 spikes/s; p < 0.05; n = 7). Impella CP support significantly increased MAP by 13 ± 1.5 mmHg at pump level 8 (p < 0.05) in the AMI group. Incremental pump support resulted in a significant decrease in RSNA (p < 0.05) in both groups. At pump level P8 in the AMI group, RSNA was decreased by 21 ± 5.5% compared to pump level P0 when the pump was not on.

CONCLUSION

Our data indicate that the improvement in kidney function following mechanical circulatory support may be mediated in part by renal sympathoinhibition.

Discussion of hemodynamic optimization strategies and the canonical understanding of hemodynamics during biventricular mechanical support in cardiogenic shock: does the flow balance make the difference?

BACKGROUND

Mechanical circulatory support (MCS) devices may stabilize patients with severe cardiogenic shock (CS) following myocardial infarction (MI). However, the canonical understanding of hemodynamics related to the determination of the native cardiac output (CO) does not explain or support the understanding of combined left and right MCS. To ensure the most optimal therapy control, the current principles of hemodynamic measurements during biventricular support should be re-evaluated.

METHODS

Here we report a protocol of hemodynamic optimization strategy during biventricular MCS (VA-ECMO and left ventricular Impella) in a case series of 10 consecutive patients with severe cardiogenic shock complicating myocardial infarction. During the protocol, the flow rates of both devices were switched in opposing directions (+ / - 0.7 l/min) for specified times. To address the limitations of existing hemodynamic measurement strategies during biventricular support, different measurement techniques (thermodilution, Fick principle, mixed venous oxygen saturation) were performed by pulmonary artery catheterization. Additionally, Doppler ultrasound was performed to determine the renal resistive index (RRI) as an indicator of renal perfusion.

RESULTS

The comparison between condition 1 (ECMO flow > Impella flow) and condition 2 (Impella flow > VA-ECMO flow) revealed significant changes in hemodynamics. In detail, compared to condition 1, condition 2 results in a significant increase in cardiac output (3.86 ± 1.11 vs. 5.44 ± 1.13 l/min, p = 0.005) and cardiac index (2.04 ± 0.64 vs. 2.85 ± 0.69, p = 0.013), and mixed venous oxygen saturation (56.44 ± 6.97% vs. 62.02 ± 5.64% p = 0.049), whereas systemic vascular resistance decreased from 1618 ± 337 to 1086 ± 306 s*cm-5 (p = 0.002). Similarly, RRI decreased in condition 2 (0.662 ± 0.05 vs. 0.578 ± 0.06, p = 0.003).

CONCLUSIONS

To monitor and optimize MCS in CS, PA catheterization for hemodynamic measurement is applicable. Higher Impella flow is superior to higher VA-ECMO flow resulting in a more profound increase in CO with subsequent improvement of organ perfusion.

Improvement of persistent anuria in severe myocardial infarction: the potential role of Impella 5.5 as a bridge to decision

A man in his 40s with ST-segment elevation myocardial infarction complicating cardiogenic shock was transferred to our hospital. Emergent percutaneous coronary intervention for the left anterior descending and left circumflex arteries supported with Impella CP was performed. However, his cardiac function was severely impaired, and anuria developed, necessitating continuous renal replacement therapy (CRRT). After Impella CP was removed on day 6, the patient remained dependent on inotropes and CRRT. Following volume reduction to manage pulmonary congestion, symptoms of low perfusion appeared. Then, Impella 5.5 was inserted on day 38 as a bridge to decision. On day 52, the urine volume reached >2000 mL/day, and CRRT was discontinued. On day 56, the patient was transferred to a certified facility for left ventricular assist device implantation or heart transplantation. This case suggests the potential of Impella 5.5 as a bridge to decision in patients with organ failure caused by low cardiac output.

