**4. IABP during ECMO**

acceptable contractility on echocardiography and stable hemodynamics (MAP, CVP and heart rate) has to be checked. We provide a schematic view of the Flow-chart for ECMO management form step 1 to step 4 and complete weaning (**Figure 2**). Hypotension, a rising

**Figure 3.** Flow-chart describing the suggested therapeutical strategy according to patient's clinical conditions and needs.

**Figure 2.** Flow-chart for ECMO management.

190 Advances in Extra-corporeal Perfusion Therapies

Intra-aortic balloon pump (IABP) has long been clinically applied to augment pulsatility, decrease afterload, and improve blood flow in native coronary arteries and bypass grafts [44, 45].

The inflations and deflations of the 30–50 ml balloon delivered by the IABP device are synchronized with cardiac cycle: the deflation just before systolic ejection aims to decrease afterload and improve LV ejection, while the inflation during diastole warrants increased diastolic perfusion aiming at improve coronary, cerebral, and visceral blood flow.

Despite the controversial data from the Intra-Aortic Balloon Pump in cardiogenic SHOCK (IABP-SHOCK) II trial [1], IABP currently remains one of the most commonly used mechanical circulatory support devices in the treatment of acute heart failure. When administered promptly, it can play a critical role in the rescue of patients with acute myocardial damage, reversing the ongoing vicious cycle leading to death. It has been shown in animal models that IABP may improve several parameters of LV performance during VA-ECMO support [46]. Currently, several centers use IABP during VA-ECMO therapy to reduce LV afterload and warrant pulsatility in the end-organ capillary bed [47]. In a group of 219 patients treated with VA-ECMO after cardiac surgery, Doll et al. [18] found that the use of IABP during ECMO support was associated with a significantly higher survival rate. Ma et al. [48] reported 54 adult patients with acute heart failure who received combined ECMO and IABP support, all of whom showed improvements in terms of overall circulation. Thirty-four of the patients were successfully weaned from mechanical circulatory support, and 21 (39%) survived to hospital discharge. Petroni et al. [49] showed that adding an IABP to peripheral VA-ECMO was associated with improved LV function, and discontinuation of intra-aortic balloon pumping was associated with higher pulmonary artery wedge pressure, increased LV end-, and end-diastolic diameters, while decreasing pulse pressure (15 ± 13 versus 29 ± 22 mmHg; P = 0.02) [49]. Park et al. [50] did not find any mortality or morbidity benefit with IABP in the group of 96 VA-ECMO-treated patients with cardiogenic shock due to acute myocardial infarction. Recent data coming out from the Shock trial suggest that cardiac power output (CPO = cardiac output × MAP × 0.022) may be the best predictor of the effectiveness of IABP during impending cardiogenic shock [51]. Impella or VA-ECMO is needed when CPO is very low or upgrading of the MCS is necessary. Eventually the upgrade to ECMO or ECPELLA (VA-ECMO + IMPELLA) may portend both optimal perfusion and ventricular unloading aiming to myocardial recovery. Etiologic definition and eventual correction of the cause should be mandatory to increase the chance of recovery.

if perfusion is adequate everywhere to avoid to misdiagnose the "Harlequin syndrome" due to inadequate mixing of the two parallel circulations (ECMO and native heart) [23, 54, 55].

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As a matter of fact, IABP should be already in place at the time of VA-ECMO implantation, as stated by ELSO Guidelines 2017 [www.elso.org]. For those patients who do not have one, it should be placed via the contralateral femoral artery, associating earlier the hemodynamic effects of IABP to those of VA-ECMO; from a mechanistic point of view IABP could neutralize

The role of IABP in patients suffering from cardiogenic shock should be highlighted as (I) it is rapidly deployable at any hospital and therefore reduces the duration of "uncontrolled shock"; (II) it allows, thereafter, safe transport to MCS units; (III) it does allow foe exploiting the same vascular access for Impella implant; and (IV) it has a major role in weaning from

Despite the controversial data from the intra-aortic balloon pump in cardiogenic SHOCK (IABP-SHOCK) II trial, which could not demonstrate a survival benefit for the IABP application, IABP currently remains one of the most commonly used mechanical circulatory support devices in the treatment of acute heart failure. The bad news is that for none of the percutaneous devices, used in LV venting, a survival benefit has yet been documented in adequately sized randomized clinical trials (RCTs). A meta-analysis, by Cheng et al., including a total of 100 patients in three small RCTs with the TandemHeart and the Impella PL2.5 pump did not see a survival benefit in comparison to the IABP, despite better hemodynamic

