Executive Summary – Guidelines for Mechanical Circulatory Support of the Brazilian Society of Cardiology

One of the main determinant factors for a successful MCSD implantation is patient eligibility. Correct selection of patients involves – (1) patients with advanced HF to which the risk of MCSD implantation surpasses mortality risk for current disease (making it a beneficial intervention); (2) patients with moderately advanced HF, i.e., implantation of MCSD would not increase patient’s morbidity and mortality due to increased complication rate; (3) no contraindications for MCSD implantation.2,3

In advanced heart failure (HF), the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) proposed seven clinical profiles (and modifiers) for a convenient, easy classification of disease status, risk of implantation of mechanical circulatory support devices (MCSDs) and adequate time for intervention (Chart 1). 1 One of the main determinant factors for a successful MCSD implantation is patient eligibility. Correct selection of patients involves -(1) patients with advanced HF to which the risk of MCSD implantation surpasses mortality risk for current disease (making it a beneficial intervention); (2) patients with moderately advanced HF, i.e., implantation of MCSD would not increase patient's morbidity and mortality due to increased complication rate; (3) no contraindications for MCSD implantation. 2,3 Perioperative renal failure, pre-existing right HF, liver dysfunction, mechanical ventilation in the pre-operative period, low weight or overweight and reoperation have been related to worse clinical outcomes after MCSD implantation. [3][4][5] The main scores for risk prediction in MCSD implantation are described in Chart 2.

Echocardiography
Evaluation of patients candidates for MCDS should include a transthoracic echocardiogram (TEE) complemented by a transesophageal echocardiography (TEE).
The effects of MCDS on right ventricular function depend on the balance between the benefits of decompression of the left chambers (reduction of the left ventricular afterload) and greater volumetric load to the right atrium (RA; increase of the right ventricular preload). Decompression of left chambers also cause changes in the geometry of the right chambers, such as leftward shift of interatrial (IAS) and interventricular septum (IVS), structural changes of tricuspid annulus, which can aggravate a pre-existing tricuspid insufficiency (TI) and right ventricular overload. 10 Considering that right ventricular cardiac output determines left ventricular preload, a significant reduction in right ventricular function results in decreased output by the MCSD. It is estimated that approximately 30% of patients with left ventricular assist device develop limiting right ventricular dysfunction. For these reasons, a careful evaluation of right ventricular function is mandatory before MCDS implantation.
In the presence of moderate-to-severe dysfunction, the requirement of a permanent biventricular support cannot be ruled out. 11 In the assessment of right ventricular function before MCSD implantation, it is recommended the measurement of the right ventricle, as well as a semiquantitative assessment of right ventricular longitudinal and radial contractility combined with quantitative parameters, including fractional area change (FAC; FAC < 20% are associated with increased risk of right ventricular dysfunction after MCSD implantation), 12 tricuspid annular plane systolic excursion (TAPSE) determined by M mode, peak systolic velocity of lateral tricuspid ring, measured by tissue Doppler (s'), and right ventricular performance index. 13,14 Predictors of right ventricular dysfunction before mechanical circulatory support device implantation Right ventricular dysfunction is multifactorial and includes an increase in preload, ventricular ischemia and mechanical interdependence of ventricular geometry. It is one of the most severe complications of left ventricular assist device, observed in up to 30% of cases and associated with a six-fold increase in morbidity and mortality (increased risk in up to 67%). 11,15 Risk factors and the main risk score for right ventricular dysfunction after MCSD implantation are described in Charts 3 and 4.
Implantation of a MCSD in the left ventricle should be performed with caution in patients with important right ventricular dilation, moderate-to-severe tricuspid insufficiency, tricuspid valve annulus > 45 mm and CVP > 15 mmHg. By this means, hemodynamic variables directly reflect a preload or afterload increase and right ventricular contractility reductions, whereas venous congestion and organ hypoperfusion, consequence of right ventricular dysfunction, indicate hepatic and renal dysfunctions 15,21 Positive hemodynamic indicators of adequate right ventricular function that might reduce the risk of post-MCSD implantation dysfunction are: CVP ≤ 8 mmHg; PCP ≤ 18 mmHg; CVP/PCP ≤ 0,66; pulmonary vascular resistance (PVR) < 2 wood units and right ventricular work index ≥ 400 mL/m 2 .

Sex Female
Pre-implantation support Intra-aortic balloon pump and vasopressor requirement 3. Bridge to transplantation: situations in which the patient is in progressive severity and heart transplantation cannot be performed in a short term. Support devices may provide hemodynamic support and clinical stability until transplantation is performed.

Types of temporary mechanical circulatory support devices
Main characteristics of temporary MCSDs available in Brazil are described in Chart 5. 24

Indications and contraindications
Although temporary MCSDs are primarily indicated for patients INTERMACS levels 1 and 2, INTERMACS level 3 patients, dependent of high doses of inotropes or at high risk of hemodynamic instability may also be considered eligible.
Contraindications for temporary MCDS include limiting clinical situations that require individualized approach and involvement of other professionals (e.g. oncologist for establishment of cancer prognosis).