The Use of Cardioprotective Devices and Strategies in Patients Undergoing Percutaneous Procedures and Cardiac Surgery

In the United States, about one million people are seen to visit the operating theater for cardiac surgery annually. However, nearly half of these visits result in complications such as renal, neurological, and cardiac injury of varying degrees. Historically, many mechanisms and approaches have been explored in attempts to reduce injuries associated with cardiac surgery and percutaneous procedures. Devices such as cardioplegia, mechanical circulatory support, and other methods have shown promising results in managing and preventing life-threatening cardiac-surgery-related outcomes such as heart failure and cardiogenic shock. Comparably, cardioprotective devices such as TandemHeart, Impella family devices, and venoarterial extracorporeal membrane oxygenation (VA-ECMO) have also been proven to show significant cardioprotection through mechanical support. However, their use as interventional agents in the prevention of hemodynamic changes due to cardiac surgery or percutaneous interventions has been correlated with adverse effects. This can lead to a rebound increased risk of mortality in high-risk patients who undergo cardiac surgery. Further research is necessary to delineate and stratify patients into appropriate cardioprotective device groups. Furthermore, the use of one device over another in terms of efficacy remains controversial and further research is necessary to assess device potential in different settings. Clinical research is also needed regarding novel strategies and targets, such as transcutaneous vagus stimulation and supersaturated oxygen therapy, aimed at reducing mortality among high-risk cardiac surgery patients. This review explores the recent advances regarding the use of cardioprotective devices in patients undergoing percutaneous procedures and cardiac surgery.

TNF-α and IL-1β Promote Renal Podocyte Injury in T2DM Rats by Decreasing Glomerular VEGF/eNOS Expression Levels and Altering Hemodynamic Parameters

PURPOSE

Diabetic nephropathy (DN) is a serious microvascular complication in those with type 2 diabetes mellitus (T2DM). Evidence confirms that serum tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the T2DM stage are proposed as prognostic markers for DN development, but it is unclear how they affect renal podocyte-associated nephrin and WT-1 expression. In the presence of podocyte injury, glomerular vascular endothelial growth factor (VEGF), endothelial nitric oxide synthase (eNOS) and hemodynamic parameters are dysregulated. The current research aimed to clarify the relationship of TNF-α and IL-1β with podocyte injury by altering VEGF/eNOS expression and hemodynamic parameters.

METHODS

A high-fat diet/streptozotocin-induced DN rat model was established. Serum TNF-α and IL-1β levels were tracked in the pre-T2DM, T2DM and DN stages. In the DN stage, the mRNA and protein expression levels of renal TNF-α, IL-1β, VEGF, eNOS, nephrin and WT-1 were studied. Renal hemodynamic parameters, including peak systolic velocity, end-diastolic flow velocity and mean velocity were measured with a color Doppler ultrasound technique.

RESULTS

Compared to those in the normal control (CTL) group, serum TNF-α and IL-1β levels increased significantly in the pre-T2DM stage (obesity, insulin resistance and hyperlipidemia), T2DM stage (hyperglycemia) and DN stage (abnormal renal functions) (all: P < 0.05) in the DN group. Serum TNF-α and IL-1β levels in the T2DM stage were significantly higher than those in the pre-T2DM stage (two: P < 0.05). Compared to the CTL group, renal nephrin, WT-1, TNF-α, IL-1β, eNOS and VEGF expression and hemodynamic parameters in the DN stage all showed significant differences separately (all: P < 0.05).

CONCLUSION

Increased serum and renal TNF-α and IL-1β levels played important roles in reducing renal nephrin and WT-1 expression levels, which may be related to the fact that the former affected renal VEGF/eNOS expression and blood flow parameters in the DN rats.

Renal Protection and Hemodynamic Improvement by Impella® Microaxial Pump in Patients with Cardiogenic Shock

Acute kidney injury is one of the most frequent and prognostically relevant complications in cardiogenic shock. The purpose of this study was to evaluate the potential effect of the Impella® pump on hemodynamics and renal organ perfusion in patients with myocardial infarction complicating cardiogenic shock. Between January 2020 and February 2022 patients with infarct-related cardiogenic shock supported with the Impella® pump were included in this single-center prospective short-term study. Changes in hemodynamics on different levels of Impella® support were documented with invasive pulmonal arterial catheter. As far as renal function is concerned, renal perfusion was assessed by determining the renal resistive index (RRI) using Doppler sonography. A total of 50 patients were included in the analysis. The increase in the Impella® output by a mean of 1.0 L/min improved the cardiac index (2.7 ± 0.86 to 3.3 ± 1.1 p < 0.001) and increased central venous oxygen saturation (62.6 ± 11.8% to 67.4 ± 10.5% p < 0.001). On the other side, the systemic vascular resistance (1035 ± 514 N·s/m5 to 902 ± 371 N·s/m5p = 0.012) and the RRI were significantly reduced (0.736 ± 0.07 to 0.62 ± 0.07 p < 0.001). Furthermore, in the overall cohort, a baseline RRI ≥ 0.8 was associated with a higher frequency of renal replacement therapy (71% vs. 39% p = 0.04), whereas the consequent reduction of the RRI below 0.7 during Impella® support improved the glomerular filtration rate (GFR) during hospital stay (15 ± 3 days; 53 ± 16 mL/min to 83 ± 16 mL/min p = 0.04). Impella® support in patients with cardiogenic shock seems to improve hemodynamics and renal organ perfusion. The RRI, a well-known parameter for the early detection of acute kidney injury, can be directly influenced by the Impella® flow rate. Thus, a targeted control of the RRI by the Impella® pump could mediate renal organ protection.