When administered in a timely manner, IABP can play a critical role in the rescue of patients with acute myocardial damage. It has been shown in animal models that insertion of IABP during VA-ECMO support may improve several parameters of LV performance and can

The combination of IABP and VA-ECMO can be found in the nationwide Japanese Diagnosis Procedure Combination national inpatient database; IABP combined with VA-ECMO was associated with reduced mortality and successful weaning from VA-ECMO. They also concluded, of course, that randomized controlled studies are required to confirm the mortality-

Despite the lack of clarity, in a systematic literature search, the use of concomitant IABP with ECMO is widespread. IABP was present in approximately 55% of all ECMO cases reviewed, stretching across all etiologies of cardiac failure beyond acute myocardial infarction (AMI). The rationale for concomitant IABP use is primarily for LV venting [58]. The incremental benefit of IABP support for afterload reduction and increasing organ perfusion in the presence of ECMO support is relatively minimal. Regarding improved diastolic pressures and coronary flow, despite the previously held belief of an estimated 11% survival benefit from pooled analyses of retrospective studies of IABP use in AMI, it is now known from the prospective and randomized IABP-SHOCK II study that the use of IABP in this cohort had no survival

reduce mean arterial pressure as well as oxygen saturation in the coronary sinus [24].

reducing effect of the combination of IABP and VA-ECMO [57].

VA-ECMO and therefore reduces the burden of the complications related to ECLS.

some of the unwanted effects of VA-ECMO [56].

effects [57].

benefit [59].

A marked increase in systemic blood pressure caused by VA-ECMO and retrograde aortic ECMO flow may increase cardiac afterload, together with severe systolic dysfunction, resulting in LV overload with a subsequent increase in left atrial pressure, severe pulmonary edema, myocardial ischemia, elevated pulmonary pressures, blood stasis, and potential thrombus formation, jeopardizing ventricular recovery.

Echocardiographic monitoring should be strictly recommended to detect a fluid overload early, and a Swan-Ganz catheter should be inserted to measure the pulmonary capillary wedge pressure to detect high left ventricular filling pressures as an indicator for left ventricular distension. Ventilation with low tidal volumes and positive end-expiratory pressure (PEEP) has been suggested to keep the lung open. A higher PEEP is advisable in patients with ongoing pulmonary edema. Early extubation is feasible and desired when the patient has a low risk of pulmonary edema because optimal unloading.

To date, there are several possibilities to decrease the likelihood of left ventricular distension on ECMO, but the cohort of patients who benefit from left ventricular venting is unclear.

Decreasing afterload leads to a decrease in workload and O2 consumption. In case of an extremely poor left ventricular function, it is advisable to administer inotropes with a sufficient mean arterial pressure of 50–60 mmHg. Physiologic lactate levels, normal pH levels, and regular central venous saturations as a guide and flow rates of 2.5–4 L/min are probably sufficient in most cases. Even if sometimes lower pump flow rates also reduce the perfusionrelated afterload [21].

Intra-aortic balloon pumping (IABP) concomitant to retrograde aortal perfusion is seen controversial as the inflated balloon in the descending aorta might hinder proper perfusion. IABP counterpulsation is a device that inflates and deflates a 30–50 cm balloon in the descending aorta. The balloon inflations and deflations are synchronized with cardiac cycle, and, therefore, deflation just before systolic ejection may decrease afterload and improve LV ejection. Moreover, increased diastolic pressure on IABP could also improve coronary blood flow [52, 53].

Despite the general expectations that IABP is useful during VA-ECMO for a supposed "perfusion benefit" which indeed is overcome by ECMO blood flow, our belief is that the rationale of the combined use of VA-ECMO and IABP is to provide a pressure unloading to the left ventricle especially when a certain amount of residual SV is provided by the native circulation.

Although in a very unstable patient ECMO can stabilize end organs and restore their function, the lack of left ventricular unloading and reduced ventricular work threaten the myocardium worsening the already impaired myocardial performance superimposing an extremely high afterload further compromising wall tension and myocardial oxygen demand. Multiple studies have shown that coronary perfusion worsens, especially if the patient is cannulated peripherally. Because relative cerebral or coronary hypoxia occurs in many situations due to a "watershed" effect, it is imperative to check blood saturations at multiple sites to determine if perfusion is adequate everywhere to avoid to misdiagnose the "Harlequin syndrome" due to inadequate mixing of the two parallel circulations (ECMO and native heart) [23, 54, 55].