Intra-aortic balloon pump (IABP)
The mechanism of action of the IABP is aortic counterpulsation, which increases diastolic pressure at aortic root, promoting an increase in coronary perfusion, afterload reduction, and consequently an increment in cardiac output by 15%.

AMI: acute myocardial infarction
Although IABP is still used in the clinical practice especially in younger patients with less severe cardiogenic shock, the efficacy of the method should be carefully evaluated based on improvement of objective parameters of tissue microperfusion. Lack of improvement of these variables in a short time period (hours) justifies the selection of more invasive devices.

Definition and benefits
Percutaneous circulatory devices enable active support without requiring a synchronism with the cardiac cycle. The main benefits are maintenance of tissue perfusion, improvement of coronary perfusion, and reduction of myocardial oxygen consumption, filling pressures and ventricular wall stress, providing a circulatory support in cardiogenic shock. 25,26 Recommendations for percutaneous circulatory support device implantation

Impella ®
Impella device is composed of a continuous axial flow pump, that aspirates blood directly from the left ventricle and directs it to the aorta (works in series with left ventricle). It allows the flow of 2.5 L/min (Impella® 2.5), 4.0 L/min (Impella® CP) or 5.0 L/min (Impella® 5.0). The model currently available in Brazil is Impella® CP. 24,27

TandemHeart™
TandemHeart™ system is composed of a centrifugal extracorporeal pump, a femoral cannula, a transseptal cannula and a control console. It pumps blood from the left atrium through a transseptal cannula to the ileo-femoral arterial system. Both TandemHeart ™ and the left ventricle work in parallel and contribute to aortic blood flow. 24,27 Extracorporeal membrane oxygenation

Definition, types and benefits
Extracorporeal membrane oxygenation (ECMO) is an invasive temporary mechanical support that provides partial or total cardiopulmonary support for patients with cardiogenic shock and/or acute respiratory insufficiency. There are two types of ECMO -venoarterial and venovenous. With quick installation technology, ECMO promotes rapid reversal of circulatory failure and/or anoxia.
Other conventional centrifugal pumps may be used with the same purpose.

Definition, types and benefits
Paracorporeal circulatory support devices are surgically implanted pumps that promote hemodynamic support in individuals with refractory cardiogenic shock with high mortality risk.
A CentriMag® is a continuous flow, magnetically levitated centrifugal blood pump. It provides up to 10 L/minute of blood flow and low shear stress, promoting low thrombogenicity, moderate anticoagulation levels and minimum hemolysis during support. 24 Berlin Heart EXCOR® is a pulsatile-flow pump that provides up to 8 L/min of blood flow, with batteries connected to a transport system, allowing an up to ten hours of patient's mobility.

Types of long-term mechanical circulatory support devices
Due to technological progress, advances in long-term MCSD models have occurred during the last years, regarding pumping system and flow type, enabling its reduction in size, greater efficiency and lower complication rates (Figure 1).
The long-term MCSDs available in Brazil are described in Chart 6.

Indications and contraindications
In making decision process for long-term MCSDs, some important factors should be considered. In case of bridge to transplantation, transplant waiting time should be taken into account; for waiting time shorter than 30 days, there would be a low benefit-cost ratio. Also, the use of these devices in INTERMACS level 2 patients may have unfavorable results.

Optimization and management of right ventricular function
Right ventricular failure is still one of the main factors that affect patients' survival after MCSD implantation. 28 Its diagnostic criteria are -signs and symptoms for persistent right ventricular dysfunction; CVP > 18 mmHg with cardiac index < 2,0 L/min.m 2 in the absence of ventricular arrhythmias or pneumothorax; requirement of ventricular support devices; or requirement for inhaled nitric oxide or inotropic therapy for more than one week after device implantation. 29 Implantation of a MCSD increases cardiac output and consequently causes an increment in venous return to the right ventricle. To counteract this preload increase, right ventricular compliance should improve with reduction of its afterload (decrease in left ventricular filling pressure and pulmonary arterial pressure). However, leftward shift of IVS may occur in case of excessive left ventricular emptying. 29 In addition to its contractility, optimization of right ventricular preload and afterload is crucial to prevent right ventricular failure in the perioperative period. CVP and systolic pulmonary pressure should be maintained lower than 16 mmHg and 65 mmHg , respectively. For maintenance of coronary perfusion, use of inotropes that cause pulmonary vasodilation (milrinone or dobutamine) and maintain adequate systemic pressure (adrenaline) is recommended. In addition, the use of specific pulmonary vasodilators, such as nitric oxide should be considered ( Figure 2). 30

Complications after long-term MCSD implantation
The main complications related to long-term MCSD implantation are described in Chart 8.

Proposal of prioritization criteria for cardiac transplant in patients with MCSD
With increasing number of MCDSs, this document proposes a change in the prioritization criteria for patients in the cardiac transplant waiting list. These new criteria are described in Chart 9.

Severe malnutrition
Significative peripheral artery disease