Cardiogenic shock remains a major cause of morbidity and mortality for patients with acute myocardial infarction and advanced heart failure. Intra-aortic balloon pump has been the most widely used short-term mechanical circulatory support device to rapidly stabilize hemodynamics. However, it provides modest support, current evidence does not show a decrease in mortality, and the latest guidelines no longer recommend its routine use. Several percutaneous mechanical circulatory support devices have been introduced into clinical practice (Impella, extracorporeal membrane oxygen, TandemHeart), providing a greater level of hemodynamic support. These resource-intensive devices demand a careful selection of patients that stand to benefit the most. Premature initiation of mechanical circulatory support exposes the patient to unnecessary risk, whereas delaying therapy leads to irreversible end-organ injury, rendering any intervention medically futile. Cannulation methods, pump designs, and circuit configurations differ between devices, as do the adverse effects and physiological impact on the myocardium, which needs to be factored into consideration before deployment on the patient in cardiogenic shock. This article will review the commonly used percutaneous mechanical circulatory support devices in the setting of cardiogenic shock, compare their advantages and disadvantages, evaluate key clinical trials, and discuss a practical approach to guide clinicians' decision and management.

Background:Peripheral veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is used to support circulatory failure refractory to conventional therapy. However, data on the heart-ECMO interaction at different levels of ECMO blood flow during the immediate period after ECMO initiation are sparse. We evaluated the effects of varying ECMO blood flow rate on left ventricular systolic function.Methods:Adult patients who were supported by peripheral V-A ECMO in a tertiary referral center were recruited. Serial hemodynamic and cardiac performance parameters were measured by transthoracic echocardiogram within the first 48 hours after implementation of V-A ECMO. Measurements at 100%, 120%, and 50% of target blood flow (TBF) were compared.Results:A total of 45 patients were included, 32 (71.1%) were male, and the median age was 57 (50-64) years. The main indications for V-A ECMO were myocardial infarction 25 (55.6%) and myocarditis 6 (13.3%). With a decrease in extracorporeal blood flow from 100% to 50% of TBF, mean arterial pressure dropped from 75±18 to 67±20 mmHg (p<0.001), but stroke volume increased from 15 (8-25) to 21 (13-34) mL (p<0.001), and cardiac index increased from 0.8 (0.5-1.3) to 1.2 (0.7-1.7) L/min/m2 (p<0.001). All indices of left ventricular contractility improved at 50% compared with 100% TBF: the global longitudinal strain improved from -2.8 (-5.4-0) to -4.7 (-8.2- -1.1)% (p<0.001); left ventricular ejection fraction increased from 16.8 (10.0-28.5) to 28.2 (18.0-35.5)% (p<0.001); and left ventricular outflow tract velocity time integral increased from 4.7 (2.7-7.8) to 7.7 (3.9-11.3) cm (p<0.001). The addition of echocardiographic parameters improved the discrimination of the SAVE score in predicting hospital mortality (AUROC 0.71 vs 0.58).Conclusions:In the initial period of V-A ECMO support, left ventricular systolic function quantified bedside echocardiography was inversely related to ECMO blood flow rate. The heart-ECMO interaction should be considered when determining goals of ECMO flow after initiation.

