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

Early risk predictors of acute kidney injury and short-term survival during Impella support in cardiogenic shock

Acute kidney injury (AKI) is one of the most frequent and prognostic-relevant complications of cardiogenic shock (CS) complicating myocardial infarction (MI). Mechanical circulatory assist devices (MCS) like left ventricular Impella microaxial pump have increasingly been used in the last decade for stabilization of hemodynamics in those patients. Moreover, a protective effect of Impella on renal organ perfusion could recently be demonstrated. However, data identifying early risk predictors for developing AKI during Impella support in CS are rare. Data of hemodynamics and renal function from 50 Impella patients (January 2020 and February 2022) with MI-related CS (SCAI stage C), were retrospectively analyzed using e.g. multivariate logistic regression analysis as well as Kaplan-Meier curves and Cox regression analysis. 30 patients (60%) developed AKI. Central venous pressure as an indicator for venous congestion (OR 1.216, p = 0.02), GFR at admission indicating existing renal damage (OR 0.928, p = 0.002), and reduced central venous oxygen saturation (SvO2) as a marker for decreased tissue perfusion (OR 0.930, p = 0.029) were independently associated with developing an AKI. The 30-day mortality rate was significantly higher in patients with AKI stage 3 (Stage 1: 0%, Stage 2: 0%, Stage 3; 41.6%, p = 0.014) while AKI stage 3 (HR 0.095, p = 0.026) and norepinephrine dosage (HR 1.027, p = 0.008) were independent predictors for 30-day mortality. AKI as a complication of MI-related CS occurs frequently with a major impact on prognosis. Venous congestion, reduced tissue perfusion, and an already impaired renal function are independent predictors of AKI. Thus, timely diagnostics and a focused treatment of the identified factors could improve prognosis and outcome.

Outcomes of Impella 5.0 and 5.5 for cardiogenic shock: A single-center 137 patient experience

BACKGROUND

This study evaluated the outcomes of patients with cardiogenic shock (CS) supported with Impella 5.0 or 5.5 and identified risk factors for in-hospital mortality.

METHODS

Adults with CS who were supported with Impella 5.0 or 5.5 at a single institution were included. Patients were stratified into three groups according to their CS etiology: (1) acute myocardial infarction (AMI), (2) acute decompensated heart failure (ADHF), and (3) postcardiotomy (PC). The primary outcome was survival, and secondary outcomes included adverse events during Impella support and length of stay. Multivariable logistic regression was performed to identify risk factors for in-hospital mortality.

RESULTS

One hundred and thirty-seven patients with CS secondary to AMI (n = 47), ADHF (n = 86), and PC (n = 4) were included. The ADHF group had the highest survival rates at all time points. Acute kidney injury (AKI) was the most common complication during Impella support in all 3 groups. Increased rates of AKI and de novo renal replacement therapy were observed in the PC group, and the AMI group experienced a higher incidence of bleeding requiring transfusion. Multivariable analysis demonstrated diabetes mellitus, elevated pre-insertion serum lactate, and elevated pre-insertion serum creatinine were independent predictors of in-hospital mortality, but the etiology of CS did not impact mortality.

CONCLUSIONS

This study demonstrates that Impella 5.0 and 5.5 provide effective mechanical support for patients with CS with favorable outcomes, with nearly two-thirds of patients alive at 180 days. Diabetes, elevated pre-insertion serum lactate, and elevated pre-insertion serum creatinine are strong risk factors for in-hospital mortality.

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.

Monitoring a Mystery: The Unknown Right Ventricle during Left Ventricular Unloading with Impella in Patients with Cardiogenic Shock

