*1.3.1 Indications to VA-ECMO support: cardiogenic shock*

In patients with cardiogenic shock, echocardiographic examination is necessary to determine cause and indication for extracorporeal support [41] (**Table 1**). Even more, the echo exam can identify situations that may contraindicate the placement of circulatory assistance.

The echo examination must be as complete as possible and must highlight the morphology and the systolic and diastolic functions of the ventricles, evaluate the valve continence and the presence of pericardial effusion, and seek, in greater detail, the cause of cardiogenic shock (i.e. regional or global dysfunction of the left ventricle) [39]. In the study of cardiac valvular function, the study of the aortic valve is fundamental since its regurgitation can create unfavourable conditions for the positioning of VA-ECMO, given the increase in the afterload that the VA-ECMO generates. Clearly aortic dissection is an absolute contraindication for VA-ECMO placement. In addition, the morphology and the structure of the right atrium and of the right heart in general must be carefully evaluated. In fact, the presence of leads (pacemaker or ICD), a prominent Chiari network, a PFO, a tricuspid valve prosthesis, they are all elements that can compromise or make atrial cannulation impossible [11].

## *1.3.2 Monitoring during ECMO performance*

The echocardiographic examination must fundamentally focus on the systolic function of the left ventricle. The systolic function is evaluated with conventional parameters such as the size of the left ventricle (LV), ejection fraction (EF), mitral regurgitation dP/dt, and aortic velocity time integral (VTI) [39]. The blood flow of ECMO can be adjusted based on the overall assessment of ventricular systolic function and cardiac preload. Some authors have systematically studied the effect of the flow rate of oxygenation of the extracorporeal membrane on changes in cardiac parameters [44]. A decrease of flow from 4 to 0.7 L/min leads to a 22% increase in the E/E′ ratio (from 5.9 to 7.2; p < 0.001), an increase of 17% in EF (from 15 to 17.5%; 0.001), increase of 12 and 45% of VTI (from 8 to 11.6 cm; p < 0.001), and increase of 12% of the left ventricular tele-diastolic volume (from 95 to 108 ml, p < 0.001) [44, 45].

**Figure 7.** *Presence of abundant pericardial effusion (light blue arrow) at TTE.*

A serious problem in the ultrasound evaluation is the detection of an evolving pericardial effusion to the cardiac tamponade (**Figure 7**), due to the passage of wires or cannulae with rupture of the cardiac chambers [11, 14, 16]. Following anticoagulant therapy, necessary in VA-ECMO, the pericardial blood collection can become consistent at many hours from the positioning, and only a series of ultrasound analysis allows the recognition of this clinical situation.

Thrombosis is a major complication during VA-ECMO and can be catastrophic when cerebral embolism occurs [46, 47]. Factors predisposing thrombosis are related to the blood/circuit contact and its activation as well as to the turbulence linked to the lumen of the cannulae [48]. Thrombosis can be more or less evident at ultrasound, and a real pitfall is represented by spontaneous intracavitary echo contrast (smoke) [49]. The evaluation of the opening of the aortic valve guarantees a certain pulsatility to the flow and avoids the stasis linked to the stagnant flow on the closed valve and predictor of thrombosis [46–49]. If the valve does not open, it is necessary to open the valve through changes in the flow of the VA-ECMO, the use of inodilator drugs, or the insertion of the intra-aortic balloon pump (IABP), which also favours the decompression of the left ventricle. Furthermore, in these cases it is necessary to optimise anticoagulation, which can be evaluated with specific point of care (thrombo-elastographic examination (TEG)) [50].

The increase in the afterload generated by the VA-ECMO can promote mitralaortic valve regurgitation, compromising myocardial oxygenation and favouring the left ventricular distension not good for cardiac functional recovery.

#### *1.3.3 ECHO in VA-ECMO*

The difficult management of the patient in VA-ECMO must be accompanied by a continuous echocardiographic evaluation, carried out at least two times a day and whenever there is an unforeseen haemodynamic instability. The study of cardiac function should allow to optimise the flows of the mechanical support and the concomitant therapies. The ECHO evaluation must precede the start of the ECMO, follow the initial support phase, evaluate the evolution of the cardiac function in the stabilisation phase, and evaluate the cardiac functional recovery dictating the weaning time from the extracorporeal support.

**81**

**Figure 8.**

*Echocardiography Evaluation in ECMO Patients DOI: http://dx.doi.org/10.5772/intechopen.85047*

At the start of the VA-ECMO, it is necessary to concentrate the attention on the venous drainage to be able to maintain the flow rate. Flow reduction may be due to obstructions (thrombus) or malposition of the cannula or hypovolaemia [11, 48]. A sudden reduction in perfusion pressure and low flow could lead to the search for aortic dissection or severe aortic valve regurgitation resulting in dilation of the left ventricle.

VA-ECMO is usually a medium-short duration assay, allowing the recovery of cardiac function or the bridge to other solutions (LVAD or HTx). At this time, echocardiographic monitoring is essential to monitor cardiac function recovery or lack of it. One of the major problems, especially in the peripheral configuration of the VA-ECMO, is the distension of the left ventricle, such as to increase the tele-diastolic pressure and compromise the functional recovery of the heart [51, 52]. During peripheral VA-ECMO, LV preload usually decreases, but the LV afterload increases, resulting in a distension of the left ventricle associated with failure to open the aortic valve. The flow thus becomes continuous and non-pulsatile with consequent stasis, tendency to thrombosis, and embolization. This situation compromises the recovery of the heart. The therapeutic strategy consists in venting the left ventricle [52] (**Figure 8**). The opening of the aortic valve can be done simply by trying to reduce the ECMO flow, but almost always you have to proceed with the IABP or better with the use of Impella® (ABIOMED, Inc., 22 Cherry Hill Drive, Danvers, MA 01923, USA) [53]. The most effective system is the cannulation of the left ventricular apex through a mini-thoracotomy, a procedure that can be performed under ultrasound guidance [52]. Echocardiographic monitoring has a key role in monitoring the distension of the left ventricle which leads to an increase in capillary pressure, interstitial pulmonary oedema, and bi-ventricular insufficiency. An alternative but less effective venting system is represented by an EndoVent in the pulmonary artery that, rather than detecting the left ventricle as it would take, reduces its preload [54]. Another solution for left ventricular decompression, in patients receiving extracorporeal

*The light blue indicates the presence of intraventricular vent for the unloading of the left ventricle.*

*1.3.4 ECMO start*

*1.3.5 ECMO support*