(VA-ECMO + IMPELLA) may portend both optimal perfusion and ventricular unloading aiming to myocardial recovery. Etiologic definition and eventual correction of the cause should

A marked increase in systemic blood pressure caused by VA-ECMO and retrograde aortic ECMO flow may increase cardiac afterload, together with severe systolic dysfunction, resulting in LV overload with a subsequent increase in left atrial pressure, severe pulmonary edema, myocardial ischemia, elevated pulmonary pressures, blood stasis, and potential thrombus

Echocardiographic monitoring should be strictly recommended to detect a fluid overload early, and a Swan-Ganz catheter should be inserted to measure the pulmonary capillary wedge pressure to detect high left ventricular filling pressures as an indicator for left ventricular distension. Ventilation with low tidal volumes and positive end-expiratory pressure (PEEP) has been suggested to keep the lung open. A higher PEEP is advisable in patients with ongoing pulmonary edema. Early extubation is feasible and desired when the patient has a

To date, there are several possibilities to decrease the likelihood of left ventricular distension on ECMO, but the cohort of patients who benefit from left ventricular venting is unclear.

extremely poor left ventricular function, it is advisable to administer inotropes with a sufficient mean arterial pressure of 50–60 mmHg. Physiologic lactate levels, normal pH levels, and regular central venous saturations as a guide and flow rates of 2.5–4 L/min are probably sufficient in most cases. Even if sometimes lower pump flow rates also reduce the perfusion-

Intra-aortic balloon pumping (IABP) concomitant to retrograde aortal perfusion is seen controversial as the inflated balloon in the descending aorta might hinder proper perfusion. IABP counterpulsation is a device that inflates and deflates a 30–50 cm balloon in the descending aorta. The balloon inflations and deflations are synchronized with cardiac cycle, and, therefore, deflation just before systolic ejection may decrease afterload and improve LV ejection. Moreover,

Despite the general expectations that IABP is useful during VA-ECMO for a supposed "perfusion benefit" which indeed is overcome by ECMO blood flow, our belief is that the rationale of the combined use of VA-ECMO and IABP is to provide a pressure unloading to the left ventricle especially when a certain amount of residual SV is provided by the native circulation. Although in a very unstable patient ECMO can stabilize end organs and restore their function, the lack of left ventricular unloading and reduced ventricular work threaten the myocardium worsening the already impaired myocardial performance superimposing an extremely high afterload further compromising wall tension and myocardial oxygen demand. Multiple studies have shown that coronary perfusion worsens, especially if the patient is cannulated peripherally. Because relative cerebral or coronary hypoxia occurs in many situations due to a "watershed" effect, it is imperative to check blood saturations at multiple sites to determine

increased diastolic pressure on IABP could also improve coronary blood flow [52, 53].

consumption. In case of an

be mandatory to increase the chance of recovery.

192 Advances in Extra-corporeal Perfusion Therapies

formation, jeopardizing ventricular recovery.

related afterload [21].

low risk of pulmonary edema because optimal unloading.

Decreasing afterload leads to a decrease in workload and O2

As a matter of fact, IABP should be already in place at the time of VA-ECMO implantation, as stated by ELSO Guidelines 2017 [www.elso.org]. For those patients who do not have one, it should be placed via the contralateral femoral artery, associating earlier the hemodynamic effects of IABP to those of VA-ECMO; from a mechanistic point of view IABP could neutralize some of the unwanted effects of VA-ECMO [56].

The role of IABP in patients suffering from cardiogenic shock should be highlighted as (I) it is rapidly deployable at any hospital and therefore reduces the duration of "uncontrolled shock"; (II) it allows, thereafter, safe transport to MCS units; (III) it does allow foe exploiting the same vascular access for Impella implant; and (IV) it has a major role in weaning from VA-ECMO and therefore reduces the burden of the complications related to ECLS.

Despite the controversial data from the intra-aortic balloon pump in cardiogenic SHOCK (IABP-SHOCK) II trial, which could not demonstrate a survival benefit for the IABP application, IABP currently remains one of the most commonly used mechanical circulatory support devices in the treatment of acute heart failure. The bad news is that for none of the percutaneous devices, used in LV venting, a survival benefit has yet been documented in adequately sized randomized clinical trials (RCTs). A meta-analysis, by Cheng et al., including a total of 100 patients in three small RCTs with the TandemHeart and the Impella PL2.5 pump did not see a survival benefit in comparison to the IABP, despite better hemodynamic effects [57].