The Therapeutic Use of Impella Device in Cardiogenic Shock: A Systematic Review

Impella (Abiomed, Danvers, MA) devices nowadays have been linked to cardiogenic shock (CS) due to the importance of their use as therapeutic instruments. This study aims to review pathophysiologic mechanisms of cardiogenic shock and the implementation of Impella to overcome this condition. To investigate several different types of studies and analyze the use of Impella device in cardiogenic shock and the outcomes of heart malfunctioning and determine its positive and negative impacts as a therapeutic tool in cardiac ischemia and use as a resource in critical patients, we conducted a systematic review through different databases (PubMed, ScienceDirect, and Google Scholar) following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist and used the Medical Subjects Heading (MeSH) search strategy to obtain significant articles. We found 883 papers in total, and after removing duplicates, applying inclusion/exclusion criteria, and finding the most significant information, we ended up with 30 articles that were reviewed containing information about the impact of Impella device in cardiogenic shock in different locations. The study strongly concludes that Impella device in the setting of cardiogenic shock has more advantages than disadvantages in terms of outcomes and complications as a non-pharmacologic tool. Improvements in left ventricular ejection fraction and signs and symptoms of cardiogenic shock criteria were determinants. Nevertheless, complications during the implementation and use of the device were established; in this manner, the evaluation and treatment of each patient separately are imperative. Consequently, more studies on this relevant topic are needed.

Nephrology Considerations in the Management of Durable and Temporary Mechanical Circulatory Support

Durable and temporary mechanical circulatory support (MCS) use is growing for a range of cardiovascular indications. Kidney dysfunction is common in people evaluated for or receiving durable or temporary MCS and portends worse outcomes. This kidney dysfunction can be due to preexisting kidney chronic kidney disease (CKD), acute kidney injury (AKI) related to acute cardiovascular disease necessitating MCS, AKI due to cardiac procedures, and acute and chronic MCS effects and complications. Durable MCS, with implantable continuous flow pumps, is used for long-term support in advanced heart failure refractory to guideline-directed medical and device therapy, either permanently or as a bridge to heart transplantation. Temporary MCS-encompassing in this review intra-aortic balloon pumps (IABP), axial flow pumps, centrifugal flow pumps, and venoarterial ECMO-is used for diverse situations: high-risk percutaneous coronary interventions (PCI), acute decompensated heart failure, cardiogenic shock, and resuscitation after cardiac arrest. The wide adoption of MCS makes it imperative to improve understanding of the effects of MCS on kidney health/function and of kidney health/function on MCS outcomes. The complex structure and functions of the kidney, and the complex health states of individuals receiving MCS, makes investigations in this area challenging, and current knowledge is limited. Fortunately, the increasing nephrology toolbox of noninvasive kidney health/function assessments may enable development and testing of individualized management strategies and therapeutics in the future. We review technology, epidemiology, pathophysiology, clinical considerations, and future directions in MCS and nephrology.

Impact of left ventricular unloading using a peripheral Impella®-pump in eCPR patients

BACKGROUND

Extracorporeal cardiopulmonary resuscitation (eCPR) is a rapidly growing treatment strategy due to increasing survival rates in selected patients. Additional left ventricular mechanical unloading, using a transfemoral micro-axial blood pump (Impella® Denver, Massachusetts, USA), might improve patients' outcomes. In this regard, we sought to investigate patients who suffered OHCA (out-of hospital cardiac arrest) or IHCA (in-hospital cardiac arrest) with subsequent eCPR via VA-ECMO (veno-arterial extracorporeal membrane oxygenation) and concomitant Impella® implantation based on survival and feasibility of ECMO weaning.