Background: Right ventricular (RV) dysfunction or failure occurs in more than 30% of patients in cardiogenic shock (CS). However, the importance of timely diagnosis of prognostically relevant impairment of RV function is often underestimated. Moreover, data regarding the impact of mechanical circulatory support like the Impella on RV function are rare. Here, we investigated the effects of the left ventricular (LV) Impella on RV function. Moreover, we aimed to identify the most optimal and the earliest applicable parameter for bedside monitoring of RV function by comparing the predictive abilities of three common RV function parameters: the pulmonary artery pulsatility index (PAPi), the ratio of right atrial pressure to pulmonary capillary wedge pressure (RA/PCWP), and the right ventricular stroke work index (RVSWI). Methods: The data of 50 patients with CS complicating myocardial infarction, supported with different flow levels of LV Impella, were retrospectively analyzed. Results: Enhancing Impella flow (1.5 to 2.5 L/min ± 0.4 L/min) did not lead to a significant variation in PAPi (p = 0.717), RA/PCWP (p = 0.601), or RVSWI (p = 0.608), indicating no additional burden for the RV. PAPi revealed the best ability to connect RV function with global hemodynamic parameters, i.e., cardiac index (CI; p < 0.001, 95% CI: 0.181-0.663), pulmonary capillary wedge pressure (PCWP; p = 0.005, 95% CI: -6.721--1.26), central venous pressure (CVP; p < 0.001, 95% CI: -7.89-5.575), and indicators of tissue perfusion (central venous oxygen saturation (SvO2); p = 0.008, 95% CI: 1.096-7.196). Conclusions: LV Impella does not impair RV function. Moreover, PAPi seems to be to the most effective and valid predictor for early bedside monitoring of RV function.

Late Kidney Injury After Admission to Intensive Care Unit for Acute Heart Failure

Late kidney injury (LKI) in patients with acute heart failure (AHF) requiring intensive care is poorly understood.We analyzed 821 patients with AHF who required intensive care. We defined LKI based on the ratio of the creatinine level 1 year after admission for AHF to the baseline creatinine level. The patients were categorized into 4 groups based on this ratio: no-LKI (< 1.5, n = 509), Class R (risk; ≥ 1.5, n = 214), Class I (injury; ≥ 2.0, n = 78), and Class F (failure; ≥ 3.0, n = 20). Median follow-up after admission for AHF was 385 (346-426) days. Multivariate logistic regression analysis revealed that acute kidney injury (AKI) during hospitalization (Class R, odds ratio [OR]: 1.710, 95% confidence interval [CI]: 1.138-2.571, P = 0.010; Class I, OR: 6.744, 95% CI: 3.739-12.163, P < 0.001; and Class F, OR: 9.259, 95% CI: 4.078-18.400, P < 0.001) was independently associated with LKI. Multivariate Cox regression analysis showed that LKI was an independent predictor of 3-year all-cause death after final follow-up (hazard ratio: 1.545, 95% CI: 1.099-2.172, P = 0.012). The rate of all-cause death was significantly lower in the no-AKI/no-LKI group than in the no-AKI/LKI group (P = 0.048) and in the AKI/no-LKI group than in the AKI/LKI group (P = 0.017).The incidence of LKI was influenced by the presence of AKI during hospitalization, and was associated with poor outcomes within 3 years of final follow-up. In the absence of LKI, AKI during hospitalization for AHF was not associated with a poor outcome.

Organ dysfunction, injury, and failure in cardiogenic shock

BACKGROUND

Cardiogenic shock (CS) is caused by primary cardiac dysfunction and induced by various and heterogeneous diseases (e.g., acute impairment of cardiac performance, or acute or chronic impairment of cardiac performance).

MAIN BODY

Although a low cardiac index is a common finding in patients with CS, the ventricular preload, pulmonary capillary wedge pressure, central venous pressure, and systemic vascular resistance might vary between patients. Organ dysfunction has traditionally been attributed to the hypoperfusion of the organ due to either progressive impairment of the cardiac output or intravascular volume depletion secondary to CS. However, research attention has recently shifted from this cardiac output ("forward failure") to venous congestion ("backward failure") as the most important hemodynamic determinant. Both hypoperfusion and/or venous congestion by CS could lead to injury, impairment, and failure of target organs (i.e., heart, lungs, kidney, liver, intestines, brain); these effects are associated with an increased mortality rate. Treatment strategies for the prevention, reduction, and reversal of organ injury are warranted to improve morbidity in these patients. The present review summarizes recent data regarding organ dysfunction, injury, and failure.

CONCLUSIONS

Early identification and treatment of organ dysfunction, along with hemodynamic stabilization, are key components of the management of patients with CS.