**4. Circuit and cannulation techniques**

The standard configuration for interventional cardiology procedures is a peripheral veno-arterial extracorporeal membrane oxygenation (V-A ECMO), with cannulation of the femoral artery and vein. They are usually using high-flow arterial cannulas (18-20Fr) and multistage venous cannulas with the distal end positioned in the superior vena cava under fluoroscopic guidance (**Figures 1**–**3**).

Cannulation can be performed under echography guidance, with percutaneous technique (with the use of percutaneous devices of haemostasis, such as Proglide (Abbott Park, IL, USA) or Manta (Teleflex, USA)) or with surgical isolation of the femoral vessels, depending on the anatomical characteristics of the patient. Based on the pre-procedural CT analysis, arterial cannulation sites other than the femoral arteries can be chosen, when these are not suitable for use due to insufficient calibres or extreme atheroma (**Figures 4**–**6**).

The most frequently used alternative site is the axillary artery, which, in most cases, has an adequate calibre to ensure systemic perfusion with the advantage of offering an antegrade flow and is rarely affected by atheromatous or calcific processes.

**Figure 1.** *Placement of the venous cannula in the superior vena cava.* *ECMO in Cath-Lab for Coronary, Structural or Combined Percutaneous Cardiac Interventional... DOI: http://dx.doi.org/10.5772/intechopen.105933*

**Figure 2.** *Control of venous cannula positioning.*

**Figure 3.** *Venous cannula in superior vena cava.*

The standard circuit, consisting of venous and arterial lines connected to a centrifugal pump, oxygenator, and heat exchanger, can be processed according to the needs deriving from the patient's pathology or technical characteristics of the procedure. For example, it may be necessary to unload the left ventricle (i.e., TAVI procedures in cases of severe aortic regurgitation), which is carried out with the introduction of catheters of adequate calibre in the left ventricle (not less than 6 Fr) inserted with transseptal or transaortic approach or in the pulmonary artery through the femoral or jugular vein and connected on the venous line (**Figures 7** and **8**).

The use of a percutaneous left ventricular drainage that limits ventricular distension, in cases of severe aortic regurgitation [28], guarantees greater procedural hemodynamic stability and facilitates the release of the aortic valve prosthesis for the correction of the regurgitation itself (in fact, it allows to obtain the almost total absence of systolicization of the left ventricle, a function similar to rapid ventricular

#### **Figure 4.**

*Angiographic control prior to arterial puncture at the site chosen for cannulation, performed from the contralateral arterial access.*

stimulation, limiting the risk of "pop up" of the valve prosthesis). Limiting ventricular distension and the consequent increase in oxygen consumption is a crucial factor in limiting the hemodynamic and arrhythmic instability of a heart in critical conditions and can, therefore, represent strength in the treatment of situations, such as cardiogenic shock or the complications of percutaneous interventions. In fact, the ECMO protects the entire organism from the low cardiac output deriving from a condition of cardiogenic shock, but paradoxically the least protected organ is the heart itself because it undergoes distension of its cavities with an increase in oxygen requirements (Law of Laplace) and, therefore, the risk of ischemia. The possibility of draining the left cavities reduces this problem and makes the manoeuvres to remedy any complications more effectively (i.e., defibrillation in case of serious arrhythmias or repositioning of an aortic prosthesis for massive regurgitation).

In other cases, double venous cannulation, both femoral and jugular, may be necessary, for example for the treatment of tricuspid regurgitation, where the encumbrance of the single multistage cannula in the right atrium (diameter 22–23 Fr) would not allow the passage of catheters (with a diameter of 24Fr in the case of the Triclip) and the manoeuvres of percutaneous tricuspid repair. In these cases, a cannula is

*ECMO in Cath-Lab for Coronary, Structural or Combined Percutaneous Cardiac Interventional... DOI: http://dx.doi.org/10.5772/intechopen.105933*

**Figure 5.** *Surgical femoral accesses for TAVI (A) and ECMO (B).*

placed in the inferior vena cava with the upper end at the level of the hepatic veins and a second cannula in the right internal jugular vein (14–17Fr) is added, with the end at the level of the superior atrio-caval junction for ensuring adequate venous drainage (**Figures 9**–**11**).

In addition, leads can be created on the arterial line to allow procedures to be performed with a single arterial access (especially PCI or in TAVI procedures for the passage of the reference pigtail for valve implantation), obviously, in these cases, it must be carried out a careful evaluation of the resistance to flow deriving from the encumbrance provided by the catheter inside the arterial line, so that sufficient systemic perfusion is guaranteed without increasing the risk of haemolysis, which would nullify the advantage of "saving" arterial access to the patient.