METHODS

From January 2016 until December 2020, 108 patients underwent eCPR at our institution. Data prior to eCPR and early outcome parameters were analyzed comparing patients who were supported with an additional Impella® (2.5 or CP) (ECMO+Impella®, n = 18) and patients without additional (ECMO, n = 90) support during V-A ECMO therapy. The primary endpoint was in-hospital mortality; secondary endpoints were, among others: ECMO explantation, need for hemodialysis, stroke, and need for blood transfusions.

RESULTS

Low-flow time was significantly lower in the ECMO+Impella group (60 min vs. 55 min, p = .01). All-cause mortality was significantly lower in the ECMO+Impella® group (82% vs. 56%, p = .01). The time of circulatory support was shorter in the ECMO cohort (2.0 ± 1.73 vs. 4.76 ± 2.88 p = .05). ECMO decannulation was significantly more feasible in patients with ECMO+Impella® (72% vs. 32%, p = .01). Patients treated with additional Impella® showed significantly more acute kidney injury with the need for dialysis (72% vs. 18%, p ≤ .01).

CONCLUSION

Concomitant Impella® support might positively influence survival and ECMO weaning in eCPR patients. Treatment-associated complications such as the need for dialysis were more common in this highly selected patient group. Further studies with larger numbers are necessary to evaluate the clinical relevance of concomitant LV-unloading in eCPR patients using an Impella® device.

Left Ventricle Architecture and Valvular Integrity Following Microaxial Mechanical Support: A Two-Year Follow-Up Study

Although the use of microaxilar mechanical circulatory support systems may improve the outcome of patients with cardiogenic shock (CS), little is known about its effect on the long-term structural integrity of left ventricular (LV) valves as well as on the development of LV-architecture. Therefore, we aimed to study the integrity of the LV valves and architecture and function after Impella support. Thus, 84 consecutive patients were monitored over two years having received Impella^TM CP (n = 24) or 2.5 (n = 60) for refractory CS (n = 62) or for high-risk percutaneous coronary interventions (n = 22) followed by optimal medical treatment. Beside a significant increase in LV ejection fraction after two years (p ≤ 0.03 vs. pre-implantation), we observed a statistically significant decrease in LV dilation (p < 0.001) and severity of mitral valve regurgitation (p = 0.007) in the two-year follow-up period, suggesting an improved LV architecture. Neither the duration of support, nor the size of the Impella device or the indication for its use revealed any devastating impact on aortic or mitral valve integrity. These findings indicate that Impella device is a safe means of support of LV-function without detrimental long-term effects on the structural integrity of LV valves regardless of the size of the device or the indication of support.

Biventricular Unloading with Impella and Venoarterial Extracorporeal Membrane Oxygenation in Severe Refractory Cardiogenic Shock: Implications from the Combined Use of the Devices and Prognostic Risk Factors of Survival

Since mechanical circulatory support (MCS) devices have become integral component in the therapy of refractory cardiogenic shock (RCS), we identified 67 patients in biventricular support with Impella and venoarterial Extracorporeal Membrane Oxygenation (VA-ECMO) for RCS between February 2013 and December 2019 and evaluated the risk factors of mortality in this setting. Mean age was 61.07 ± 10.7 and 54 (80.6%) patients were male. Main cause of RCS was acute myocardial infarction (AMI) (74.6%), while 44 (65.7%) were resuscitated prior to admission. The mean Simplified Acute Physiology Score II (SAPS II) and Sequential Organ Failure Assessment Score (SOFA) score on admission was 73.54 ± 16.03 and 12.25 ± 2.71, respectively, corresponding to an expected mortality of higher than 80%. Vasopressor doses and lactate levels were significantly decreased within 72 h on biventricular support (p < 0.05 for both). Overall, 17 (25.4%) patients were discharged to cardiac rehabilitation and 5 patients (7.5%) were bridged successfully to ventricular assist device implantation, leading to a total of 32.8% survival on hospital discharge. The 6-month survival was 31.3%. Lactate > 6 mmol/L, vasoactive score > 100 and pH < 7.26 on initiation of biventricular support, as well as Charlson comorbity index > 3 and prior resuscitation were independent predictors of survival. In conclusion, biventricular support with Impella and VA-ECMO in patients with RCS is feasible and efficient leading to a better survival than predicted through traditional risk scores, mainly via significant hemodynamic improvement and reduction in lactate levels.