Background Current ways to diagnose citrate accumulation (CA) in patients receiving regional citrate anticoagulation (RCA) continuous renal replacement therapy (CRRT) are confounded by various clinical factors. Serum citrate measurement emerges as a more direct way to diagnose CA, but its clinical utility and optimal cut-off values remain undefined. This study examined serum citrate kinetics and its diagnostic performance for CA in patients receiving RCA CRRT. Methods A multi-center prospective study carried out in 2 tertiary referral center ICUs in Hong Kong with serum citrate levels measured at baseline, 2-, 6-, 12-, 24-, 36-, 48- and 72-hours after initiation of RCA CRRT and their relationships with development of CA examined. Results Amongst the 133 patients analyzed, 18 patients (13.5%) developed CA. The serum citrate levels at baseline, 2-, 6- and 12-hours after initiation of RCA CRRT in patients who had CA were significantly higher than the non-CA group (P &lt; 0.001, for all). The CA group also had higher serum citrate levels than the non-CA group [median (IQR): 0.93(0.81–1.16) mmol/L vs. 0.37(0.26–0.57) mmol/L, P &lt; 0.001]. Using a cut-off of 0.85 mmol/L, serum citrate level had a sensitivity (SN) of 0.77 and a specificity (SP) 0.96 for the diagnosis of CA (AUROC 0.90, P &lt; 0.001). The 2-hr and 6-hr serum citrate levels had good discriminatory abilities for predicting subsequent development of CA (AUROC 0.86 and 0.83 for 2-hr and 6-hr citrate levels using cut-off values of 0.34 and 0.63 mmol/L respectively; P &lt; 0.001). Conclusion Serum citrate levels were significantly higher in patients with CA compared with patients without CA. Serum citrate levels showed good performance in diagnosing and predicting the development of CA.

Venoarterialextracorporeal membrane oxygenation (VA-ECMO) is a bridging therapy for refractory cardiogenic shock, and limb ischemia is a concern with femoral cannulation. Because of the rich collateral pelvic circulatory supply, buttock ischemia is not common and is usually a complication after aneurysmal aortic repair or internal iliac artery embolization after pelvic trauma. Gluteal necrosis occurring as an extracorporeal membrane oxygenation complication has not been reported in the literature. In this case series, we report three patients with ischemic buttock after initiating VA-ECMO and discuss the risk factors and the clinical and radiological features supportive of the diagnosis. We review the gluteal and pelvic vascular anatomy, postulate how cannula size, ethnicity, catecholamines, and reversal of gluteal arterial flow contributed to this rare entity in our patients and explain how these findings have changed our institution's practice. ASAIO

Introduction: Peripheral veno-arterial extracorporeal membrane oxygenation (V-A ECMO) poses increased afterload to the injured heart. The reactivity of myocardial contractility to ECMO blood flow during various phases of acute myocardial dysfunction has not been examined. Hypothesis: We hypothesized that myocardial contractility is more reactive to the afterload effects of peripheral V-A ECMO during the acute stage of myocardial dysfunction. Methods: Adult patients who were supported by peripheral V-A ECMO between April 2019 and October 2020 were recruited. Serial hemodynamic and cardiac performance parameters were measured by TTE within 48 hours after initiation of V-A ECMO (“acute phase”) and upon weaning (“delayed phase”). Measurements were obtained at 100%, 120%, and 50% of ECMO target blood flow. Results: A total of 30 patients were included, 22 (71%) were male, and the mean±SD age was 54±13 years. The main indications of ECMO were myocardial infarction (19 patients, 63%) and myocarditis (5, 17%). TTE was performed on a median of day 1 (1-1) (n=30, “acute phase”) and day 4.5 (3-6) (n=24, “delayed phase”) after initiation of ECMO. Left ventricular contractility was reactive to afterload effects from V-A ECMO in both the acute and delayed phases, with an improvement in LVEF during ECMO flow reduction from 21.5 to 30.9% (p<0.001) and 34.5 to 41.7% (p=0.002), respectively. The change in LVEF was similar in the acute phase compared with the delayed phase when considering the whole cohort [median (IQR) change in LVEF: 8.88 (5.26 - 13.7)% vs 6.12 (0.64 - 15.60)%, p=0.38]. Of the 24 patients who had a TTE during the delayed phase, 16 (66.7%) had myocardial recovery and were weanable from ECMO support. The reactivity of LVEF to ECMO blood flow was similar in the patients who were weanable compared with patients who were not weanable [median (IQR) change in LVEF: 10.21 (2.61 - 16.21)% vs 3.20 (-2.13 - 6.79)%, p=0.14]. Conclusions: In conclusion, we demonstrated that the reactivity of left ventricular contractility to afterload effects of V-A ECMO was not significantly different at different stages of acute myocardial dysfunction. Future studies should examine the predictive value and clinical utility of these echocardiographic measurements in patients on V-A ECMO.