When administered in a timely manner, IABP can play a critical role in the rescue of patients with acute myocardial damage. It has been shown in animal models that insertion of IABP during VA-ECMO support may improve several parameters of LV performance and can reduce mean arterial pressure as well as oxygen saturation in the coronary sinus [24].

The combination of IABP and VA-ECMO can be found in the nationwide Japanese Diagnosis Procedure Combination national inpatient database; IABP combined with VA-ECMO was associated with reduced mortality and successful weaning from VA-ECMO. They also concluded, of course, that randomized controlled studies are required to confirm the mortalityreducing effect of the combination of IABP and VA-ECMO [57].

Despite the lack of clarity, in a systematic literature search, the use of concomitant IABP with ECMO is widespread. IABP was present in approximately 55% of all ECMO cases reviewed, stretching across all etiologies of cardiac failure beyond acute myocardial infarction (AMI).

The rationale for concomitant IABP use is primarily for LV venting [58]. The incremental benefit of IABP support for afterload reduction and increasing organ perfusion in the presence of ECMO support is relatively minimal. Regarding improved diastolic pressures and coronary flow, despite the previously held belief of an estimated 11% survival benefit from pooled analyses of retrospective studies of IABP use in AMI, it is now known from the prospective and randomized IABP-SHOCK II study that the use of IABP in this cohort had no survival benefit [59].

Early IABP, or, when CPO is very low and Impella offering the adequate flow, would significantly impact the management of cardiogenic shock as it would avoid the administration of "toxic doses" of inotropes, allowing for smoother transition to VA-ECMO and routine unloading of the LV [44–60].

• Reversibility of left ventricle damage: ventricular unloading is pivotal to increase the

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• Aortic regurgitation: addressing aortic valve may be needed to avoid blood recirculation

**Figure 6** shows the decisional process of management of conditions that may require unloading if not properly treated, the only condition where unloading seems to be mandatory is smoking effect or slow flow through the MV. **Figure 7** shows the possible surgical invasive, minimally invasive and percutaneous approaches aiming at ventricle unloading. When atrial unloading may be sufficient, a percutaneous left atrial septostomy may be accomplished, which allows blood from the LA to drain down its pressure gradient into the right atrium (RA) to then be drained via the venous cannula. This procedure is quite common in many hemodynamic lab especially used to treat pediatric patients. A cannula may also be placed into the LA through a transseptal puncture to facilitate drainage [66]. In addition, the left atrium or left ventricle can be directly cannulated allowing blood to be vented into the venous arm of the ECMO circuit. The transition to a BiVAD (TandemHeart or Centrimag or Rotaflow) could be considered if the oxygenator is no longer needed [67]. Finally, the use of a left ventricular assist device such as the Impella (Abiomed, Danvers, MA) or BiPella (left and right Impella RP) [68] to provide left ventricular decompression as well as forward flow has been

**Figure 4.** Factors driving unloading need in crash and burn patients. It has to be considered the possibility of unloading LV if signs of fluid overload (high pulsatility and LV distension at Echo and hemodynamic data) are not effectively treated with diuretics. Unloading is needed when there is low or absent LVEF, absent pulsatility without vasodilatation,

described and is gaining success due to its ease also bedside.

smoking effect or slow flow through the MV.

chance of recovery.

and stagnation.

Even though, the combined use of IABP and VA-ECMO or Impella and VA-ECMO is well described to improve the hemodynamic facilitating and supporting conditions for recovery or ventricular assist device implantation [61, 62].

Recently, a simulation published on the ASAIO Journal [63] has supported the relevance of optimal medical management, fluid removal while minimizing VA-ECMO flow, reducing blood pressure, and eventually adding inotropes to reduce PCWP and prevent pulmonary edema [64]. Recent clinical data support this notion for different clinical settings and do not advocate a routine combination of VA-ECMO and IABP. Clinical studies have shown a slight reduction in PCWP, LV dimensions, and pulmonary edema in-line with the computer simulation [65].

Patients showing PCWP above 25 mmHg or a virtually non-ejecting LV will require interventional or surgical adjunct measures, which theoretically reduce PCWP by more than 5 mmHg. It has to be kept in mind that sometimes when you think of adding an unloading is too late for the patient, a proactive management reasoning on the patient characteristics and hemodynamics is pivotal.

In a recent computer simulation, this combined approach showed only limited LV unloading, although pulsatility and increased stroke volume were noted. The CPO before VA-ECMO implantation and the native heart stroke volume after VA-ECMO implantation could be relevant determinants of the effectiveness of IABP also during VA-ECMO perfusion (**Figure 3**), while a low PAPi may push toward biventricular support with Impella or TandemHeart.
